Use of the Extended BLT Equation for ElectromagneticWave Coupling Analysis

The growth of high-speed electronic and wireless systems has increased the threat of both unintentional and intentional electromagnetic interference (EMI/IEMI). Analyses of the coupling of electromagnetic waves onto the conductors of electrical systems, are needed in order to accurately determine the susceptibility of both simple and complex electronic devices. Current technology allows for these devices' CAD models to be evaluated in an electromagnetic simulator, where both their radiative and non-radiative responses to their environment are observed. However, an increase in the complexity of the models increases the computational cost of the simulation. Reduction in the simulation's time and memory usage is achieved through the use of transmission line methods. This study serves to determine the coupling of an electromagnetic plane wave onto a uniform transmission line above a ground plane. The transmission line is terminated with load resistances comparable to practical loads. Excitation of the line is produced by an EM wave that is normal to the ground plane, with an electric field that is linearly polarized, and oriented in the direction of the lateral face of the transmission line. Inclusion of a ground plane introduces an additional EM wave source that is reflected from the ground plane. Although delayed, it is combined with the incident plane wave from the source through the use of a Green's function derived by Tesche and Butler (F. M. Tesche and C. M. Butler, Interaction Notes, Note 588). The voltages and currents induced on these transmission lines from the field sources are calculated using the Extended-BLT (Baum-Liu- Tesche) Equation derived in the same literature. This multi-conductor transmission-line method, allows for the topography of the system to be converted into matrices and super matrices, in order to solve for the propagating voltage and current along the lines. This methodology is derived in the notes of Carl Baum (C. E. Baum, T. K. Liu, and F. M. Tesche, Interaction Notes, EMP-3, Notes 1-635), this being the traditional BLT equation. To verify these results, a full wave EM solver is used to simulate the setup, along with experimental measurements. Modifications to the Green's functions provided by Tesche, Keen and Butler (F. M. Tesche, J. M. Keen, and C. M. Butler, URSI Radio Sci., 312, pp. 32-47), are necessary since a finite ground plane is used in the experimental setup. This work looks to further this approach with wide frequency-range coverage, along with near-field effects, with excitation from oblique incidence angles, and the effects of polarization utilizing the methods found in various texts (specifically F. M. Tesche, M. V. Ianoz, and T. Karlsson, John Wiley and Sons, pp. 183-217). In doing so attempts to extend the BLT equation further to include a transmission line enclosed in a structure with a large conductance, along with an aperture are made. Applying techniques from texts by Tesche, allows for a dyadic Green's function to be used based off the geometric properties of the aperture. This Green's function is then incorporated into the BLT equation to produce the excitation source of the transmission line enclosed in the conductor.