PE模型SSFT解电波传播问题的虚部增量法

Image increment method on solving wave propagation problems with SSFT of PE

针对抛物方程(PE)模型分步傅里叶变换(SSFT)法步进求解电波传播时的吸收层滤波繁冗问题,提出修正折射指数虚部增量法。通过将传统窗函数滤波过程综合到大气折射效应计算中去,使滤波功能等价为修正折射指数的虚部增量,能够使场解在吸收层内平滑衰减为零,避免电波在上边界上的强反射。该方法省去了专门的滤波过程,降低了计算量,当存在多个折射率剖面时,其优势尤其明显。理论推导和仿真分析结果表明了该方法的正确性和有效性。

To overcome the cumbersome filtering problem in the absorbing layer when solving wave propagation questions step- by-step with the usage of the split step Fourier transform （SSFT） of the parabolic equation （PE） model, an image increment method was proposed. The traditional window filtering procedure was synthesized into the computing of the refraction effect. The filtering function was equated to an image increment of the modified refractive index. Then, in the absorption layer, the field was smoothly attenuated to zero and the strong reflection of the wave was avoided. The proposed method omits the specialized filtering procedure, and the cost of the computing is reduced, particularly when multi-refractivity profiles exist. The correctness and the validity of the method are verified by results of theoretical derivation and simulation.