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Dr Tim Brown

Lecturer in RF Antennas and Propagation

Qualifications: CEng, PhD, MIET

Email:
Phone: Work: 01483 68 9810
Room no: 15 BA 02

Further information

Biography

Tim re-joined CCSR in January 2007 as a lecturer in RF Antennas and Propagation, before which he was both a student in the same department and then a doctoral candidate graduating in 2004. His PhD thesis was in the area of antennas for mobile terminals. Since then Tim has broadened his research experience in MIMO channel propagation modelling as well as intelligent antenna design.

Research Interests

Antennas and propagation, RF devices for applications including land mobile satellite communications, wireless communication devices, UWB radar, RFID, NFC, localisation techniques and cognitive radio.

Research Collaborations

COST ic1004 - Cooperative Radio Communications for Green Smart Environments - www.ic1004.org

Further details can be found on my personal web page.

Publications

Highlights

  • Brown TWC, Eggers PCF, Olesen K, Pedersen GF. (2010) 'Artificial Wideband Multi User Channels for Rural High Speed Vehicle to Vehicle Links'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, 29 (1), pp. 29-36.
    doi: 10.1109/JSAC.2011.110104
  • Mansor MF, Brown TWC, Evans BG. (2010) 'Satellite MIMO Measurement With Colocated Quadrifilar Helix Antennas at the Receiver Terminal'. IEEE Antennas and Wireless Propagation Letters, 9, pp. 712-715.
    doi: 10.1109/LAWP.2010.2058990
  • Goulianos AA, Brown TWC, Evans BG, Stavrou S. (2009) 'Wideband Power Modeling and Time Dispersion Analysis for UWB Indoor Off-Body Communications'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, 57 (7), pp. 2162-2171.
    doi: 10.1109/TAP.2009.2021928

Journal articles

  • Ma H, Brown TWC. (2012) 'Egg quantity determination based on characteristic polarisation state'. Institution of Engineering and Technology Electronics Letters, 48 (9), pp. 472-474.
    doi: 10.1049/el.2011.3915
    Full text is available at: http://epubs.surrey.ac.uk/634480/

    Abstract

    Due to the disability of the traditional complex natural resonant method, the characteristic polarisation state method is proposed to determine egg quantity in a box with a two by three egg configuration. Parameters are investigated for different egg quantity scenarios and the results show a potential way to determine number in terms of characteristic angle β.

  • King PR, Brown TWC, Kyrgiazos A, Evans BG. (2011) 'Empirical-Stochastic LMS-MIMO Channel Model Implementation and Validation'. IEEE IEEE Transactions on Antennas and Propagation, 60 (2), pp. 606-614.
    doi: 10.1109/TAP.2011.2173448
    Full text is available at: http://epubs.surrey.ac.uk/7393/

    Abstract

    Land Mobile Satellite (LMS) networks, forming a key component of future mobile Internet and broadcasting, can benefit from Multiple-Input Multiple-Output (MIMO) techniques to improve spectral efficiency and outage. LMS-MIMO networks can be obtained using multiple satellites with single polarization antennas with spatial multiplex channel coding, or by a single satellite with dual polarization antennas providing polarization multiplex channel coding. In this paper, a guide is presented showing the steps required to implement a simple empirical-stochastic dual circular polarized LMS-MIMO narrowband channel model with validation both with and without a line of sight. The model is based on an S-band tree-lined road measurement campaign using dual circular polarizations at low elevations. Application of the model is aimed at LMS-MIMO physical layer researchers and system designers, who need an easy to implement and reliable model, representative of typical LMS-MIMO channel conditions.

  • Di Bari R, Brown TWC, Gao S, Underwood C. (2011) 'Dual-Polarized Printed S-Band Radar Array Antenna for Spacecraft Applications'. IEEE IEEE Antennas and Wireless Propagation Letters, 10, pp. 987-990.
    doi: 10.1109/LAWP.2011.2167951
    Full text is available at: http://epubs.surrey.ac.uk/439773/

    Abstract

    A novel dual-polarized broadband antenna array for S-band is presented. This antenna is composed of 6 × 2 microstrip antenna elements with a hybrid feed-line network providing an isolation ≥ 18.6 dB between the H- and V-ports. The operative bandwidth is from 3.15 to 3.25 GHz, and the peak measured gain is approximately 19 dBi. The array is suitable for spacecraft operation because of the selected materials, its low profile (~8 mm thickness), and light weight. It has potential applications in synthetic aperture radar (SAR), remote sensing, and wireless communications.

