Thu, 24 Jul 2008 15:21:45 BST CiteULike: dcastros Leong http://www.citeulike.org/user/dcastro/author/Leong CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dcastro/article/2859756 <i>Antennas and Propagation, IEEE Transactions on, Vol. 55, No. 3. (2007), pp. 868-876.</i><br /><br />The analysis of resonant-type antennas based on the fundamental infinite wavelength supported by certain periodic structures is presented. Since the phase shift is zero for a unit-cell that supports an infinite wavelength, the physical size of the antenna can be arbitrary; the antenna's size is independent of the resonance phenomenon. The antenna's operational frequency depends only on its unit-cell and the antenna's physical size depends on the number of unit-cells. In particular, the unit-cell is based on the composite right/left-handed (CRLH) metamaterial transmission line (TL). It is shown that the CRLH TL is a general model for the required unit-cell, which includes a nonessential series capacitance for the generation of an infinite wavelength. The analysis and design of the required unit-cell is discussed based upon field distributions and dispersion diagrams. It is also shown that the supported infinite wavelength can be used to generate a monopolar radiation pattern. Infinite wavelength resonant antennas are realized with different number of unit-cells to demonstrate the infinite wavelength resonance Infinite Wavelength Resonant Antennas With Monopolar Radiation Pattern Based on Periodic Structures A Lai KMKH Leong T Itoh doi:10.1109/TAP.2007.891845 Antennas and Propagation, IEEE Transactions on, Vol. 55, No. 3. (2007), pp. 868-876. 2008-06-03T18:57:48-00:00 2007 Antennas and Propagation, IEEE Transactions on 55 3 868 876 antenna crlh metamaterial http://www.citeulike.org/user/dcastro/article/2839871 <i>Microwave Conference, 2006. 36th European (2006), pp. 937-939.</i><br /><br />This paper reviews applications of the infinite wavelength supported by certain metamaterials accomplished to date by the authors' group. In particular, novel microwave resonators, dividers, and antennas based on the fundamental infinite wavelength supported by the composite right/left-handed metamaterial transmission line are presented. Applications and the unique properties of these novel microwave devices are also presented Applications of Infinite Wavelength Phenomenon A Lai KMKH Leong Tatsuo Itoh doi:10.1109/EUMC.2006.281075 Microwave Conference, 2006. 36th European (2006), pp. 937-939. 2008-05-28T07:02:30-00:00 2006 Microwave Conference, 2006. 36th European 937 939 metamaterial http://www.citeulike.org/user/dcastro/article/2839866 <i>Microwave Symposium Digest, 2005 IEEE MTT-S International (2005), 4 pp..</i><br /><br />A class-F power amplifier at 2.4GHz using a novel harmonic tuner based on a composite right/left handed (CRLH) transmission line (TL) is proposed and experimentally tested. Two structures are presented. One structure uses one open CRLH-TL stub to suppress 2nd, 3rd harmonics and the fundamental frequency is matched to 50/spl Omega/. The other structure uses two open CRLH-TL stubs in order to suppress 2nd, 3rd, 4th harmonics and the fundamental frequency is matched to specific impedance. The structure proposed is used to design a class-F power amplifier. A maximum drain efficiency of 64% is obtained. Class-F power amplifier using a multi-frequency composite right/left-handed transmission line harmonic tuner A Dupuy KMKH Leong T Itoh doi:10.1109/MWSYM.2005.1517142 Microwave Symposium Digest, 2005 IEEE MTT-S International (2005), 4 pp.. 2008-05-28T06:59:29-00:00 2005 Microwave Symposium Digest, 2005 IEEE MTT-S International 4 pp. amplifier crlh metamaterial power http://www.citeulike.org/user/dcastro/article/2839865 <i>Antennas and Propagation Society International Symposium, 2005 IEEE, Vol. 3A (2005), pp. 798-801 vol. 3A.