The Research Of Dual-band Modified Cassegrain Antenna With Polarized-twist

The feed caliber block and sub-reflector surface caliber shelter in Cassegrain antenna, resulting in a decrease in the gain of the antenna and its side lobe level rise. In order to solve the above problems, this paper presents Cassegrain antenna with modified polarized-twist reflector. Through theoretical analysis, CST and FEKO simulation and actual test, the antenna designed in this paper basically reached the expected targets. The main research contents of this paper are mainly including the following several aspects:1. Through theoretical analysis, the pattern of the antenna was drawn. When it comes to theoretical analysis, Cassegrain antenna with modified polarized-twist reflector has slight different with standard Cassegrain antenna. It can be turn into standard Cassegrain antenna through hyperbolic geometry properties, and then it was analyzed by equivalent parabolic method. Complicated integral existed when antenna’s secondary pattern was calculated. Approximate method and difference methods were adopted in this paper, and it got the value of the complicated integral.2. Layers of the structure of the antenna’s sub-reflector simulated and optimized by CST software. At first, the reason-ability and reliability of the software is checked by computing the instance of published results and comparing with the simulated results. Using the medium equivalent principle, multiple dielectric layers, especially the cellular structure in the sub-reflector surface were simplified. This equivalent principle was proved accurately. Based on the above theory, the size of the sub-reflector surface structure was adjusted and optimized, and ideal results are obtained.3. Antenna reflector structure was analyzed by the method of equivalent circuit, meaning while it was simulated and optimized by CST software. This paper was obtained the surface structures’ initial values of the polarized-twist reflector by t the method of equivalent circuit. And layers of the structure of the antenna’s reflector simulated and optimized by CST software as well. Polarization twist efficiency was decided by the thickness of cellular structure. Therefore, this article principally studied the thickness of cellular structure. This paper studied the influence on the polarization twist efficiency with different incident angles which were from 0 degree to 45 degree. This paper obtained a relatively ideal solution and polarization twist deficiencies were increased obviously by comparing the four schemes.4. Antenna was simulated by FEKO software. The structure of the antenna is too complicated to simulate the actual model of antenna. This paper obtained antenna pattern by adopting approximation method.5. Physical processed out and also be tested. By comparing the theoretical analysis, FEKO simulation and actual test, the antenna designed in this paper basically reached the expected target. The pattern of the antenna, gain, side-lobe level etc. differences between these three were presented. And this paper analyzed the reason of their differences.