  • Whitlock RSC, Brown TWC. (2011) 'Enhanced timing advance in TDM cellular radio systems'. INST ENGINEERING TECHNOLOGY-IET ELECTRON LETT, 47 (14), pp. 829-830.
    doi: 10.1049/el.2011.1374
    Full text is available at: http://epubs.surrey.ac.uk/427909/

    Abstract

    The rationale for this Letter is to present a method which would enhance the resolution and accuracy of timing advance (TA) in 2G GSM TDMA and 3G UMTS TDD networks. The method would enable a stationary or slow-moving mobile station (MS) to determine its location using trilateration, with enhanced resolution and accuracy. An outstanding feature of the method is that the only changes required are to software. Low resolution TA samples would be processed into enhanced resolution measurements by applying fractional bit perturbations (dither) over an extended sampled measurement period. The existing TA mechanism and word length for ensuring correct MS uplink arrival times would remain unchanged. It is proposed that enhanced timing advance (ETA) could provide a low risk, low cost alternative to location finding technologies such as angle of arrival, time of arrival, enhanced observed time difference, uplink time difference of arrival and GPS, at the same time satisfying the FCC mobile E-911 accuracy requirement.

  • Konstantinou K, Kang S, Brown TWC, Tzaras C. (2011) 'Measurement and Modelling of the Propagation Channel between Low Height Terminals'. Institution of Engineering and Technology IET Microwaves, Antennas and Propagation, 5 (4), pp. 412-418.
    doi: 10.1049/iet-map.2010.0197
    Full text is available at: http://epubs.surrey.ac.uk/427911/

    Abstract

    The evaluation of communication systems with low-height terminals requires path loss models that are applicable to low-height links. For the terminology low-height, the range 0.5 (mobile-) to 3m (fixed-node) above ground is considered. Herein, empirical non-time-dispersive propagation models for relaying systems with low-height terminals are proposed. The models consist of line-of-sight and non-line-of-sight branches. Single- and two-slope modelling approaches were examined. The models take into account the effect of frequency, transmitter and receiver height, and environment. They are complemented by shadowing and fast-fading distribution and correlation statistics. The performance of the models in producing accurate estimations is evaluated by comparison with sets of independent data.