</i><br /><br />An FDTD method, combined with thin wire and thin slot algorithms used to analyze a metamaterial based on periodic mushroom structures, is proposed. This proposed method is suitable for analyzing problems with fine structural details. Two examples of mushroom structures are investigated to compare the results between simulation and measurement to show left-handed propagation properties. Accuracy of the proposed method is verified compared to the measurement results. Efficient FDTD method for analysis of left-handed mushroom structure Wei-Yang Wu A Lai KMKH Leong Chih-Wen Kuo T Itoh doi:10.1109/APS.2005.1552377 Antennas and Propagation Society International Symposium, 2005 IEEE, Vol. 3A (2005), pp. 798-801 vol. 3A. 2008-05-28T06:58:07-00:00 2005 Antennas and Propagation Society International Symposium, 2005 IEEE 3A 798 801 vol. 3A crlh fdtd metamaterial mushroom http://www.citeulike.org/user/dcastro/article/2839856 <i>Microwave Symposium, 2007. IEEE/MTT-S International (2007), pp. 1423-1426.</i><br /><br />In this paper, a mode selective metamaterial which supports either forward or backward waves within the same frequency bandwidth is presented. The choice between dispersion operations is based on the mode excitation applied to the metamaterial. A demonstration microstrip prototype of this novel dual-mode composite right/left-handed metamaterial is realized and characterized. The metamaterial is right-handed under even-mode excitation and is left-handed under odd-mode excitation in the 1.86 GHz -2.00 GHz frequency range. Circuit simulations with the numerical and experimental results of the dual-mode metamaterial transmission line are performed to demonstrate electromagnetic wave steering and spatial multiplexing at a fixed frequency based on dispersion selectivity. Dual-Mode Metamaterial with Backward and Forward Wave Selectivity A Lai KMK Leong T Itoh doi:10.1109/MWSYM.2007.380499 Microwave Symposium, 2007. IEEE/MTT-S International (2007), pp. 1423-1426. 2008-05-28T06:51:03-00:00 2007 Microwave Symposium, 2007. IEEE/MTT-S International 1423 1426 metamaterial http://www.citeulike.org/user/dcastro/article/2839849 <i>Microwave Symposium Digest, 2005 IEEE MTT-S International (2005), 4 pp..</i><br /><br />A novel N-port series divider based on a composite right/left-handed (CRLH) transmission line (TL) supporting a wave with an infinite wavelength is presented. This novel divider evenly divides power in phase to an infinite number of ports at its infinite wavelength frequency. In addition, it is shown that the novel series divider's performance is not dependent on the location of its output ports. The basic operating principle is based on the fact that a CRLH TL is able to support a wave with an infinite wavelength. As a result, all points along the CRLH TL have the same magnitude and phase. A 3-port series divider consisting of a 8 unit-cell CRLH TL is shown to exhibit 0.22 dB maximum magnitude difference and 1.32/spl deg/ maximum phase difference between output ports at its infinite wavelength frequency. In addition, a 5-port series divider consisting of a 13 unit-cell CRLH TL is fabricated and shown to exhibit 0.30 dB maximum magnitude difference and 6.3/spl deg/ maximum phase difference between output ports at its infinite wavelength frequency. Both simulation and experimental results are shown to support the authors' claims. A novel N-port series divider using infinite wavelength phenomena A Lai KMKH Leong T Itoh doi:10.1109/MWSYM.2005.1516834 Microwave Symposium Digest, 2005 IEEE MTT-S International (2005), 4 pp.. 2008-05-28T06:43:47-00:00 2005 Microwave Symposium Digest, 2005 IEEE MTT-S International 4 pp. array metamaterial http://www.citeulike.org/user/dcastro/article/2839848 <i>Antennas and Propagation Society International Symposium, 2005 IEEE, Vol. 2B (2005), pp. 218-221 vol. 2B.</i><br /><br />The paper presents the design of an electrically small antenna employing a composite right/left-handed (CRLH) transmission line. The physical size and operating frequency of the antenna depend on the unit cell size and equivalent transmission line model parameters. Therefore, the small antenna is realized by miniaturizing the unit cell and increasing the shunt inductance and series capacitance. A four unit cell resonant antenna is designed and tested at 1.06 GHz. The length, width and height of the proposed antenna are (1/19)/spl lambda//sub 0/, (1/23)/spl lambda//sub 0/, and (1/83)/spl lambda//sub 0/, respectively. Design of resonant small antenna using composite right/left-handed transmission line Cheng-Jung Lee KMKH Leong T Itoh Antennas and Propagation Society International Symposium, 2005 IEEE, Vol. 2B (2005), pp. 218-221 vol. 2B. 2008-05-28T06:43:43-00:00 2005 Antennas and Propagation Society International Symposium, 2005 IEEE 2B 218 221 vol. 2B antenna crlh resonant small tl http://www.citeulike.org/user/dcastro/article/2839847 <i>Microwave Symposium Digest, 2006. IEEE MTT-S International (2006), pp. 935-938.