Dr James Kelly

Lecturer in Microwave Antennas

MEng (Hons), PhD, PG Cert ULT, MIEEE

j.r.kelly@surrey.ac.uk

Wednesdays 1-2pm

About

Biography

I am a Lecturer (Assistant Professor) in Microwave Antennas within the Department of Electrical and Electronic Engineering and a member of the Institute for Communication Systems (ICS) at the University of Surrey. I joined the University of Surrey in October 2013. Before this I was a Lecturer at Anglia Ruskin University in Cambridge, England. From 2007 to 2012 I worked as a research fellow/associate at Loughborough University, as well as the Universities of Birmingham, Durham, and Sheffield.

I have approximately 2.5 years of industry experience. From 1999 to 2000, I worked for the International Rail Vehicle Consultancy, Interfleet Technology. During 2001 and 2012, respectively I worked within the Rolls-Royce Strategic Research Centre and at Airbus Defence and Space Ltd (then EADS Astrium).

I received the Master's degree in electronic and electrical engineering (2002) and the Ph.D. degree in microwave filters (2007) from Loughborough University, Leicestershire, England.

I have published over 80 academic papers in peer reviewed international journals and conference proceedings. In 2009 I delivered the key note speech at an IET seminar in London. The topic of the seminar was “Adaptable and tunable antenna technology for handsets and mobile computing products”. I also co-chaired a session on adaptive antennas for software defined radio during the 2009 IEEE International Symposium on Antennas and Propagation, in Toronto, Canada.

I am a member of the Institution of Engineering and Technology (IET), the Institute of Electrical and Electronics Engineers (IEEE), and the IEEE Industrial Electronics Society. I frequently act as a referee for various international journal publications, including the IEEE Transactions on Antennas and Propagation, the IEEE Antennas and Wireless Propagation Letters, and the IET Microwaves, Antennas & Propagation.

Areas of specialism

Microwave Antennas

University roles and responsibilities

Additional Learning Support (ALS) Tutor for Electronic Engineering

Research

Research interests

My main research focus is reconfigurable microwave and millimeter wave antennas. Other research interests: small antennas, handset antennas, millimeter wave antennas, ultra-wideband antennas, body-worn antennas, reconfigurable microwave filters, metamaterials.

Research projects

Informed RF for 5G and Beyond (EP/N020391/1)

Project seeks to devise high performance communication systems using a holistic design approach uniting Microwave Engineering with Signal Processing and considering RF imparements as degrees-of-fredom to be exploited in the design process

Metrology for 5G Communications

The overall objective of the project is to develop traceable metrology required by 5G communications, to improve the associated measurement uncertainties and to provide metrological support on activities related to standardisation for 5G.

Millimeter-wave Antennas and Components for Future Mobile Broadband Networks: MILLIBAN (EP/P008380/1)

Project seeks to develop antennas and components for future generations of mobile communication systems

Teaching

Antennas and Propagation (EEEM006)

Laboratories, Design & Professional Studies II (EEE1028)

Laboratories, Design & Professional Studies III (EEE2036)

Publications

Idris IH, Hamid MR, Jamaluddin MH, Rahim MKA, Kelly JR, Majid HA (2014) Single-, dual- and triple-band frequency reconfigurable antenna, Radioengineering23(3)pp. 805-811

The paper presents a frequency reconfigurable slot dipole antenna. The antenna is capable of being switched between single-band, dual-band or triple-band operation. The antenna incorporates three pairs of pindiodes which are located within the dipole arms. The antenna was designed to operate at 2.4 GHz, 3.5 GHz and 5.2 GHz using the aid of CST Microwave Studio. The average measured gains are 1.54, 2.92 and 1.89 dBi for low, mid and high band respectively. A prototype was then constructed in order to verify the performance of the device. A good level of agreement was observed between simulation and measurement.

Borja A, Kelly JR (2015) Reconfigurable Microwave Circuit Based on a Single Triangular Microstrip Patch, 2015 IEEE INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION & USNC/URSI NATIONAL RADIO SCIENCE MEETINGpp. 2253-2254 IEEE

Kelly JR, Borja AL (2014) Hardware block for use in programmable microwave function arrays, Electronics Letters50(15)pp. 1076-1077

DOI: 10.1049/el.2014.0970

Ultimately, the research presented will lead to the development of a microwave integrated circuit that is analogous to a field programmable gate array. An early step towards the development of this technology is presented. Specifically, a 3-port device, based on a single resonant element, namely a microstrip square patch, is described. The device operates simultaneously as a filter and an antenna. Filter performance is obtained between ports 1 and 2. Antenna performance is obtained on port 3. © 2014 The Institution of Engineering and Technology.

Wang Z, Kelly JR, Hall PS, Borja AL, Gardner P (2014) Reconfigurable parallel coupled band notch resonator with wide tuning range, IEEE Transactions on Industrial Electronics61(11)pp. 6316-6326

DOI: 10.1109/TIE.2014.2311386

This paper presents a new form of reconfigurable band notch resonator with a wide tuning range. The whole structure consists of a through line and two parallel coupled resonators. This paper presents an accurate lumped element equivalent circuit for the parallel coupled resonator. The mechanism giving rise to the wide tuning range is also investigated. The first harmonic of the fundamental stop-band is analyzed and compared with that of the varactor-coupled resonator. Measurement results show that the stop-band of the filter can be tuned from 0.6 to 4.0 GHz. This is achieved by varying the capacitance of two pairs of varactor diodes. The stop-band tuning range is restricted by the capacitance variation which can be achieved using the varactor diode. The potential tuning range of a filter based on this resonator is greater than one decade. © 1982-2012 IEEE.

