Sat, 26 Jul 2008 06:07:49 BST CiteULike: dcastro's Hall http://www.citeulike.org/user/dcastro/author/Hall CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dcastro/article/3040183 <i>Military Communications Conference, 2005. MILCOM 2005. IEEE (2005), pp. 1819-1824 Vol. 3.</i><br /><br />Wireless local area network (WLAN) systems are typically designed to provide fixed or nomadic access. Using WLAN systems for military purposes raises the question of how WLAN terminals can be utilized in a fully mobile outdoor environment. In these environments, there typically exists multipath propagation with a large delay spread in the radio channel. This paper investigates the effect of terminal movement on the physical layer performance and capacity of IEEE 802.11b WLAN systems in a realistic outdoor mobile environment. Several wireless network interface cards are measured in laboratory conditions using a simulated radio channel. The measurement results indicate that WLAN systems can operate in mobile outdoor environment up to a certain mobile speed, and there are significant differences between equipment from product vendors. The effect of terminal movement to the physical layer performance of the IEEE 802.11b wireless LAN systems in simulated UMTS vehicular channel A Silvennoinen M Hall SG Haggman doi:10.1109/MILCOM.2005.1605937 Military Communications Conference, 2005. MILCOM 2005. IEEE (2005), pp. 1819-1824 Vol. 3. 2008-07-24T15:09:19-00:00 2005 Military Communications Conference, 2005. MILCOM 2005. IEEE 1819 1824 Vol. 3 80211 channel mobile umts wlan http://www.citeulike.org/user/dcastro/article/3025727 <i>Electronics Letters, Vol. 35, No. 13. (1999), pp. 1034-1036.</i><br /><br />A novel compact, conformal, dual-band, dual-polarisation antenna is presented. This antenna is capable of generating two distinct frequencies with different polarisation and radiation pattern characteristics: a monopolar mode for terrestrial cellular communication and a circularly polarised, upward oriented pattern for satellite mobile communication. Bandwidths of 2 and 4%, respectively, have been obtained in the two modes Compact dual-band dual-polarisation microstrip patch antenna E Lee PS Hall P Gardner doi:10.1049/el:19990730 Electronics Letters, Vol. 35, No. 13. (1999), pp. 1034-1036. 2008-07-21T21:51:15-00:00 1999 Electronics Letters 35 13 1034 1036 antenna compact dual dual-band microstrip patch polarisation http://www.citeulike.org/user/dcastro/article/3025726 <i>Antennas and Propagation Society International Symposium, 1989. AP-S. Digest (1989), pp. 458-462 vol.1.</i><br /><br />It is demonstrated that a thick patch with an annular gap matching capacitor is an optimum element from a practical design point of view, giving wide bandwidth operation, although at the expense of poor cross polarization. Feed inductance and radiation pattern effects are examined and a new patch equivalent circuit is developed that gives significantly improved results over the existing lumped element model Microstrip patch antennas on thick substrates PS Hall JS Dahele PM Haskins doi:10.1109/APS.1989.134719 Antennas and Propagation Society International Symposium, 1989. AP-S. Digest (1989), pp. 458-462 vol.1. 2008-07-21T21:51:11-00:00 1989 Antennas and Propagation Society International Symposium, 1989. AP-S. Digest 458 462 vol.1 antenna microstrip patch http://www.citeulike.org/user/dcastro/article/1366339 <i>Wireless Personal Communications, Vol. 41, No. 4. (June 2007), pp. 487-505.</i> The Effect of Terminal Movement on the Performance of IEEE 802.11 g Wireless LAN Systems in Simulated Radio Channels Silvennoinen Aki Hall Michael Haggman Sven-Gustav doi:10.1007/s11277-006-9155-1 Wireless Personal Communications, Vol. 41, No. 4. (June 2007), pp. 487-505. 2007-06-05T21:33:41-00:00 2007 Wireless Personal Communications 0929-6212 41 4 487 505 Springer 80211 channel mobile radio simulation wlan http://www.citeulike.org/user/dcastro/article/2809087 <i>Antennas and Propagation, 2007. EuCAP 2007. The Second European Conference on (2007), pp. 1-4.</i><br /><br />Dipole loaded with left handed transmission lines allows operation with higher order mode current distributions and small size. Use in a meandered configuration can give polarisation orthogonal to the dipole length. In this paper a new printed implementation using distributed elements is proposed with improved efficiency. Comparisons are made between this antenna and previous antenna structures implemented with lumped and distributed elements, consisting of interdigitated capacitors and meandered line inductors. The simulated results show good input impedance match and radiation pattern typical of a dipole. This antenna also achieved an improved radiation efficiency of 73.84% and a gain of 0.809 dBi was obtained. Experimental results validate the performance of this antenna. Dipole with left handed loading with optimised efficiency Qing Liu Peter Hall Alejandro Borja Antennas and Propagation, 2007. EuCAP 2007. The Second European Conference on (2007), pp. 1-4. 2008-05-18T14:13:40-00:00 2007 Antennas and Propagation, 2007. EuCAP 2007. The Second European Conference on 1 4 dipole handed left http://www.citeulike.org/user/dcastro/article/2809085 <i>Microwave Conference, 2006. 36th European (2006), pp. 1048-1051.</i><br /><br />A meandered dipole with polarisation orthogonal to its length is presented. The dipole is made by loading a folded dipole in a way similar to a left handed transmission line. A prototype has been designed and constructed. Results confirm that good input matching and radiation pattern are achieved, although gain is low due to losses in the loading structure Orthogonally Polarised Dipole Antenna using Left Handed Transmission Lines H Iizuka PS Hall doi:10.1109/EUMC.2006.281113 Microwave Conference, 2006. 36th European (2006), pp. 1048-1051. 2008-05-18T14:13:31-00:00 2006 Microwave Conference, 2006. 36th European 1048 1051 antenna crlh dipole lh metamaterial tl http://www.citeulike.org/user/dcastro/article/2802015 <i>Electronics Letters, Vol. 35, No. 25. (1999), pp. 2163-2164.