Dr Mohsen Khalily


Lecturer in Antenna and Propagation
Senior Member IEEE, Fellow of the Higher Education Academy
+44 (0)1483 686003
10 CII 02

Research

Research interests

Research collaborations

Supervision

Postgraduate research supervision

My teaching

Courses I teach on

Postgraduate taught

Electronic Engineering MSc

My publications

Publications

Khalajmehrabadi A, Rahim MKA, Khalily M (2011) Dual band double stacked dielectric resonator antenna with a P-shape parasitic strip for circular polarization, 2011 IEEE International RF and Microwave Conference, RFM 2011 - Proceedings pp. 444-447
In this paper the A-shape dielectric resonator antenna is modified for circular polarization in low frequencies of wireless applications. In order to have a wide bandwidth, a dielectric with low permittivity is employed. Another dielectric resonator owning a high permittivity is stacked to the other one, which is assigned to provide circular polarization. A Pshape parasitic strip is embedded between the two resonators to guide electrical and magnetic fields for a low axial ratio (AR) over a wide bandwidth. The proposed DRA with good radiation characteristics offers a bandwidth of 34% between 2.90 GHz and 4.11 GHz and an axial ratio of 18%between 3.40 GHz and 4.04GHz for the first band and a bandwidth of 18% between 5.16 GHz and 6.16 GHz for the second band that all support 2.4 GHz Bluetooth, WLAN, 3.3-3.6 GHz (WiMax), 3.8-4.1 GHz (C-band), 4.8-6.2 GHz (5.2, 5.5 & 5.8 GHz-WLAN & WiMax) © 2011 IEEE.
Alavi SE, Soltanian MRK, Amiri IS, Khalily M, Supa'at ASM, Ahmad H (2016) Towards 5G: A Photonic Based Millimeter Wave Signal Generation for Applying in 5G Access Fronthaul, SCIENTIFIC REPORTS 6 ARTN 19891 NATURE PUBLISHING GROUP
Khalily M, Kamarudin MR, Mokayef M, Jamaluddin MH (2014) Omnidirectional circularly polarized dielectric resonator antenna for 5.2-GHz WLAN applications, IEEE Antennas and Wireless Propagation Letters 13 pp. 443-446
The rectangular dielectric resonator antenna (RDRA) is presented to generate linearly polarized (LP) with omnidirectional radiation patterns. The proposed omnidirectional LP DRA is fed centrally by a coaxial probe and offers an impedance bandwidth of 130 MHz between 5.15 and 5.35 GHz for |S11|
Khalily M, Kamarudin MR, Mokayef M, Danesh S, Ghahferokhi SEA (2014) A new wideband circularly polarized dielectric resonator antenna, Radioengineering 23 (1) pp. 175-180
A wideband and compact circularly polarized (CP) C-shaped dielectric resonator antenna (DRA) is presented and investigated. The proposed C-shaped DR is excited by a simple stripe line connected to a coplanar waveguide (CPW) feeding line. The C-shaped DRA is circularly polarized with 19% axial ratio (AR) bandwidth. It is found that the CP bandwidth can be expanded by using a narrow short circuit strip. The final design achieves CP with 50% AR bandwidth. The proposed circularly polarized DRA (CPDRA) with good radiation characteristics offers an impedance bandwidth of 58% between 3.45 and 6.26 GHz for VSWR d 2. The proposed DRA is fabricated and tested. Very good agreement between simulated and measured results is obtained.
Khalily M, Rahim MKA, Kamarudin MR (2010) A novel P-shape dielectric resonator antenna for wideband application, 2010 IEEE Asia-Pacific Conference on Applied Electromagnetics, APACE 2010 - Proceedings
A novel P-shape wideband dielectric resonator antenna design is presented for wireless application in this paper. It is described by using a P-shape dielectric resonator with high dielectric constant (µr = 30) that is placed on the truncated ground plane, a wideband impedance bandwidth of about 64% (for VSWRd2), covering the frequency range of 3.40-6.58GHz is achieved. Analysis of the proposed antenna is performed using CST Microwave Studio software. © 2010 IEEE.
Khalily M, Nasir J, Kamarudin MR, Selvaraju R, Jamaluddin MH (2014) Gain enhanced UWB dielectric resonator antenna, Progress in Electromagnetics Research Symposium pp. 2248-2251
An ultra-wideband dielectric resonator antenna (DRA) with enhanced gain is presented and investigated for wireless applications. The antenna has a compact shape with UWB characteristics. The radiator's structure is a split Z-shaped DRA with dielectric constant (µr) of 10. The antenna is mounted on a copper ground plane of size 75 × 90mm2 and is fed by a split bevel-shaped strip to improve the impedance matching. Also, an air gap has been introduced between DR and ground plane to reduce the Q factor and dielectric constant, which in turn improves the impedance bandwidth. Extensive parametric studies have been carried out on different parameters in order to achieve an optimum structure. Ansoft HFSS v14 has been used for the simulation of the proposed antenna. The simulated results show that the antenna can efficiently operate over the frequency range from 2.5 GHz to 10.6 GHz covering the entire UWB range.
Khalily M, Tafazolli R, Rahman TA, Kamarudin MR (2016) Design of Phased Arrays of Series-Fed Patch
Antennas With Reduced Number of the Controllers
for 28-GHz mm-Wave Applications,
IEEE Antennas and Wireless Propagation Letters 15 pp. 1305-1308 IEEE
New modified 2 × 2 and 3 × 3 series-fed patch antenna arrays with beam-steering capability are designed and fabricated for 28-GHz millimeter-wave applications. In the designs, the patches are connected to each other continuously and in symmetric 2-D format using the high-impedance microstrip lines. In the first design, 3-D beam-scanning range of ± 25° and good radiation and impedance characteristics were attained by using only one phase shifter. In the second one, a new mechanism is introduced to reduce the number of the feed ports and the related phase shifters (from default number 2 N to the reduced number N + 1 in the serial feed (here N = 3) and then the cost, complexity, and size of the design. Here, good scanning performance of a range of ± 20°, acceptable sidelobe level, and gain of 15.6 dB are obtained. These features allow to use additional integrated circuits to improve the gain and performance. A comparison to the conventional array without modification is done. The measured and simulated results and discussions are presented.
Bala BD, Rahim MKA, Murad NA, Samsuri NA, Khalily M (2015) Dual band dielectric resonator based metamaterial antenna, ISAP 2014 - 2014 International Symposium on Antennas and Propagation, Conference Proceedings pp. 79-80
© 2014 Institute of Antenna Engineers of Taiwan.A dielectric resonator based metamaterial antenna is presented for dual band operations. The hybrid design uses the dielectric resonator (DR) and split ring resonator (SRR) to radiate two resonant modes. The antenna has a compact size of 40 × 40 mm2. The peak realized gain of 6.24 dBi and 6.04 dBi is obtained at 5.5 GHz and 5.8 GHz respectively. Also a peak efficiency of 94% is obtained across the covering frequency. The antenna has potential applications for WiMAX (5.5 GHz) and WLAN (5.8 GHz) operations.
Khalily M, Rahim MKA, Kamarudin MR, Shaneshin M, Danesh S (2011) Ultra wideband printed monopole antenna with dual-band circular polarization, Proceedings of the 5th European Conference on Antennas and Propagation, EUCAP 2011 pp. 365-368
An ultra wideband printed monopole antenna with dual band circular polarization for wireless application is presented. The antenna dimensions are 30 × 30 × 1.6 mm3. The proposed antenna is able to cover frequency range between 2.65 GHz and 11GHz with impedance bandwidth is around 122%. With the use of I-shape slit in the radiation element and the T-slot in the ground plane, the ultra wideband and circular polarization are excited. In addition, the rectangular slit is added in the ground plane, to enhance the impedance- and Axial Ratio - bandwidth. Furthermore, the dual band circular polarization with right hand circular polarization at 3.1 GHz and the left hand circular polarization at 7GHz are obtained. Also, the 3-dB axial ratio bandwidths are about 242 and 246 MHZ at the lower and upper band without rectangular slit and 356 and 546 MHZ at the lower and upper band with rectangular slit, respectively. © 2011 EurAAP.
Nasir J, Jamaluddin MH, Khalily M, Kamarudin MR, Ullah I, Selvaraju R (2015) A reduced size dual port MIMO DRA with high isolation for 4G applications, International Journal of RF and Microwave Computer-Aided Engineering 25 (6) pp. 495-501
© 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:495-501, 2015. © 2014 Wiley Periodicals, Inc.A dual-port reduced size multiple input multiple output (MIMO) Dielectric Resonator Antenna (DRA) has been studied and proposed. The MIMO antenna consists of a Rectangular Dielectric Resonator antenna, which is fed by two symmetrical feed lines for orthogonal mode excitation. The proposed antenna is suitable for operation over various long term evolution (LTE) bands. A measured bandwidth of 264 MHz for |S11|
Iddi HU, Kamarudin MR, Rahman TA, Abdulrahman AY, Khalily M, Jamlos MF (2013) Triple-band CPW-FED planar monopole antenna for WLAN/WiMax application, Microwave and Optical Technology Letters 55 (9) pp. 2209-2214
A triple-band planar monopole antenna is presented in this article. The antenna consists of three strips which correspond to operating frequency bands of 2.4, 3.5, and 5.8 GHz. The proposed antenna has been designed, simulated, and fabricated on 20 × 38 mm2 FR4 board. There is good agreement between simulation and measurement results in terms of return loss and radiation pattern. The proposed antenna provides measured -10 dB bandwidths of 200 MHz for the 2.4 GHz (from 2.36 to 2.56 GHz); 620 MHz for the 3.5 GHz (from 3.48 to 4.10 GHz); and 1.38 GHz for 5.8 GHz (from 5.65 to 7.03 GHz). Moreover, the antenna provides the measured gain of 4.73, 1.66, and 3.28 dBi for 2.4, 3.5, and 5.8 GHz, respectively. The radiation characteristics have proven that the proposed antenna seems to be a good potential candidate for WLAN/WiMAX applications. © 2013 Wiley Periodicals, Inc.
Roslan SF, Kamarudin MR, Khalily M, Jamaluddin MH (2015) An MIMO F-shaped dielectric resonator antenna for 4G applications, Microwave and Optical Technology Letters 57 (12) pp. 2931-2936
© 2015 Wiley Periodicals, Inc.A multiple input multiple output (MIMO) F-shaped dielectric resonator antenna (DRA) for mobile device is presented in this article. The F-shaped DRA is mounted on FR4 as a substrate. The measured impedance bandwidth for Port 1 is 36% (2.30-3.31 GHz) while Port 2 is 31% (2.30-3.14 GHz), respectively with isolation of -33 dB. Two orthognal modes are excited in this design which are TE1´1y mode at Port1 and TE´11x at Port 2. Correlation coefficient of a MIMO F-shaped DRA is 0.04 with diversity gain nearly 10 dB over operating frequency. The antenna provides gain 1.99 dBi for Port 1 and 1.85 dBi for Port 2 at frequency 2.6 GHz. The parameters, isolation, gain, correlation coefficient, and diversity gain of the MIMO rectangular dielectric resonator antenna are studied, and reasonable agreement between the measured and simulated results is observed.
Sa'Don SNH, Kamarudin MR, Khalily M (2014) Indoor transparent antenna for television reception, Progress in Electromagnetics Research Symposium pp. 1969-1974
The characteristics of indoor transparent antenna are investigated. The purpose of the antenna is applied for television signal reception which is operating at Ultra High Frequency band. The antenna was made from silver coated polyester film (AgHT-4), the transparent con-ductive material and it is attached on a layer of glass substrate. The antenna size has width and length of 120mm × 150 mm. It was fed by a co-planar waveguide due to the opportunity of low ra-diation loss and to reduce reflection of the antenna. The frequency range of 500MHz to 800MHz is chosen as it is the UHF television reception band and allocated by Federal Communications Commission. Due to the television station provided in Malaysia, each station have different channel with its own specification frequencies. The channels also are based on the transmitter base station location. Since the proposed project launches at Universiti Teknologi Malaysia, Skudai, Johor, Malaysia so all the channel is following the frequency from GunungPulai, Johor transmitter base station. The channel utilizations are Channel 55 (742-750 MHz): TV1, Chan-nel 26 (510-518 MHz): TV3, Channel 42 (638-646 MHz): NTV7, Channel 44 (654-662 MHz): TV9 and Channel 46 (670-678 MHz): 8TV. Then, the proposed antenna was designed by using Computer Simulation Software (CST) Microwave Studio to obtain the simulation result. The simulated bandwidth of the antenna obtained is 448MHz (502MHz to 950 MHz) with bandwidth of 61.71%. It has a potential to be realized for TV reception because of the omni-directional radiation pattern and gain is more than 2.0 dBi.