Wei JD, Chen XZ, Kelly JR, Cui YZ (2015) Blast furnace stockline measurement using radar,IRONMAKING & STEELMAKING42(7)pp. 533-541 MANEY PUBLISHING

DOI: 10.1179/1743281214Y.0000000258

Kelly JR, Borja A (2015) Reconfigurable Microwave Circuit Based on Three Triangular Microstrip Patches, 2015 IEEE INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION & USNC/URSI NATIONAL RADIO SCIENCE MEETINGpp. 2251-2252 IEEE

Chen G, Xiao Pei, Kelly James, Li B, Tafazolli Rahim (2017) Full-Duplex Wireless-Powered Relay in Two Way Cooperative Networks,IEEE Access5pp. 1548-1558 IEEE

DOI: 10.1109/ACCESS.2017.2661378

This paper investigates a full duplex wirelesspowered two way communication networks, where two hybrid access points (HAP) and a number of amplify and forward (AF) relays both operate in full duplex scenario. We use time switching (TS) and static power splitting (SPS) schemes with two way full duplex wireless-powered networks as a benchmark. Then the new time division duplexing static power splitting (TDD SPS) and full duplex static power splitting (FDSPS) schemes as well as a simple relay selection strategy are proposed to improve the system performance. For TS, SPS and FDSPS, the best relay harvests energy using the received RF signal from HAPs and uses harvested energy to transmit signal to each HAP at the same frequency and time, therefore only partial self-interference (SI) cancellation needs to be considered in the FDSPS case. For the proposed TDD SPS, the best relay harvests the energy from the HAP and its self-interference. Then we derive closed-form expressions for the throughput and outage probability for delay limited transmissions over Rayleigh fading channels. Simulation results are presented to evaluate the effectiveness of the proposed scheme with different system key parameters, such as time allocation, power splitting ratio and residual SI.

Kelly JR (2015) PIFA with Reconfigurable Frequency Bandwidth, 2015 IEEE INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION & USNC/URSI NATIONAL RADIO SCIENCE MEETINGpp. 2255-2256 IEEE

Uchendu Iyemeh Egwenike, Kelly James (2017) Ultrawide isolation bandwidth Compensated Power Divider for UWB applications,Microwave and Optical Technology Letters59(12)pp. 3177-3180 John Wiley & Sons

DOI: 10.1002/mop.30899

This article presents design analyses for achieving an ultrawide isolation bandwidth compensated power divider (CPD). The CPD offers improvement in complexity, size and insertion when compared with alternative techniques for increasing isolation bandwidth. A prototype CPD with -15dB isolation bandwidth of 114% was fabricated and measured to validate the analyses.

Wang Z, Hall P, Kelly JR, Gardner P (2017) Wideband Frequency Domain and Space Domain Pattern Reconfigurable Circular Antenna Array,IEEE Transactions on Antennas and Propagation65(10)pp. 5179-5189 IEEE

DOI: 10.1109/TAP.2017.2740969

This paper presents a wideband circular antenna array with a frequency domain and space domain reconfigurable radiation pattern. A wideband circular array antenna is designed with omni-directional radiation pattern, in azimuth direction, throughout the whole frequency band. The antenna array consists of eight TEM horn antennas. The antenna array exhibits an omni-directional azimuthal radiation pattern when all eight ports are excited with signals of the same magnitude and phase. The antenna array is fed through eight reconfigurable bandstop filters and a power splitter. This enables it to provide an omni-directional azimuthal pattern along with a single directional pattern null in a given spatial direction and at a certain frequency. Both the spatial direction and the frequency can be altered. The antenna works from 0.8 GHz to 3.0 GHz. The antenna array will be useful in combating interference in wideband communication systems. It will also be of value in surveillance military applications.

da Costa I, Filgueiras H, Kelly J, Arismar Cerqueira S, Xiao P (2018) Mechanical Beam Steering Circular Patch Antenna,EuCAP 2018 Proceedings

This work reports preliminary results and a prototype of an innovative mechanical beam steering circular patch antenna for 5G indoor cellular access networks with sub6 GHz operation. The beam steering is achieved using 18 screws installed around the circular patch radiator, working as a reflector by proper managing the screws position and height. The new antenna can steer its main beam over 360º in azimuth plane and from -30º to 30º in the elevation plane with gain up to 8.01 dBi at 4.6 GHz.

Allayioti Marion, Kelly James R., Mittra Raj (2018) Beam and Polarisation Reconfigurable Microstrip Antenna Based on Parasitics,Microwave and Optical Technology Letters60(6)pp. 1460-1464 Wiley

DOI: 10.1002/mop.31184

This paper presents a dual-notch polarization and beam reconfigurable microstrip antenna. It uses parasitics which incorporate switches to steer its beam away from boresight and dual-notches which, again, incorporate switches to reconfigure between linear and circular polarization. The antenna is a low profile microstrip patch antenna which only uses a single feed, allowing it to be compact and simple in terms of its structure.