</i><br /><br />Active receiving antennas with an integrated filter, amplifier, mixer and local oscillator have significant radiation at the local oscillator frequency. This radiation may be out of band and could be a problem in cluttered environments. In this Letter, the problem is evaluated through measurements and simulation on integrated microstrip patch antennas Local oscillator radiation from active integrated antennas G Ma PS Hall P Gardner M Hajian doi:10.1049/el:19991482 Electronics Letters, Vol. 35, No. 25. (1999), pp. 2163-2164. 2008-05-15T15:30:24-00:00 1999 Electronics Letters 35 25 2163 2164 active antennas integrated local oscillator http://www.citeulike.org/user/dcastro/article/2782058 <i>Antennas and Propagation Society International Symposium, 1999. IEEE, Vol. 2 (1999), pp. 912-915 vol.2.</i><br /><br />Two different types of novel dual band antennas suitable for a data communicator device are reported. The first antenna is a dual frequency, dual polarization microstrip patch antenna, capable of generating two distinct frequencies with different polarization characteristics and radiation patterns. This antenna has been intended for coverage of the GSM/Iridium's satellite frequencies. The second antenna modified bent folded monopole antenna having two resonant frequencies, with a frequency separation of 1.9. This antenna could be used in the GSM/DCS1800 frequencies. The limitations of both antennas are also briefly mentioned Multi-band antennas E Lee PS Hall P Gardner D Kitchener doi:10.1109/APS.1999.789460 Antennas and Propagation Society International Symposium, 1999. IEEE, Vol. 2 (1999), pp. 912-915 vol.2. 2008-05-10T00:00:58-00:00 1999 Antennas and Propagation Society International Symposium, 1999. IEEE 2 912 915 vol.2 antenna multiband http://www.citeulike.org/user/dcastro/article/2782051 <i>Antennas and Propagation, IEEE Transactions on, Vol. 51, No. 4. (2003), pp. 722-729.</i><br /><br />This paper proposes two novel designs of a multiband antenna using multiple rings. The first design consists of a set of self-similar circular rings. This is an alternative to the recently reported triangular fractal Sierpinski gasket monopole antenna, and comparison is made to this and the circular disk monopole antenna. The second design is realized by varying the shape of the circular structure to an elliptical one. Larger bandwidth and improved patterns are achieved. In comparison to the circular disk, improved radiation pattern control at higher operating bands, due to the discrete structure of the multiple rings, is shown by numerical and experimental results. The bandwidth is significantly larger than the Fractal Sierpinski gasket and Parany monopole. Multiband multiple ring monopole antennas CTP Song PS Hall H Ghafouri-Shiraz doi:10.1109/TAP.2003.811097 Antennas and Propagation, IEEE Transactions on, Vol. 51, No. 4. (2003), pp. 722-729. 2008-05-09T23:56:12-00:00 2003 Antennas and Propagation, IEEE Transactions on 51 4 722 729 antenna multiband http://www.citeulike.org/user/dcastro/article/2782025 <i>Electronics Letters, Vol. 37, No. 20. (2001), pp. 1213-1214.</i><br /><br />A dual-polarised microstrip antenna capable of achieving a wide bandwidth, a high isolation, low cross-polarisation levels and low backward radiation levels is presented. The H-shaped coupling aperture is used. For wide bandwidth and easy integration with active circuits, it uses the aperture-coupled stacked microstrip square patches. Measured return loss exhibits a bandwidth of over 20.9%, and isolation is better than 36 dB over the bandwidth. Cross-polarisation levels and the front-to-back ratio are better than 22 and 21 dB, respectively Wideband dual-polarised microstrip patch antenna SC Gao LW Li P Gardner PS Hall doi:10.1049/el:20010828 Electronics Letters, Vol. 37, No. 20. (2001), pp. 1213-1214. 2008-05-09T23:50:34-00:00 2001 Electronics Letters 37 20 1213 1214 antenna dual microstrip patch polarisation wideband http://www.citeulike.org/user/dcastro/article/2782022 <i>Electronics Letters, Vol. 37, No. 18. (2001), pp. 1106-1107.</i><br /><br />A dual-polarised aperture-coupled microstrip antenna with a wide bandwidth, a high isolation, low cross-polarisation levels and low backward radiation levels is presented. The square patch is fed at two corners via H-shaped apertures. The measured return loss exhibits a bandwidth of over 24.4% and the isolation is better than 30 dB over the bandwidth. The cross-polarisation levels and the front-to-back ratio are better than -23 and 22 dB, respectively Dual-polarised wideband microstrip antenna SC Gao LW Li P Gardner PS Hall doi:10.1049/el:20010760 Electronics Letters, Vol. 37, No. 18. (2001), pp. 1106-1107. 2008-05-09T23:49:22-00:00 2001 Electronics Letters 37 18 1106 1107 antenna dual microstrip polarisation wideband http://www.citeulike.org/user/dcastro/article/2782007 <i>Phased Arrays, IEE Colloquium on (1991), pp. 9/1-9/4.</i><br /><br />The integration of circuit and antennas functions to form active radiating elements is an important area of interest for future phased arrays. Radiation from active circuits is analysed using equivalent source method and results presented for isolated transistors and transistor amplifiers. An active patch element with application to phased arrays is then described Microstrip active antennas PS Hall PM Haskins JS Dahele Phased Arrays, IEE Colloquium on (1991), pp. 9/1-9/4. 2008-05-09T23:43:12-00:00 1991 Phased Arrays, IEE Colloquium on 9/1 9/4 active antenna microstrip http://www.citeulike.org/user/dcastro/article/2782003 <i>Electronics Letters, Vol. 34, No. 14. (1998), pp. 1367-1368.</i><br /><br />The authors report a novel active integrated receiving antenna providing between 12 and 24 dB gain when referred to a passive equivalent at 1.335 GHz. The antenna is of a compact coplanar form, integrating DC and RF requirements to obtain both high gain and low noise Compact low noise receiving antenna TD Ormiston P Gardner PS Hall Electronics Letters, Vol. 34, No. 14. (1998), pp. 1367-1368. 2008-05-09T23:43:01-00:00 1998 Electronics Letters 34 14 1367 1368 active antenna compact low noise receiver http://www.citeulike.org/user/dcastro/article/2776279 <i>Microwaves, Antennas and Propagation, IEE Proceedings -, Vol. 150, No. 4. (2003), pp. 290-294.