MoradiKordalivand A, Rahman TA, Khalily M (2014) Common Elements Wideband MIMO Antenna System for WiFi/LTE Access-Point Applications, IEEE Antennas and Wireless Propagation Letters 13 pp. 1601-1604
A wideband multiple-input-multiple-output (MIMO) antenna system with common elements suitable for WiFi/2.4 GHz and Long Term Evolution (LTE)/2.6 GHz wireless access point (WAP) applications is presented. The proposed MIMO antenna system consists of four wideband microstrip feedline printed monopole antennas with common radiating element and a ring-shaped ground plane. The radiator of the MIMO antenna system is designed as the shape of a modified rectangle with a four-stepped line at the corners to enhance the impedance bandwidth. According to the common elements structure of the MIMO antenna system, isolation between the antennas (ports) can be challenging. Therefore, the ground plane is modified by introducing four slots in each corner to reduce the mutual coupling. For an antenna efficiency of more than 60%, the measured impedance bandwidth for reflection coefficients below -10 dB was observed to be 1100 MHz from 1.8 to 2.9 GHz. Measured isolation is achieved greater than 15 dB by using a modified ground plane. Also, a low envelope correlation coefficient (ECC) less than 0.1 and polarization diversity gain of about 10 dB with the orthogonal mode of linear polarization and quasi-omnidirectional pattern during the analysis of radiation characteristic are achieved. Therefore, the proposed design is a good candidate for indoor WiFi and LTE WAP applications due to the obtained results.
Khalily M, Rahim MKA, Kishk AA, Danesh S (2013) Wideband P-shaped dielectric resonator antenna, Radioengineering 22 (1) pp. 281-285
A novel P-shaped dielectric resonator antenna (DRA) is presented and investigated for wideband wireless application. By using P-shaped resonator, a wideband impedance bandwidth of 80 % from 3.5 to 8.2 GHz is achieved. The antenna covers all of wireless systems like C-band, 5.2, 5.5 & 5.8 GHz-WLAN & WiMAX. The proposed antenna has a low profile and the thickness of the resonator is only 5.12 mm, which is 0.06-0.14 free space wavelength. A parametric study is presented. The proposed DRA is built and the characteristics of the antenna are measured. Very good agreement between numerical and measured results is obtained.
Khalily M, Kamarudin MR, Jamaluddin MH (2013) A novel square dielectric resonator antenna with two unequal inclined slits for wideband circular polarization, IEEE Antennas and Wireless Propagation Letters 12 pp. 1256-1259
A novel dielectric resonator antenna (DRA) is presented for wideband circular polarization (CP). Two unequal inclined slits are loaded on the diagonal of the square DR to excite a CP mode. The effect of variation of ratio between the length of the slits on the CP and impedance characteristics is studied. The DR is excited by a proper tapered strip, connected to the input microstrip line from one side, and finally matched by a chip resistor from the lateral side. As the key parameters, the position of the excitation and matching lines and the impedance of the chip resistor are carefully optimized to adjust and improve the CP. The proposed configuration offers a relatively compact and easy-to-fabricate feeding network and multiresonant performance providing a 3-dB axial-ratio and impedance bandwidth of about (43-50)% around 3.7 GHz, gain between 4 and 6 dBi. The CP and impedance parameters of the antenna are studied, and reasonable agreement between the measured and simulated results is observed. © 2013 IEEE.
Khalily M, Rahim MKA, Kamarudin MR, Ismail MF (2010) Wide-band rectangular dielectric resonator antenna design, 2010 IEEE Asia-Pacific Conference on Applied Electromagnetics, APACE 2010 - Proceedings
In this paper a novel design procedure to obtain wideband and small size dielectric antennas using high dielectric constant material is described. It is shown that by selecting the resonator shape and creating a notch on the dielectric resonator, it is possible to design rectangular dielectric resonator antenna which compact size and wide frequency coverage. Simple formulas are presented to illustrate the design procedure and allow a quick dimensioning of the antenna. Utilizing the proposed configuration and skillfully varying its aspect ratio, an appropriate structure is obtained that illustrates more than 47.03% impedance bandwidth (for VSWR
Hakimi S, Rahim SKA, Abedian M, Noghabaei SM, Khalily M (2014) CPW-Fed transparent antenna for extended ultrawideband applications, IEEE Antennas and Wireless Propagation Letters 13 pp. 1251-1254
A novel coplanar waveguide-fed transparent antenna for ultrawideband applications with enhanced bandwidth is presented. In this design, different techniques have been used to broaden the bandwidth. The rectangular radiator of the antenna is equipped by the staircase technique to increase the overlapped resonant frequencies. Moreover, two major and minor symmetrical rectangular stubs are mounted on top of the quarter-circle slot ground by using a dual axis to significantly increase the bandwidth between 3.15 and 32 GHz for VSWR
Al-Samman AM, Rahman TA, Nasir J, Jamaluddin MH, Khalily M, Kamarudin MR (2015) Path loss model and root mean square delay spread characterization of near-ground outdoor UWB channel, 2015 9th European Conference on Antennas and Propagation, EuCAP 2015
© 2015 EurAAP.The large bandwidth of ultra wideband (UWB) makes it attractive in high speed transmission applications. However, the possibility of frequency selectivity of the channel is high due to this bandwidth. Channel characterization is important to study the behavior of the channel. The ground reflection effects are important parameters affecting the ultra wideband channel. In this paper, based on outdoor time domain measurements, path loss model and root mean square (RMS) delay spread characteristics for near-ground (NG) UWB channel have been presented. Moreover, the interdependencies of these characteristics of the multipath channel are also investigated. The NG UWB channel characteristics are compared to the UWB channel above the ground. From the results it has been found that the path loss in NG UWB channel is less as compared to the above ground case. Also, the values of RMS delay spread are low.
Khalily M (2016) Rectangular Dielectric Resonator Antenna Array
for 28GHz Applications,
Progress In Electromagnetics Research C 63 pp. 53-61 EMW Publishing
In this paper, a Rectangular Dielectric Resonator Antenna (RDRA) with a modified feeding
line is designed and investigated at 28 GHz. The modified feed line is designed to excite the DR with
relative permittivity of 10 which contributes to a wide bandwidth operation. The proposed single
RDRA has been fabricated and mounted on a RT/Duroid 5880 (µr = 2.2 and tan´ = 0.0009) substrate.
The optimized single element has been applied to array structure to improve the gain and achieve
the required gain performance. The radiation pattern, impedance bandwidth and gain are simulated
and measured accordingly. The number of elements and element spacing are studied for an optimum
performance. The proposed antenna obtains a reflection coefficient response from 27.0 GHz to 29.1 GHz
which cover the desired frequency band. This makes the proposed antenna achieve 2.1 GHz impedance
bandwidth and gain of 12.1 dB. Thus, it has potential for millimeter wave and 5G applications.
Alavi SE, Amiri IS, Khalily M, Fisal N, Supa'at ASM, Ahmad H, Idrus SM (2014) W-Band OFDM for Radio-over-Fiber Direct-Detection Link Enabled by Frequency Nonupling Optical Up-Conversion, IEEE Photonics Journal 6 (6)
© 2009-2012 IEEE.A system involving W-band (75-110 GHz) optical millimeter (mm)-wave generation using the external optical modulator (EOM) in a radio-over-fiber (RoF) link is presented for satisfying the requirements for multi-gigabit-per-second data rates. A 90-GHz mm-wave signal was generated by a nonupling (nine times) increase in only a 10-GHz local oscillator by biasing the EOM at its zero level and choosing an appropriate modulation index. To achieve a fast transmission speed wirelessly, high spectral efficiency (SE), and better transmission performance, orthogonal frequency-division multiplexing (OFDM) is used. The bit error rate (BER) and error vector magnitude (EVM) of the system were measured for three different fiber lengths and for a wireless distance of 1-5 m. The results show that the system with the SE of
Khalily M, Kamarudin MR, Danesh S (2013) Planar wideband circularly polarized dielectric resonator antenna, IEEE Antennas and Propagation Society, AP-S International Symposium (Digest) pp. 1238-1239
A wideband and compact circularly polarized (CP) C-shaped dielectric resonator antenna (DRA) is presented. The proposed C-shaped DR is excited by a microstrip feed in one side of the dielectric substrate. DR is housed inside the thin dielectric substrate above the vertical ground plane edge. By using one narrow short circuit strip, CP bandwidth of the proposed antenna is enhanced. The final design achieves CP with 44% axial ratio (AR) bandwidth. The proposed circularly polarized DRA with good radiation characteristics offers an impedance bandwidth of 67% between 3.35 and 6.76GHz for VSWR
Khalily M, Rahim MKA, Murad NA, Samsuri NA, Kishk AA (2013) Rectangular ring-shaped dielectric resonator antenna for dual and wideband frequency, Microwave and Optical Technology Letters 55 (5) pp. 1077-1081
A new modified planar dielectric resonator antenna (DRA) is presented and investigated. The proposed DRA is excited by a microstrip feed that is extended as a probe in the proximity of the DR. On the opposite side to the probe excitation printed narrow strips directly connected to the ground plane edge are used to improve the radiation characteristics of the antenna by keeping a unidirectional broadside radiation. In addition, the short circuit strips introduce a second frequency band. Thus, a dual-band antenna is achieved. The measured bandwidths are about 73% (2.78-5.95 GHz) for the wideband DRA as well as 8% (2.4-2.6 GHz) and 56% (3.3-5.85 GHz) for the dual-band DRA. The minimum and maximum gain enhancements of about 0.6 and 1.2 dB from 3.5 to 6 GHz are obtained. Parametric study and measurement results are presented and discussed. © 2013 Wiley Periodicals, Inc.
Abedian M, Rahim SKA, Khalily M (2012) Two-segments compact dielectric resonator antenna for UWB application, IEEE Antennas and Wireless Propagation Letters 11 pp. 1533-1536
A new compact two-segments dielectric resonator antenna (TSDR) for ultrawideband (UWB) application is presented and studied. The design consists of a thin monopole printed antenna loaded with two dielectric resonators with different dielectric constant. By applying a combination of U-shaped feedline and modified TSDR, proper radiation characteristics are achieved. The proposed antenna provides an ultrawide impedance bandwidth, high radiation efficiency, and compact antenna with an overall size of 18 × 36 × 11 mm 3. From the measurement results, it is found that the realized dielectric resonator antenna with good radiation characteristics provides an ultrawide bandwidth of about 110%, covering a range from 3.14 to 10.9 GHz, which covers UWB application. © 2002-2011 IEEE.
Khalily M, Rahim MKA, Kishk AA (2012) Planar wideband circularly polarized antenna design with rectangular ring dielectric resonator and parasitic printed loops, IEEE Antennas and Wireless Propagation Letters 11 pp. 905-908
A wideband circularly polarized (CP) rectangular dielectric resonator (DR) parasitically coupled to a printed rectangular loops is presented. The DR is housed in a thin dielectric substrate with a microstrip line and narrow strip printed from one side and a ground plane and conducting loops and lines connected to the ground plane. The DR is linearly polarized, and for CP, we introduced printed conducting loops in the other side of the DR, which produce the orthogonal polarization with the required quadratic phase. Several loops are used to achieve the wide CP band. The final design achieves CP with 51% bandwidth. The reflection coefficient, axial ratio (AR), radiation patterns, gain, and efficiency of the antenna are studied, and reasonable agreement between the measured and simulated results is observed. © 2011 IEEE.
Selvaraju R, Khalily M, Kamarudin MR, Jamaluddin MH, Nasir J (2014) Dual band rectangular dielectric resonator antenna design, Progress in Electromagnetics Research Symposium pp. 2244-2247
A Dual band rectangular dielectric resonator antenna (RDRA) capable of frequency tunings at two different resonant modes is presented and investigated. In this design two rectangular dielectric resonators with different permittivity situated on top of the substrate are employed. The antenna is fed by 50© microstrip feedline etched on the top of the Fr-4 epoxy printed circuit board (PCB) with a total size of 80 × 50 × 1.6mm3 and µrs = 4.6 (loss tangent = 0.02). In order to excite two resenant frequencies, two RDRA with relative permittivity of µr1 = 10 and µr2 = 30 are chosen to operate at 2.4 GHz and 3.8 GHz. From the parametric study the lower permitivity DRA resonates at 3.8 GHz whereas the higher permitivity DRA resonates at 2.4 GHz. Ansoft HFSS v14 has been used for the simulation of the proposed dual-band antenna. The simulation results show that the 3.8 design can efficiently perform in both frequency bands.
Nasir J, Jamaluddin MH, Khalily M, Kamarudin MR, Irfanullah I, Nor NM (2015) A dual-port MIMO DRA with high isolation for LTE application, 2014 IEEE Asia-Pacific Conference on Applied Electromagnetics, APACE 2014 - Proceeding pp. 55-58
© 2014 IEEE.In this paper a compact dual-port Multiple Input Multiple Output (MIMO) Dielectric Resonator Antenna (DRA) with high isolation has been presented and discussed. The DR is fed by two probe feeds, one touching the side wall of the DR while the other is drilled in the middle of the DR. Both the ports are excited in orthogonal modes with the same resonance frequency in the DR, thus resulting in high isolation. The presented antenna is suitable to operate at LTE bands 7 and 38. The bandwidth achieved is 310 MHz and an isolation of +15 dB has been obtained. Besides, the Envelop Correlation Coefficient (ECC), and Diversity Gain (DG) has also been studied for the proposed antenna.