Alqurashi K. Yahya, Filgueiras H.R.D., da Costa I. F., Cerqueira S. Jr. Arismar, Xiao Pei, Chen Zhe, Wong Hang, Kelly J.R. (2018) Millimeter Wave Beam Steerable/Reconfigurable Liquid Metal Array Antenna,Proceedings of ICEAA - IEEE APWC - FEM 2018pp. 814-815 Institute of Electrical and Electronics Engineers (IEEE)

DOI: 10.1109/APWC.2018.8503677

Users within mobile networks require ever increasing data rates. However, the frequency spectrum, reserved for mobile networks, is highly saturated. The millimeter wave spectrum, by contrast is relatively under utilised. Nonetheless, this area of the spectrum suffers from higher propagation losses, necessitating the use of highly directional antennas. To support mobility these antennas require beam steering capabilities. For several applications wide beam scanning capability is required. A valuable approach for increasing the beam scanning range is to use element factor plus array factor control [1]. Although several authors have presented designs based on this approach the lobe performance of those antennas is generally quite poor. In this paper we seek to address that issue.

Borja A. L., Kabiri Yasin, Belenguer A., Kelly J. R. (2018) Programmable Multi-Functional RF/Microwave Circuit for Antenna and Filter Operation,IEEE Transactions on Antennas and Propagation66(8)pp. 3865-3876 Institute of Electrical and Electronics Engineers (IEEE)

DOI: 10.1109/TAP.2018.2835728

This paper describes a multi-functional microwave device that can be reconfigured to behave either as a filter or an antenna. The device is based around a single resonant element, referred to as a building block element that is connected to 4 ports. The resonant element is a microstrip square patch working in the 2.45 GHz unlicensed Industrial Scientific and Medical (ISM) band used for IEEE 802.11 WiFi. The proposed building block is simple in its design and construction. The paper also presents devices composed of three building blocks, which can realize more complex filtering and antenna mode performance. In addition, PIN diodes have also been incorporated into the devices in order to facilitate electronic control. Measured results, pertaining to fabricated prototypes, show that filter and antenna operation can be achieved, in the same device at a frequency of around 2.45 GHz with acceptable insertion loss and efficiency. In the future, it is anticipated that this could lead to a new paradigm, namely a device that is analogous to a field programmable gate array (FPGA) operating in the microwave frequency regime.

Kelly James R., Tanha Mandana Ardeshir (2018) Reconfigurable 26GHz Liquid Metal Antenna Capable of Low Loss Continuous Beam Steering,Proceedings of the 2018 IEEE Conference on Antenna Measurements and Applications, 3-6 September 2018, Västerås, Sweden Institute of Electrical and Electronics Engineers (IEEE)

For this first time this paper presents a concept for a high gain millimeter wave beam steerable antenna that supports continuous steering over a 360° scan range and promises to yield extremely low power losses. The concept does not require phase shifters which suffer from high insertion losses at millimeter wave frequencies or mechanical movement, in the conventional sense, which has the disadvantages of poor reliability and slow response times due to high inertia.

Allayioti Marion (2018) Beam reconfigurable microstrip antennas based on parasitics with linear and circular polarisation capability.,

Millimetre wave beam and polarization reconfigurable antennas for future wireless communications are investigated in this thesis. The millimetre wave frequency spectrum has recently attracted large attention from researchers and the industry of wireless communications. Millimetre wave frequencies is considered to be the frequency spectrum between 30 GHz and 300 GHz. However, the industry considers the spectrum above 10 GHz as millimetre wave, due to the fact that it shows similar propagation characteristics with the spectrum above 30 GHz. The aforementioned spectrum of frequencies offers a lot of advantages compared to lower frequency spectrum, due to the fact that it offers large and mostly unexploited bandwidths. The need for very high data rates, in future wireless communications, increases the need for bandwidth. Millimetre wave frequencies can be used to fulfill future bandwidth demands. Although millimeter wave frequencies offer several advantages and good potential for future wireless communications, they also impose several challenges. This thesis discusses the need for highly directive and beam reconfigurable antennas for such high frequencies. It also discusses how an antenna design can benefit from being circularly polarised for several wireless communication applications and how antennas for future wireless communications must be able to reconfigure several parameters, without compromising the performance, cost and size, giving the exibility to a wireless terminal to operate in several different modes. This thesis proposes novel reconfigurable antennas for portable devices, which can be used at millimetre wave frequencies, and which offer high gain, wide steering range, low scan loss and multi-parameter reconfigurability; essential characteristics that antennas designed for future wireless communications should offer.

Hill Timothy A., Kelly James R. (2019) 28 GHz Taylor Feed Network for Sidelobe Level Reduction in 5G Phased Array Antennas,Microwave and Optical Technology Letters61(1)pp. 37-43 Wiley

DOI: 10.1002/mop.31509

This paper presents a design procedure for a phased array feed network. The procedure is validated by designing and fabricating a set of 28 GHz 8-element beam steerable antennas. Within the feed, a Taylor n-bar amplitude taper is implemented using unequal power dividers. At boresight, the taper reduced the sidelobe level by 2.84 dB to -15.2 dB. Beam steering from 0° ? 48° is achieved using meanders. An empirical formula for the meander widths is proposed, enabling independent control of amplitude and phase. Empirical formulae for the initial parameters of the unequal dividers are also proposed. The wide transmission lines in this feed network are compatible with low-cost PCB fabrication techniques.