</i><br /><br />Two methods for achieving a complete RF front end equipped with its radiator within a single chip package are presented. This packaging technique, which uses a parasitic radiator, provides an alternative solution to problems associated with reduced size electrically small antennas, such as restoration of the antenna gain to 6 dBi and increasing its bandwidth to over 4%. Several parasite configurations have been described and sensitivity of the overall antenna performance to coupling height, parasite dimension, and position with respect to the feed antenna have been assessed. Circular polarisation of such a configuration using a truncated square parasite has also been demonstrated. Novel RF front end antenna package PCT Song PS Hall H Ghafouri-Shiraz doi:10.1049/ip-map:20030414 Microwaves, Antennas and Propagation, IEE Proceedings -, Vol. 150, No. 4. (2003), pp. 290-294. 2008-05-09T16:41:52-00:00 2003 Microwaves, Antennas and Propagation, IEE Proceedings - 150 4 290 294 antenna front-end rf http://www.citeulike.org/user/dcastro/article/2776238 <i>Antennas and Propagation Society International Symposium, 1998. IEEE, Vol. 3 (1998), pp. 1620-1623 vol.3.</i><br /><br />A rectangular cavity-backed active slot loop antenna has been investigated and the experimental results show that a 30 dB oscillator noise reduction can be achieved for the active slot loop antenna at a carrier frequency of 3.42 GHz and an offset frequency of 40 kHz. The advantage of the active slot loop antenna is that it is easy to fabricate and compatible with the micromachining process. The authors build a cavity-backed active slot loop antenna for the K band using silicon micromachining techniques, and it is believed that this novel active slot loop silicon micromachined antenna should be well suited to short range radars and communication systems Cavity-backed active slot loop antenna M Zheng PS Hall Q Chen VF Fusco doi:10.1109/APS.1998.690864 Antennas and Propagation Society International Symposium, 1998. IEEE, Vol. 3 (1998), pp. 1620-1623 vol.3. 2008-05-09T16:13:48-00:00 1998 Antennas and Propagation Society International Symposium, 1998. IEEE 3 1620 1623 vol.3 active antenna http://www.citeulike.org/user/dcastro/article/2776128 <i>Electronics Letters, Vol. 33, No. 22. (1997), pp. 1830-1831.</i><br /><br />A novel miniaturised quarter wavelength, H-shaped antenna which will find applications in monolithic microwave integrated circuit (MMIC) design is presented. The antenna occupies approximately one tenth of the substrate area of a half wavelength patch antenna. The effect on the resonance frequency, bandwidth and gain of the antenna are reported Miniaturised microstrip antenna for MMIC applications D Singh P Gardner PS Hall Electronics Letters, Vol. 33, No. 22. (1997), pp. 1830-1831. 2008-05-09T15:21:05-00:00 1997 Electronics Letters 33 22 1830 1831 antenna compact small http://www.citeulike.org/user/dcastro/article/2776108 <i>Electronics Letters, Vol. 33, No. 21. (1997), pp. 1799-1800.</i><br /><br />Experimental results obtained from an active transponder circuit mounted in a car windscreen are reported. The transponder receives a signal at 10 GHz and doubles the frequency which is transmitted at 20 GHz. The effect of glass superstrate on the active transponder circuit is reported Frequency doubling active transponder in car windscreen D Singh P Gardner PS Hall Electronics Letters, Vol. 33, No. 21. (1997), pp. 1799-1800. 2008-05-09T15:17:53-00:00 1997 Electronics Letters 33 21 1799 1800 active antenna http://www.citeulike.org/user/dcastro/article/2776106 <i>Electronics Letters, Vol. 33, No. 6. (1997), pp. 505-506.</i><br /><br />A new compact frequency doubling active transponder using a push-push technique is presented. Two outputs in anti-phase from the receiving patch antenna are amplified nonlinearly using MMICs and combined in phase suppressing the fundamental and enhancing the second harmonic. The doubled signal is then transmitted from a second patch antenna with a measured conversion gain of 6 dB Integrated push-push frequency doubling active microstrip transponder D Singh P Gardner PS Hall Electronics Letters, Vol. 33, No. 6. (1997), pp. 505-506. 2008-05-09T15:16:23-00:00 1997 Electronics Letters 33 6 505 506 active antenna microstrip http://www.citeulike.org/user/dcastro/article/2776105 <i>Microwave Conference and Exhibition, 1997 27th European, Vol. 2 (1997), pp. 1181-1185.</i> Frequency Doubling Integrated Push-push Active Microstrip Transponder D Singh P Gardner PS Hall Microwave Conference and Exhibition, 1997 27th European, Vol. 2 (1997), pp. 1181-1185. 2008-05-09T15:16:22-00:00 1997 Microwave Conference and Exhibition, 1997 27th European 2 1181 1185 active antenna microstrip http://www.citeulike.org/user/dcastro/article/2776101 <i>Low Cost Antenna Technology (Ref. No. 1998/206), IEE Colloquium on (1998), pp. 8/1-8/5.</i><br /><br />Experimental results achieved from a frequency doubling active transponder circuit mounted in a car windscreen are reported. The transponder receives a signal at 10 GHz, doubles the frequency and retransmits it at 20 GHz. The effect of the windscreen glass superstrate on the circuit and antenna properties are also reported An active antenna transponder in a car windscreen D Singh P Gardner PS Hall Low Cost Antenna Technology (Ref. No. 1998/206), IEE Colloquium on (1998), pp. 8/1-8/5. 2008-05-09T15:16:14-00:00 1998 Low Cost Antenna Technology (Ref. No. 1998/206), IEE Colloquium on 8/1 8/5 active antenna http://www.citeulike.org/user/dcastro/article/2776100 <i>RF and Microwave Components for Communication Systems (Digest No.: 1997/126), IEE Colloquium on (1997), pp. 9/1-9/4.</i><br /><br />This paper considers how a compact low noise active antenna may be constructed. The design approach is to achieve a highly compact design by intimately integrating the DC and RF requirements. Low noise is theoretically demonstrated and design topologies identified A novel highly compact low noise active antenna TD Ormiston P Gardner PS Hall RF and Microwave Components for Communication Systems (Digest No.: 1997/126), IEE Colloquium on (1997), pp. 9/1-9/4. 