Khalily M, Rahim MKA (2010) A novel hybrid design of printed hemicylindrical dielectric resonator monopole antenna with multi-bands operation, Progress In Electromagnetics Research C 15 pp. 175-186
A novel complex structure of Printed Dielectric Resonator Monopole Antenna (PDRMA) with multi-bands operation is presented and investigated. In the proposed structure, a printed fork-like stepped monopole antenna is used for exciting two new modified hemicylindrical dielectric resonators with a great relative permittivity of 80. A narrow medium substrate with a low permittivity is also applied between two mentioned dielectric resonators and the monopole antenna, to improve the matching, especially at the lower frequencies. By using this novel designed antenna applying two dielectric resonators with very high permittivity, many frequency wide bands for VSWR
Khalily M, Rahim MKA, Khalajmehrabadi A, Kamarudin MR (2011) A compact circularly polarized and wideband rectangular dielectric resonator antenna, 2011 IEEE International RF and Microwave Conference, RFM 2011 - Proceedings pp. 448-451
A Rectangular Dielectric Resonator Antenna (RDRA) made of a high permittivity (µ r = 30) ceramic material is presented. It is shown that by selecting the resonator shape and creating a L-shape hole inside the dielectric resonator, it is possible to design RDRA which compact size and wide frequency coverage. The radiation characteristics of the RDRA are broad and stable across a matching band of 3.6 to 9.6 GHz. Also, left hand circular polarization (LHCP) is occurred in the center frequency of 4.3 GHz. The proposed antenna has good radiation characteristics over the operating bandwidth. © 2011 IEEE.
Khalily M, Rahim MKA, Kishk AA (2011) Bandwidth enhancement and radiation characteristics improvement of rectangular dielectric resonator antenna, IEEE Antennas and Wireless Propagation Letters 10 pp. 393-395
A simple, compact, wideband rectangular dielectric resonator antenna (RDRA) is presented. The bandwidth is enhanced using a proper tapered strip excitation from one side of the DR. The radiation characteristics are improved by adding a shorted narrow strip to the opposite side of the excitation. In addition, by using this shorted strip, further improvement of the bandwidth is obtained. A parametric study on the strip dimension is carried out. The proposed DRA with good radiation characteristics offers a measured bandwidth of 96% between 2.13 and 6.08 GHz for VSWR
Maina I, Rahman TA, Khalily M (2015) Bandwidth enhanced and sidelobes level reduced radial line slot array antenna at 28 ghz for 5G next generation mobile communication, ARPN Journal of Engineering and Applied Sciences 10 (14) pp. 5752-5757
© 2006-2015 Asian Research Publishing Network (ARPN).Radial Line Slot Array Antenna has simple structure and exhibit good radiation characteristics. It is low cost, easy to manufacture with high gain and it found application in services like Direct Broadcast Services and Wireless LAN. Its features make it attractive for millimeter wave mobile broadband applications like the fifth generation (5G) mobile communication system. Also, it can be designed for circular, linear or elliptical polarization. But achieving a reduced sidelobes level has not been an easy task in its design. This paper presents a simple technique to improve the impedance bandwidth and reduce the sidelobes level in linearly polarized Radial Line Slot Array Antenna at 28 GHz for 5G mobile communication system. In the design, high frequency laminate RT duroid 5880 and air gap were utilized with a modified dielectric coated 50 O SSMA connector as the coaxial to waveguide transition. The technique was experimented via simulation on Computer Simulation Technology Microwave Studio 2014 software. The simulation result gave a return loss of -18.98 dB at 28 GHz. Gain of 23.3 dB, 10 dB impedance bandwidth of 1.28 GHz, sidelobes levels of: -16.5 dB (Eplane); -17.5 dB (H- plane) and efficiency of 96 % were also realized.
Alabidi ES, Kamarudin MR, Rahman TA, Khalily M, Jusoh M (2014) Radiation characteristics improvement of monopole antenna above glass substrate for WBAN applications, Life Science Journal 11 (SPEC.) pp. 124-131
A P-shaped monopole antenna (PSMA) attached with a glass substrate is proposed for wireless body area networks (WBAN) applications. The study investigates the performance of PSMA above reflection plane substrates with different material of glass and a perfect electric conductor (PEC). The PSMA prototype is fabricated on the FR4 substrateto be operated between 3.1 to 5.1 GHz frequency band. It is discovered that the PSMA efficiency could be enhanced by integrating the ground plane with a glass for the brain and chest human body. For brain model, the antenna efficiency of 78.8%, 80.3% and 85.6% is achieved for 3.3, 4.45 and 5 GHz respectively. The antenna efficiency in the chest model is improved to 75.2%, 76.35% and 81.2% at particular 3.3, 4.45 and 5 GHz respectively. Therefore, this study concludes that the reflection plane help to increase the gain and efficiency of close proximity of body surface. Additionally, the PSMA with reflection plane improves SAR when placed near human body if compared to the other antennas. A fascinating conformity was found between the simulation and measurement results that potentialto be deployed for WBAN applications.
Abedian M, Rahim SKA, Danesh S, Khalily M, Noghabaei SM (2013) Ultrawideband dielectric resonator antenna with WLAN band rejection at 5.8 GHz, IEEE Antennas and Wireless Propagation Letters 12 pp. 1523-1526
A novel compact ultrawideband (UWB) dielectric resonator antenna (DRA) with a band rejection at 5.8 GHz is proposed and studied. The antenna is composed of a thin monopole printed antenna loaded with DR that is housed into a dielectric substrate and an L-shaped parasitic strip connected to the ground plane. The L-shaped strip andmetallic sheet are utilized to improve impedance bandwidth. A modified metallic sheet underneath the dielectric resonator has been applied to create a band rejection at frequency 5.8 GHz. The measurement results exhibit acceptable performances in terms of reflection coefficient, radiation pattern, efficiency, and realized gain. © 2013 IEEE.
Khalily M, Rahim MKA, Kamarudin MR (2011) Modified cylindrical dielectric resonators excited with loaded fork monopole antenna, Microwave and Optical Technology Letters 53 (12) pp. 2887-2890
A novel hybrid dielectric resonator antenna (DRA) excited by a printed monopole antenna is proposed and implemented. This new microstrip-fed fork-like stepped monopole antenna is designed to obtain a wide impedance bandwidth from 2 to 6 GHz. A quad-band characteristic is achieved by incorporating two modified cylindrical dielectric resonators with a high dielectric constant of 80, on top of the monopole exciter. Measured results demonstrated that the proposed DRA can be used in multiband wireless operations, covering GSM, PCS, UMTS, WLAN, and WiMax systems, from 1.75 to 5.85 GHz. Experimental and simulation results show a good agreement. © 2011 Wiley Periodicals, Inc.
Orakwue SI, Ngah R, Rahman TA, Sa Ad BM, Khalily M (2015) Steerable array antenna using a 2 × 2 butler matrix for 5G applications, Jurnal Teknologi 77 (10) pp. 117-121
© 2015, Penerbit UTM Press. All rights reserved.This paper presents the design of a beam steerable array antenna based on branch line coupler (BLC) at 28 GHz frequency band for fifth generation (5G) wireless applications. The array is designed using Rogers RT/duroid 5880 substrate material of 0.254 mm thickness and dielectric constant of 2.2. The designed antenna has six elements array and is fed by a BLC which serves as a beamformer to obtain the beam scanning ranging from -16 to +16 degrees. The maximum gain of 14.5 dBi and a wideband that cover from 25.2 GHz to 32 GHz was obtained by measurement. The proposed antenna is applicable to 28 GHz frequency band proposed for 5G wireless communications. All simulated and measured results are clearly presented.
Khalily M, Jamaluddin MH, Rahman TA, Nasir J, Kamarudin MR (2015) MIMO dielectric resonator antenna for LTE femtocell access point applications, 2015 9th European Conference on Antennas and Propagation, EuCAP 2015
© 2015 EurAAP.A four-port MIMO dielectric resonator antenna (DRA) is studied and proposed. The antenna consisting of four rectangular dielectric resonator (RDR) elements, each one is fed by a coplanar feed line, is fabricated on FR4 substrate. A parametric study is carried out and the presented antenna has been fabricated. The presented MIMO DRA having good MIMO characteristics offers a measured bandwidth of 250 MHz between 2480 MHz and 2730MHz for S11
Rahim SA, Danesh S, Okonkwo UA, Sabran M, Khalily M (2012) UWB monopole antenna with circular polarization, Microwave and Optical Technology Letters 54 (4) pp. 949-953
In this article, ultra-wideband (UWB) monopole antenna with circular polarization (CP) is designed and implemented. The proposed antenna consists of an asymmetric shaped radiator fed by a microstrip line and a limited ground plane on the back side of the substrate. The overall size of proposed antenna is 28 mm × 29 mm, which is suitable for mobile devices. The antenna is fabricated on inexpensive FR4 a dielectric constant of, loss tangent tan = 0.019 with thickness of 1.6-mm. The measured results show that the proposed monopole antenna has a very wide bandwidth from 2.98 to 10.93 GHz that covers the UWB application range and defined by 10-dB return loss. Furthermore, a very wide CP bandwidth of 3-dB axial ratio bandwidth that ranges from 7.18 to 10.01 GHz is achieved. © 2012 Wiley Periodicals, Inc.
Roslan SF, Kamarudin MR, Khalily M, Jamaluddin MH (2015) A coplanar waveguide rectangular dielectric resonator antenna (RDRA) for 4G applications, Jurnal Teknologi 73 (1) pp. 97-100
© 2015 Penerbit UTM Press. All rights reserved.This paper presents the design of coplanar waveguide (CPW) rectangular dielectric resonator antenna (RDRA) with and without metallic strip, operating at 2.6 GHz for long term evolution (LTE) applications. The CPW RDRA without metallic strip produces impedance bandwidth of 51 %. Then, a metallic strip was added on top of the dielectric resonator (DR) in order to enhance the impedance bandwidth; thus give more flexibility for the system to cover more applications. A good agreement between simulation and measurement results, in terms of reflection coefficient magnitude and radiation pattern is presented. The simulated and measured impedance BWs for S11
Mataria A, Kamarudin MR, Khalily M (2015) Compact dual-band dielectric resonator antenna for 2.4/5.8 GHZ WLAN applications, Jurnal Teknologi 77 (10) pp. 35-40
© 2015, Penerbit UTM Press. All rights reserved.Design of a Dual-Band Dielectric Resonator Antenna (DRA) for the radio-frequency identification (RFID) and wireless local area network (WLAN) is presented. The necessity of a compact sized dual-band antenna is to allow the manufacturers to produce small size high-performance WLAN access points. The proposed antenna consists of printed TShaped monopole antenna and rectangular dielectric resonator to operate simultaneously at 2.4 and 5.8 GHz. The monopole antenna was printed on a standard 1.6 mm FR4 substrate material. Impedance bandwidth for -10 dB return loss in the 2.35 GHz and 5.86 GHz center frequency reaches 0.25 GHz (2.22 GHz to 2.47 GHz) and 0.28 GHz (5.72 GHz to 6 GHz), respectively. A good agreement is achieved between measured and simulated results. This compact antenna fed by a 50 O microstrip line is a low-profile and easy to manufacture antenna.
Roslan SF, Kamarudin MR, Khalily M, Jamaluddin MH (2014) An MIMO rectangular dielectric resonator antenna for 4G applications, IEEE Antennas and Wireless Propagation Letters 13 pp. 321-324
A multiple-input-multiple-output (MIMO) rectangular dielectric resonator antenna (RDRA) for 2.6-GHz Long Term Evolution (LTE) applications is investigated and presented. Two orthogonal modes of the RDRA are excited by using two different feed mechanisms: coplanar waveguide (CPW) and coaxial probe. The measured impedance bandwidth for port 1 and port 2 is 47% (2.09-3.38 GHz) and 25% (2.40-3.09 GHz), respectively. The measured correlation coefficient is 0.03 with nearly 10 dB diversity gain at frequency 2.6 GHz. The MIMO RDRA gives isoltion of above 20 dB over the operating frequency. The gain of 4.97 dBi is obtained for port 1 and 4.51 dBi for port 2 at 2.6 GHz. The S-parameters, isolation, gain, correlation coefficient, and diversity gain of the MIMO RDRA are studied, and reasonable agreement between the measured and simulated results is observed. © 2002-2011 IEEE.
Alabidi ES, Kamarudin MR, Rahman TA, Khalily M, Abdulrahman AY, Jamlos MF, Jais MI (2014) Radiation characteristics improvement of monopole antenna for WBAN applications, International Journal of Multimedia and Ubiquitous Engineering 9 (2) pp. 53-64
The design, simulation and fabrication of a P-shaped monopole antenna for wireless body area networks (WBAN) applications is presented in this paper. It is noted that the radiation characteristics was improved by attaching a P-shaped element to the ground plane. The simulation of the proposed antenna in the free space and close proximity of body surface has been done using CST Microwave Studio. The proposed antenna is designed on the FR4 substrate with dielectric constant of 4.4 and 1.6mm thickness; and the operating frequency band is between 3.1 to 5.1GHz. The final optimized design has dimensions of 32mm ×28mm. The proposed antenna improves the gain of close proximity of body surface. In addition, the antenna improves the reflection coefficient when placed close human body compared to other antennas. It was observed that there is good agreement between the simulation and measurement results, thereby showing that the antenna is potential to be deployed for WBAN application. © 2014 SERSC.