Kabiri Yasin, Borja Alejandro L., Kelly James, Xiao Pei (2019) A technique for MIMO antenna design with flexible element number and pattern diversity,IEEE Accesspp. 1-1 Institute of Electrical and Electronics Engineers (IEEE)

DOI: 10.1109/ACCESS.2019.2910822

This paper presents a new technique for designing Multiple Input Multiple (MIMO) Output antennas having pattern diversity. Massive MIMO is expected to form part of 5G communications and will require antennas having a very large number of elements. However, due to the size limitation, it is highly challenging to preserve high isolation between the ports. Pattern diversity technique are also highly desirable and can facilitate MIMO systems with diversity gain. However, achieving that within a compact antenna where there is limited space between the elements is also challenging. In this paper a technique is introduce and applied to 4-element and 6-element MIMO antennas. This technique can improve the isolation between the ports and it also yields pattern diversity for MIMO antennas with various numbers of elements. The technique is verified via experimental measurement.

Dias Filgueiras Hugo Rodrigues, Kelly James R., Xiao Pei, da Costa I. F., Cerqueira S. Jr. Arismar (2019) Wideband Omnidirectional Slotted-Waveguide Antenna Array Based on Trapezoidal Slots,International Journal of Antennas and Propagation Hindawi

This manuscript presents a novel approach for designing wideband omnidirectional slotted-waveguide antenna arrays, which is based on trapezoidal-shaped slots with two different electrical lengths, as well as a twisted distribution of slot groups along the array longitudinal axis. The trapezoidal section is formed by gradually increasing the slot length between the waveguide interior and exterior surfaces. In this way, a smoother impedance transition between waveguide and air is provided in order to enhance the array operating bandwidth. Additionally, we propose a twisting technique, responsible to improve the omnidirectional pattern, by means of reducing the gain ripple in the azimuth plane. Experimental results demonstrate 1.09 GHz bandwidth centered at 24 GHz (4.54% fractional bandwidth), gain up to 14.71 dBi over the operating bandwidth and only 2.7 dB gain variation in the azimuth plane. The proposed antenna array and its enabling techniques present themselves as promising solutions for mm-wave application, including 5G enhanced mobile broadband (eMBB) communications.

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.

Alqurashi Khaled Yahya, Kelly James R. (2018) Continuously tunable frequency reconfigurable liquid metal microstrip patch antenna,Proceedings of the 2017 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meetingpp. 909-910 Institute of Electrical and Electronics Engineers (IEEE)

DOI: 10.1109/APUSNCURSINRSM.2017.8072497

This paper presents a continuously tunable microstrip patch antenna formed from liquid metal (eutectic gallium indium). The concept and design of the antenna have been validated through computer simulation. The antenna is capable of reconfiguring its operating frequency in a continuous manner. The proposed design consists of a microstrip patch which is excited via aperture coupling. The EGaIn liquid metal is contained within a microfluidic channel which is formed within a polydimethylsiloxane (PDMS) substrate. Frequency tuning is achieved by altering the amount of fluid within the channel to vary the electrical length of the antenna. The simulated antenna provides a frequency tuning range of approximately 104% and a total usable spectrum (S11 <; -10 dB) of 105%. The antenna can be tuned from 3.21 GHz to 10.12 GHz. The maximum realized gain is 6.9 dBi and the total efficiency is 82%.

Hill Timothy A. (2020) Millimetre wave lens and transmitarray antennas for scan loss mitigation,

DOI: 10.15126/thesis.00853272

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.

Additional publications

Journal Papers

[1] James R. Kelly, Titos Kokkinos, and Alexandros P. Feresidis, “Analysis and design of sub-wavelength resonant cavity type 2-D leaky-wave antennas,” IEEE Trans. Antennas and Propag., vol. 56, no. 9, pp. 2817-25, Sept. 2008.

[2] James R. Kelly and Rob D. Seager, “Lumped element equivalent circuit for the cymbal resonator bandpass filter,” Microw. and Optical Tech. Lett., vol. 50, no. 9, pp. 2381–4, Jun. 2008.

[3] James R. Kelly and Rob D. Seager, “Approximating the Eigenvalues of Planar Isosceles Triangular Patch Resonators using Galerkin’s Method,” Microw. and Optical Tech. Lett., vol. 51, no. 2, pp. 306 – 11, Dec. 2008.

[4] James R. Kelly and Rob D. Seager, “A Compact Triangular Patch Bandpass Filter,” Microw. and Optical Tech. Lett., vol. 51, no. 2, pp. 566-70, Dec. 2008.

[5] James R. Kelly and Rob D. Seager, “Novel Metallodielectric Electromagnetic Bandgap Structure,” Microw. and Optical Tech. Lett., vol. 51, no. 2, pp. 311–5, Dec. 2008.

[6] James R. Kelly, and Alexandros P. Feresidis, “Array antenna with increased element separation based on a Fabry-Perot resonant cavity with AMC Walls,” IEEE Trans. Antennas and Propag., vol. 57, no. 3, pp. 682-7, March 2009.

