半空间垂直对称振子辐射特性分析

Radiation Analysis of Vertical Symmetry Dipole in the Half-space

短波天线多近地架设,因而分析地面对天线性能的影响在电磁场辐射问题中显得日益重要,实际分析中常把地面看成一种平面分层媒质。分层媒质中天线的辐射问题由于涉及到Sommerfeld积分,因而计算相当困难。利用矩量法结合复镜像理论计算了半空间中垂直对称振子的电流分布,并且利用鞍点法计算的远场Sommerfeld积分近似公式求解辐射场,在保证计算精度的基础上大大缩短了计算时间。

Short- wave antennas are usually set close on the ground, so it is more and more important to analyze the influence of ground to antennas in the radiation of electromagnetic field. As a matter of fact, the ground is often seen as plane - stratified media. It is difficult to calculate the radiation of anteunas in layered medium due to the sommerfeld integral. The paper uses the method of moments and discrete complex image method to compute the current distribution of vertical symmetry dipole in the half - space, uses far - field approximate expressions of sommerfeld integral based on the saddle- point method to compute the radiation patterns, the computing time is shorten evidently on the premise of ensuring the computing precision.