Research On Reconfigurable Microstrip Antenna For Wireless Communication

In recent years, with the rapid advancement and deployment of wireless communications,the reconfigurable antenna has stimulated an unprecedented enthusiasm in both academia andindustry. In this thesis, several novel reconfigurable patch antennas with differentreconfigurable characteristics for potentially commercial applications have been proposed.The main contents and contributions of the dissertation are summarized as follows: Firstly, an approach to design circularly polarized patch antenna with frequencyreconfiguration is proposed. By varying the capacitance values of four pairs of varactordiodes with single DC voltage, the resonant frequencies of the two orthogonal modes (TM01and TM10) of a rectangular patch can be simultaneously changed. Moreover, by introducing aspecific difference between the length and width of the rectangular-ring slot, good CPperformances can be obtained over a broad frequency tuning range. In addition, a dual-bandfrequency reconfigurable patch antenna with independent frequency reconfiguration byintegrating varactor diodes into a traditional stacked patch antenna is proposed. Secondly, a method to design quadri-polarization reconfigurable patch antenna ispresented. By controlling the operating states of four pairs of PIN diodes in the feed networkto change four signal transmission paths, the feed point of the circular patch can be switched;therefore, the reconfiguration between four linear polarization directions at a 45° interval(22.5°,67.5°,112.5°,and 157.5°) can be realized. Then, a polarization reconfigurable patchantenna by using SP4T switch instead of four pairs of PIN diodes in the feed network, whichneed no extra DC bias circuit, is designed. Thirdly, a guideline of designing a frequency and polarization reconfigurable patchantenna is introduced. Two pairs of varactor diodes are introduced to bridge the gaps betweenthe circular patch and four sector-shaped patches; the states of the varactors are controlled bytwo DC signals. By adjusting the reverse bias voltage of the varactors, the operatingfrequencies of the two orthogonal modes (TM01 and TM10) can be tuned and the proposedantenna can switch between linear polarization (LP), left-hand circular polarization (LHCP)and right-hand circular polarization (RHCP). Furthermore, the operating frequency of eachpolarization state can be independently tuned. Then, a miniature frequency and polarizationreconfigurable patch antenna by introducing four metal viahole connected to ground insteadof four sector-shaped patches, which has same reconfigurable characteristic, is presented.