[7] F. Ghanem, P. Hall, and J. Kelly, “A two-port frequency reconfigurable antenna for cognitive radios” IET Electron. Lett., vol. 45, no. 11, pp. 534-6, May 21, 2009.

[8] Z. H. Hu, C. T. P. Song, J. Kelly, P. S. Hall, and P. Gardner, “Wide tunable dual-band reconfigurable antenna,” IET Electron. Lett., vol. 45, no. 22, pp.1109-10, Oct. 22, 2009.

[9] J.R. Kelly, P.S. Hall, P. Gardner, and F. Ghanem, “Integrated narrow/band-notched UWB antenna,” IET Electron. Lett., vol. 46, no. 12, pp. 814- 16, Jun. 2010.

10] Z.P. Wang, J. Kelly, P.S. Hall, “Reconfigurable bandstop filter with wide tuning range,” IET Electron. Lett., vol. 46, no. 11, pp. 771-2, May 2010.

[11] Z.H. Hu, P.S. Hall, J.R. Kelly and P. Gardner, “Wideband Conical Monopole Antenna with Frequency Band Notched Behaviour,” IET Electron. Lett., vol. 46, no. 23, pp. 1542-3, Nov. 2010.

[12] J.R. Kelly, and P.S. Hall, “Integrated Wide-Narrow Band Antenna for Switched Operation,” Microw. and Optical Tech. Lett., vol. 52, no. 8, pp. 1705–7, Aug. 2010.

13] J.R. Kelly, PS Hall, “Reconfigurable ultra‐wideband slot antenna,” Microwave and Optical Technology Letters vol. 52, no. 9, pp. 1988-90, Jun. 2010.

[14] Z.H. Hu, P.S. Hall, J.R. Kelly, and P. Gardner, “Novel UWB Pyramidal Monopole Antenna with Wide Tunable Band Notched Behaviour” IET Electron. Lett., vol. 46, no. 24, pp. 1588-90, 2010.

[15] J.R. Kelly, P.S. Hall, P. Gardner, “Ultra-Wideband Antenna with On/Off Band-Notch Control” Microw. and Optical Tech. Lett., vol. 52, no. 12, pp. 2743–46, Sept. 2010.

[16] A.L. Borja, J.R. Kelly, Q. Liu, P.S. Hall, and Z.H.S. Hu, “Dipole Antenna with Left-Handed Loading Operating at a Zero Order Mode,” Progress In Electromag. Research C, vol. 19, pp. 85-92, 2011.

[17] James R. Kelly, Peter S. Hall, Peter Gardner, “Band-Notched Ultra-Wideband Antenna Incorporating a Microstrip Open-Loop Resonator,” IEEE Trans. Antennas and Propag., vol. 59, no. 8, pp. 3045-8, 10 May 2011.

[18] Elham Ebrahimi, James R. Kelly, and Peter S. Hall, “Integrated Wide-Narrowband Antenna for Multi-Standard Radio,” IEEE Trans. Antennas and Propag., vol. 59, no. 7, pp. 2628-35, 2011.

[19] ZH Hu, PS Hall, JR Kelly, P Gardner, “Improved band‐notched wideband conical monopole antenna,” Microwave and Optical Technology Letters, vol. 53, no. 8, pp. 1825-9, 2011.

[20] J.R. Kelly, P. Song, P.S. Hall, and A.L. Borja, “Reconfigurable 460 MHz to 12 GHz Antenna with Integrated Narrowband Slot” Progress In Electromagnetics Research C, vol. 24, pp. 137-45, 2011.

[21] Z.P. Wang, P.S. Hall, J. Kelly, and P. Gardner, “TEM horn antenna with multi-pole band notch characteristic,” IET Electron. Lett., vol. 47, no. 25, pp.1357–8, 8 Dec. 2011.

[22] Z.H. Hu, J.R. Kelly, P.S. Hall, “Wideband Conical Monopole Antenna with Integrated Stopband Filter” Progress In Electromagnetics Research C, Vol. 27, pp. 223-38, 2012

[23] Alejandro L. Borja, Angel Belenguer, Joaquin Cascon and James R. Kelly, “A Reconfigurable Passive UHF Reader Loop Antenna for Near-Field and Far-Field RFID Applications,” IEEE Antennas and Wireless Propagation Letters, vol. 11, pp. 580–3, 2012.

[24] Zhengpeng Wang, P. S. Hall, James R. Kelly and Peter Gardner, “Microstrip Tunable Bandpass Filter with the Co-linear Resonators,” International Journal of Antennas and Propagation, 2013.

[25] Alejandro Lucas Borja, James R. Kelly, Fuli Zhang, and Eric Lheurette, “Editorial: Metamaterials,” International Journal of Antennas and Propagation, 2 pages, 2013.

[26] ZP Wang, PS Hall, J Kelly, P Gardner, “Coplanar Waveguide Reconfigurable Bandpass Filter Based on A Varactor Loaded Colinear Resonator,” Microw. and Optical Tech. Lett., vol. 55, no. 10, pp. 2389-93, 2013.