2008-05-09T15:16:11-00:00 1997 RF and Microwave Components for Communication Systems (Digest No.: 1997/126), IEE Colloquium on 9/1 9/4 active antenna compact low noise http://www.citeulike.org/user/dcastro/article/2776060 <i>Microwave and Millimeter Wave Technology, 2002. Proceedings. ICMMT 2002. 2002 3rd International Conference on (2002), pp. 618-621.</i><br /><br />In this paper, a non-linear circuit model of a FET has been incorporated into the finite-difference time-domain (FDTD) method when microwave active antennas are analysed. The FET, operating in class A mode, is biased and its non-linear properties (second harmonics) are investigated in a patch antenna configuration. The algorithm and the simulation results will be useful in the development of high power integrated active antenna modules. FDTD analysis of microwave active antenna including nonlinear model of FET transistor Y Zhang P Gardner H Ghafouri-Shiraz PS Hall Microwave and Millimeter Wave Technology, 2002. Proceedings. ICMMT 2002. 2002 3rd International Conference on (2002), pp. 618-621. 2008-05-09T14:56:17-00:00 2002 Microwave and Millimeter Wave Technology, 2002. Proceedings. ICMMT 2002. 2002 3rd International Conference on 618 621 active analysis antenna fdtd fet microwave model nonlinear http://www.citeulike.org/user/dcastro/article/2774771 <i>Microwaves, Antennas and Propagation, IEE Proceedings -, Vol. 145, No. 4. (1998), pp. 313-320.</i><br /><br />Active antenna oscillator arrays have been considered in millimetre-wave communication systems to increase the power levels for low cost radio modules, and in radar systems for high power generation. The authors have investigated the performance of active antenna oscillator arrays, particularly the data-rate limitations, the modulation effects on the radiation pattern, and the bit error rate performance of these arrays, in practical applications. Also, a closed-form solution for the phase dynamics of a single injection-locked oscillator has been derived Performance of active antenna oscillator arrays under modulation for communication systems C Kykkotis PS Hall H Ghafouri-Shiraz Microwaves, Antennas and Propagation, IEE Proceedings -, Vol. 145, No. 4. (1998), pp. 313-320. 2008-05-09T08:36:03-00:00 1998 Microwaves, Antennas and Propagation, IEE Proceedings - 145 4 313 320 active antenna array oscillator http://www.citeulike.org/user/dcastro/article/2774766 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 50, No. 11. (2002), pp. 2639-2646.</i><br /><br />Harmonic radiation from microstrip patch oscillators is examined experimentally and theoretically using both a single and dual parallel-tuned circuit Van der Pol oscillator model. Closed-form expressions are obtained for the fundamental and first harmonic voltage amplitudes, and results show reasonably good agreement with a commercial circuit simulator. Such expressions will be useful for designers of active integrated antennas, giving them greater physical insight into their operation. Experimental results are presented for three configurations of a patch oscillator, i.e., rectangular patch, circular-sector patch, and quarter-wave shorted patch. The latter two configurations present very low resistance at the first harmonic frequency and this leads to improved harmonic suppression performance. This is in qualitative agreement with theoretical predictions. Analysis and control of harmonic radiation from active integrated oscillator antennas MJ Cryan GR Buesnel PS Hall doi:10.1109/TMTT.2002.804634 Microwave Theory and Techniques, IEEE Transactions on, Vol. 50, No. 11. (2002), pp. 2639-2646. 2008-05-09T08:35:55-00:00 2002 Microwave Theory and Techniques, IEEE Transactions on 50 11 2639 2646 active antenna integrated oscillator http://www.citeulike.org/user/dcastro/article/2774606 <i>Microwave Symposium Digest, 1997., IEEE MTT-S International, Vol. 2 (1997), pp. 591-594 vol.2.</i><br /><br />Active antenna oscillator arrays have been considered in millimetre-wave communication systems for increased power levels in low cost radio modules. In this paper, we have investigated the data-rate limitations, the modulation effects on the radiation pattern, and the bit error rate performance of antenna oscillator arrays in practical applications Active antenna oscillator arrays in communication systems C Kykkotis PS Hall H Ghafouri-Shiraz doi:10.1109/MWSYM.1997.602862 Microwave Symposium Digest, 1997., IEEE MTT-S International, Vol. 2 (1997), pp. 591-594 vol.2. 2008-05-09T07:25:59-00:00 1997 Microwave Symposium Digest, 1997., IEEE MTT-S International 2 591 594 vol.2 active antenna array oscillator http://www.citeulike.org/user/dcastro/article/2774502 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 50, No. 1. (2002), pp. 201-206.</i><br /><br />Active patch antennas are simple to fabricate, compact, and low cost, but have inherently poor phase noise and stability. In this paper, a phase-locked loop (PLL) integrated with a 4-GHz active patch antenna was investigated in order to reduce the phase noise and stabilize the frequency of the oscillator. Both these aims were realized by careful integration and optimization of the PLL parameters. Experimental results showed that a phase noise reduction in excess of 55 dB was achieved using this technique. A standalone voltage-controlled oscillator and passive patch technique can provide lower phase noise, but the active patch lends itself to effective integration. Measurement techniques were demonstrated to measure the phase noise and stability of the patch oscillator Phase-locked-loop control of active microstrip patch antennas JW Andrews PS Hall doi:10.1109/22.981266 Microwave Theory and Techniques, IEEE Transactions on, Vol. 50, No. 1. (2002), pp. 201-206. 2008-05-09T06:40:39-00:00 2002 Microwave Theory and Techniques, IEEE Transactions on 50 1 201 206 active antenna microstrip patch pll http://www.citeulike.org/user/dcastro/article/2762216 <i>Electronics Letters, Vol. 34, No. 3. (1998), pp. 228-229.</i><br /><br />The authors present a set of experimental results which demonstrate that it is possible to control the level of harmonic and spurious radiation emitted from a microstrip patch oscillator by means of at least two mechanisms. A discussion of these mechanisms is included, and it is also argued that an unambiguous method of classifying similar results is required Harmonic control in active integrated patch oscillators GR Buesnel MJ Cryan PS Hall Electronics Letters, Vol. 34, No. 3. (1998), pp. 228-229. 