| As one of the most important forms of satellite communication antennas,reflector antennas has the advantage of high gain,low sidelobe,stable performance,simple structure and low processing cost.In order to make more full use of frequency band resources and realize the portability of satellite communication terminals,reflector antennas are currently developing in the direction of broadband,multi-band sharing,dual polarization,and miniaturization of antenna systems.In this paper,Ku broadband reflector antenna,K/Ka dual-band broadband reflector antenna and X/K/Ka multi-band dual circularly polarized satellite antenna system are designed.The main work is introduced simply as follows:1.The design of reflector antenna and feeding structure.Using the MATLAB-HFSS-API co-simulation method,three kinds of hat-type feeding reflector antennas are designed,including Ku broadband reflector antenna,K/Ka dual-band broadband reflector antenna and X/K/Ka multi-band reflector antenna.For the 0.5-meter Ku-band broadband reflector antenna,the outer wall of the feeding waveguide is loaded with a corrugated sleeve structure,which significantly improves the illumination characteristics of the feed.Finally,the aperture efficiency of the reflector antenna in the entire frequency band is greater than 68.4%.For the 0.5-meter K/Ka dual-band broadband reflector antenna,the feeding waveguide and hat-shaped subsurface shared by the dual-band are designed.The sidelobe envelope meets the ITU-580 standard in the entire frequency band.The antenna efficiency is greater than 60.4%.In addition,a 0.9-meter X/K/Ka multi-band reflector antenna for medium-orbit satellite communication is designed.The circular waveguides with coaxial form are employed to achieve the dual-channel feeding structure.The efficiency of the X-band antenna reaches 62.34%.The sidelobe envelope of the pattern basically meets the ITU-580 standard,and the K/Ka-band antenna efficiency is greater than 47.76%.The performance of the 0.9-meter X/K/Ka multi-band reflector antenna meets the design index requirements.2.The design of X-band and K/Ka-band duplexers.According to the requirements of the index,two duplexers are designed to work in the X and K/Ka bands.For the X-band duplexer,a T-junction is used as the common end structure.In order to realize the miniaturization of the feeding network,a 10th-order coaxial cavity band-pass filter is employed.The isolation of the co-polar transceiver ports is greater than 59.4d B,which meets the requirements.The performance of the X-band duplexer satisfies the requirements. The K/Ka-band duplexer adopts the H-plane tee as the common end structure.A corrugated filter is designed in the receiving channel,and a band-pass filter loaded with an inductive diaphragm is used in the transmitting channel,so that the isolation of the transceiver port is greater than 100 d B.The performance of the K/Ka-band duplexer meets the requirements.3.The design of X/K/Ka multi-band feeding network.According to the requirements,a multi-band miniaturized feeding network is designed.The X-band dual-polarization four-port network is obtained.Firstly,the coaxial turnstile-type OMT is used for polarization separation.Then,the E-plane 3d B coupler is used to extract the left and right circular polarization.Finally,the duplexer is used to isolate the transceiver.The receiving to transmitting isolation reaches 86.09 d B,which meets the requirements.In the K/Ka frequency band,the turnstile-type OMT is used for polarization separation.Then,the duplexer is used for frequency separation.Finally,the 3d B coupler is used to extract the left and right circularly polarized signals,and the K/Ka frequency band dual-polarization four-port network is obtained.The receiving to transmitting isolation reaches 110 d B,which meets the requirements.4.The design of multi-band satellite communication system.The X/K/Ka multi-band reflector,hat-shaped feed,and integrated feed network are integrated into an X/K/Ka multi-band antenna system.The overall simulation is analyzed to verify that the main performance of the antenna system,meeting the design requirements. |