Danesh S, Rahim SKA, Abedian M, Khalily M, Hamid MR (2013) Frequency-reconfigurable rectangular dielectric resonator antenna, IEEE Antennas and Wireless Propagation Letters 12 pp. 1331-1334
A coplanar waveguide (CPW) reconfigurable dielectric resonator antenna (DRA) is presented and investigated. The DRA is capable of frequency tuning at three different frequency bands between 3.45 and 6.77 GHz. The overall size of the antenna is 50 × 57 mm2. The dielectric material is a rectangular block of ceramic with a permittivity of 15. Two switches, implemented using p-i-n diodes, are located on the lines of a feed network that is connected to the dielectric element. Single-band modes with impedance bandwidths of 8% and 16% are achieved by switching 'on' one of three connecting feedline networks, whereas a wide band, with an impedance bandwidth of 65%, is achieved by switching 'on' two connecting lines. Frequencies in the single band can be independently controlled using switch positions without affecting the wideband mode. The prototype has a low profile with a dielectric resonator thickness of 4 mm. The characteristics of this antenna were studied, and good agreement was found between the numerical and measured results. © 2002-2011 IEEE.
Danesh S, Rahim SKA, Khalily M, Kamarudin MR (2013) Ultra wideband dielectric resonator antenna design, IEEE Antennas and Propagation Society, AP-S International Symposium (Digest) pp. 1700-1701
An ultra-wideband dielectric resonator antenna (DRA) is studied and investigated for wireless application. The dielectric resonator is fed by a microstrip line. The overall size of the proposed DR antenna is 20 × 35 mm2, and the thickness of the dielectric resonator is only 5.12 mm, which is suitable for mobile device. The design simulation is done by using computer simulation Technology Microwave studio suite 2012 (CST). The results represent that by using N-shaped dielectric resonator, a wideband impedance bandwidth of 111% for VSWRd 2 covering a frequency range from 3.59 to 12.61 GHz. A parametric study is presented. © 2013 IEEE.
Aabidi ES, Kamarudin MR, Rahman TA, Khalily M (2014) Planar monopole antenna for WBAN, Progress in Electromagnetics Research Symposium pp. 1936-1939
This paper presents circular-shape monopole antenna for wireless body area net-work (WBAN) applications at 3.1 to 5.1 GHz and 6.5 to 8 GHz. The design and simulation of proposed antenna for WBAN applications in the free space and close proximity of body surface has been done by using CST Microwave Studio. The proposed antenna was designed on FR4 substrate with dielectric constant (µr) of 4.4 and thickness of 1.6 mm. The final optimized design is 50 × 40mm2. The simulated current distribution on the radiating patch for the proposed circular-shaped monopole antenna frequencies of 3.3 and 7.5 GHz in the free space is presented. The size of circular-shape monopole antenna it is suitable for WBAN application.
Wahid WI, Kamarudin MR, Khalily M, Peter T (2015) Circular polarized transparent antenna for 5.8 GHz WLAN applications, Progress in Electromagnetics Research Letters 57 pp. 39-45
© 2015, Electromagnetics Academy. All Rights Reserved.A novel design for a transparent circularly polarized circular slot antenna fed by a coplanar waveguide (CPW) is presented in this paper. The circular polarization is achieved by introducing a tapered split gap in the ring patch of the circular slot antenna in combination with unequal CPW ground arms. The antenna is designed using AgHT-4 laminated on a 2mm thick glass with a relative permittivity of 7. The proposed antenna is designed to operate at 5.8 GHz for WLAN applications. The tapered split gap and inequality in the lengths of the CPW ground arms contribute to a 3 dB axial ratio bandwidth from 5.4 to 6.2GHz. The proposed antenna has been studied theoretically and fabricated. The measured results show that the proposed antenna has a gain of 0.92 dB at 5.8 GHz. Reflection coefficient (S11), axial ratio (AR), and radiation patterns are presented and briefly discussed.
Khalily M (2016) Design of an MIMO Dielectric Resonator Antenna for 4G Applications, Wireless Personal Communications: an international journal 88 (3) pp. 525-536 Springer
A two-port MIMO Dielectric Resonator Antenna (DRA) has been proposed and studied. The antenna consists of a single Rectangular DRA (RDRA) element housed in a thin FR4 substrate, that is fed by two microstrip feed lines. Both the feeding lines excite (Formula presented.) mode in the RDRA. The mutual coupling between the ports has been decreased by employing two symmetrical slits in the ground plane. The proposed antenna has been fabricated and a parametric study has been carried out to obtain the optimum parameters. The presented antenna with acceptable MIMO characteristics, covers a measured bandwidth of 80 MHz (2.56?2.64 GHz) for |S11|
Chagharvand S, Hamid MR, Kamarudin MR, Khalily M (2015) Wideband slot antenna for 4G applications, 2014 IEEE Asia-Pacific Conference on Applied Electromagnetics, APACE 2014 - Proceeding pp. 279-281
© 2014 IEEE.This paper presents a Wideband Slot Antenna for 4G applications. The presented antenna includes a T-shape resonator fed by a coplanar waveguide (CPW). The prototype of the proposed antenna has been fabricated and measured results show that wideband operation has been obtained. The radiation characteristics of the offered antenna such as impedance bandwidth, gain and radiation pattern have been measured. The wideband frequency range from 1.72 GHz to 2.85 GHz has been achieved and covered several LTE bands.
Chagharvand S, Hamid MRB, Kamarudin MR, Khalily M (2014) Dual band slot antenna for 3.5 WiMAX and 5.8 WLAN, Jurnal Teknologi (Sciences and Engineering) 68 (1) pp. 119-122
This paper presents a single layer planar slot antenna for dual band operation. The antenna is fed by a coplanar waveguide (CPW) with two inverted C-shaped resonators to achieve the dual band operation. The impedance bandwidth for |S11|
Danesh S, Abdul Rahim SK, Khalily M (2012) A wideband trapezoidal dielectric resonator antenna with circular polarization, Progress in Electromagnetics Research Letters 34 pp. 91-100
A new design of a circularly-polarized (CP) trapezoidal dielectric resonator antenna (DRA) for wideband wireless application is presented. A single-layered feed is used to excite the trapezoidal shaped dielectric resonator to increase resonant frequency and axial ratio. Besides its structure simplicity, ease of fabrication and low-cost, the proposed antenna features good measured impedance bandwidth, 87.3% at 4.21GHz to 10.72 GHz frequency bands. Moreover, the antenna also produces 3-dB axial ratio bandwidth of about 850 MHz from 5.13 GHz to 6 GHz. The overall size of DRA is 21 mm × 35 mm, which is suitable for mobile devices. Parametric study and measurement results are presented and discussed. Very good agreement is demonstrated between simulated and measured results.
Molu M, Xiao P, Khalily M, Zhang L, Tafazolli R (2017) A Novel Equivalent Definition of Modified Bessel Functions for Performance Analysis of Multi-Hop Wireless Communication Systems, IEEE Access 5 pp. 7594-7605 IEEE
A statistical model is derived for the equivalent signal-to-noise ratio of the Source-to-Relay-to-Destination (S-R-D) link for Amplify-and-Forward (AF) relaying systems that are subject to block Rayleigh-fading. The probability density function and the cumulated density function of the S-R-D link SNR involve modified Bessel functions of the second kind. Using fractional-calculus mathematics, a novel approach is introduced to rewrite those Bessel functions (and the statistical model of the S-R-D link SNR) in series form using simple elementary functions. Moreover, a statistical characterization of the total receive-SNR at the destination, corresponding to the S-R-D and the S-D link SNR, is provided for a more general relaying scenario in which the destination receives signals from both the relay and the source and processes them using maximum ratio combining (MRC). Using the novel statistical model for the total receive SNR at the destination, accurate and simple analytical expressions for the outage probability, the bit error probability, and the ergodic capacity are obtained. The analytical results presented in this paper provide a theoretical framework to analyze the performance of the AF cooperative systems with an MRC receiver.
Danesh S, Kamarudin M, Rahman T, Abedian M, Jamaluddin M, Khalily M (2016) A C-shaped dielectric resonator antenna with frequency reconfigurable for ISM and LTE band applications, Microwave and Optical Technology Letters 59 (1) pp. 134-138 Wiley
A frequency tunable dielectric resonator antenna (DRA) is studied and presented for ISM and LTE band applications. Here, the frequency operation of the proposed DRA is switched from dual band to narrowband mode by using the PIN diode switches. The switches are employed by RF PIN diodes and placed on the feed line network to excite the dielectric resonator (DR). The proposed reconfigurable DRA has a compact size with a thickness of 3 mm and the overall size of 30 × 37 mm2 that is proper for mobile devices. The measured and simulated results indicate that the proposed DRA provides a single and dual band modes which covers the ISM applications and 2.6 GHz LTE system, respectively.
Zainal N, Kamarudin M, Yamada Y, Seman N, Khalily M, Jusoh M (2016) Sidelobe reduction of unequally spaced arrays for 5G applications, 2016 10th European Conference on Antennas and Propagation (EuCAP)
Unequally spaced arrays technique offers an alternative for limited sidelobe level reduction compared to conventional array antennas with equally spaced elements. In this paper, the abilities and design of microstrip linear array antenna, fed by multiport feeding with uniform excitation coefficient in all array elements are presented for sidelobe level reduction at 28 GHz. By using the proximity coupled feed, simulation result gave -10 dB impedance bandwidth of 1.42 GHz and reflection coefficient of -35.5 dB has been achieved. The sidelobe level at broadside decreased from -11.77 dB to -14.76 dB (N = 4) and -12.77 dB to -15.98 dB (N = 8) with unequally spaced array. This feature is suitable for 5G applications.
Shahadan N, Kamarudin M, Jamaluddin M, Khalily M, Jusoh M (2016) Switched parasitic dielectric resonator antenna array using capacitor loading for 5G Applications, 2016 10th European Conference on Antennas and Propagation (EuCAP)
This paper presents a brief account of the findings on a switched parasitic dielectric resonator antenna (DRA) array excited in a higher-order mode. The scanning phase can be changed by using switching technique and capacitor loading at the parasitic element. The driven DR and parasitic DRs have a dielectric constant of 10 and were fed by a microstrip slot aperture. The impact of mutual coupling on the reflection coefficient was examined through a numerical calculation which combines both ANSYS HFSS and MATLAB. This phased array was shown to be able to steer the antenna beam from ?26 degrees to +26 degrees at 15 GHz, which is considered suitable for 5G applications. The impedance matching was maintained at all beam steering angles and a bandwidth of 2.6 GHz has been achieved.
Danesh S, Kamarudin M, Rahman, Abedian M, Khalily M (2016) A Wideband Frequency Reconfigurable Rectangular Dielectric Resonator Antenna, 2016 10th European Conference on Antennas and Propagation (EuCAP)
A wideband frequency reconfigurable dielectric resonator antenna (DRA) is presented and discussed. The proposed antenna is capable of frequency switching at two different bands between 4.12 GHz and 8.85 GHz. The rectangular dielectric resonator with a permittivity of 15 is fed by U-shaped microstrip feed line. By setting the switch on the connecting lines of a network that feeds the dielectric element and changing the state of switch from ON to OFF, a shift of the well-matched operating frequency range is obtained. The total antenna dimensions are 40 × 45 × 4.5748 mm3. The results indicate that the proposed antenna with acceptable performance provides two wideband modes with the impedance bandwidth of 49% and 25%.
Shahadan N, Jamaluddin M, Kamarudin M, Yamada Y, Khalily M, Jusoh M, Dahlan S (2017) Steerable Higher-order Mode Dielectric Resonator Antenna with Parasitic Elements for 5G Applications, IEEE Access IEEE
This paper presents the findings of a steerable higher-order mode (TEy1´3) dielectric resonator antenna with parasitic elements. The beam steering was successfully achieved by switching the termination capacitor on the parasitic element. In this light, all of the dielectric resonator antennas (DRAs) have the same dielectric permittivity similar to that of 10 and was excited by a 50© microstrip with a narrow aperture. The effect of the mutual coupling on the radiation pattern and the reflection coefficient, as well as the array factor were investigated clearly using MATLAB ver. 2014b and ANSYS HFSS ver. 16. As the result, the antenna beam of the proposed DRA array managed to steer from -32° to +32° at 15 GHz. Furthermore, the measured antenna array showed the maximum gain of 9.25 dBi and the reflection coefficients which are less than -10 dB with the bandwidth more than 1.3 GHz, which is viewed as desirable for Device-to-Device communication (D2D) in 5G Internet of Things (IoT) applications.
Molu Mehdi M., Xiao Pei, Khalily Mohsen, Cumanan Kanapathippillai, Zhang Lei, Tafazolli Rahim (2017) Low-Complexity and Robust Hybrid Beamforming Design for Multi-Antenna Communication Systems, IEEE Transactions on Wireless Communications 17 (3) pp. 1445-1459 Institute of Electrical and Electronics Engineers (IEEE)
This paper proposes a low-complexity hybrid beamforming
design for multi-antenna communication systems. The
hybrid beamformer comprises of a baseband digital beamformer
and a constant modulus analog beamformer in radio frequency
(RF) part of the system. As in Singular-Value-Decomposition
(SVD) based beamforming, hybrid beamforming design aims to
generate parallel data streams in multi-antenna systems, however,
due to the constant modulus constraint of the analog beamformer,
the problem cannot be solved, similarly. To address this problem,
mathematical expressions of the parallel data streams are
derived in this paper and desired and interfering signals are
specified per stream. The analog beamformers are designed by
maximizing the power of desired signal while minimizing the
sum-power of interfering signals. Finally, digital beamformers are
derived through defining the equivalent channel observed by the
transmitter/receiver. Regardless of the number of the antennas
or type of channel, the proposed approach can be applied to
wide range of MIMO systems with hybrid structure wherein
the number of the antennas is more than the number of the
RF chains. In particular, the proposed algorithm is verified for
sparse channels that emulate mm-wave transmission as well as
rich scattering environments. In order to validate the optimality,
the results are compared with those of the state-of-the-art and
it is demonstrated that the performance of the proposed method
outperforms state-of-the-art techniques, regardless of type of the
channel and/or system configuration.
