外推和几何修正在天线方向图修正中的应用

Extraplolation and geometric correction in the application of the antenna pattern correction

由于微波暗室难以满足大尺寸高频率天线的远场条件,为了避免远场测量时环境的杂波影响,加强保密,提出了一种近场外推算法。当天线纵向尺寸较小时,可将辐射的球面波近似成柱面波,对其进行柱面波函数展开,经过严格的理论推导最终建立起近场外推到远场算法,最终实现近场数据快速得到远场方向图特性。采用近场外推的方法能够很好地避开在大尺寸天线测量中很难满足远场条件的困难。但是在测量中,天线往往会偏离转台的中心而产生远场与方位角不对应的错误结果,必须对其进行几何修正。提出了一种远场方向图的几何修正方法,并利用MATLAB软件对算法进行了仿真分析,将外推结果与修正结果进行比较,得到修正后的方向图与理想天线远场方向图基本吻合,从而验证了方法的可靠性,具有一定的实用价值。

Because microwave chamber is difficult to meet the large-size high-frequency antenna far field conditions,in or- der to avoid the far field measurement environment noise influence, strengthen the confidentiality, and work out the near- field extrapolations method. If an antenna is short in vertical plane, its irradiating field in horizontal plane can be consid- ered as cylinder wave distribution. With expanding the function of cylinder wave and establishing the convolution extrapo- lating relationship,the near-field data can be used to gain the far-field pattern quickly. The near-field extrapolations can avoid far-field conditions that are difficult to meet thejarge-size antenna measurement. However,in the measurement,the antenna will often deviate from the center of the turntable and produce error results which does not correspond to the far- field azimuth. We must carry on the geometric correction. A far-field pattern of geometric correction method is presented. By theoretical model and simulation for a simple long antenfia in MATLAB. Compared the results of the extrapolation and correction results,get correction pattern and ideal antenna far-fleld pattern are consistent with each other. Prove that the method is reliable, and has a certain practice value.