  • Zhu F, Gao S, Ho ATS, Brown TWC, Li JZ, Xu JD. (2011) 'LOW-PROFILE DIRECTIONAL ULTRA-WIDEBAND ANTENNA FOR SEE-THROUGH-WALL IMAGING APPLICATIONS'. PROGRESS IN ELECTROMAGNETICS RESEARCH-PIER, 121, pp. 121-139.
    doi: 10.2528/PIER11080907
  • Brown TWC, Eggers PCF, Olesen K, Pedersen GF. (2010) 'Artificial Wideband Multi User Channels for Rural High Speed Vehicle to Vehicle Links'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, 29 (1), pp. 29-36.
    doi: 10.1109/JSAC.2011.110104
  • Makaratat K, Brown TWC, Stavrou S, Evans B. (2010) 'Complex correlation on linear array angle-of-arrival estimation measurement of ultra wideband propagation channels'. INST ENGINEERING TECHNOLOGY-IET IET MICROWAVES ANTENNAS & PROPAGATION, 4 (9), pp. 1354-1369.
    doi: 10.1049/iet-map.2008.0300
  • Mansor MF, Brown TWC, Evans BG. (2010) 'Satellite MIMO Measurement With Colocated Quadrifilar Helix Antennas at the Receiver Terminal'. IEEE Antennas and Wireless Propagation Letters, 9, pp. 712-715.
    doi: 10.1109/LAWP.2010.2058990
  • Brown TWC, Ekpe UM. (2010) 'When is Clarke's approximation valid?'. IEEE IEEE Antennas and Propagation Magazine, 52 (3), pp. 171-181.
    doi: 10.1109/MAP.2010.5586617
  • Brown TWC, Eggers PCF, Pedersen GF. (2010) 'Experimental interference assessment between two independent and simultaneous 4 x 4 MIMO handset user links operating at 5 GHz'. INST ENGINEERING TECHNOLOGY-IET ELECTRONICS LETTERS, 46 (4), pp. 309-310.
    doi: 10.1049/el.2010.3282
    Full text is available at: http://epubs.surrey.ac.uk/266408/
  • Goulianos A, Brown TWC, Stavrou S, Evans BG. (2010) 'Power Delay Profile Modelling on the UWB Off-Body Propogation Channel'. IEEE IET Journal on Microwaves, Antennas and Propogation, 4 (1), pp. 62-71.
    doi: 10.1049/iet-map.2008.0356
  • Goulianos AA, Brown TWC, Stavrou S. (2010) 'Power Delay Profile modelling of the ultra wideband off-body propagation channel'. IET Microwaves, Antennas and Propagation, 4 (1), pp. 62-71.
    doi: 10.1049/iet-map.2008.0356
  • Goulianos AA, Brown TWC, Evans BG, Stavrou S. (2009) 'Wideband Power Modeling and Time Dispersion Analysis for UWB Indoor Off-Body Communications'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, 57 (7), pp. 2162-2171.
    doi: 10.1109/TAP.2009.2021928
  • Makaratat K, Brown TWC, Stavrou S. (2008) 'Modified UWB Spatio-Temporal Channel Simulation Including Pulse Distortion and Frequency Dependence'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, 7, pp. 553-556.
    doi: 10.1109/LAWP.2008.2001174
  • Brown TWC. (2008) 'Indoor MIMO Measurements Using Polarization at the Mobile'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, 7, pp. 400-403.
    doi: 10.1109/LAWP.2008.2000737
    Full text is available at: http://epubs.surrey.ac.uk/427910/
  • Brown TWC, Eggers PCF, Olesen K. (2007) 'Simultaneous 5 GHz co-channel mutiple-input multiple-output links at microcellular boundaries: interference or cooperation?'. INST ENGINEERING TECHNOLOGY-IET IET MICROWAVES ANTENNAS & PROPAGATION, 1 (6), pp. 1152-1159.
    doi: 10.1049/iet-map:20060214
    Full text is available at: http://epubs.surrey.ac.uk/427913/
  • Brown TWC, Saunders SR, Stavrou S, Fiacco M. (2007) 'Characterization of polarization diversity at the mobile'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, 56 (5), pp. 2440-2447.
    doi: 10.1109/TVT.2007.898371
    Full text is available at: http://epubs.surrey.ac.uk/265990/
  • Makaratat K, Brown TWC, Stavrou S. (2007) 'Estimation of time of arrival of UWB multipath clusters through a spatial correlation technique'. INSTITUTION ENGINEERING TECHNOLOGY-IET IET MICROWAVES ANTENNAS & PROPAGATION, 1 (3), pp. 666-673.
    doi: 10.1049/iet-map:20060087
  • Brown TWC, Saunders SR, Evans BG. (2005) 'Analysis of mobile terminal diversity antennas'. IEE-INST ELEC ENG IEE PROCEEDINGS-MICROWAVES ANTENNAS AND PROPAGATION, 152 (1), pp. 1-6.
    doi: 10.1049/ip-map:20045013
    Full text is available at: http://epubs.surrey.ac.uk/439775/

Conference papers

  • Brown TWC, Kyrgiazos A. (2011) 'On the small scale modelling aspects of dual circular polarised land mobile satellite MIMO channels in line of sight and in vehicles'. IEEE Rome: European Conference of Antennas and Propagation, pp. 3562-3565.
    Full text is available at: http://epubs.surrey.ac.uk/719196/

    Abstract

    A new modelling method suited to the dual circular polarised (MIMO) channel applicable to land mobile satellite (LMS) communications in line of sight cases is presented. In this scenario, it is necessary to apply correlated fading to the co-polarised and cross- polarised channels separately in order to model the evident polarization multiplexing in such channels found from measurement data. Comparisons between model and measured data for satellite elevations of 30o are presented for validation. Influence of the vehicle interior on the channel model is also analysed.

  • Brown TWC, Diakos T. (2011) 'On the design of NFC Antennas for contactless payment applications'. IEEE Proceedings of the 5th European Conference on Antennas and Propagation (EUCAP), Rome: European Conference of Antennas and Propagation, pp. 44-47.
    Full text is available at: http://epubs.surrey.ac.uk/719195/

    Abstract

    The increasing interest in using the Near Field Communications (NFC) technology [1] at 13.5MHz is growing rapidly in the area of contactless payments, as well as numerous other applications, between devices that are within 10cm distance apart. However, there is growing concern that the use of such devices for contactless payments invites problems with regards to using metallic objects in the vicinity of the two devices to act as “rogue” antennas and eavesdrop information whilst a financial transaction is taking place. This paper will present aspects of designing H-antennas both for the two devices while also identifying the means by which rogue antennas can be designed from real life metallic structures such as a trolley.