</i><br /><br />This paper presents a methodology of designing a microwave bandstop filter and a bandpass filter by using a Composite Right/Left Handed transmission line (CRLH-TL) as part of a transversal filter. The CRLH-TL can be engineered to have specific phase slope and phase offset. Connecting the CRLH-TL and the conventional microstrip delay line at both input and output can establish a transversal filter where the signal merging at the output has broadband out of phase characteristics. Therefore, the bandstop filter can be created with signal rejection over a wide frequency range. The measured 3dB bandwidth of the bandstop filter is 130% and the minimum insertion loss at the next passband is ¿1.7dB. In addition, based on the bandstop filter a bandpass filter with a wide signal rejection range is developed by creating a frequency dependent defect in one branch of the bandstop filter. This is implemented by either attaching a microstrip open stub or capacitively coupling a microstrip resonator to the microstrip delay line. The 3dB passband bandwidth and the minimum insertion loss are 18%, ¿1.5dB and 8%, ¿2dB corresponding to the open stub and the resonator scheme, respectively. Metamaterial Transmission Line Based Bandstop and Bandpass Filter Designs Using Broadband Phase Cancellation Cheng-Jung Lee KMKH Leong Tatsuo Itoh doi:10.1109/MWSYM.2006.249870 Microwave Symposium Digest, 2006. IEEE MTT-S International (2006), pp. 935-938. 2008-05-28T06:43:41-00:00 2006 Microwave Symposium Digest, 2006. IEEE MTT-S International 935 938 filter metamaterial tl http://www.citeulike.org/user/dcastro/article/2839846 <i>Microwave Conference, 2006. APMC 2006. Asia-Pacific (2006), pp. 1060-1066.</i><br /><br />In this paper, a free space power combining oscillator antenna array using a metamaterial based injection locking coupling network is described and demonstrated. The unique metamaterial series coupling network utilizes the infinite wavelength phenomenon which allows it to support an infinitely long wave at a non-zero frequency. It is demonstrated that equal phase/amplitude oscillator synchronization can be achieved without regards to the antenna element spacing in the array. A small scale prototype oscillator array is designed to have compact, non-uniform element spacing to demonstrate the concept. An EIRP of 18 dBm at 2.37 GHz is measured. Power combining oscillator array using metamaterial based injection locking coupling network KMK Leong A Lai T Itoh doi:10.1109/APMC.2006.4429592 Microwave Conference, 2006. APMC 2006. Asia-Pacific (2006), pp. 1060-1066. 2008-05-28T06:43:38-00:00 2006 Microwave Conference, 2006. APMC 2006. Asia-Pacific 1060 1066 active array metamaterial oscillator http://www.citeulike.org/user/dcastro/article/2839828 <i>Antenna Technology Small Antennas and Novel Metamaterials, 2006 IEEE International Workshop on (2006), pp. 404-407.</i> Composite Right/Left-Handed Metamaterial Antennas A Lai KMKH Leong T Itoh Antenna Technology Small Antennas and Novel Metamaterials, 2006 IEEE International Workshop on (2006), pp. 404-407. 2008-05-28T06:41:50-00:00 2006 Antenna Technology Small Antennas and Novel Metamaterials, 2006 IEEE International Workshop on 404 407 antenna crlh metamaterial http://www.citeulike.org/user/dcastro/article/2839827 <i>Microwave Symposium, 2007. IEEE/MTT-S International (2007), pp. 1745-1748.