2008-05-06T18:28:41-00:00 1998 Electronics Letters 34 3 228 229 active integrated oscillator patch http://www.citeulike.org/user/dcastro/article/2762215 <i>Electronics Letters, Vol. 33, No. 24. (1997), pp. 1998-1999.</i><br /><br />A microstrip patch oscillator is modelled using a dual LCR Van der Pol oscillator. Closed form expressions are obtained for the fundamental and first harmonic voltage amplitudes and results show reasonably good agreement with a commercial circuit simulator. These type of expressions will be useful for computer aided design of active antennas and give circuit designers greater physical insight into their operation Analysis of harmonic radiation from an integrated active antenna MJ Cryan PS Hall Electronics Letters, Vol. 33, No. 24. (1997), pp. 1998-1999. 2008-05-06T18:28:41-00:00 1997 Electronics Letters 33 24 1998 1999 active antenna integrated http://www.citeulike.org/user/dcastro/article/2762213 <i>Antennas and Propagation, Tenth International Conference on (Conf. Publ. No. 436), Vol. 1 (1997), pp. 518-521 vol.1.</i><br /><br />Integrated active antennas are of increasing interest as system designers require more complex functions to be implemented in reduced space. Many of these systems require very low levels of harmonic and spurious radiation in order to meet electromagnetic compatibility specifications. Active antennas introduce nonlinear devices directly into the antenna and thus they can exhibit high levels of harmonic radiation, moreover, due to size constraints, filters can not be easily added as in conventional systems. In the case of active receiving antennas it seems that by suppressing the harmonic resonances of the antenna the harmonic reception problem can be reduced. However, with patch oscillators, due to the interdependence of the active device and the patch, the solution to the problem of harmonic radiation is more complex. This work aims to investigate these problems, especially in the case of the patch oscillator since these devices seem to pose the greatest challenge. The final goal is to obtain closed form expressions for the level of harmonics in terms of physical circuit parameters. Although numerical methods could be used to solve this problem it is felt that greater physical insight can be obtained from closed form expressions, allied to this they will be useful for CAD of patch oscillators. Closed form expressions would allow designers to realise low levels of harmonic radiation either by modifying the patch geometry or by altering the active device configuration Spectral control of integrated active antennas MJ Cryan PS Hall Antennas and Propagation, Tenth International Conference on (Conf. Publ. No. 436), Vol. 1 (1997), pp. 518-521 vol.1. 2008-05-06T18:28:38-00:00 1997 Antennas and Propagation, Tenth International Conference on (Conf. Publ. No. 436) 1 518 521 vol.1 active antenna integrated http://www.citeulike.org/user/dcastro/article/2762212 <i>RF and Microwave Components for Communication Systems (Digest No.: 1997/126), IEE Colloquium on (1997), pp. 7/1-7/5.</i><br /><br />The FDTD method is a full wave numerical method which has been extended to analyse hybrid systems incorporating lumped elements and semiconductor devices (using equivalent circuits). A simple implementation of a matched gain block in the extended FDTD algorithm is proposed. The behaviour of the gain block is examined through a simple circuit to validate its characteristics. As a test structure of considerable complexity, a novel microstrip active circulator is analysed. Results compared with those obtained using the HP-MDS circuit simulator show good agreement FDTD analysis of microstrip configurations incorporating gain blocks C Kalialakis MJ Cryan P Gardner PS Hall RF and Microwave Components for Communication Systems (Digest No.: 1997/126), IEE Colloquium on (1997), pp. 7/1-7/5. 2008-05-06T18:28:37-00:00 1997 RF and Microwave Components for Communication Systems (Digest No.: 1997/126), IEE Colloquium on 7/1 7/5 analysis fdtd microstrip http://www.citeulike.org/user/dcastro/article/2762208 <i>Microwave and Guided Wave Letters, IEEE [see also IEEE Microwave and Wireless Components Letters], Vol. 7, No. 7. (1997), pp. 190-191.</i><br /><br />An active circulator is integrated with a quarter-wave short-circuited microstrip patch antenna to produce a fully duplexed transceiver with transmit and receive operation at the same frequency and with the same polarization. The active circulator antenna is shown to have 14-dBi transmit gain and 7.4-dBi receive gain with a transmit-receive isolation of 26.9 dB at 3.745 GHz. This active antenna has potential uses in both short-range communication and radar systems An integrated active circulator antenna MJ Cryan PS Hall doi:10.1109/75.594860 Microwave and Guided Wave Letters, IEEE [see also IEEE Microwave and Wireless Components Letters], Vol. 7, No. 7. (1997), pp. 190-191. 2008-05-06T18:26:34-00:00 1997 Microwave and Guided Wave Letters, IEEE [see also IEEE Microwave and Wireless Components Letters] 7 7 190 191 active antenna circulator integrated http://www.citeulike.org/user/dcastro/article/2762206 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 48, No. 6. (2000), pp. 1017-1023.</i><br /><br />A study on the analysis and design of active integrated antennas based on active quasi-circulators is reported in this paper. The antenna consists of a novel hybrid active circulator and a short-circuited quarter-wavelength microstrip antenna, which combine to form an active antenna with transmit and receive action at the same frequency. A full-wave model of the configuration using the extended finite-difference time-domain method is devised to analyze its operation, to study parasitic electromagnetic coupling effects, and to derive design guidelines. Experimental results for a hybrid model are also presented Analysis and design of integrated active circulator antennas C Kalialakis MJ Cryan PS Hall P Gardner doi:10.1109/22.904739 Microwave Theory and Techniques, IEEE Transactions on, Vol. 48, No. 6. (2000), pp. 1017-1023. 