  • Ekpe UM, Brown TWC, Evans BG. (2011) 'Channel characteristics analysis of the dual circular polarized land mobile satellite MIMO radio channel'. Proceedings - 2011 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications, APWC'11, , pp. 781-784.
    doi: 10.1109/APWC.2011.6046797
    Full text is available at: http://epubs.surrey.ac.uk/430844/
  • Makaratat K, Brown TWC, Stavrou S, Evans B. (2009) 'Classification of UWB Multipath Clusters and Its Distortion Effects on Positioning Error'. 2009 3RD EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, VOLS 1-6, Berlin, GERMANY: , pp. 191-195.
    Full text is available at: http://epubs.surrey.ac.uk/425664/

    Abstract

    Quantification of distortion effects on UWB system performances in terms of positioning error is analysed in this research. UWB multipath distorted channels are simulated in each frequency subband, over 2-11 GHz. Its characteristics are modelled corresponding to multipath clusters along the propagation paths. The classification of clusters and physics. based distortion mechanisms are generalized to be included into the simulation algorithm. Finally, distortion impacts on system performances regarding to frequency dependent characteristics and positioning errors are investigated.

  • Perez-Fontan F, Moraitis N, Brown TWC, Frigyes I, Horvarth P, Abele A, Cerdeira RP. (2009) 'Overview of activities carried out within SatNex on land mobile satellite and satellite to indoor channel modeling'. 3rd European Conference on Antennas and Propagation, Berlin: EuCAP 2009
    Full text is available at: http://epubs.surrey.ac.uk/425668/
  • Mansor MF, Brown TWC, Evans BG. (2009) 'Mutual coupling analysis of a dual circularly polarised contrawound quadrifilar helix antenna (CQHA) in land mobile satellite (LMS) MIMO systems'. The Institution of Engineering and Technology. IET Conference Publications, Edinburgh: 27th IET and AIAA International Communications Satellite Systems Conference (ICSSC 2009) (552 CP)
    Full text is available at: http://epubs.surrey.ac.uk/427914/
  • Brown TWC, Khan UH. (2009) 'Enhancement of the Intelligent Quadrifilar Helix using MIMO Antenna Selection at a WLAN Access Point'. IEEE 2009 3RD EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, VOLS 1-6, Berlin, GERMANY: 3rd European Conference on Antennas and Propagation, pp. 1009-1012.
    Full text is available at: http://epubs.surrey.ac.uk/425665/
  • Mansor MF, Brown TWC, Evans BG. (2009) 'A Dual Circularly Polarised Contrawound Quadrifilar Helix Antenna for Land Mobile Satellite MIMO Terminal'. IEEE 2009 3RD EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, VOLS 1-6, Berlin, GERMANY: 3rd European Conference on Antennas and Propagation, pp. 1072-1076.
    Full text is available at: http://epubs.surrey.ac.uk/425662/
  • Ekpe UM, Brown TWC, Evans BG. (2009) 'Unleashing the Polarisation Domain for Land Mobile Satellite MIMO Systems'. IEEE 2009 3RD EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, VOLS 1-6, Berlin, GERMANY: 3rd European Conference on Antennas and Propagation, pp. 2199-2202.
    Full text is available at: http://epubs.surrey.ac.uk/425669/
  • Ekpe UM, Brown TWC, Evans BG. (2009) 'Markov chain analysis for land mobile satellite MIMO channels'. IET Conference Publications, Edinburgh: 27th IET and AIAA International Communications Satellite Systems Conference (ICSSC 2009) (552 CP)
    doi: 10.1049/cp.2009.1192
    Full text is available at: http://epubs.surrey.ac.uk/430845/
  • Makaratat K, Stavrou S, Brown TWC. (2008) 'Simulation of UWB distortion combined with indoor spatio- temporal channels'. IET Seminar Digest, 2008 IET Seminar on Wideband and Ultrawideband Systems and Technologies: Evaluating current Research and Development 2008 (12352)
    Full text is available at: http://epubs.surrey.ac.uk/427906/
  • Goulianos AA, Brown TWC, Stavrou S. (2008) 'A novel path-loss model for UWB off-body propagation'. IEEE Vehicular Technology Conference, pp. 450-454.
  • Goulianos AA, Brown TWC, Stavrou S. (2008) 'Ultra-wideband measurements and results for sparse off-body communication channels'. 2008 Loughborough Antennas and Propagation Conference, LAPC, , pp. 213-216.
    doi: 10.1109/LAPC.2008.4516904
  • Eggers PCF, Brown TWC, Olesen K, Pedersen GF. (2007) 'Assessment of capacity support and scattering in experimental high speed vehicle to vehicle MIMO links'. IEEE The 65th IEEE Vehicular Technology Conference, Dublin, Republic of Ireland: VTC 2007-Spring, pp. 466-470.
  • Makaratat K, Stavrou S, Brown TWC. (2007) 'Study of UWB multipath clusters based signal array processing'. Edinburgh: European Conference of Antennas and Propagation 2007 (11961)
  • Brown TWC, Saunders SR. (2007) 'The intelligent quadrifilar helix: A compact MIMO antenna for IEEE 802.11n'. IET Seminar Digest, Edinburgh: European Conference of Antennas and Propagation 2007 (11961)
    Full text is available at: http://epubs.surrey.ac.uk/427907/
  • Pedersen GF, Andersen JB, Eggers PCF, Brown TWC, Neilsen JO, Yamamoto A, Hayashi T, Ogawa K. (2007) 'Small Terminal MIMO Channels with user interaction'. Edinburgh: European Conference of Antennas and Propagation
  • Brown TWC, Chew KCD, Saunders SR. (2003) 'Analysis of the diversity potential of an intelligent quadrifilar helix antenna'. Twelfth International Conference on Antennas and Propagation: Conference Publication No. 491, Exeter, UK: ICAP 2003 2, pp. 194-198.
    doi: 10.1049/cp:20030048
    Full text is available at: http://epubs.surrey.ac.uk/439774/