Khalily M, Ghoraishi M, Taheri S, Payami S, Tafazolli R (2018) Polarimetric Wideband Directional Channel
Measurement and Analysis for Outdoor Small Cell
Scenarios at 32 GHz and 39 GHz,
EuCAP 2018 Proceedings IEEE
Wideband millimeter-wave (mmWave) directional
propagation measurements were conducted in the 32 GHz and
39 GHz bands in outdoor line-of-sight (LoS) small cell scenarios.
The measurement provides spatial and temporal statistics that
will be useful for small-cell outdoor wireless networks for future
mmWave bands. Measurements were performed at two outdoor
environments and repeated for all polarization combinations.
Measurement results show little spread in the angular and delay
domains for the LoS scenario. Moreover root-mean-squared
(RMS) delay spread at different polarizations show small difference
which can be due to specific scatterers in the channel.
Khalily M, Ghoraishi M, Taheri S, Payami S, Tafazolli R (2018) Millimeter-Wave Directional Path Loss Models in
the 26 GHz, 32 GHz, and 39 GHz Bands for Small
Cell 5G Cellular System,
EuCAP 2018 Proceedings IEEE
This paper presents empirically-based large-scale
propagation path loss models for small cell fifth generation (5G)
cellular system in the millimeter-wave bands, based on practical
propagation channel measurements at 26 GHz, 32 GHz, and
39 GHz. To characterize path loss at these frequency bands
for 5G small cell scenarios, extensive wideband and directional
channel measurements have been performed on the campus of the
University of Surrey. Close-in reference (CI), and 3GPP path loss
models have been studied, and large-scale fading characteristics
have been obtained and presented.
Khalily M, Taheri S, Xiao P, Entezami F, Hill T, Tafazolli R (2018) 26 GHz Indoor Wideband Directional Channel
Measurement and Analysis in LoS and NLoS
Scenarios,
Proceedings of EuCAP 2018 IEEE
This paper presents details of the indoor wideband
and directional propagation measurements at 26 GHz in which
a wideband channel sounder using a millimeter wave (mmWave)
signal analyzer and vector signal generator was employed. The
setup provided 2 GHz bandwidth and the mechanically steerable
directional lens antenna with 5 degrees beamwidth provides 5
degrees of directional resolution over the azimuth. Measurements
provide path loss, delay and spatial spread of the channel.
Angular and delay dispersion are presented for line-of-sight (LoS)
and non-line-of-sight (NLoS) scenarios.
Khalily Mohsen, Taheri Sohail, Payami Sohail, Ghoraishi Mir, Tafazolli Rahim (2018) Indoor Wideband Directional Millimeter Wave Channel Measurements and Analysis at 26 GHz, 32 GHz, and 39 GHz, Transactions on Emerging Telecommunications Technologies. Special Issue: Spectrum Extensions for 5G and Beyond 5G Networks 29 (10) e3311 Wiley
This paper presents details of the wideband directional propagation
measurements of millimetre-wave (mmWave) channels
in the 26 GHz, 32 GHz, and 39 GHz frequency bands
in an indoor typical office environment. More than 14400
power delay profiles (PDPs) were measured across the 26
GHz band and over 9000 PDPs have been recorded for the
32 GHz and 39 GHz bands at each measurement point. A
mmWave wideband channel sounder has been used, where
signal analyzer and vector signal generator was employed.
Measurements have been conducted for both co- and crossantenna
polarization. The setup provided 2GHz bandwidth
and the mechanically steerable directional horn antenna with
8 degrees beamwidth provides 8 degrees of directional resolution
over the azimuth for 32 GHz and 39 GHz while 26
GHz measurement setup provides the angular resolution of
5 degrees. Measurements provide path loss, delay and spatial
spread of the channel. Large-scale fading characteristics,
RMS delay spread, RMS angular spread, angular and
delay dispersion are presented for three mmWave bands
for the line-of-sight (LoS) scenario.
Dahri M, Jamaluddin M, Khalily M, Inam M, Selvaraju R, Kamarudin M (2018) Polarization Diversity and Adaptive Beamsteering for 5G Reflectarrays: A Review, IEEE Access 6 pp. 19451-19464 Institute of Electrical and Electronics Engineers (IEEE)
The growing demands of advanced future communication
technologies require investigating the possible enhancement
in the current features of a reflectarray antenna. Its design
and experimental features need a thorough investigation before
a plausible transition towards millimeter wave frequencies. This
article provides a detailed review covering various fundamental
and advanced design tactics for polarization diversity and
beamsteering in the reflectarray antenna. The diversity in the
polarization has been discussed for linear and circular polarized
designs in reflectarrays. The importance of electronically tunable
materials and different lumped components for adaptive beamsteering
in reflectarrays has also been highlighted. Each design
has been critically analyzed and possibilities of its compatibility
with future 5G systems have been provided.
Golazari S, Khalily M, Entezami F, Xiao P (2018) Performance Analysis of the Loop-Shaped Plasma Antenna Under Different Pressure Conditions, IEEE ISNCC 2018 : 2018 IEEE International Symposium on Networks, Computers and Communications Institute of Electrical and Electronics Engineers (IEEE)
This study examines the effect of different pressures
on the radiation characteristics of the loop-shaped plasma antenna
filled by two gases; Argon and Nitrogen. Proposed loop plasma
antennas operating at LTE and Wi-Fi frequency bands have been
designed and its performance studied at three different pressures
of 2.28, 5 and 10 Torr. The radiation characteristics of the both
loop-shaped plasma antennas have been investigated and
presented for three different pressures. To analyze the
performance of the proposed antenna, full-wave simulation were
run using the finite integral method software, CST Microwave
Studio.
Araghi A, Khalily M, Xiao P, Kosari A, Zarrabi H, Tafazolli R (2018) Millimeter-Wave MIMO Balanced Antipodal Vivaldi Antenna Design for Autonomous Cars, IEEE ISNCC 2018 : 2018 IEEE International Symposium on Networks, Computers and Communications Institute of Electrical and Electronics Engineers (IEEE)
This paper introduces a millimeter-wave multipleinput-
multiple-output (MIMO) antenna for autonomous (selfdriving)
cars. The antenna is a modified four-port balanced
antipodal Vivaldi which produces four directional beams and
provides pattern diversity to cover 90 deg angle of view. By using
four antennas of this kind on four corners of the car?s bumper, it
is possible to have a full 360 deg view around the car. The
designed antenna is simulated by two commercially full-wave
packages and the results indicate that the proposed method can
successfully bring the required 90 deg angle of view.
Khalily Mohsen, Tafazolli Rahim, Xiao Pei, Kishk Ahmed A. (2018) Microstrip Array Antenna with Improved Radiation Characteristic for Different 5G Applications, IEEE Transactions on Antennas and Propagation 66 (9) pp. 4641-4647 Institute of Electrical and Electronics Engineers (IEEE)
A Ka-band inset-fed microstrip patches linear antenna
array is presented for the fifth generation (5G) applications
in different countries. The bandwidth is enhanced by stacking
parasitic patches on top of each inset-fed patch. The array
employs 16 elements in an H-plane new configuration. The
radiating patches and their feed lines are arranged in an
alternating out-of-phase 180-degree rotating sequence to decrease
the mutual coupling and improve the radiation pattern symmetry.
A (24.4%) measured bandwidth (24.35 to 31.13 GHz)is achieved
with -15 dB reflection coefficients and 20 dB mutual coupling
between the elements. With uniform amplitude distribution, a
maximum broadside gain of 19.88 dBi is achieved. Scanning the
main beam to 49.5° from the broadside achieved 18.7 dBi gain
with -12.1 dB sidelobe level (SLL). These characteristics are in
good agreement with the simulations, rendering the antenna to
be a good candidate for 5G applications.
Araghi Ali, Khalily Mohsen, Xiao Pei, Tafazolli Rahim (2020) Multiple-Beam mmW-Slotted-Waveguide
Leaky Wave Antenna with Control on Polarization,
2020 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting Institute of Electrical and Electronics Engineers (IEEE)
By performing the Floquet-mode analysis of a periodic
slotted waveguide, a multiple-beam leaky wave antenna
is proposed in the millimetre-wave (mmW) band. Considering
the direction of surface current lines on the broad/side-walls of
the waveguide, the polarization of constructed beams are also
controlled. The simulation results are well matched with the
initial mathematical analysis.
Khalily Mohsen, Tafazolli Rahim, Xiao Pei, Kishk Ahmed A. (2018) Broadband mm-Wave Microstrip Array Antenna with Improved Radiation Characteristics for Different 5G Applications, IEEE Transactions on Antennas and Propagation 44 (9) pp. 4641-4647 Institute of Electrical and Electronics Engineers (IEEE)
A Ka-band inset-fed microstrip patches linear antenna
array is presented for the fifth generation (5G) applications
in different countries. The bandwidth is enhanced by stacking
parasitic patches on top of each inset-fed patch. The array
employs 16 elements in an H-plane new configuration. The
radiating patches and their feed lines are arranged in an
alternating out-of-phase 180-degree rotating sequence to decrease
the mutual coupling and improve the radiation pattern symmetry.
A (24.4%) measured bandwidth (24.35 to 31.13 GHz)is achieved
with -15 dB reflection coefficients and 20 dB mutual coupling
between the elements. With uniform amplitude distribution, a
maximum broadside gain of 19.88 dBi is achieved. Scanning the
main beam to 49.5æ
from the broadside achieved 18.7 dBi gain
with -12.1 dB sidelobe level (SLL). These characteristics are in
good agreement with the simulations, rendering the antenna to
be a good candidate for 5G applications.
Mao Chunxu, Khalily Mohsen, Singh Vikrant, Xiao Pei (2020) Low-Profile Vertically Polarized Wearable Antenna with Omni-Directional Radiation, 2020 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting
In this paper, a single-layer planar antenna with vertical polarization and omni-directional radiation is proposed for wearable applications. The antenna consists of two identical shorted patches which are face-to-face located and fed by a microstrip line at the center. Due to the structural symmetry, the current distribution and electric-field distribution are symmetrical regarding the feed, which result in vertical linear polarization normal to the antenna and omni-directional radiation pattern in the azimuthal plane. To verify the design concept, an antenna prototype operating at 2.45 GHz is designed, fabricated and tested. Measured results concur well with the simulations, showing that the antenna has a good impedance matching, omnidirectional radiation pattern, and vertical polarization in the band of interest. The proposed antenna can be a good candidate for wearable and other wireless communication systems.
Brown Tim, Khalily Mohsen (2018) Integrated Shield Edge Diffraction Model for Narrow Obstructing Objects, IEEE Transactions on Antennas and Propagation IEEE
A new simple and accurate model defined as shield
edge diffraction is derived and validated suitable for frequencies
above 10GHz diffracting around obstructions that are narrow
compared to the Fresnel zone width. The model includes new
simple Fresnel diffraction parameters similar to those used with
traditional knife edge diffraction, which can in the same way be
integrated into deterministic and empirical path loss models.
Capability of the model extends beyond current single and
double knife edge models whereby it includes the effects of the
antennas? far field distances as well as their gain and phase
patterns, which subsequently have a severe effect on the
diffraction loss in short range links. The models are validated
using both anechoic chamber as well as real environment based
measurements at 10-12GHz and 26GHz.
Alibakhshikenari Mohammad, Virdee Bal, Shukla Panchamkumar, See Chan, Abd-Alhameed Raed, Khalily Mohsen, Falcone Francisco, Limiti Ernesto (2018) Antenna Mutual Coupling Suppression Over Wideband Using Embedded Periphery Slot for Antenna Arrays, Electronics 7 (9) MDPI
This paper presents a new approach to suppress interference between neighbouring radiating elements resulting from surface wave currents. The proposed technique will enable the realization of low-profile implementation of highly dense antenna configuration necessary in SAR and MIMO communication systems. Unlike other conventional techniques of mutual coupling suppression where a decoupling slab is located between the radiating antennas the proposed technique is simpler and only requires embedding linear slots near the periphery of the patch. Attributes of this technique are (i) significant improvement in the maximum isolation between the adjacent antennas by 26.7 dB in X-band and >15 dB in Ku and K-bands; (ii) reduction in edge-to-edge gap between antennas to 10 mm (0.37 »); and (iii) improvement in gain by >40% over certain angular directions, which varies between 4.5 dBi and 8.2 dBi. The proposed technique is simple to implement at low cost.