</i><br /><br />This paper presents a broadband quadrature hybrid which makes use of the broadband power division properties of conventional Wilkinson power splitters along with broadband phase difference achieved using metamaterial based delay lines. The bandwidth of the 90degplusmn5deg phase difference and 0.48 dB power difference between the outputs of the Wilkinson power splitter and metamaterial delay line combination is 67%. The full four-port coupler is formed employing an additional combiner. A phase/power difference between the hybrid outputs of 90degplusmn10deg and 1.2 dB, respectively, are observed over the same 67% bandwidth. To demonstrate the applicability of the proposed broadband quadrature hybrid, a continuous phase shifter which is based on the vector sum method is tested. Broadband Quadrature Hybrid Design Using Metamaterial Transmission Line and Its Application in the Broadband Continuous Phase Shifter Cheng-Jung Lee KMKH Leong T Itoh doi:10.1109/MWSYM.2007.380066 Microwave Symposium, 2007. IEEE/MTT-S International (2007), pp. 1745-1748. 2008-05-28T06:41:48-00:00 2007 Microwave Symposium, 2007. IEEE/MTT-S International 1745 1748 broadband crlh metamaterial tl http://www.citeulike.org/user/dcastro/article/2839825 <i>Microwave Symposium, 2007. IEEE/MTT-S International (2007), pp. 1623-1626.</i><br /><br />Metamaterial-based composite right/left-handed transmission lines are used in the design of fixed frequency and tunable ring resonators. Under specific design conditions, the first two resonant modes can be narrowly spaced. A simple passive band-pass filter is demonstrated at 2.92 GHz with a bandwidth of about 9% using this concept. This type of design is also used as a tunable resonator and a tuning range of 30% is demonstrated. Fixed Frequency and Tunable Metamaterial-Based Ring Resonators with Narrowly Spaced Resonances CA Allen KMK Leong T Itoh doi:10.1109/MWSYM.2007.379997 Microwave Symposium, 2007. IEEE/MTT-S International (2007), pp. 1623-1626. 2008-05-28T06:41:40-00:00 2007 Microwave Symposium, 2007. IEEE/MTT-S International 1623 1626 metamaterial resonator ring http://www.citeulike.org/user/dcastro/article/2809071 <i>Antennas and Propagation Society International Symposium 2006, IEEE (2006), pp. 394-397.</i><br /><br />Application of left-handed (LH) metamaterials in the field of microwave engineering has grown rapidly following their experimental verification. In particular, the LH transmission line (TL) has been used to realize various microwave devices not possible with conventional TLs alone. The purpose of this paper is to summarize some of the recent advances in microwave devices based on LH TLs. In particular, devices based on the unique characteristics of the composite right/left-handed (CRLH) TL, which is the general model of a practical LH TL, are presented. Microwave devices based on left-handed transmission lines A Lai KMKH Leong T Itoh doi:10.1109/APS.2006.1710541 Antennas and Propagation Society International Symposium 2006, IEEE (2006), pp. 394-397. 2008-05-18T14:06:55-00:00 2006 Antennas and Propagation Society International Symposium 2006, IEEE 394 397 crlh lh metamaterial microwave tl http://www.citeulike.org/user/dcastro/article/2801467 <i>Potentials, IEEE, Vol. 22, No. 3. (2003), pp. 16-21.</i><br /><br />Antenna arrays are individual radiating elements combined so that they function and perform like a single large antenna. Besides high radiating beam directionality, antenna arrays offer the capability to scan the main beam and control sidelobe radiation electronically. Retrodirective antenna arrays, as the name suggests, have a special feature. When receiving a signal from an unspecified direction, the array can automatically transmit a signal response to that same direction without any previous knowledge of the source direction. This function is performed automatically without the use of phase-shifters or digital circuitry. Compared to other array antennas that rely on digital signal processing (DSP) for beam direction control, this approach is much simpler and potentially faster because digital calculation is not needed. The automatic beam control nature of retrodirective arrays is well suited for RFID (radio frequency identification) and microwave tracking beacon applications. The article discusses the basic functionality as well as the ongoing research efforts and developments in retrodirective array architectures. Self-phasing attributes of different arrays are presented, as well as their applicability in practical communication systems. Moving forward in retrodirective antenna arrays KMKH Leong RY Miyamoto T Itoh doi:10.1109/MP.2003.1232308 Potentials, IEEE, Vol. 22, No. 3. (2003), pp. 16-21. 