    Abstract

    Antenna diversity has been used as a method to mitigate multipath fading. For mobile communications, this has usually been at the base station, but there is an increasing demand for diversity antennas to be implemented at the mobile. In this case, there is often a main antenna, as in any other handset, and also a smaller diversity antenna. With such antennas, it is difficult for both to maintain high mean effective gain (MEG), which is a disadvantage to the overall system performance. Also, implementing more than two elements usually increases the handset volume. An intelligent quadrifilar helix antenna (IQHA) (see Leach, S.M. et al., IEE Proc. on Microwaves, Antennas and Propag., vol.147, no.3, p.219-23, 2000) is based on four helix antenna elements that can be combined to allow beam steering towards satellites and terrestrial base stations. Combining the elements in an appropriate fashion gives scope for a four-branch diversity system. The paper investigates why an IQHA provides good diversity potential. An IQHA is primarily an angular diversity system and it is shown that the equal gain combining (EGC) method (see Saunders, S.R., "Antennas and Propagation for Wireless Communication Systems", Wiley, 1999) provides the highest system gain since there is a significant increase in MEG. The analysis is carried out both for the standard sized IQHA and the reduced-size meandered IQHA.

  • Brown TWC, Saunders SR. (2001) 'Modelling polarisation diversity at the mobile terminal'. INST ELECTRICAL ENGINEERS INSPEC INC ELEVENTH INTERNATIONAL CONFERENCE ON ANTENNAS AND PROPAGATION, VOLS 1 AND 2, UNIV MANCHESTER, INST SCI & TECHNOL, MANCHESTER, ENGLAND: 11th International Conference on Antennas and Propagation (ICAP 2001) (480), pp. 432-435.

Teaching

  • EEEM006 - Antennas and Propagation (including propagation and antennas laboratory)
  • EEEM044 - RF Systems and Circuit Design (including RF circuits, broadcasting, and small devices)
  • EEEM020 - Microwave Engineering (including waveguides, MMICs, LTCCs and 60GHz propagation)
  • EEE3033 - RF and Microwave Fundamentals (including low noise amplifiers, antennas and radar application)
  • Course organiser for short courses on Antennas and Propagation, RF Systems and Circuits, Microwave Engineering and Emerging Technologies in Mobile Communications - see http://www.ee.surrey.ac.uk/CE

Departmental Duties

  • IET Student Advisor
  • Exchange Programmes Coordinator
  • Elec Eng Soc Staff Representative
  • Marketing