不规则地形条件下双向DMFT电波传播特性算法研究

 在传统中心差分离散混合傅里叶变换(DMFT)抛物方程模型基础上,针对传统算法计算动态阻抗边界条件时的数值振荡及忽略后向传播与散射造成计算误差增大的问题,提出基于前-后向混合差分方法的递归双向DMFT(TW-DMFT)模型,以一阶前-后向差分方程代替传统的中心差分方程拟合阻抗边界条件,以递归双向传播模型改进传统单向预测模型.仿真分析了双向DMFT模型计算不同边界及媒介条件下单刃峰和实际地形的电波传播分布特性,与传统算法及几何绕射理论(GTD)进行比较,新算法提高稳定性及精度的同时弥补了传统算法的不足,更具有普适性.

Study on Two-way DMFT Algorithm of Predicting Radio Propagation Characteristics in Irregular Terrain Environment

Traditional central differential discrete mixed Fourier transform(DMFT) algorithms suffer from numerical oscillation when computing the mixed dynamic impedance boundary conditions,and from increased errors for neglecting backward-propagation and diffraction waves.A recursive two-way DMFT(TW-DMFT) algorithm is proposed in this paper using a mixed forward-backward difference method which is based on the traditional algorithm.The first order forward-backward difference equation is used to substitute for traditional central difference equation to fit the impedance boundary condition,and the recursively two-way parabolic equation model is used to improve the traditional one-way models.Compared with the traditional algorithm and geometrical theory of diffraction(GTD),the stability and accuracy which make up the deficiency and applicability of the traditional algorithm are improved by the TW-DMFT algorithm,which are verified by the simulation results that calculated in complex environments including single knife-edges and real terrain for different boundaries and media.