Research On Relationship Between Axial Ratio And Antenna Structure

In satellite communication,navigation and radar systems,linear polarization antenna is difficult to meet the increasingly strict requirements.The circularly polarized antenna has many advantages,such as low polarization loss and resistance to multipath interference,so the circularly polarized antenna has been more and more widely used.In the recent 20 years,the rapid development of satellite communications system puts forward stricter requirements to the performance of the circularly polarized antenna.Based on the project of National Natural Science Foundation of China,this paper introduced a new type of stereo polyhedral circularly polarized antenna with single feed and double feed.The main contribution of this paper contains both instructive theoretical analysis,design method and a wide beam circularly polarized antenna with practical value.The main work of this paper is:1)Factors affecting axial ratio beam width of the circularly polarized antenna are analyzed.By the combined method of theoretical analysis and simulation verification,the changing mechanism of axial ratio in the main angle and wide angle is analyzed respectively.The formula of the influence on axial ratio by the amplitude and phase error between the two orthogonal polarization components is deduced.The influence on axial ratio beam-width by the antenna structure,size and material of the substrate is analyzed by simulation.A series of conclusion that can guide the design of circularly polarized antenna is arrived.2)A stereo polyhedral circularly polarized antenna with folding structure is introduced.This antenna achieves fine half power beam width and 3 dB axial ratio beam width through folding the patch.The relationship between beam width and folding the patch is analyzed.Steps of designing the stereo polyhedral circularly polarized antenna with single feed are given.The simulation results show that the half power beam width of the antenna reaches 110°,and the 3 dB axial ratio beam width reaches 200°.The test results coincide with the simulation results,so the reliability of the simulation is verified.The research work in this paper provides a new technical way to design the circularly polarized antenna with wide beam,which contributes to the development of the new type of stereo polyhedral circularly polarized antenna.