2008-05-06T18:26:27-00:00 2000 Microwave Theory and Techniques, IEEE Transactions on 48 6 1017 1023 active analysis antenna circulator design ntegrated http://www.citeulike.org/user/dcastro/article/2762205 <i>Electronics Letters, Vol. 33, No. 25. (1997), pp. 2091-2092.</i><br /><br />The full wave design of an active integrated antenna using the extended FDTD method is presented. An active circulator using three gain blocks and a short circuited quarter wavelength patch are combined to form a transceiver. The effects of parasitic coupling are identified, and the isolation between transmit-receive is predicted FDTD simulation of active integrated antenna C Kalialakis MJ Cryan PS Hall P Gardner Electronics Letters, Vol. 33, No. 25. (1997), pp. 2091-2092. 2008-05-06T18:26:26-00:00 1997 Electronics Letters 33 25 2091 2092 active antenna fdtd integrated simulation http://www.citeulike.org/user/dcastro/article/2762145 <i>Antennas and Propagation, 2001. Eleventh International Conference on (IEE Conf. Publ. No. 480), Vol. 2 (2001), pp. 475-478 vol.2.</i><br /><br />Two active integrated antennas are implemented to act as direct-conversion receivers. These active antennas can be applied for Doppler frequency detection, I&Q demodulation and direction finding Active integrated antennas using the direct-conversion detection G Ma PS Hall P Gardner M Hajian Antennas and Propagation, 2001. Eleventh International Conference on (IEE Conf. Publ. No. 480), Vol. 2 (2001), pp. 475-478 vol.2. 2008-05-06T17:42:44-00:00 2001 Antennas and Propagation, 2001. Eleventh International Conference on (IEE Conf. Publ. No. 480) 2 475 478 vol.2 active antenna integrated http://www.citeulike.org/user/dcastro/article/2762144 <i>Electronics Letters, Vol. 37, No. 1. (2001), pp. 3-4.</i><br /><br />A zero-IF receiver is implemented based on the active antenna design. The active devices, Schottky diodes, are compactly integrated with two patch antenna elements to act as the mixers. The active antenna can perform both direct-conversion demodulation and direction finding Zero-IF detection active antenna G Ma S Hall P Gardner M Hajian doi:10.1049/el:20010018 Electronics Letters, Vol. 37, No. 1. (2001), pp. 3-4. 2008-05-06T17:42:42-00:00 2001 Electronics Letters 37 1 3 4 active antenna http://www.citeulike.org/user/dcastro/article/2762143 <i>Microwave and Millimeter Wave Technology, 2000, 2nd International Conference on. ICMMT 2000 (2000), pp. 261-264.</i><br /><br />In this paper, two active antennas with modulation and demodulation functions are introduced. A patch antenna integrated with two Schottky diodes is implemented to fulfil single sideband modulation and I&Q demodulation. A variation of this configuration can carry out double sideband modulation with carrier suppression and homodyne detection. Moreover, some parameters of the active antennas, such as conversion loss and radiation pattern are measured. The active antennas have potential use for direct-conversion radio transceivers in digital communication Direct downconversion active antennas for modulation and demodulation G Ma PS Hall P Gardner M Hajizn doi:10.1109/ICMMT.2000.895671 Microwave and Millimeter Wave Technology, 2000, 2nd International Conference on. ICMMT 2000 (2000), pp. 261-264. 2008-05-06T17:42:41-00:00 2000 Microwave and Millimeter Wave Technology, 2000, 2nd International Conference on. ICMMT 2000 261 264 active antenna http://www.citeulike.org/user/dcastro/article/2762142 <i>Antennas and Propagation Society International Symposium, 2001. IEEE, Vol. 3 (2001), pp. 436-439 vol.3.</i><br /><br />A dual band antenna suitable for mounting on a chip case is introduced. Through an aperture, the power is coupled from the antenna to the circuit (or vice versa). The antenna has compact configuration (11 mm×10mm at 1828 MHz), reasonable gain (about -2.5dBi at 1828 MHz) and low manufacturing cost Dual band antenna mounted on chip case G Ma P Gardner PS Hall doi:10.1109/APS.2001.960128 Antennas and Propagation Society International Symposium, 2001. IEEE, Vol. 3 (2001), pp. 436-439 vol.3. 2008-05-06T17:42:39-00:00 2001 Antennas and Propagation Society International Symposium, 2001. IEEE 3 436 439 vol.3 antenna dual-band http://www.citeulike.org/user/dcastro/article/2762141 <i>Antennas and Propagation Society International Symposium, 1999. IEEE, Vol. 4 (1999), pp. 2378-2381 vol.4.</i><br /><br />Active receiving antennas with integrated amplifier, mixer and local oscillators have significant radiation at the local oscillator frequency. Although this radiation may be out of band, it will be a problem in cluttered environments. In this paper the problem is evaluated through measurements and simulation on integrated microstrip patch antennas at 1.9 GHz. Radiation levels are compared for various substrate materials and configurations. It is concluded that, although reduction in local oscillator radiation can be made, the primary factor is the trade-off between manufacturing simplicity and performance Local oscillator radiation from active integrated antennas G Ma PS Hall P Gardner M Hajian doi:10.1109/APS.1999.789288 Antennas and Propagation Society International Symposium, 1999. IEEE, Vol. 4 (1999), pp. 2378-2381 vol.4. 2008-05-06T17:42:39-00:00 1999 Antennas and Propagation Society International Symposium, 1999. IEEE 4 2378 2381 vol.4 active antenna integrated oscillator http://www.citeulike.org/user/dcastro/article/2762093 <i>Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 3 (1998), pp. 1899-1902 vol.3.</i><br /><br />The new features of a cavity backed active slot-loop antenna are discussed in this paper. By using a high Q cavity, 35 dBc phase noise level reduction at 200 kHz from the carrier has been achieved. Once in resonance, the established TE₁₁₀ cavity fields rotate the principle E-plane of the slot-loop antenna through 90°. This results in an exchange of E- and H-plane locations in the radiation pattern together with reduced cross-polarisation levels. Thus the presence of the cavity tuned into and out of resonance allows the antenna to have its polarisation properties orthogonally switched Cavity induced polarisation switching in a slot-loop active antenna Q Chen M Zheng VF Fusco PS Hall doi:10.1109/MWSYM.1998.700865 Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 3 (1998), pp. 1899-1902 vol.3. 