Design Of Wideband Fabry-perot Resonant Cavity Antennas

In recent years, there have been great requirements in the directional performance of modern antennas, mainly driven by the growing demand for the development of modern radar, electronic warfare and wireless communications. Resonant cavity antennas have attracted widespread attention owing to their unique characteristics of simple structure, easy processing, low cost and high gain. Based on the Fabry-Perot interference theory, in this thesis the traditional Fabry-Perot resonant cavity antennas are analyzed. Aiming at widening the gain bandwidth of the resonant cavity antennas, an in-depth study is made for the design of wideband Fabry-Perot resonant cavity antennas. The author′s major contributions are summarized as follows.1. A partially reflecting surface with a positive slope of the curve of reflection phase is designed. Its upper and lower surfaces are coated with periodic circular metal patches respectively, but their radii are different. By mounting the partially reflecting surface to the upper side of the microstrip patch antenna, the resonant cavity antenna features high gain and wideband operating characteristics. Measured results for the antenna show that-10 d B bandwidth of the reflection coefficients is 1.46 GHz(12 GHz-13.46 GHz), with the resonant frequency of 12.8 GHz and the relative bandwidth of 11.4 %. Simulated results indicate that the resonant cavity antenna has the maximum 19.7 d Bi gain at 13.1 GHz, and-3d B gain bandwidth is 0.94 GHz(12.28 GHz-13.22 GHz) with the relative bandwidth of 7.3 %.2. To optimize the operating bandwidth of the resonant cavity antenna and improve its radiation pattern, similarly a partially reflecting surface with a positive slope of the curve of reflection phase is designed. Its upper and lower surfaces are coated with periodic square metal patches respectively, but their side lengths are different. By mounting the partially reflecting surface to the upper side of the microstrip patch antenna, the resonant cavity antenna features high gain and wideband operating characteristics. Measured results for the antenna show that-10 d B bandwidth of reflection coefficients is 2.7 GHz(11.25 GHz-13.95 GHz), with the resonant frequency of 12.25 GHz and the relative bandwidth of 22 %. Simulated results show that the resonant cavity antenna has the maximum gain 21.1 d Bi at 11.9 GHz and-3d B gain bandwidth is 1 GHz(11.5 GHz-12.5 GHz) with the relative bandwidth of 8.3 %.3. A partially reflecting surface with a positive slope of the curve of reflection phase is designed. Its upper and lower surfaces are coated with periodic rectangular metal patches. By mounting the partially reflecting surface to the upper side of the microstrip patch antenna after appropriately adjusting the size of the metal patches, the resonant cavity antenna features dual-band and dual-polarized wideband operating characteristics. Measured results indicate that-10 d B bandwidth of reflection coefficients of the antenna at the X polarization direction is 1.76 GHz(9.7 GHz-11.48 GHz), with the relative bandwidth of 17 %, and-10 d B bandwidth of the reflection coefficients of the antenna at the Y polarization direction is 0.8 GHz(9.3 GHz-10.1 GHz), with the relative bandwidth of 7.36 %. Simulated results show that the maximum gain of the antenna at the X polarization direction is 15.5 d Bi, with the-3d B gain bandwidth of 1GHz(9.8 GHz to 10.8 GHz) and the relative bandwidth of 9.7 %, and the maximum gain of the antenna at the Y polarization direction is 19.6 d Bi, with the-3d B gain bandwidth is 0.6 GHz(9.5 GHz to 10.1 GHz) and the relative bandwidth of 5.12 %.