Mao Chunxu, Khalily Mohsen, Xiao Pei, Brown Tim, Gao Steven (2019) Planar Sub-Millimeter-Wave Array Antenna with Enhanced Gain and Reduced Sidelobes for 5G Broadcast Applications, IEEE Transactions on Antennas and Propagation 67 (1) pp. 160-168 IEEE
In this paper, a compact, broadband, planar array antenna with omnidirectional radiation in horizontal plane is proposed for the 26 GHz fifth-generation (5G) broadcast applications. The antenna element is composed of two dipoles and a substrate integrated cavity (SIC) as the power splitter. The two dipoles are placed side-by-side at both sides of the SIC and they are compensated with each other to form an omni-directional pattern in horizontal plane. By properly combing the resonant frequencies of the dipoles and the SIC, a wide impedance bandwidth from 24 to 29.5 GHz is achieved. To realize a large array while reducing the complexity, loss and size of the feeding network, a novel dual-port structure combined with radiation and power splitting functions is proposed for the 1st time. The amplitude and phase on each element of the array can be tuned, and therefore, the grating lobes level can be significantly reduced. Based on the dual-port structure, an 8-element array with an enhanced gain of over 12 dBi is designed and prototyped. The proposed antenna also features low profile, low weight and low cost, which is desirable for 5G commercial applications. Measured results agree well with the simulations, showing that the proposed high-gain array antenna has a broad bandwidth, omni-directional pattern in horizontal plane, and low side-lobes.
Alibakhshikenari Mohammad, Virdee Bal S., Shukla Panchamkumar, See Chan H., Abd-Alhameed Raed, Khalily Mohsen, Falcone Francisco, Limiti Ernesto (2018) Interaction Between Closely Packed Array Antenna Elements Using Metasurface for Applications Such as MIMO Systems and Synthetic Aperture Radars, Radio Science 53 (11) pp. 1368-1381 American Geophysical Union (AGU)
The paper presents a technique to enhance the isolation between adjacent radiating elements which is common in densely packed antenna arrays. Such antennas provide frequency beam-scanning capability needed in Multiple-Input Multiple-Output (MIMO) systems and Synthetic Aperture Radars (SARs). The method proposed here uses a metamaterial decoupling slab (MTM-DS), which is located between radiating elements, to suppress mutual-coupling between the elements that would otherwise degrade the antenna efficiency and performance in both the transmit and receive mode. The proposed MTM-DS consists of mirror imaged E-shaped slits engraved on a microstrip patch with inductive stub. Measured results confirm over 9?11 GHz with no MTM-DS the average isolation (S12) is -27 dB; however, with MTM-DS the average isolation improves to -38 dB. With this technique the separation between the radiating element can be reduced to 0.66»o, where »0 is free space wavelength at 10 GHz. In addition, with this technique there is 15% improvement in operating bandwidth. At frequencies of high impedance match of 9.95 GHz and 10.63 GHz the gain is 4.52 dBi and 5.40 dBi, respectively. Furthermore, the technique eliminates poor front-to-back ratio encountered in other decoupling methods. MTM-DS is also relatively simple to implement. Assuming adequate space is available between adjacent radiators the MTM-DS can be fixed retrospectively on existing antenna arrays, which makes the proposed method versatile.
Babale Suleiman Aliyu, Rahim Sharul Kamal Abd., Barro Oumar Alassane, Himdi Mohamed, Khalily Mohsen (2018) Single Layered 4 x 4 Butler Matrix Without Phase-shifters and Crossovers, IEEE Access IEEE
Traditional design of 4 x 4 Butler matrix (BM) uses couplers, phase shifters (PS) and
crossovers. Due to some troublesome issues related to PS and the crossovers involved in the design of BM
which degrades its performance, this paper presents a planar 4 x 4 BM without PS and crossovers. It is
accomplished with the help of a modified coupler. The modified coupler is realized to have a 450
output
phase difference which replaces the function of the 450
phase shifters. The 450
output phase differences
obtained from this type of coupler combined with quadrature coupler gives the desired phase differences
required at the output of the BM. The BM is meant to operate at 6 GHz. The simulated and measured reflection
coefficients and isolations at all ports are below ?17 dB at the center frequency. The result also shows an
amplitude imbalance within ±3 dB with phase mismatch of about ±3° at the center frequency. The ?10 dB
reflection coefficient bandwidth is 37.10% and the transmission bandwidth between ?5 dB and ?9 dB is
about 31.0%. Both the simulated and experimental radiation patterns obtained by exciting the input ports (P1
to P4) of the BM produces four orthogonal beams deposed at +15.3°, ?47.6°, +47.6° and ?15.3°. This
beam steering depicts a stable beam scanning angle of the BM which is in good agreement with the theoretical
predictions.
Pon Lai Ly, Rahim Sharul Kamal Abdul, Leow Chee Yen, Himdi Mohamed, Khalily Mohsen (2019) Displacement-tolerant Printed Spiral Resonator with Capacitive Compensated-plates for Non-radiative Wireless Energy Transfer, IEEE Access IEEE
A printed spiral resonator without external lumped elements is proposed. Instead of employing surface-mount device (SMD) capacitors, series-parallel capacitive plates are designed and etched on the same substrate to achieve simultaneous conjugate matching between a pair of symmetrical near-field coupled resonators. Simulations are conducted with the aid from CST Microwave Studio. The
proposed design displayed satisfactory tolerance towards planar displacement at z-axis plane, lateral
displacement at x- and y-axis planes as well as concurrent planar and lateral displacement. Positioned at
perfect alignment with a transfer distance of 15 mm, the simulated and measured maximum power transfer
efficiency achieved are 79.54% and 74.96% respectively. The variation ratio for planar displacement acquired is 0.29% when receiving resonator is rotated from -180º till 180º with step size of 15º. Under rotational angle from 0º till 180º, the measured average variation ratio for lateral displacement at x- and yaxis up to 15 mm is 20.14%. Feasibility of sustaining power transfer efficiency under various offsets depicts the possibility of integrating the proposed simple design for low power wireless energy transfer applications such as wireless charging for handheld devices in consumer electronics and implanted biomedical devices.
Alibakhshikenari M., Khalily Mohsen, Virdee B. S., Ali A., Shukla P., See C. H., Abd-Alhameed R. A., Falcone F. J., Limiti E. (2019) Double-Port Slotted-Antenna with Multiple Miniaturized Radiators for Wideband Wireless Communication Systems and Portable Devices, Progress In Electromagnetics Research C 90 pp. 1-13 EMW Publishing
Proof-of-concept is presented of a novel slot antenna structure with two excitation ports. Although this antenna provides a wide impedance bandwidth, its peak gain and optimum radiation efficiency are observed at its mid-band operational frequency. The antenna structure is etched on the top side of a dielectric substrate with a ground plane. The antenna essentially consists of a rectangular patch with two dielectric slots in which multiple coupled patch arms embedded with H-shaped slits are loaded. The two dielectric slots are isolated from each other with a large H-shaped slit. The radiation characteristics of the proposed antenna in terms of impedance bandwidth, gain and efficiency can be significantly improved by simply increasing the number of radiation arms and modifying their dimensions. The antenna's performance was verified by building and testing three prototype antennas. The final optimized antenna exhibits a fractional bandwidth of 171% (0.5-6.4 GHz) with a peak gain and maximum radiation efficiency of 5.3 dBi and 75% at 4.4 GHz, respectively. The antenna has physical dimensions of 27×37×1.6 mm3 corresponding to electrical size of 0.0452»0×0.0627»0×0.0026»0, where »0 is free-space wavelength at 0.5 GHz. The antenna is compatible for integration in handsets and other broadband wireless systems that operate over L-, S-, and C-bands.
Hill T. A., Kelly J. R., Khalily M., Brown T. W. C. (2019) Conformal Transmitarray for Scan Loss Mitigation with Thinned Reconfiguration, Proceedings of the 2019 13th European Conference on Antennas and Propagation (EuCAP) Institute of Electrical and Electronics Engineers (IEEE)
A conformal transmitarray with thinned control is
presented, operating at 28 GHz. Its side panels are rotated to
align with the maximum steering angle, increasing the gain
and reducing the scan loss. The transmitarray is fed by an
8-element linear phased array antenna. Beam focusing to +/-
53 degrees is demonstrated for two different directions, using
combinations of crossed-slot unit cells. A unit cell placement rule
is proposed to significantly reduce (i.e. thin) the required number
of reconfigurable unit cells. A filling factor of 43% was achieved
compared to a fully populated design. This reduces the cost and
biasing complexity. By minimising scan loss, this antenna could
improve the performance of 5G small-cell access points.
Araghi Ali, Khalily Mohsen, Ghannad Amirhossein Alizadeh, Xiao Pei, Tafazolli Rahim (2019) Compact Dual Band Antenna for Off-Body-Centric Communications, Proceedings of the 13th European Conference on Antennas and Propagation (EuCAP 2019) European Association on Antennas and Propagation
A compact size, dual-band wearable antenna for
off-body communication operating at the both 2.45 and 5.8
GHz industrial, scientific, and medical (ISM) band is
presented. The antenna is a printed monopole on an FR4
substrate with a modified loaded ground plane to make the
antenna profile compact. Antennas? radiation characteristics
have been optimized while the proposed antenna placed close
to the human forearm. The fabricated antenna operating on
the forearm has been measured to verify the simulation results.
Alibakhshikenari Mohammad, Virdee Bal Singh, Khalily Mohsen, See Chan Hwang, Abd-Alhameed Raed, Falcone Francisco, Limiti Ernesto (2019) New Approach to Suppress Mutual Coupling Between Longitudinal-Slotted Arrays Based on SIW Antenna Loaded with Metal-Fences Working on VHF/UHF Frequency-Bands: Study, Investigation, and Principle, Proceedings of the 2018 Asia-Pacific Microwave Conference (APMC) pp. 1564-1566 Institute of Electrical and Electronics Engineers (IEEE)
In this work it is demonstrated that substrate integrated waveguide longitudinal slotted array antenna (SIWLSAA) which is loaded with metal fences exhibits high-isolation across VHF/UHF bands. A reference SIWLSAA used for comparison purpose comprises of 3×63×6 slotted arrays constructed on the top and bottom sides of the FR-4 lossy substrate has maximum isolation of ?63 dB between its radiation slots. Improvement in isolation is demonstrated using a simple new technique based on inserting a metal fence between each row of slot arrays. The resulting isolation is shown to be is better than ?83 dB across 200 MHz to 1.0 GHz with gain greater than 1.5 dBi., and side-lobe level less than - 40 dB. The proposed SIWLSAA is compact and has dimensions of 40×10×540×10×5mm3 (0.026»0×0.006»0×0.002»0) where »0 is 200 MHz. The proposed structure should find application in multiple-input multiple-output (MIMO) and radar systems.
Alibakhshikenari Mohammad, Virdee Bal Singh, Khalily Mohsen, See Chan Hwang, Abd-Alharueed Raed, Falcone Francisco, Limiti Ernesto (2019) A New Study to Suppress Mutual-Coupling Between Waveguide Slot Array Antennas Based on Metasurface Bulkhead for MIMO Systems, Proceedings of the 2018 Asia-Pacific Microwave Conference (APMC) pp. 500-502 Institute of Electrical and Electronics Engineers (IEEE)
In this paper, a new method is proposed to reduce
mutual coupling between waveguide slot array (WSA)
antennas based on metasurface technology. This is achieved
by placing a metasurface bulkhead between the two WSA
antennas. Performance of the dual-waveguide antenna
structure is shown to substantially enhance when compared
against an identical reference WSA antenna with no
metasurface. WSA antennas used in the study has dimensions
40×20×5mm3 and operates over 1.7-3.66 GHz, which
corresponds to a fractional bandwidth of 73.13%. The
average isolation of the reference WSA antennas is -20 dB;
however, with a metasurface bulkhead the isolation is shown
to increase to -36.5 dB. In addition, the bandwidth extends by
~10%, and the gain improves by 14.66%. The proposed
method is should find application in MIMO systems where
high isolation between neighbouring radiation elements is
required to improve the antenna characteristics, and
mimimise array phase errors, which is necessary to enhance
the system performance.
Alizadeh Ghannad Amir, Khalily Mohsen, Xiao Pei, Tafazolli Rahim, Kishk Ahmed A. (2019) Enhanced Matching and Vialess Decoupling of Nearby Patch Antennas for MIMO System, IEEE Antennas and Wireless Propagation Letters pp. 1-1 Institute of Electrical and Electronics Engineers (IEEE)
Simultaneous improvement of matching and isolation for a modified two-element microstrip patch antenna array is proposed. Two simple patch antennas in a linear array structure are designed, whereas, the impedance matching and isolation are improved without using any conventional matching networks. The presented low profile multifunctional via-less structure comprises of only two narrow T-shaped stubs connected to feed lines, a narrow rectangular stub between them, and a narrow rectangular slot on the ground plane. This design provides a simple, compact structure with low mutual coupling, low cost and no adverse effects on the radiation and resonance. To validate the design, a compact very-closely-spaced antenna array prototype is fabricated at 5.5 GHz which is suitable for multiple-input-multiple-output (MIMO) systems. The measured and simulated results are in good agreement with a 16 dB, and 40 dB of improvements in the matching and isolation, respectively.
Ghorbani Mehdi, Khalily Mohsen, Xiao Pei, Tafazolli Rahim (2019) A Wideband High Flat Gain Waveguide-Fed Aperture Antenna Using Superstrate and Shield, IEEE Xplore Digital Library IEEE
In this paper, a high flat gain waveguide-fed aperture antenna has been proposed. For this purpose, two layers of FR4 dielectric as superstrates have been located in front of the aperture to enhance the bandwidth and the gain of the antenna. Moreover, a conductive shield, which is connected to the edges of the ground plane and surrounding aperture and superstrates, applied to the proposed structure to improve its radiation characteristics. The proposed antenna has been simulated with HFSS and optimized with parametric study and the following results have been obtained. The maximum gain of 13.0 dBi and 0.5-dBi gain bandwidth of 25.9 % (8.96 ? 11.63 GHz) has been achieved. The 3-dBi gain bandwidth of the proposed antenna is 40.7% (8.07-12.20 GHz), which has a suitable reflection coefficient (d-10dBi) in whole bandwidth. This antenna comprises a compact size of (1.5»×1.5»), easy structure and low-cost fabrication.
