Cone Beam Fabry-perot Cavity Antenna Research

Conical beam antennas (CBA) are a kind of antenna whose pattern and polarization are symmetrical in radial direction. The maximum radial direction diverges from the normal direction with a specified angle. Because of their omni-direction characteristic in azimuth, a large coverage area can be achieved. Therefore, CBAs are widely used in vehicle satellite communication, wireless local area networks, and navigational tracking systems. Fabry-Perot (FP) antennas are resonant cavity antennas with high efficiency. Conical radiation pattern with a desired flare angle can be implemented based on space selection characteristics of the resonant cavity. In this paper, FP antennas with conical beam are investigated to obtain high gain performance, and that is of great importance in theoretical research and engineering applications.Firstly, we summarize the background, the art of state and the development trends of FP antennas and conical antennas. Secondly, the operation principle of conical beams are investigated with emphasis on appropriate selection of circular patch antenna modes. Then, the condition of achieving conical beams is discussed from the view of multi-reflection. A maximum directivity formula is further derived for ideal uniform aperture field distribution. In chapter three, a design on FP antennas with conical beam is presented by illustrating designs on the overall structure, the primary radiated source, the FFS (frequency selective surface) superstate and optimization of the entire antenna in detail. A simulation model based on the image theory and a defect mode method is emphasized. In chapter four, the effects on the gain homogeneity is analyzed from the views of the polarization sensitivity, the incident angle sensitivity and the elements'displacement.Finally, a Fabry-Perot antenna with 30°conical beam at 12.5GHz is developed with a diameter of 8.25 times wavelength. Gain of 12 dBi is successfully achieved. Simulated ripple of gain is smaller than 0.3dB. The relative aperture efficiency is more than 17%. Measured results are in good agreement with simulation ones.