2008-05-15T12:15:00-00:00 2003 Potentials, IEEE 22 3 16 21 antenna array http://www.citeulike.org/user/dcastro/article/2782004 <i>Microwave Conference, 2006. 36th European (2006), pp. 1044-1047.</i><br /><br />This paper presents a resonant type dual-band antenna with compact size which is realized by using an anisotropic metamaterial. The artificial anisotropic medium is implemented by employing a composite right/left-handed transmission line. The dispersion relation and the antenna physical size only depend on the composition of the unit cell and the number of cells used. By engineering the characteristics of the unit cells to be different in two orthogonal directions, the corresponding propagation constants can be controlled, thus enabling dual-band antenna resonances. In addition, the antenna dimensions can be markedly minimized by maximally reducing the unit cell size. The proposed antenna is designed at frequencies for PCS/Bluetooth applications. The physical size of the proposed dual-band antenna is 1/17lambda₀x1/17lambda₀x1/19lambda₀ where lambda₀ is the free space wavelength at 2.37GHz Compact Dual-Band Antenna Using an Anisotropic Metamaterial Cheng-Jung Lee KMKH Leong Tatsuo Itoh doi:10.1109/EUMC.2006.281112 Microwave Conference, 2006. 36th European (2006), pp. 1044-1047. 2008-05-09T23:43:04-00:00 2006 Microwave Conference, 2006. 36th European 1044 1047 antenna compact dual-band metamaterial http://www.citeulike.org/user/dcastro/article/2762089 <i>Wireless Communication Technology, 2003. IEEE Topical Conference on (2003), pp. 190-193.</i><br /><br />This paper discusses the recent developments by the author's group in the field of RF front-end technology. This includes standalone RF front-end components such as a self-heterodyne mixer as well as more functional front-end circuitry such as digital and analog beamformers. Advanced and intelligent RF front end technology KMKH Leong T Itoh doi:10.1109/WCT.2003.1321485 Wireless Communication Technology, 2003. IEEE Topical Conference on (2003), pp. 190-193. 2008-05-06T17:15:56-00:00 2003 Wireless Communication Technology, 2003. IEEE Topical Conference on 190 193 receiver rf http://www.citeulike.org/user/dcastro/article/2762088 <i>Antennas and Propagation Society International Symposium, 2003. IEEE, Vol. 2 (2003), pp. 647-650 vol.2.</i><br /><br />The integration of electronics and antennas forming a single front-end component offers several benefits for modem microwave and millimeter-wave system designs, such as compactness, lower power consumption, and multi-functionality. This paper highlights some of the work carried out by the author's research group in the area of active integrated antennas (AIAs). The study of both active circuits and antennas has led to some insight into the design of new antenna array architectures for retrodirective antenna arrays and smart-antennas, which are also discussed in this paper. Integration of electronics and antennas KMKH Leong T Itoh doi:10.1109/APS.2003.1219319 Antennas and Propagation Society International Symposium, 2003. IEEE, Vol. 2 (2003), pp. 647-650 vol.2. 2008-05-06T17:15:55-00:00 2003 Antennas and Propagation Society International Symposium, 2003. IEEE 2 647 650 vol.2 active antenna integrated http://www.citeulike.org/user/dcastro/article/2755596 <i>Antennas and Propagation Society International Symposium, 2003. IEEE, Vol. 1 (2003), pp. 212-215 vol.1.</i><br /><br />Active integrated antennas (AIAs) represent a new class of microwave and millimeter wave front-end circuitry, offering several attractive features such as compact circuit implementation, light weight, better efficiency, and multi-functionality. This is because the radiating antenna is used as a functional part of the microwave circuit. The paper presents several developments in the research area of active integrated antennas for microwave and millimeter wave front end applications. Developments in active integrated antennas KMKH Leong T Itoh Antennas and Propagation Society International Symposium, 2003. IEEE, Vol. 1 (2003), pp. 212-215 vol.1. 2008-05-05T08:03:34-00:00 2003 Antennas and Propagation Society International Symposium, 2003. IEEE 1 212 215 vol.1 active antenna integrated