2008-05-06T17:16:12-00:00 1998 Microwave Symposium Digest, 1998 IEEE MTT-S International 3 1899 1902 vol.3 active antenna http://www.citeulike.org/user/dcastro/article/2762092 <i>Electronics Letters, Vol. 34, No. 1. (1998), pp. 3-4.</i><br /><br />A micromachined rectangular cavity-backed microstrip patch antenna has been developed on high resistivity silicon wafers. This novel path antenna has a much reduced effective dielectric constant and wide bandwidth Broadband microstrip patch antenna on micromachined silicon substrates M Zheng Q Chen PS Hall VF Fusco Electronics Letters, Vol. 34, No. 1. (1998), pp. 3-4. 2008-05-06T17:16:11-00:00 1998 Electronics Letters 34 1 3 4 antenna broadband microstrip patch http://www.citeulike.org/user/dcastro/article/2762090 <i>Microwaves, Antennas and Propagation, IEE Proceedings -, Vol. 148, No. 1. (2001), pp. 15-20.</i><br /><br />The use of a cavity coupled to an active integrated antenna oscillator is described. The cavity increases the loaded Q factor of the oscillator, thus improving stability and reducing the phase noise. Cavity stabilisation of a microstrip patch and slot ring oscillators is described. In both cases, phase noise at a frequency offset of 10 kHz is reduced by the order of 20 dB. A first-order analysis based on measured and simulated cavity Q factors is shown to give similar results. A Van der Pol analysis of a two-element array of patch oscillators, with a single extended coupled cavity, indicates that the likelihood of mutual locking in an array which has oscillators with slightly different free running frequencies is enhanced albeit at the expense of increased start-up time Cavity control of active integrated antenna oscillators M Zheng P Gardener PS Hall Y Hao Q Chen VF Fusco doi:10.1049/ip-map:20010221 Microwaves, Antennas and Propagation, IEE Proceedings -, Vol. 148, No. 1. (2001), pp. 15-20. 2008-05-06T17:15:59-00:00 2001 Microwaves, Antennas and Propagation, IEE Proceedings - 148 1 15 20 active antenna integrated oscillator http://www.citeulike.org/user/dcastro/article/2762086 <i>Antennas and Propagation, Tenth International Conference on (Conf. Publ. No. 436), Vol. 1 (1997), pp. 506-509 vol.1.</i><br /><br />Printed antennas mounted inside mobile communications equipment experience some detuning due to changes in the external environment. Such detuning can be offset by using a varactor tuned antenna. In this paper varactor tuning is integrated with a diode detector to monitor external effects. PC mounted software is then used to allow adaptive retuning. Although successful automatic retuning is achieved, significant intermodulation products due to these non-linear devices are present Microstrip patch antenna with integrated adaptive tuning PS Hall SD Kapoulas R Chauhan C Kalialakis Antennas and Propagation, Tenth International Conference on (Conf. Publ. No. 436), Vol. 1 (1997), pp. 506-509 vol.1. 2008-05-06T17:15:55-00:00 1997 Antennas and Propagation, Tenth International Conference on (Conf. Publ. No. 436) 1 506 509 vol.1 antenna integrated microstrip patch http://www.citeulike.org/user/dcastro/article/2762087 <i>Design of Mobile Handset Antennas for Optimal Performance in the Presence of Biological Tissue (Digest No. 1997/022), IEE Colloquium on (1997), pp. 3/1-3/3.</i><br /><br />The effect of the hand or body on printed antennas used in pagers and cellular telephone handsets is of concern as significant reduction of antenna efficiency can result due to changes in the input return loss. This change is due to the local conditions loading the antenna and changing its resonant frequency. Similarly effects may also be observed in fixed equipment when mounted in different environments. Varactor diodes can be integrated with printed antennas to change the resonant frequency. Diode tuning has been integrated with adaptive feedback to produce automatic retuning systems. In these arrangements the detuning is sensed by a directional coupler. The directional coupler needs good isolation to give adequate detector sensitivity. In principle this directional coupler could be associated with the antenna but more easily integrated into the transmitter circuit. Receive operation requires a directional coupler located within the receiver. In this paper we present an automatic retuning method in which the patch detuning is sensed by a detector diode integrated within the patch to form a more compact arrangement. Thus in principle our arrangement is suitable for transmit only. However it may also be appropriate in time division duplex systems or those where the transmitter can be periodically switched on. In arrangements where this is not possible or receive only systems, then a feedback signal from the receiver will be needed Adaptive tuning of microstrip antennas PS Hall SD Kapoulas R Chauhan C Kalialakis Design of Mobile Handset Antennas for Optimal Performance in the Presence of Biological Tissue (Digest No. 1997/022), IEE Colloquium on (1997), pp. 3/1-3/3. 2008-05-06T17:15:55-00:00 1997 Design of Mobile Handset Antennas for Optimal Performance in the Presence of Biological Tissue (Digest No. 1997/022), IEE Colloquium on 3/1 3/3 antenna microstrip http://www.citeulike.org/user/dcastro/article/2759136 <i>Microwaves, Antennas and Propagation, IEE Proceedings -, Vol. 141, No. 5. (1994), pp. 359-366.</i><br /><br />The current interest in active microstrip antennas has highlighted the need for analysis of the radiation characteristics of such antennas. The paper describes the extension of the small magnetic dipole source analysis of microstrip line discontinuities to active devices. The analysis is then combined with the patch cavity model to form a flexible, approximate analysis suitable for implementation in active antenna computer-aided design packages. Computed results agree well with measurements and show that radiation from the active device and associated matching circuits can be significant. The analysis indicates that reduced radiation pattern perturbation will result from the active device being integrated within the periphery of the patch Analysis of radiation from active microstrip antennas PS Hall IL Morrow Microwaves, Antennas and Propagation, IEE Proceedings -, Vol. 141, No. 5. (1994), pp. 359-366. 