[27] Zhengpeng Wang ; Kelly, J.R. ; Hall, P.S. ; Borja, A.L. ; Gardner, P., "Reconfigurable Parallel Coupled Band Notch Resonator With Wide Tuning Range," IEEE Trans. on Industrial Electronics, vol. 61, no. 11, pp. 6316-26, Nov. 2014.

[28] Kelly, J.R.; Borja, A.L., "Hardware block for use in programmable microwave function arrays," IET Electronics Letters, vol. 50, no. 15, pp. 1076-7, July 2014.

[29] Kelly, J.R.; Borja, A.L., "Microwave multi-tool" IET Electron. Lett., vol. 50, no. 15, pp. 1035, 2014.

[30] Idris, I. H., Hamid, M.R., Jamaluddin, M.H., Rahim M. K. A., Kelly, J. R., Majid, H.A., "Single-, Dual- and Triple-band Frequency Reconfigurable Antenna", Radioengineering, vol. 23, no. 3, pp. 805-11, 2014.

[31] I.H. Idris, M.R. Hamid, M.H. Jamaluddin, M.K.A. Rahim, J. Kelly, “Slot dipole antenna with single and dual band tuning characteristic”, IET Electron. Lett., vol. 50, no. 21, pp. 1506–7, Oct. 2014.

[32] J Wei, X Chen, Z Wang, J Kelly, P Zhou, “3-Dimension Burden Surface Imaging System with T-shaped MIMO Radar in the Blast Furnace,” ISIJ International. vol. 55 no. 3, pp. 592-9, 2015.

33] J. D. Wei; X. Z. Chen; J. R. Kelly; Y. Z. Cui, "Blast furnace stockline measurement using radar," Ironmaking & Steelmaking. vol. 42, no. 7, pp. 533-41, Aug, 2015.

[34] Sahar Chagharvand, Mohamad Rijal Hamid, Muhammad Ramlee Kamarudin, James R. Kelly, “Wide-to-narrowband reconfigurable Vivaldi antenna using switched-feed technique,” Telecommunication Systems., pp. 1-7, March 2016.

[35] I. Uchendu and J. R. Kelly, "Survey of beam steering techniques available for millimeter wave applications," Progress In Electromagnetics Research B, vol. 68, pp. 35-54, 2016.

[36] S Chagharvand, MR Hamid, MR Kamarudin, JR Kelly, “Wide and multi-band reconfigurable Vivaldi antenna with slot-line feed,” Telecommunication Systems, pp. 1-7, 2016.

[37] C. Gaojie, P. Xiao, Bing Li, J. Kelly, R. Tafazolli, “Full-Duplex Wireless-Powered Relay in Two Way Cooperative Networks,” IEEE Access., pp. 1548–58, Jan. 2017.

[38] Iyemeh E. Uchendu, James R. Kelly, “Ultrawide isolation bandwidth Compensated Power Divider for UWB applications,” Microw. and Optical Tech. Lett., 22nd Sept. 2017.

[39] Z. P. Wang, P. S. Hall, J. R. Kelly, and P. Gardner, “Wideband Frequency Domain and Space Domain Reconfigurable Circular Antenna Array,” IEEE Trans. Antennas and Propag., vol. 65, no. 10, pp. 5179–89, Oct. 2017.

[40] Marion Allayioti, James Kelly, “Beam and Polarisation Reconfigurable Microstrip Antenna Based on Parasitics,” accepted for publication, Microwave and Optical Technology Letters.

Conference Papers

[1] J. Kelly, A. Chauraya, R. Seager, J. Vardaxoglou, “Metallodielectric electromagnetic Bandgap (MEBG) Lumped Element Equivalent Circuit,” in PREP Poster proceedings, University of Hertfordshire, 2004.

[2] J. Kelly, A. Chauraya, R. Seager, J. Vardaxoglou, “Metallodielectric Electromagnetic Bandgap (MEBG) Lumped Element Equivalent Circuit,” in ARMMS, Milton House Hotel, Oxford, 2004.

[3] A. Chauraya, J. Kelly, R. Seager, J. Vardaxoglou, “Frequency Switchable Microstrip Filter for Microwave Frequencies,” in European Microwave Conference, Paris, France, 2006.

[4] J. Kelly, T. Kokkinos, and A. P. Feresidis, “Modelling and Design of Sub-wavelength Metamaterial Resonant Cavity Antennas,” Metamaterials, 2007.

[5] J.R. Kelly, G. Passalacqua, A. P. Feresidis, F. Capolino, M. Albani, Y. C. Vardaxoglou “Dual-Band Leaky Wave Antenna Design,” European Conference on Antennas and Propagation, 2007.

[6] J. Kelly, G. Passalacqua, A. P. Feresidis, F. Capolino, M. Albani, Y. C. Vardaxoglou, “Simulations and Measurements of Dual-Band 2-D Periodic Leaky Wave Antenna,” in Loughborough Antennas and Propagation Conference, Loughborough, UK, 2007.

[7] J. Kelly, and R. Seager, “Slit-Slot Loaded Parallel Coupled-Line Filter,” in Loughborough Antennas and Propagation Conference, Loughborough, UK, 2007.

[8] A. Chauraya, J. Kelly, G. K. Palikaras , C. B. Mulenga, J. A. Flint, A. P. Feresidis and J. C. Vardaxoglou, G. Passalacqua, F. Capolino, and M. Albani, “Planar and Cylindrical Metamaterial Structures for Antenna Applications,” in URSI 2007.

