| Summary: | 碩士 === 國立臺灣大學 === 電信工程學研究所 === 103 === In this thesis, three reconfigurable slot antennas are proposed using varactor diodes to respectively realize the frequency reconfiguration, polarization reconfiguration, and pattern reconfiguration. All the antennas are based on planar slot radiators, and these antennas can be applied and adapted to various communication systems and environments.
To begin with, the frequency-reconfigurable coplanar waveguide (CPW) resonator antenna is proposed for dual-band operation. The two resonant frequencies can be determined by the two varactor diodes independently and respectively. The equivalent circuit model of the proposed frequency-tunable antenna is also presented and analyzed.
Furthermore, a polarization-reconfigurable antenna is realized with a dual-feed slot loop antenna and our proposed reconfigurable circuit. The proposed circuit with varactor diodes serves as phase shifters and a power divider. As a result, the polarization can alter from left- (right-)handed circular to left- (right-)handed elliptical with arbitrary axial ratio to linear polarization.
Finally, with the proposed circuits and simple slot array arrangement, one- and two-dimensional beam-steering antennas are implemented. The directions of main beams can be adjusted within ±20° from the broadside and the sidelobe levels remain below 15 dB. The reflection coefficients are below 10 dB. All the simulated and measured results are presented and reach a good agreement.
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