二维散射中利用FDTD时域近区场推算远区场的方法

FDTD in 2—D EM Scattering Problems

时域有限差分法(FDTD)由于其诸多优点,成为处理电磁散射的重要方法之一。但 FDTD 只能求出有限区域内的场,而散射问题中往往需要远区场。本文针对二维散射,结合信号处理的理论,提出利用 FDTD 的近区场推算远区场的方法。以 TM 入射为例,进行了数值模拟,计算了导体方柱和表面涂敷有耗媒质后的方柱的远区场和宽频带上的雷达散射宽度,并将导体方柱的 FDTD 结果与短量法(M_0M)解的结果相比较。计算实例表明,本文提出的方法和推导的公式是正确的。

FDTD is one of the most effective methods insolving EM scattering problems.But FDTD can only give solutions in definite area.However,the far zone scattered field is the desired result in many EM scattering problems.In this paper,a method of FDTD near zone to far zone transformation in 2—D case is put forward by use of the theory of signal process.The scattering in 2—D TM illumination case is computed.The scatterers are PEC and PEC covered by one or two layers of lossy medium.The far zone field and radar cross section over a wide frequency band have been calculated and compared with M_0M.Numerical results agree well with those calculatet by the above method.