采用滑动窗时域有限差分法对不规则地形电波传播预测

为了解决大区域电波传播精确预测时计算量大的问题,采用滑动窗时域有限差分方法对不规则地形上短波频段的地波传播进行预测.将经典FDTD(finite-difference time-domain)与脉冲追踪相结合,采用UPML吸收边界处理有耗地形,使垂直于地面的二维FDTD计算区域随脉冲传播而滑动,在迭代过程中保存必要的场分量,处理后得到不规则地形上的路径损耗与传播路径的关系曲线,并与经典的几何绕射理论的计算结果进行了比较.结果表明,其优点在于保持FDTD全波时域分析准确性高的特点同时降低了计算量.讨论了计算区域在滑动过程中由于包含的后向波信息的局部性对计算结果的影响,以及顶部吸收边界对侧向波的反射带来的误差.数值仿真结果表明了此方法的有效性.

Predicting radiowave propagation over irregular terrain basedon moving window finite -difference time -domain methods

In o rder to model g round w av e pro pagation accurately , MW FDTD ( moving w indow finite-di fferencetime-domain) w as applied to predicting the pa th loss o f g ro und w av e ov er irregular terrain. Thi s is ahybrid approach f rom FDTD and tracing pulse. UPML ABC w as used to deal w ith lossy terrain. Tw o-dimension FDTD calculatio n regio n mov es wi th pro pagation pulse. Necessa ry field intensity w as sav ed a ndthe path loss wa s obtained. The resul t obtained by MWFDTD was compared wi th the result obtained byU TD. Thi s method not o nly contains cha racteristics of FDTD but al so reduces the time of running FDTDprog ram. Finally , the accuracy o f MWFDTD af fected by ref lectio n w av e f rom ABC and the error causedby the local moving window w ere discussed. The simula tion resul t show s tha t thi s approach is ef ficient.