Browsing by Author "Chang, K"

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A novel amplifying antenna array using patch-antenna couplers - Design and measurement
(2002-08-01)
Tsai, CH
;
Yang, YCA
;
Chung, SJ
;
Chang, K
;
電信工程研究所
This paper proposes a novel amplifying antenna array using the patch-antenna coupler formed by placing one or two open-ended microstrip lines (coupled lines) near and along the nonradiating edge(s) of a patch antenna. An X-band five-element array with broadside 25-dB Chebyshev radiation is demonstrated. When the input signal is fed to the center element, with most of the power radiating from the antenna, part of it is tapped to the coupled lines, amplified by an FET amplifier, and fed to the next antenna element. This process is repeated after all the antenna elements are fed with suitable power. The amplitude distribution of the fields radiated from the antennas is controlled by the coupling coefficient from the patch to the coupled line, which, in turn, is governed by the coupling length and gap between the patch and line. The measured return loss of the designed five-element array is -27 dB at the center frequency of 10 GHz with 2% 10-dB bandwidth. The radiation pattern possesses a transmitting gain of 15.9 dB, a half-power beamwidth of 17degrees, and a sidelobe level of -22 dB.
A planar Van Atta array reflector with retrodirectivity in both E-plane and H-plane
(2000-02-01)
Tseng, WJ
;
Chung, SJ
;
Chang, K
;
電信工程研究所
;
Institute of Communications Engineering
A planar antenna array reflector with retrodirectivity in both the E-plane and the H-plane is analyzed and demonstrated at X band. The reflector consists of six pairs of slot-coupled patch antennas arranged using the Van Atta approach. The total reflected field from the reflector is separated into three primary components; that is, the reradiation field from the patch antennas (RFPA), the scattering field from the patch antennas (SFPA), and the scattering field from the ground plane (SFGP). The first two components are calculated by using the method of moments together with a mixed potential integral equation and the last one is by the physical optics (PO) method combined with the method of equivalent currents (MEC). By tuning the microstrip-line lengths, the total reflected held contributed by the three components is designed to possess a broad-beamed pattern in both the E-plane and the H-plane. The measured patterns show good agreement with the designed ones.
A retrodirective microstrip antenna array
(1998-12-01)
Chung, SJ
;
Chang, K
;
電信工程研究所
;
Institute of Communications Engineering
A Van Atta retrodirective reflector was designed and developed, using an aperture-coupled microstrip antenna array. This reflector possesses the advantage of reflecting high fields to the source point over a wide range of incidence angles and, owing to the low cost and comformability of the structure, is suitable for applications in intelligent vehicle highway systems (IVHS). An approximate theory associated with the reradiation and scattering principles of the reflector is presented for the purpose of understanding and designing the reflector. The utility of the retrodirective reflector was demonstrated by comparison with a plate reflector and a microstrip antenna array without a feed structure. Finally, a reflector with switches in the middle of the microstrip feed lines was investigated for possible applications in communications and remote identification.