Research And Design Of Multi-Band Antennas With Hat Feed

The reflector antenna has been playing an important role in the field of satellite communications with its excellent performance.The development trend of reflector antennas is toward to wideband and multi-band.In addition,low sidelobe and high gain are also the pursuing goals of reflector antennas.As the key part of a reflector antenna,the feed affects the performance of the antenna to a great extent.Better performance of reflector antennas can be achived by the improvement of the feed.A hat shaped feed is composed of a secondary reflector and a feed.It can be designed to improve the efficiency of a reflector antenna.More and more attention is paid to the hat shaped feed recently.The hat-shaped feed are studied in this paper.The main works are:1.Introduction to the basic theory and a design method of the hat feed.The hat feed has a different structure from the traditional ring focus ellipsoidal feed.Hence a method of desiging a hat feed is different too.A designing strategy is intruduced to achieve a higher efficiency of a ring focuse antenna.2.Using HFSS-MATLAB co-simulation method,an X-band hat feed reflector antenna is designed.The influences of the size of the ring focus radius,the adjusting rod,the secondary reflector,the corrugated sleeve and choke groove on the performance of the antenna are analyzed in detail,which provides experience for the fellowing design of multi-band hat feed antannas.3.An X/K/Ka-band hat feed reflector antenna is designed by loading the hat shaped feed with a dielectric rod.The efficiency of the antenna in K/Ka band is effectively improved,while the efficiency of the antenna is also high in X band.4.An X/K/Ka-band hat feed reflector antenna and its circularly polarized feed network are designed.The feed in X band is a coaxial waveguide,while the inner circular conductor of the coaxial waveguide as the circular waveguide feed in K/Ka-band.The resistance matching performance in Ka band can be improved by dielectric steps.The resistance matching performance in X band can be improved by irises and tapered structure.The analysis shows that the antenna reaches a high efficiency.