Ghorbani Mehdi, Khalily Mohsen, Ghorbaninejad Habib, Xiao Pei, Tafazolli Rahim (2019) Bandwidth Enhancement and Radiation Characteristics Improvement of Triangular Dielectric Resonator Antenna, Proceedings of The 2019 International Symposium on Networks, Computers and Communications (ISNCC'19) Institute of Electrical and Electronics Engineers (IEEE)
In this paper, an ultra-wideband, Dielectric
Resonator Antenna (DRA) has been proposed. The proposed
antenna is based on isosceles triangular DRA (TDRA), which is
fed from the base side using a 50© probe. For bandwidth
enhancement and radiation characteristics improvement, a
partially cylindrical-shape hole is etched from its base side
which approached probe feed to the center of TDRA. The
dielectric resonator (DR) is located over an extended conducting
ground plane. This technique has significantly enhanced
antennas bandwidth from 48.8% to 80% (5.29-12.35 GHz),
while the biggest problem was radiation characteristics. The
basis antenna possesses negative gain in a wide range of
bandwidth from 7.5 GHz to 10.5 GHz down to -13.8 dBi. Using
this technique improve antenna gain over 1.6 dBi for whole
bandwidth, while peak gain is 7.2 dBi.
Paracha K. N., Abdul Rahim S. K., Soh P. J., Khalily Mohsen (2019) Wearable Antennas: A Review of Materials, Structures and Innovative Features for Autonomous Communication and Sensing, IEEE Access Institute of Electrical and Electronics Engineers (IEEE)
Wearable antennas have gained much attention in recent years due to their attractive features and possibilities in enabling lightweight, flexible, low cost and portable wireless communication and sensing. Such antennas need to be conformal when used on different parts of the human body, thus need to be implemented using flexible materials and designed in a low profile structure. Ultimately, these antennas need to be capable of operating with minimum degradation in proximity to the human body. Such requirements render the design of wearable antennas challenging, especially when considering aspects such as their size compactness, effects of structural deformation and coupling to the body, and fabrication complexity and accuracy. Despite slight variations in severity according to applications, most of these issues exist in the context of body-worn implementation. This review aims to present the different challenges and issues in designing wearable antennas, their material selection, and fabrication techniques. More importantly, recent innovative methods in back radiations reduction techniques, circular polarization (CP) generation methods, dual polarization techniques and providing additional robustness against environmental effects are first presented. This is followed by a discussion of innovative features and their respective methods in alleviating these issues recently proposed by the scientific community researching in this field.
Gupta Surbhi, Sharma Anand, Das Gourab, Gangwar Ravi Kumar, Khalily Mohsen (2019) Wideband Circularly Polarized Dielectric Resonator Antenna Array With Polarization Diversity, IEEE Access 7 pp. 49069-49076 Institute of Electrical and Electronics Engineers (IEEE)
In this paper, a design approach for aperture coupled modified cylindrical dielectric resonator antenna (cDRA) array is discussed. The proposed radiating element is dual cylindrical ceramic blocks placed with a small gap. The proposed aperture excites dual radiating mode pattern inside modified cDRA, i.e., HEM11´ and TE01´ . The arrangement of radiating elements, i.e., dual cylindrical ceramic blocks, provides lower Q -factor (wider impedance bandwidth). Conversion from a single radiating element to an array arrangement provides the gain enhancement of 3.0 dBi in the complete operating frequency range. The proposed aperture offers circularly rotating EM wave within frequency range 4.5?5.7 GHz. Antenna prototype is fabricated for the validation of simulated near as well as far-field parameters. Practically measured outcomes confirm that it is working in between the frequency range 4.7?6.4 GHz. The 3-dB axial ratio bandwidth of the proposed radiator is about 23.52% (4.5?5.7 GHz). Directional radiation pattern and circular polarization features make the proposed radiating structure more appropriate for WLAN (5.2 GHz) and local thermal equilibrium (LTE) band 46 (5.5 GHz) applications.
Alibakhshikenari Mohammad, Khalily Mohsen, Virdee Bal Singh, See Chan Hwang, Abd-Alhameed Raed A., Limiti Ernesto (2019) Mutual-Coupling Isolation Using Embedded Metamaterial EM Bandgap Decoupling Slab for Densely Packed Array Antennas, IEEE Access 7 pp. 51827-51840 IEEE
This article presents a unique technique to enhance isolation between transmit/receive radiating elements in densely packed array antenna by embedding a metamaterial (MTM) electromagnetic bandgap (EMBG) structure in the space between the radiating elements to suppress surface currents that would otherwise contribute towards mutual coupling between the array elements. The proposed MTM-EMBG structure is a cross-shaped microstrip transmission line on which are imprinted two outward facing E-shaped slits. Unlike other MTM structures there is no short-circuit grounding using via-holes. With this approach, the maximum measured mutual coupling achieved is -60 dB @ 9.18 GHz between the transmit patches (#1 & #2) and receive patches (#3 & #4) in a four-element array antenna. Across the antenna?s measured operating frequency range of 9.12 to 9.96 GHz, the minimum measured isolation between each element of the array is 34.2 dB @ 9.48 GHz, and there is no degradation in radiation patterns. The average measured isolation over this frequency range is 47 dB. The results presented confirm the proposed technique is suitable in applications such as synthetic aperture radar (SAR) and multiple-input multiple-output (MIMO) systems.
Bashar Manijeh, Burr Alister G., Haneda Katsuyuki, Cumanan Kanapathippillai, Molu Mehdi M., Khalily Mohsen, Xiao Pei (2019) Evaluation of Low Complexity Massive MIMO Techniques Under Realistic Channel Conditions, IEEE Transactions on Vehicular Technology Institute of Electrical and Electronics Engineers (IEEE)
A low complexity massive multiple-input multipleoutput
(MIMO) technique is studied with a geometry-based
stochastic channel model, called COST 2100 model. We propose
to exploit the discrete-time Fourier transform of the antenna
correlation function to perform user scheduling. The proposed
algorithm relies on a trade off between the number of occupied
bins of the eigenvalue spectrum of the channel covariance matrix
for each user and spectral overlap among the selected users.
We next show that linear precoding design can be performed
based only on the channel correlation matrix. The proposed
scheme exploits the angular bins of the eigenvalue spectrum
of the channel covariance matrix to build up an ?approximate
eigenchannels? for the users. We investigate the reduction of
average system throughput with no channel state information at
the transmitter (CSIT). Analysis and numerical results show that
while the throughput slightly decreases due to the absence of
CSIT, the complexity of the system is reduced significantly.
Khalily Mohsen, Brown Tim W. C., Tafazolli Rahim (2019) Machine Learning Based Approach for Diffraction Loss Variation Prediction by the Human Body, IEEE Antennas and Wireless Propagation Letters Institute of Electrical and Electronics Engineers (IEEE)
This paper presents a machine learning (ML) based
model to predict the diffraction loss around the human body.
Practically, it is not reasonable to measure the diffraction loss
changes for all possible body rotation angles, builds and line
of sight (LoS) elevation angles. A diffraction loss variation
prediction model based on a non-parametric learning technique
called Gaussian process (GP) is introduced. Analysed results state
that 86% correlation and normalised mean square error (NMSE)
of 0.3 on the test data is achieved using only 40% of measured
data. This allows a 60% reduction in required measurements in
order to achieve a well-fitted ML loss prediction model. It also
confirms the model generalizability for non-measured rotation
angles.
Alqurashi Khaled Yahya, Crean Carol, Kelly James R., Brown Tim W. C., Khalily Mohsen (2019) Liquid Metal Application for Continuously Tunable Frequency Reconfigurable Antenna, Proceedings of the 13th European Conference on Antennas and Propagation (EuCAP 2019) Institute of Electrical and Electronics Engineers (IEEE)
This paper presents two different designs for frequency reconfigurable antennas capable of continuous tuning. The radiator, for both antenna designs, is a microstrip patch, formed from liquid metal, contained within a microfluidic channel structure. Both patch designs are aperture fed. The microfluidic channel structures are made from polydimethylsiloxane (PDMS). The microfluidic channel structure for the first design has a meander layout and incorporates rows of posts. The simulated antenna provides a frequency tuning range of approximately 118% (i.e. 4.36 GHz) over the frequency range from 1.51 GHz to 5.87 GHz. An experimental result for the fully filled case shows a resonance at 1.49 GHz (1.3% error compared with the simulation). Experienced rheological behavior of the liquid metal necessitates microfluidic channel modifications. For that reason, we modified the channel structure used to realise the radiating patch for the second design. Straight channels are implemented in the second microfluidic device. According to simulation the design yields a frequency tuning range of about 77% (i.e. 3.28 GHz) from 2.62 GHz to 5.90 GHz.
Mao Chunxu, Khalily Mohsen, Xiao Pei (2019) Integrated Design of Dual-Band Antenna with Uni-/Omni-Directional Radiations, Proceedings 14th European Conference on Antennas and Propagation IEEE
A multifunctional antenna with diverse radiation
patterns in different frequency bands (2.45/5.8 GHz) is
presented in this paper. The antenna has a low profile but
exhibits an omni-directional radiation pattern in the low-band
operation and uni-directional pattern in the high-band
operation. For the high-band operation, a 2 × 2 patch arrays
are designed by employing a out-of-phase feeding method. The
low-band operation with the omni-directional pattern is
achieved by exciting four open-ended slots in-phase. The four
slots are slit in the ground of the high-band array and in this
way, this footprint of the antenna is maintained. The operating
principles of the antenna are studied with the aid of equivalent
circuit model and the current distribution. The antenna is
prototyped and measured, demonstrating good results in terms
of bandwidths, inter-channel isolation, radiation
characteristics.
Arayeshnia Amir, Araghi Ali, Khalily Mohsen, Xiao Pei, Tafazolli Rahim (2020) Trapped Microstrip-Ridge Gap Waveguide for Standalone Millimeter Wave Structures, EUCAP 2020
This paper presents a novel design of trapped microstrip-ridge gap waveguide by using partially filled air gaps in a conventional microstrip-ridge gap waveguide. The proposed method offers an applicable solution to obviate frustrating assembly processes for standalone high-frequency circuits employing the low temperature co-fired ceramics technology which supports buried cavities. To show the practicality of the proposed approach, propagation characteristics of both trapped microstrip and microstrip-ridge gap waveguide are compared first. Then, a right-angle bend is introduced, followed by designing a power divider. These components are used to feed a linear 4-element array antenna. The bandwidth of the proposed array is 13 GHz from 64~76 GHz and provides the realized gain of over 10 dBi and the total efficiency of about 80% throughout the operational band. The antenna is an appropriate candidate for upper bands of WiGig (63.72~70.2) and FCC-approved 70 GHz band (71~76 GHz) applications.
Araghi Ali, Khalily Mohsen, Xiao Pei, Tafazolli Rahim (2020) Study on the Location of mmWave Antenna for the
Autonomous Car?s Detection and Ranging Sensors,
EUCAP 2020
The effect of vehicle?s proximity on the radiation
pattern when the RADAR?s antenna is mounted on the body of autonomous cars is analysed. Two directional radiation patterns with different specifications are placed at different locations of a realistic car body model. The simulation is performed based on
ray-tracing method at 77 GHz, the standard frequency for self-driving applications. It is shown that to obtain a robust RADAR sensor, the antenna radiation pattern is better to have relatively higher gain and lower side-lobe-level (SLL), than narrower halfpower-
beamwidth (HPBW) and higher front-to-back (F/B) ratio.
Both academia and industry can benefit from this study.
Araghi Ali, Khalily Mohsen, Xiao Pei, Tafazolli Rahim (2020) Holographic-Based mmW-Wideband Bidirectional
Frequency Scanning Leaky Wave Antenna,
EUCAP 2020
Utilizing the holography theory, a bidirectional
wideband leaky wave antenna in the millimetre wave (mmW)
band is presented. The antenna includes a printed pattern of continuous metallic strips on an Alumina 99:5% sheet, and a surface wave launcher (SWL) to produce the initial reference waves on the substrate. To achieve a bidirectional radiation pattern, the fundamental TE mode is excited by applying a Vivaldi antenna (as the SWL). The proposed holographic-based leaky wave antenna (HLWA) is fabricated and tested and the measured results are aligned with the simulated ones. The antenna has 22:6% fractional bandwidth with respect to the central frequency of 30 GHz. The interference pattern is designed to generate a 15 deg backward tilted bidirectional radiation
pattern with respect to the normal of the hologram sheet. The frequency scanning property of the designed HLWA is also investigated.
Payami Sohail, Khalily Mohsen, Taheri Sohail, Nikitopoulos Konstantinos, Tafazolli Rahim (2020) Channel Measurement and Analysis for Polarimetric
Wideband Outdoor Scenarios at 26 GHz:
Directional vs Omni-Directional,
EUCAP 2020
This paper presents the measurement results and
analysis for outdoor wireless propagation channels at 26 GHz
over 2 GHz bandwidth for two receiver antenna polarization
modes. The angular and wideband properties of directional
and virtually omni-directional channels, such as angular spread,
root-mean-square delay spread and coherence bandwidth, are
analyzed. The results indicate that the reflections can have a significant
contribution in some realistic scenarios and increase the
angular and delay spreads, and reduce the coherence bandwidth
of the channel. The analysis in this paper also show that using
a directional transmission can result in an almost frequencyflat
fading channel over the measured 2 GHz bandwidth; which
consequently has a major impact on the choice of system design
choices such as beamforming and transmission numerology.