2008-05-05T20:24:25-00:00 1994 Microwaves, Antennas and Propagation, IEE Proceedings - 141 5 359 366 active antenna microstrip http://www.citeulike.org/user/dcastro/article/2759135 <i>Antennas and Propagation Society International Symposium, 2002. IEEE, Vol. 2 (2002), pp. 310-313 vol.2.</i><br /><br />On-body communications channels will become increasingly important in future wearable computing systems. To avoid the need for cables between the various parts of such distributed systems, wireless communications will be used. Efficient use of these on-body channels requires characterization and understanding of the propagation environment. This paper presents initial results and shows that significant channel loss variations can occur that are related to physiological body effects. Measurements of on-body propagation characteristics PS Hall M Ricci TM Hee doi:10.1109/APS.2002.1016087 Antennas and Propagation Society International Symposium, 2002. IEEE, Vol. 2 (2002), pp. 310-313 vol.2. 2008-05-05T20:24:21-00:00 2002 Antennas and Propagation Society International Symposium, 2002. IEEE 2 310 313 vol.2 channel propagation http://www.citeulike.org/user/dcastro/article/2759134 <i>Microwave and Millimeter Wave Technology, 2002. Proceedings. ICMMT 2002. 2002 3rd International Conference on (2002), pp. 770-772.</i><br /><br />On-body communications and computing environments will become increasingly important in the future. To avoid the need for cables between the various parts of such distributed systems, wireless communications will be used. Efficient use of these on-body channels requires characterization and understanding of the propagation environment. The paper presents initial results and shows that significant channel loss variations can occur that are related to physiological body effects. Characterization of on-body communication channels PS Hall M Ricci TW Hee Microwave and Millimeter Wave Technology, 2002. Proceedings. ICMMT 2002. 2002 3rd International Conference on (2002), pp. 770-772. 2008-05-05T20:24:19-00:00 2002 Microwave and Millimeter Wave Technology, 2002. Proceedings. ICMMT 2002. 2002 3rd International Conference on 770 772 channel communication http://www.citeulike.org/user/dcastro/article/2759133 <i>Electronics Letters, Vol. 34, No. 9. (1998), pp. 833-835.</i><br /><br />A phase locked loop (PLL) method for controlling a 4 GHz active patch antenna was investigated in order to both frequency stabilise the oscillator and to reduce the phase noise; both these aims were achieved by optimising the PLL parameters. Experimental results showed that a phase noise reduction of up to 26 dB was realised Oscillator stability and phase noise reduction in phase locked active microstrip patch antenna JW Andrews PS Hall Electronics Letters, Vol. 34, No. 9. (1998), pp. 833-835. 2008-05-05T20:24:19-00:00 1998 Electronics Letters 34 9 833 835 active antenna integrated microstrip patch http://www.citeulike.org/user/dcastro/article/2759132 <i>Microwave and Millimeter Wave Technology Proceedings, 1998. ICMMT '98. 1998 International Conference on (1998), pp. 285-288.</i><br /><br />Active microstrip patch antennas have been stabilised using cavity-backed and phase-locked-loop (PLL) controlled techniques. Experimental results show that phase noise reductions of up to 25 and 26 dB respectively can be realised Active integrated antenna oscillator stability and phase noise reduction M Zheng JW Andrews PS Hall P Gardner Q Chen VF Fusco doi:10.1109/ICMMT.1998.768281 Microwave and Millimeter Wave Technology Proceedings, 1998. ICMMT '98. 1998 International Conference on (1998), pp. 285-288. 2008-05-05T20:24:15-00:00 1998 Microwave and Millimeter Wave Technology Proceedings, 1998. ICMMT '98. 1998 International Conference on 285 288 active antenna integrated http://www.citeulike.org/user/dcastro/article/2755636 <i>European Microwave Conference, 1998. 28th, Vol. 2 (1998), pp. 735-740.</i><br /><br />Active integrated antennas, now a major research topic, offer highly compact radio front ends which will find application in a range of systems. The paper commences with a brief review of the technology and likely applications. Then some of the work at The University of Birmingham is summarised. Advances in the reduction of unwanted harmonic radiation through the use of improved antenna configurations is described. Stability and phase noise have been improved by the use of phase lock loops and resonant cavities. Finally issues relating to realisation on gallium arsenide monolithic microwave integrated circuits (MMICs) are discussed and examples at 5.8 and 30 GHz are shown. Progress in Active Integrated Antennas Peter Hall doi:10.1109/EUMA.1998.338247 European Microwave Conference, 1998. 28th, Vol. 2 (1998), pp. 735-740. 2008-05-05T08:06:18-00:00 1998 European Microwave Conference, 1998. 28th 2 735 740 active antenna integrated http://www.citeulike.org/user/dcastro/article/2755519 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 50, No. 3. (2002), pp. 937-944.</i><br /><br />This paper provide a review of the active integrated antenna (AIA) technologies. After a brief introduction on the definition and some historical remarks, the paper concentrates on the research effort on the past decades or so. The AlAs are reviewed in its various functions. First, an oscillator-type AIA is presented, followed by very interesting aspects of coupled oscillator arrays for phase control. Use of an AIA concept for efficient RF front ends is described with examples on high-power amplifier AlAs. Next, a phase-conjugation-based retrodirective array is reviewed. Finally, AIA systems for receiving, transmitting, and duplexing are reviewed Active integrated antennas K Chang York PS Hall T Itoh doi:10.1109/22.989976 Microwave Theory and Techniques, IEEE Transactions on, Vol. 50, No. 3. (2002), pp. 937-944. 2008-05-05T07:59:39-00:00 2002 Microwave Theory and Techniques, IEEE Transactions on 50 3 937 944 active antenna integrated