[9] J.R. Kelly, A. P. Feresidis, “Low-Profile High-Gain Sub-Wavelength Resonant Cavity Antennas For WiMax Applications,” in European Conference on Antennas and Propagation, 2007.

[10] J.R. Kelly, G. Passalacqua, A.P. Feresidis, F. Capolino, M. Albani, Y.C. Vardaxoglou, “Dual Frequency Leaky-Wave Antenna Analysis and Design,” in European Conference on Antennas and Propagation (EuCAP), 2007.

[11] P. Gardner, M.R. Hamid, P.S. Hall, J. Kelly, F. Ghanem and E. Ebrahimi, “Reconfigurable Antennas For Cognitive Radio: Requirements And Potential Design Approaches”, in IET Seminar on Wideband, multi-band antennas and arrays for defence or civil applications, London, UK, 2008.

[12] James Kelly and Alexandros Feresidis, “Thin 2-D leaky-wave antenna formed by a double layer periodic array,” in Loughborough Antennas and Propagation Conference, Loughborough, UK, 2008.

[13] J. R. Kelly, E. Ebrahimi, P. S. Hall, P. Gardner, and F. Ghanem, “Combined Wideband and Narrowband Antennas for Cognitive Radio Applications”, in IET Seminar on Cognitive Radio and Software Defined Radio: Technologies and Techniques, London, UK, 2008.

[14] P.S. Hall, P. Gardner, J. Kelly, E. Ebrahimi, M.R. Hamid, and F. Ghanem, “Antenna Challenges in Cognitive Radio,” in ISAP 08, Taipei, Taiwan, 2008.

[15] P.S. Hall, P. Gardner, J. Kelly, E. Ebrahimi, M.R. Hamid, F. Ghanem, F.J. Herraiz-Martinez, D. Segovia-Vargas, “Reconfigurable antenna challenges for future radio systems” in European Conference on Antennas and Propagation, Berlin, 2009.

[16] J. Kelly, P.S. Hall, P. Gardner, “Planar Band-Notched UWB Antenna,” in European Conference on Antennas and Propagation, Berlin, 2009.

[17] J. Kelly, P.S. Hall, P. Gardner, “Integrated Wide-Narrow Band Antenna for Switched Operation,” in European Conference on Antennas and Propagation, Berlin, 2009.

[18] E. Ebrahimi, J. Kelly, P. Hall, “Integrated Wide-Narrowband Antenna for Multi-Standard Radio Systems,” in URSI Festival of Radio Science, Birmingham, UK, 2009.

[19] E. Ebrahimi, J. Kelly, and P.S. Hall, “A Reconfigurable Narrowband Antenna Integrated with Wideband Monopole for Cognitive Radio Applications,” in IEEE International Symposium on Antennas and Propagation, Charleston, SC, USA, 2009.

[20] J.R. Kelly, P.S. Hall, and P. Song, “A Reconfigurable Wideband Handset Antenna Operating from 460MHz to 12GHz,” in IEEE International Symposium on Antennas and Propagation, 2009.

[21] J.R. Kelly, and P.S. Hall, “Reconfigurable Slot Antenna for Cognitive Radio Applications,” in IEEE International Symposium on Antennas and Propagation, Charleston, SC, USA, 2009.

[22] P.S. Hall, P. Gardner, Z. Hu, P. Song, J. Kelly, and M.R. Hamid, “Reconfigurable antennas for wideband wireless systems” in IET seminar on adaptable and tunable antenna technology for handsets and mobile computing products, London, UK, 2009.

[23] C.T.P. Song, Z.H. Hu, J. Kelly, P.S. Hall, and P. Gardner, “Wide Tunable Dual-Band Reconfigurable Antenna for Future Wireless Devices,” in Loughborough Antennas and Prop. Conference, 2009.

[24] Z. H. HU, C. T. P. Song, J. Kelly, P. S. Hall, and P. Gardner, “A Novel Reconfigurable UWB Chassis-Antenna for Future Mobile Terminals,” in URSI Festival of Radio Science, Birmingham, UK, 2009.

[25] J.R. Kelly, K. L. Ford, and R. Langley, “A New Approach for On-Body and Off-Body Communications,” in Loughborough Antennas & Propagation Conference, 2010.

[26] Z.H. Hu, J. Kelly, C.T.P. Song, P.S. Hall, and P. Gardner, “Novel Wide Tunable Dual-Band Reconfigurable Chassis-Antenna for Future Mobile Terminals,” in European Conference on Antennas and Propagation, Barcelona, 2010.

[27] Z.H. Hu, J. Kelly, C.T.P. Song, P.S. Hall, and P. Gardner, “Equivalent Circuit Modeling of Chassis-Antenna with Two Coupling Elements,” in IEEE International Symposium on Antennas and Propagation, Toronto, Ontario, Canada, 2010.

[28] Z.H. Hu, C.T.P. Song, J. Kelly, P.S. Hall, and P. Gardner, “Novel Reconfigurable Dual-Port UWB Chassis-Antenna,” in IEEE International Symposium on Antennas and Propagation, 2010.

