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Item type:Publication, An annular microstrip antenna with sectoral slots for RFID reader(2009-12-01); ; This paper presents an annular microstrip antenna with two sectoral slots fed by a coaxial probe on a square vertical ground plane. The proposed microstrip antenna can support the dual-band operation (UHF and microwave RFID bands). From the results, the antenna has the magnitude of S11 less than -10 dB along the bandwidth of 32 MHz (3.51%) for UHF band and 140 MHz (5.76%) for microwave band. The unidirectional beam can be achieved by the proposed microstrip antenna. The beamwidth in xz- and yz-planes is 82.8 and 89 degrees at the center frequency of 922.5 MHz and beamwidth in xz- and yz-planes is 39.8 and 28 degrees at the center frequency of 2.45 GHz, respectively. This antenna has efficiently high directivity for both bands. The simulation and measurement results are shown. ©2009 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, An eight-branch folded strip antenna with a circular parasitic patch on circular ground plane for SDARS application(2009-11-16); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Path loss prediction in durian orchard using uniform geometrical theory of diffraction(2009-11-16); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, In-depth analysis of reciprocal periodic structures of transmission lines(2009-08-31); An in-depth analysis of lossless reciprocal periodic structures of transmission lines (TLs) is presented. Interestingly, it is found that periodic structures can provide both non-negative (NNCR) and negative characteristic resistances (NCR). In addition, the magnitude of the voltage reflection coefficient associated with an equivalent model of periodic structures terminated with passive loads can be less than or equal to unity for the NNCR case, and can exceed unity and even approach infinity for the NCR case. However, associated powers are still conserved for both cases. Furthermore, an alternative derivation based on shortand open-circuited terminations for determining characteristic impedances and propagation constant of equivalent TLs is also introduced. An example of finite periodic TL structures, providing both NNCR and NCR cases, with varying the number of unit cells is also given. In addition, implementation and measurement are set up to verify theoretical and simulated results. It is found that these results are reasonably in good agreement. © The Institution of Engineering and Technology 2009. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A hybrid ring coupler quasi-optical antenna-mixer(2009-01-17); This paper proposes a hybrid ring coupler quasi-optical antenna-mixer for mitigating local oscillator retransmission. By demonstrating at K-band, the antenna element consists of back-to-back aperture coupled inverted square patch antenna to couple the RF signal at 18.8 GHz to the sigma port of a hybrid ring mixer while the LO signal at 17.5 GHz is coupled to the delta port. The HSCH-9101 Schottky diodes are used to transform the RF signal to the intermediate frequency signal at 1.3 GHz. The results show that the RF/LO isolation is better than 29 dB at 18.19 GHz, and the isotropic conversion loss of the down converted signal is better than 16 dB at 19.25 GHz. The application of the interest is an inverse measurement technique for dielectric property determination. © 2007 Elsevier GmbH. All rights reserved. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Analysis of radiation characteristics of a probe-excited rectangular ring antenna by the dyadic Green's function approach(2009-01-01); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Mutual information of mimo system in a corridor environment based on double directional channel measurement(2009-01-01); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Two-probe excited circular ring antenna for MIMO application(2009-01-01); ; Kosulvit, S.This paper presents the analysis and design of a two-probe excited circular ring antenna. The analysis is conducted by using induced emf method and transmission line model. The design process is to choose a suitable radius of the ring for a single probe antenna. Then, the suitable probe length and ring length are determined for the two-probe antenna. Finally, isolation between the two probes is enhanced by insertion of an inductor coil between the probes. The operational characteristics of the prototype antenna at the frequency of 5.2GHz are measured and compared with calculation results. It is evident that these results are in good agreement. The antenna achieved isolation in excess of 20dB and VSWR less than 2: 1 over the desired bandwidth and a bidirectional radiation pattern with 4dBi gain. This antenna is suitable for Multiple-Input Multiple-Output (MIMO) system covering a long and narrow environment. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Full-wave investigations of a probe-excited rectangular ring antenna by method of moments with RWG basis functions(2009-01-01) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Dual-band microstrip-to-coplanar strip balun transition and loop antenna application(2008-12-01); ; Lok, L. B.A microstrip-to-coplanar strip balun transition and its applicability to a single-fed dual-band tapered loop antenna are presented. The dual-band transition consists of a simple two-section transmission-line transformer and a two-section open-ended line. Closed-form design equations based on ideal transmission lines are derived and then verified with the examples of two designs. The application of the transition to a single-fed 0.9/1.8GHz dual-band tapered loop antenna is then demonstrated. The measured performance of the antenna proves the validity of the proposed dual-band transition network. © 2008 The Institution of Engineering and Technology.