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A generalized formulation of electromagnetic fields generated from a multi-phase underground cable is proposed based on a complete solution of Maxwell equations. The lateral electromagnetic field components, the shielding effect of cables and the phase currents at high frequencies of a three phase underground cable are evaluated by the newly derived formulas. The accuracies of the recently developed extended transmission line approach of underground cables are investigated based on the performance of electromagnetic field components. It is also shown that Numerical Electromagnetics Code verifies the results calculated from the new formulas presented in this article. [ABSTRACT FROM AUTHOR]

High frequency wave propagation on overhead conductors has been evaluated by TL (transmission line) approach. The results are compared with those calculated by the numerical electromagnetic code (NEC) in the frequency domain. Both results show transition of wave propagation between TEM (transverse electromagnetic) and TM (transverse magnetic) modes in the frequency region f c < f < f s where f c is the critical frequency at which the transition starts and f s is the frequency above which a surface wave is completed. In the frequency region higher than the frequency f s , the earth-return impedance has minor contribution to the wave propagation, because it is no more an earth-return wave but a surface wave. This has been also investigated in the time domain based on simulation results by FDTD (finite-difference time-domain) method to confirm the results by the TL approach. [ABSTRACT FROM AUTHOR]

We study for the first time errors in on-wafer scattering parameter measurements caused by the parasitic microstrip-like mode propagation in conductor-backed coplanar waveguide (CB-CPW). We determine upper bound for these errors for typical CPW devices such as a matched load, an open circuit, and a transmission line section. To this end, we develop an electromagnetic-simulations-based multimode three-port model for the transition between an air-coplanar probe and the CB-CPW. Subsequently, we apply this model to examine errors in the device S parameters de-embedded from measurements affected by the parasitic MSL mode. Our analysis demonstrates that the multimode propagation in CB-CPW may significantly deteriorate the S-parameters measured on wafer.

Leaky modes of multilayered substrates play an important role in efficient numerical electromagnetic solvers. In this paper, the location of the propagation constants of the transverse electric and transverse magnetic leaky modes are determined in an efficient way for multilayered substrates with commensurable layer thicknesses. It is shown that, for all practical applications, accurate quasi-static approximations for high mode orders can be derived rapidly by finding the roots of an analytically obtained polynomial. Furthermore, simple closed-form expressions are derived for some particular cases. Starting from these estimates, only a few additional Newton steps are required for a very precise determination of the propagation constants. The proposed method is validated by means of several illustrative numerical examples. [ABSTRACT FROM AUTHOR]

Recently, applications of 3-D numerical electromagnetic analysis have been increasing either for lightning electromagnetic impulse (LEMP) studies or lightning surge analyses on transmission and distribution lines. This paper is mainly concerned with the use of time- and frequency-domain codes for electromagnetic analysis of lightning surges. The thin-wire in time-domain (TWTD) code and numerical electromagnetic code (NEC-2) in the frequency domain based on the method of moments are chosen for comparative studies. The accuracy of TWTD code in the analysis of lightning surge characteristics of a double-circuit transmission tower is first investigated by comparing the computed results with the measured results on a reduced-scale tower model, computed results by NEC-2 on a full-scale tower model, and those computed by electromagnetic transients program. In the latter part of the paper, a switch model is combined with the TWTD code, and its applicability in analyzing the lightning surge characteristics of a transmission tower equipped with a surge arrester or in analyzing lightning-induced voltage on an overhead line is demonstrated. [ABSTRACT FROM AUTHOR]

Lightning current distribution in a directly hit building is studied by using a simple equivalent circuit and an electromagnetic model. The Numerical Electromagnetics Code (NEC-4) is employed for numerical electromagnetic analysis. The error in the shunt ratio of lightning current entering wiring, which is calculated using the electromagnetic model, is estimated to be less than 4%. The shunt ratios for lightning current entering the wiring on the top floor and the first floor are largest. Although they are larger for a higher building, they are almost constant if the building struck has more than five floors. They are smaller when there are more vertical conductors, or the length of the wiring is longer. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(1): 9–16, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20449 [ABSTRACT FROM AUTHOR]