非均匀光滑球面地波衰减因子的抛物方程算法

Parabolic equation algorithm of wave attenuation along inhomogeneous smooth ground

根据地波传播特性,将不均匀球形地面上空的电磁场满足的标量波动方程近似为一个抛物方程;引入分步傅立叶变换法来得到抛物方程的解的递推公式;由地波传播平地公式计算出抛物方程算法所需初值,按照递推公式可方便的递推出传播路径上空中任意点的场强值,以及分段均匀光滑球形地面上任意高度的地波衰减因子的幅度和相位。该方法的计算结果当接收点在地面上时与J.R.Wait积分法和波模转换法完全一致,但是,当传播路径超过三个分段时J.R.Wait积分法和波模转换法的计算量成指数增加,该方法的计算量则不随分段数的增加而增加,故给出的方法更适合于实际的工程计算。

Based on characteristic of ground wave, the electromagnetic scalar wave equation above the inhomogeneous spherical surface is reduced to parabolic equation, then the recursion formula of the solution is presented by split-step Fourier transform. Through the plane formula of ground wave propagation, the initial value of the solution is obtained. So the field of random point above surface is obtained through the recursion point by point with distance of propagation. And the amplitude and phase of ground wave attenuation at the random height is presented. Receiver on surface, the parabolic equation algorithmrs result is consistent with that of J. R. Wait method and wave-model transform algorithm. As the number of subsections is more than three, the quantity of calculation of J. R. Wait method and wavemodel transform algorithm increase with exponential, however, that of parabolic equation algorithm doesn＇t increase with the number of subsections. This indicates that parabolic equation algorithm is more suitable to use in project compared with J. R, Wait method and wave-model transform algorithm.