Design Of A Multi-band Reflector Anttena Based On FSS Sub-Reflector

Due to the high gain,high power capacity and broadband advantages,reflector antenna has been widely used in modern satellite communication system.The way by using a reflector antenna to achieve multi-band and multi-feed multiplexing,can not only improve the efficiency of reflector antenna but also save space.It's very useful in satellite communication system,especially for the space-borne reflector antenna.The multi-band and multi-feed reflector antenna based on FSS sub reflector has been used widely in the field of satellite communication.In this paper,in order to realize the multi-band and multi-feed multiplexing,the metal hyperbolic sub-reflector is replaced by frequency selective surface(FSS)in a Cassegrain dual reflector antenna system.The most important part of using this method is the design of the FSS element structure as the sub-reflector.Therefore,the key point of this paper is to study and research the basic theory and electromagnetic transmission characteristics on FSS.An element with double screen and double ring structure is designed and meet the reflection in the X-band and transmission in the S-band.Then,the structure of a set of Cassegrain dual-reflector antenna is designed in this paper.The metal sub-reflector is replaced by a conformal hyperbolic FSS sub-reflector.According to the design of the dual-reflector antenna structure,the corrugated horn knowledge has been introduced and a corrugated horn is designed working in the X-band.The designed corrugated horn has good radiation characteristics,cross polarization characteristics and main polarization rotation symmetry and is in line with design requirements.In order to reduce the shade of the S-band feed from the X-band feed,the working principle of the single-ring coaxial multi-mode horn is introduced and a horn working in the S-band is designed.The horn has a "saddle" radiation pattern and also has good cross polarization characteristics,which meet the design requirements.At the end of the paper,the S/X two feed horns with the hyperbolic FSS sub-reflector joint simulation to research.For the X-band,in order to verify the reflection characteristics of the hyperbolic FSS sub-reflector,this paper compared them with the reflection characteristics of the metal hyperbolic sub-reflector.The results show that there are differences in the reflection characteristics of two kinds of hyperbolic sub-reflectors in the X-band,but the amplitude distribution is consistent with the basic requirements.For the S band,the radiation characteristics of feed are influenced by the hyperbolic FSS sub-reflection.Due to the asymmetry of the transmission phase,the distortion of the amplitude pattern is caused.But change is within acceptable limits.Therefore,it is known that the hyperbolic FSS sub-reflector meets the basic requirements.According to the design of Cassegrain dual reflector antenna structure and the position of dual feeds in antenna system,and modeling in ANSYS HFSS18.The calculation method combining physical optics and physical diffraction is used.The overall simulation of the antenna system is carried out.The simulation results show that when a set of reflector is shared,both the S/X bands have good radiation characteristics and meet the initial design requirements.