球模式展开理论近远场变换及快速算法

基于球模式展开理论的近远场变换是天线球面近场测量系统实现的关键，它将待测天线在空间建立的场展开成球面波函数之和，由于其计算公式复杂，因而计算耗费时间长。该文在实际计算中利用快速傅里叶变换及矩阵的思想可以大幅度提高程序运行速度，节省计算时间。采用该方法对角锥喇叭天线的近远场数据进行仿真验证，结果表明外推远场的结果和理论值吻合良好，说明了该方法在保证计算精度的同时，可缩短计算时间。

Near-field to Far-field Transformations Based on Spherical Wave Expansions and Fast Algorithm

The theory of near-field to far-field transformation using spherical-wave expansions is the key to implement the spherical near-field antenna measurement system. It can develop the field in the space which is built by antenna expanding into the sum of spherical wave functions. Because of its complex formula, it will consume a long time to compute. The FFT transformation and the ideas of matrix are put into used in this paper, so the compute speed can be improved and the compute time can be saved. Using this method to testify the near-field data and the far-field data of a horn antenna, the results show that the far-field pattern computed from near-field date and the far-field pattern from theoretical integral equations are compared very well. It is approved that this method can guarantee the calculation precision and shortens the compute time at the same time.