有耗介质层上多导体传输线的电磁耦合时域分析方法

Time domain hybrid method for coupling analysis of multi-conductor transmission lines on the lossy dielectric layer excited by ambient wave

目前,针对空间电磁场作用有耗介质层上传输线的电磁耦合,仍缺乏有效的数值分析方法.因此,本文提出一种高效的时域混合算法,很好地解决了有耗介质层上传输线电磁耦合建模难的问题.首先,对经典传输线方程进行改进,推导了适用于有耗介质层上多导体传输线电磁耦合分析的修正传输线方程.然后,结合时域有限差分方法和相应插值技术,求解修正传输线方程,获得多导线及其端接负载上的电压和电流响应,并实现空间电磁场辐射与多导线瞬态响应的同步计算.最后,通过相应计算实例的数值模拟,与CST软件的仿真结果进行对比,验证了时域混合算法的正确性和高效性.

At present,numerical methods applied to the coupling analysis of transmission lines on the lossy dielectric layer excited by ambient wave are still rare in the literature.As a temptation to fill this gap,a novel time domain hybrid method is proposed,in which the modified transmission line(TL)equations,finite-difference time-domain(FDTD)method,and some interpolation schemes are organically combined together.It can overcome the difficulty in building the coupling model of ambient wave to transmission lines on the lossy dielectric layer greatly.In this method,the modified transmission line(TL)equations suitable for the coupling analysis of multi-conductor transmission lines(MTLs)on the lossy dielectric layer are derived from the traditional TL equations firstly.Compared with the traditional TL equations,the electromagnetic fields in the lossy dielectric layer are introduced into the equivalent distribution sources of modified TL equations.Generally,the precision of TL equations is dependent on the accuracy of equivalent distribution sources,which are obtained from the incident electric fields parallel and perpendicular to the MTLs.Therefore,the FDTD method is utilized to model the structure of lossy dielectric layer to calculate the electromagnetic field distribution surrounding the MTLs and in the dielectric layer.Since the heights and distances of MTLs can be arbitrary values,the electric fields parallel and perpendicular to the MTLs cannot be obtained from the electric fields on the edges of FDTD grids directly,which should be computed via some interpolation schemes.Then the modified TL equations are established,which should be solved by the central difference scheme of FDTD method to obtain the voltages and currents on the MTLs and terminal loads.The significant feature of this proposed method is that it can realize the synchronous calculations of electromagnetic field radiation and transient responses on the MTLs.Finally,numerical simulations of single and multiconductor transmission lines on the lossy dielectric layer excited by ambient wave at different incident angles are employed to exhibit the accuracy and efficiency of the proposed method by comparing with the simulation software CST.Because the structures of MTLs do not need to be meshed,the proposed method outperforms the simulation software CST in both memory usage and computation time.