型面周期性误差对环形桁架可展开天线电性能的影响及其消除方法

Effects of Periodic Geometric Error of AstroMesh Reflector Surface on Radiation Pattern and Its Elimination Method

环形桁架可展开天线的型面由一系列面片拼合而成,其电性能由这些面片的大小和形状决定.本文针对环形可展开天线型面周期性几何逼近误差导致天线远场方向图存在电平较高的栅瓣的问题,提出了通过破坏误差周期性来消除其对电性能影响的方法.首先,分析了型面几何逼近误差的周期性及其对天线电性能的影响;其次,提出两种消除型面几何逼近误差周期性的方法,一是在径向引入破坏因子,二是改变型面环向轮廓形状;最后,建立优化模型,求出同时满足用户电性能和结构要求的网面分环数和破坏因子.数值仿真表明本文提出的型面优化设计方法既能在保证天线增益的条件下消除栅瓣,又不导致天线结构过于复杂.

Since curved antenna surface is approximated by flat facets, the electromagnetic （EM） properties of an AstroMesh reflector are determined by the size and shape of the facets. A period disturbance technique is presented to decrease the gating lobe level generated by periodic geometric approximation error. At first, the periodicity of the error and the effects of the periodicity on EM properties are studied. Secondly, two strategies are developed to disturb the periodicity of the error, one is to introduce radial direction disturbance parameters,and the other is to change the shape of the tings.At last,an optimization model is built to obtain fewer segments, proper disturbance parameters and better EM performance.Numerical examples show that the presened method can eliminate the grating lobes level without decreasing the gain and increasing the slructural complexity of AstroMesh antennas.