Alqurashi Khaled, Kelly James R., Wang Zhengpeng, Crean Carol, Mittra Raj, Khalily Mohsen, Gao Yue (2020) Liquid Metal Bandwidth-Reconfigurable Antenna, IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS 19 (1) pp. 218-222 Institute of Electrical and Electronics Engineers
This letter shows how slugs of liquid metal can be used to connect/disconnect large areas of metalization and achieve a radiation performance not possible by using conventional switches. The proposed antenna can switch its operating bandwidth between ultrawideband and narrowband by connecting/disconnecting the ground plane for the feedline from that of the radiator. This could be achieved by using conventional semiconductor switches. However, such switches provide point-like contacts. Consequently, there are gaps in electrical contact between the switches. Surface currents, flowing around these gaps, lead to significant back radiation. In this letter, the slugs of a liquid metal are used to completely fill the gaps. This significantly reduces the back radiation, increases the bore-sight gain, and produces a pattern identical to that of a conventional microstrip patch antenna. Specifically, the realized gain and total efficiency are increased by 2 dBi and 24%, respectively. The antenna has potential applications in wireless systems employing cognitive radio (CR) and spectrum aggregation.
Beam steering impairments adversely affect antenna performance at wider steering angles. Scan loss degrades the antenna gain, and hence the link budget. To address this problem, antennas designs based on phased arrays, lenses, and transmitarrays are proposed. Millimetre wave beamforming within 5G cell sectors is considered as an application scenario. Feed networks for an 8-element phased array, operating at 28 GHz, were designed using unequal power dividers. A Taylor amplitude distribution was applied to reduce the sidelobe level to -15.2 dB at boresight. Prototypes were fabricated in microstrip, using meanders to steer the beam. Cascaded Fresnel lenses were placed around the array, to enhance the gain. By tilting the lenses to align with the steered beam, the lenses increased the gain by 3.19 dB at ±52°, and by a further 1.5 dB when repositioned in simulation. Asymmetric amplitude distributions were applied to the array to prevent the main lobe from splitting. Diffraction theory was used to analyse the focusing properties of the lens arrangement. The fabricated prototype exhibited a bandwidth of 1.75 GHz. Antennas were designed and simulated for line-of-sight MIMO scenarios. An envelope correlation coefficient below 0.0356 was maintained for both designs. 2D SISO beam steering was also simulated. Achievable data rates were estimated from the antenna parameters, and the effect of interference was evaluated. Scan loss was mitigated for the two antenna rows within the focal region. A conformal transmitarray was designed, using 1-bit unit cells based on crossed-slots. A unit cell placement rule was proposed to reduce the number of electronically reconfigurable cells by 59%. A measured gain of 12.5 dBi and a simulated total efficiency of 75% were obtained at boresight and the maximum steering angle of 53°. By combining reconfigurable lenses with phased arrays, the focusing directivity is able to mitigate scan loss.
Chu Zheng, Hao Wanming, Xiao Pei, Khalily Mohsen, Tafazolli Rahim (2020) Resource Allocations for Symbiotic Radio with Finite Block Length Backscatter Link, IEEE Internet of Things Journal Institute of Electrical and Electronic Engineers
This paper exploits a generic downlink symbiotic radio (SR) system, where a Base Station (BS) establishes a direct (primary) link with a receiver having an integrated backscatter device (BD). In order to accurately measure the backscatter link, the backscattered signal packets are designed to have ?nite block length. As such, the backscatter link in this SR system employs the ?nite block-length channel codes. According to different types of the backscatter symbol period and transmission rate, we investigate the non-cooperative and cooperative SR (i.e., NSR and CSR) systems, and derive their average achievable rate of the direct and backscatter links, respectively. We formulate two optimization problems, i.e., transmit power minimization and energy ef?ciency maximization. Due to the non-convex property of these formulated optimization problems, the semide?nite programming (SDP) relaxation and the successive convex approximation (SCA) are considered to design the transmit beamforming vector. Moreover, a low-complexity transmit beamforming structure is constructed to reduce the computational complexity of the SDP relaxed solution. Finally, the simulation results are demonstrated to validate the proposed schemes.
Khan Shahid, Ali Hazrat, Khalily Mohsen, Shah Syed Usman Ali, Kazim Jalil Ur Rehman, Ali Haider, Tanougast Camel (2020) Miniaturization of Dielectric Resonator Antenna by Using Artificial Magnetic Conductor Surface, IEEE Access 8 pp. 68548-68558 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
In this work, a dielectric resonator antenna (DRA) is miniaturized by using Artificial Magnetic conductor (AMC) surface without disturbing other important parameters. The design has three main features: (i) simple micro-strip line feeding, (ii) use of parasitic metallic strip to achieve impedance matching, and (iii) use of AMC surface for design miniaturization. The miniaturization is performed for dielectric resonator antenna at 3.5 GHz. Without changing the basic characteristic of the antenna such as gain, resonance frequency and efficiency, the size of the antenna was reduced by 85%. The AMC surface and DRA both are positioned on the FR4 substrate. The AMC surface consists of small patches of copper. DRA is mounted on the AMC surface, which significantly reduces the overall DRA volume. Nine AMC patches were introduced with a small gap between them. AMC patches were shorted with the ground metal with the help of small metallic vias. For an overall performance analysis, the design was fabricated, and measured results were taken. The fabricated design covers a bandwidth of 180 MHz for ?10 dB reference value of the reflection coefficient, which is mainly used for 5G wireless application. The design has 14.2% impedance bandwidth. Based on the analysis made for the proposed design, it is found that this simple technique highly reduces the DR volume (85%) and ground surface (15.5%) while maintaining the overall performance of the square DRA.
Payami Sohail, Khalily Mohsen, Loh Tian Hong, Nikitopoulos Konstantinos (2020) Hybrid Beamforming with Switches and Phase Shifters over Frequency-Selective Channels, IEEE Wireless Communications Letters pp. 1-1 Institute of Electrical and Electronics Engineers (IEEE)
The recent studies on hybrid beamformers with a combination of switches and phase shifters indicate that such methods can reduce the cost and power consumption of massive multiple-input multiple-output (MIMO) systems. However, most of the works have focused on the scenarios with frequency-flat channel models. This letter proposes an effective approach for such systems in frequency-selective channels and presents the closed-form expressions of the beamformer and the corresponding sum-rates. Compared to the traditional subconnected structures, our approach with a significantly smaller number of phase shifters results in a promising performance.
Niknam Sajad, Yazdi Mehran, Behboudi Amlashi Salman, Khalily Mohsen (2020) Numerical Performance Analysis of Terahertz Spectroscopy Using an Ultra-Sensitive Resonance-Based Sensor, Frontiers in Physics 8 pp. 1-7 Frontiers Media
A terahertz sensor structure is proposed that can sense any variations in analyte permittivity. The sensor essentially works according to the shifts in the resonance frequencies of its propagated spoof surface plasmonic modes. The proposed structure shows great support for surface plasmon oscillations, which is proved by the calculated dispersion diagram. To achieve this in terahertz frequencies, a metamaterial structure is presented in the form of a structure with two-dimensional periodic elements. Afterward, it is shown that the performance of the sensor can be affected by different parameters such as metal stripe thickness, length of metal stripe, and width of metal stripe as the most influential parameters. Each of the parameters mentioned can directly influence on the electric field confinement in the metal structure as well as the strength of propagation modes. Therefore, two propagation modes are compared, and the stronger mode is chosen for sensing purposes. The primary results proved that the quality factors of the resonances are substantially dependent on certain physical parameters. To illustrate this, a numerical parametric sweep on the thickness of the metal stripe is performed, and the output shows that only for some specific dimensions the electromagnetic local field binds strongly with the metal part. In a similar way, a sweeping analysis is run to reveal the outcome of the variation in analyte permittivity. In this section, the sensor demonstrates an average sensitivity value, ~1,550 GHz/Permittivity unit, for a permittivity range between 1 and 2.2, which includes the permittivity of many biological tissues in the terahertz spectrum. Following this, an analysis is presented, in the form of two contour plots, for two electrical parameters, maximum electric field and maximum surface current, based on 24 different paired values of metal thickness and metal width as the two most critical physical parameters. Using the plotted contour diagrams, which are estimated using the bi-harmonic fitting function, the best physical dimension for the maximum capability of the proposed sensor is achieved. As mentioned previously, the proposed sensor can be applied for biological sensing due to the simplicity of its fabrication and its performance.
Abediankasgari Mohammad, Khalily Mohsen, Danesh Shadi, Xiao Pei, Tafazolli Rahim (2020) Reconfigurable Dielectric Resonator Antenna Using an Inverted U-shaped Slot, Proceedings of the 2020 IEEE International Symposium on Networks, Computers and Communications (ISNCC'20) Institute of Electrical and Electronics Engineers (IEEE)
A novel reconfigurable dielectric resonator antenna (DRA) employed a T-Shaped microstrip-fed structure in order to excite the dielectric resonator is presented. By carefully adjusting the location of the inverted U-shaped slot, switches, and length of arms, the proposed antenna can support WLAN wireless system. In addition, the presented DRA can be proper for cognitive radio because of availability switching between wideband and narrowband operation. The proposed reconfigurable DRA consisting of a Roger substrate with relative permittivity 3 and a size of 20 mm × 30 mm × 0.75 mm and a dielectric resonator (DR) with a thickness of 9 mm and the overall size of 18 mm × 18 mm. Moreover, the antenna has been fabricated and tested, which test results have enjoyed a good agreement with the simulated results. As well as this, the measured and simulated results show the reconfigurability that the proposed DRA provides a dual-mode operation and also three different resonance frequencies as a result of switching the place of arms.
Danesh Shadi, Araghi Ali, Khalily Mohsen, Xiao Pei, Tafazolli Rahim (2020) Millimeter Wave Phased Array Antenna Synthesis Using a Machine Learning Technique for Different 5G Applications, Proceedings of the 2020 IEEE International Symposium on Networks, Computers and Communications (ISNCC'20) Institute of Electrical and Electronics Engineers (IEEE)
A machine learning (ML) technique has been used
to synthesis a linear millimetre wave (mmWave) phased array
antenna by considering the phase-only synthesis approach. For
the first time, gradient boosting tree (GBT) is applied to estimate
the phase values of a 16-element array antenna to generate
different far-field radiation patterns. GBT predicts phases while
the amplitude values have been equally set to generate different
beam patterns for various 5G mmWave transmission scenarios
such as multicast, unicast, broadcast and unmanned aerial vehicle
(UAV) applications.
Hill Tim, Kelly James R., Khalily Mohsen, Brown Tim W.C (2020) Cascaded Fresnel Lens Antenna for Scan Loss Mitigation in Millimeter Wave Access Points, IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION Institute of Electrical and Electronics Engineers
Millimeter wave lens antennas will be essential for future wireless access. Conventionally, they increase the gain in the boresight direction only. In this paper, cascaded Fresnel zone plate lenses are combined with a phased array to increase the gain at wide steering angles of ±52°. The side lenses are tilted to align with the maximum steering angle, and cascaded to increase the focusing gain. The inner lenses increase the gain by 2.45 dB at boresight, and by 3.19 dB at the maximum steering angle. When the side lenses are repositioned, the simulated focusing gain increases to 4.69 dB. Asymmetric amplitude distributions are proposed to prevent the main lobe from splitting. An 8-dement 7-lens prototype operating at 28 GHz achieved a gain from 12.96 dBi to 15.35 dBi with a bandwidth of at least 1.3 GHz for all measured beam directions. The maximum measured azimuthal beamwidth was 27°. A design procedure and a theoretical analysis of diffraction through the lenses are provided. By increasing the SNR, this beamfonning antenna could improve the coverage of 3-sector 5G microcell base stations, and support gigabit wireless links for vehicular, rail, and satellite communications.
Mao Chun Xu, Khalily Mohsen, Zhang Long, Xiao Pei, Sun Yuhang, Werner Douglas H. (2020) Compact Patch Antenna with Vertical Polarization and Omni-Directional Radiation Characteristics, IEEE Transactions on Antennas and Propagation Institute of Electrical and Electronics Engineers
This communication proposes a compact, low-profile patch
antenna with omni-directional radiation pattern and vertical polarization. A pair of shorted patches are excited in-phase to achieve the omni-directivity and the vertical polarization, simultaneously. The
principle is to excite two back-to-back arranged shorted patches to generate symmetrical electric field (E-field) distributions normal to the ground plane. Analytical study on how to generate the omni-directional radiation pattern is carried out. Base on this study, we found the spacing
in-between the two patches have little influence on the radiation characteristics, which provides another flexibility in the design. In addition, the shape of the patch and the corresponding field distribution
are investigated to further improve the omni-directivity. To improve the impedance bandwidth, resonant structures are inserted in-between the patches, producing the 2nd order response in frequency. The antenna has been fabricated and characterized, and the measured results are in a
reasonable agreement with the simulations, showing that the proposed antenna is suitable for potential surface-mount wireless applications.