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A time domain hybrid method consisting of transmission line (TL) equations, finite-difference time-domain (FDTD) method, and a S-parameter cascade (SC) technique with the interpolation techniques is presented for the coupling analysis of unequal length multiconductor transmission lines (MTLs) with arbitrary heights excited by ambient electromagnetic wave efficiently. In this hybrid method, the unequal length MTLs are divided into several equal length MTLs via additional nodes. For each equal length MTLs, the FDTD method combined with the TL equations (FDTD-TL) and the interpolation techniques are used to compute the transient responses on the lines. And then, the S-parameters of the nodes are utilized to realize the signal transmission between these equal length MTLs. Three cases about the unequal length MTLs with arbitrary heights on the ground or in the cavity excited by ambient wave are given to demonstrate the accuracy and efficiency of this method by comparing with the traditional FDTD method. The computation time and memory cost by this hybrid method are much less than that of the FDTD method, because the MTLs do not need to be meshed in this hybrid method. [ABSTRACT FROM AUTHOR]

A time-domain hybrid method is presented for efficiently solving the coupling problems of long cables above the ground excited by electromagnetic pulses. The proposed method is combined with transmission-line (TL) equations, finite-difference time-domain (FDTD) method, and a novel fast calculation approach for excitation fields of long cables. In this hybrid method, the effect of the ground on the incident wave is equivalent to a time-domain reflection wave source, and the excitation fields of long cables are computed by the superposition of electric fields created by the incident and reflection wave sources. Then, the TL equations are employed to build the coupling model of long cables and the excitation fields are introduced into the TL equations as distribution sources. Finally, the transient responses on long cables are obtained by the TL equations with the FDTD method. Two examples are given to demonstrate the accuracy and high efficiency of this method. It shows that this method can tremendously decrease the memory requirement and computation time compared with the FDTD method, and has the ability of fast simulating the coupling problem of long cables excited by multiple pulse sources. [ABSTRACT FROM PUBLISHER]

This paper presents a novel time domain hybrid method consisting of finite-difference time domain (FDTD) method, transmission line (TL) equations, and circuit-based method, which can be directly applied in time domain for the electromagnetic interference (EMI) analysis of the lumped circuits in a shielded device excited by ambient electromagnetic wave. The FDTD method coupled with the TL equations is utilized to model the electromagnetic properties of arbitrary structures containing transmission lines and shielded enclosure of the electronic device with any ambient excitation. With numerical simulation, an equivalent circuit model considering the external EMI effects is extracted as an excitation source for the internal lumped circuit according to Thevenin's theorem. Then, the state variable approach is used for the further EMI analysis of the internal lumped circuit in time domain. Two cases, in which a transmission line and/or a transmission line network are connected to a lumped circuit within a shielded enclosure excited by an intense electromagnetic pulse, are computed with the proposed method. The numerical results are compared with those obtained by using the FDTD method, and they are almost in perfect agreements. Meanwhile, at last, an example of this method applied for the EMI protection of an electronic device is given. [ABSTRACT FROM AUTHOR]