[29] Z. P. Wang, P. S. Hall, J. Kelly, and P. Gardner, “TEM Horn Circular Array for Wide Band Pattern Notch Reconfigurable Antenna System,” in Loughborough Antennas & Propagation Conference, Loughborough, UK, 2010.

[30] Z. P. Wang, J. Kelly, and P. S. Hall, “Wideband Reconfigurable Bandstop Filter for Future Wireless Communication,” in Loughborough Antennas & Propagation Conference, 2010.

[31] J. Holopainen, R. Valkonen, O. Kivekäs, J. Ilvonen, L. Martínez, P. Vainikainen, J. R. Kelly, P. S. Hall, “Equivalent Circuit Model-Based Approach on the User Body Effect of a Mobile Terminal Antenna,” in Loughborough Antennas & Propagation Conference, 2010.

[32] Z. H. Hu, P. S. Hall, J.R. Kelly, and P. Gardner, “Novel wideband pyramidal monopole antenna with wide tunable frequency band-notch,” in European Conference on Antennas and Propagation, Rome, Italy, 2011.

[33] Z. H. Hu, P. S. Hall, J.R. Kelly, and P. Gardner, “Wideband Omni Conical Monopole Antenna with High Q Band-Notched Behaviour,” in International Workshop on Antenna Technology (iWAT): Small Antennas, Innovative Structures and Materials, Lisbon, Portugal, 2011.

[34] J. Kelly, L. Ford, R. Langley, “Slotline structure for on/off-body communications at 2.45 GHz,” in European Conference on Antennas and Propagation, 2011.

[35] James R. Kelly, Mikolaj Chwalisz, Sana Salous, “Cognitive Radio: Sensing Engine Sensitivity,” in EURO-COST, Malaga, Spain, 2013.

[36] James K. Kelly, Sana Salous, Mikolaj Chwalisz, “On the Sensitivity of Candidate Cognitive Radio Sensing Engines,” in 1st URSI Atlantic Radio Science Conference, ExpoMeloneras Convention Centre, Gran Canaria, 2015

[37] James R. Kelly, Alejandro Borja, “Reconfigurable Microwave Circuit Based on a Single Triangular Microstrip Patch,” in IEEE AP-S Symposium on Antennas and Propagation and URSI CNC/USNC Joint Meeting, Vancouver, Canada, 2015.

[38] James R. Kelly, Alejandro Borja, “Reconfigurable Microwave Circuit Based on Three Triangular Microstrip Patches,” in IEEE AP-S Symposium on Antennas and Propagation and URSI CNC/USNC Joint Meeting, Vancouver, Canada, 2015.

[39] James R. Kelly, “PIFA with Reconfigurable Frequency Bandwidth,” in IEEE AP-S Symposium on Antennas and Propagation and URSI CNC/USNC Joint Meeting, Vancouver, Canada, 2015.

[40] Iyemeh Uchendu and James Kelly, “Combined Parasitic and Phased Array Reconfigurable Antenna,” in Loughborough Antennas and Propagation Conference, Loughborough, UK, 2015.

[41] Marion Allayioti, James R. Kelly, “Side lobe level reduction for beam steerable antenna design,” in European Conference on Antennas and Propagation, Davos, Switzerland, 2016.

[42] Marion Allayioti, James R. Kelly, “Multiple Parameter Reconfigurable Patch Antenna,” in IEEE AP-S Symposium on Antennas and Propagation and USNC-URSI Radio Science, San Diego, California, USA, 2017.

[43] Khaled Alqurashi, James R. Kelly, “Continuously Tunable Frequency Reconfigurable Liquid Metal Patch Antenna,” in IEEE AP-S Symposium on Antennas and Propagation and USNC-URSI Radio Science, San Diego, California, USA, 2017.

[44] H.R.D. Filgueiras, I. F. da Costa, Arismar Cerqueira S. Jr., R. A. Santos, D. H. Spadoti, James R. Kelly, “Mechanically Reconfigurable Slotted-Waveguide Antenna Array for 5G Networks,” in IEEE International Microwave and Optoelectronics Conference (IMOC), Brazil, 2017.

[45] I.F. da Costa, H.R.D. Filgueiras, J.R. Kelly, Arismar Cerqueira S. Jr., and Pei Xiao, “Mechanical Beam Steering Circular Patch Antenna,” accepted for publication in European Conference on Antennas and Propagation (EuCAP), London, England, 2018.

Book Chapters

[1] Lucas Borja, Alejandro; Kelly, James; Belenguer Martinez, Angel; Cascon Lopez, Joaquin; Boria , Vicente E.: Book title: Metamaterial, Chapter title: “Compact Coplanar Waveguide Metamaterial-Inspired Lines and its Use in Highly Selective and Tunable Bandpass Filters”, Intech, ISBN 979-953-307-563-0.

Patents

[1] “Reconfigurable Antenna” UK application reference GB0918477.1 filed 21st October 2009, published as international application WO2011/048357 and as EP2491613. Patent application still pending in European and US patent offices. Inventors: Peter Song, James Kelly, Peter Hall, Sampson Hu.

[2] “Energy Harvesting Utilizing Self-interface in Wireless Communication Systems “UK application reference GB1419668.7 filed 4th November 2014. Inventors: Bing Li, James Kelly, Gaojie Chen, Pei Xiao, Rahim Tafazolli