The Research And Realization Of Space-borne Phased Array Antenna For Ground-to-digital Transmission

In contrast with mechanical antenna of MSCS,the phased array antenna has advantages including fast beam tracking,great gain,and wide beam coverage.Beam tracking will not products mechanical inertia influents satellite attitude,it can better adapt to LEO.In order to achieve the high rate of data transmission and the larger EIRP,the satellite-borne phased array antenna needs to have the wide-angle coverage under certain gain.Therefore,it is necessary to investigate on the satellite-borne phased array antenna with wide-angle scanning.Based on the requirement of small satellite data transmission,considering domestic and foreign researches,this paper implements a new wide-beam circularly polarized unit antenna to accomplish the design of phased array.The test indicate the wide-angle coverage is realized.According to the requirement,the circularly polarized antenna has been designed,which works in X-band and has wide 3dB AR range and beamwidth.This antenna applies the combination mode of reflector and small pitch spiral antenna,enhancing the performance of wide-beam antenna.Simulation and test show that the antenna 3dB beam width reaches to 128 °,3dB AR range covers ?=± 50°,the height is 11mm(0.3 A),achieving the performance of wide circularly polarized beam,which provides prerequisite for the array to realize wide-angle scanning.To further optimize beamwidth and symmetry of unit antenna,the design of a "saddle shaped" circularly polarized beam antenna was realized through the peripheral design of the circular reflector.Together with analysis and testing of antenna simulation,ensures that when ?=65° and 60°,omnidirectional gain is greater than 3.3dBi and 4dBi respectively,the 3dB AR range is 85°.The antenna has wide circular polarization,which achieves the "isoflux" coverage.Based on an actual project,this paper designs a phased array antenna with wide angule scanning function working in X-band.Under the request of EIRP value,with optimazing the gain and low elevation scanning as the goal,the overall layout of array and unit is optimized.Data from simulation shows:the antenna has a scanning range with ?= 0°-360° and ? =0°?65°.Also,the gain of low elevation is greater than 10 dBi,and the scanning axial ratio is less than 5.5 dB.Finally,the antenna is processed and tested to verify the feasibility of the scheme.