Planar Peridoic Structures And Its Applications On Antenna Design

Passive electromagnetic periodic structures attract more and more attention because of their special advantages. For examples, the Artificial-Magnetic-Conductors (AMC) can lower antennas’ profiles. The Partially-Selective-Surfaces (PRS) are used to make Fabry-Perot resonant cavity. AMC and PRS are studied for low profile and high gain of antennas in this dissertation. The main works and contributions in this dissertation are outlined as follows:1. A low-profile broadband directive antenna based on AMC is designed. Firstly, the resistance and radiation characteristic of electric dipole which is parallel to PEC and PMC is analysed. A double-layered AMC with broad in-phase band is designed and combined with two broadband directive dipoles. Compared with the base station antennas, the profiles of antennas on AMC are lowered from1/4wavelength to1/8wavelenghth with the maintance of radiation characteristic. Based on the linear polarization antennas, the±450dual polarization low profile broadband antennas are designed. The antennas’ gain is more than8dBi in1.8GHz to2.4GHz operating band. The isolation of different ports is less than-20dB.2. A Planar integrated Fabry-Perot antenna with high isolation dual polarization is designed. The antenna is fed by the microstrip patch. According to the high near-field coupling in FP resonant cavity, the feedline of the antenna is separated. The horizontal polarization is excited with near-field coupling which the veritical olarization is excited with slot coupling. The antenna is designed with less than-40dB port isolation in9.7GHz to10.3GHz. The gain of dual polarization at10.0GHz is15dBi and15.2dBi.3. A Planar integrated Fabry-Perot antenna excited by multiple feed sources is designed. Because the single source in FP resonant cavity can not excite the whole antenna aperture effectively, the new FP resonant cavity is excited by multiple feed sources in order to improve the aperture efficiency. In this way, the antenna’s gain is increased by2.5dBi in9.75GHz to10.2GHz with the fixed effective radiating area.