Numerical Analysis of a Transmission Line EMP Simulator

A theoretical model is defined for an electromagnetic pulse (EMP) simulator for testing EMP effects on high altitude satellites. The simulator is composed of three flat-plate transmission line sections. The first and third sections are tapered to accommodate, respectively, a generator and a terminating resistor. This problem is analyzed in the frequency domain over those frequency components which are known to contribute most significantly to a typical EMP waveform. The analysis uses a numerical technique to solve the basic problem of an unknown current distribution on a curved, tapered strip, excited by a known electric field. The unknown current is solved by the method of moments, using triangular basis functions. As a check, input impedances are computed for the triangular dipole, showing good agreement with experimental results. For the transmission line simulator, computed input impedance, VSWR, power dissipated in the terminating resistor, and the power lost to radiation are presented as a function of frequency. The computed current distributions are used to calculate the electric fields between and immediately beyond the parallel plates. Although a considerable portion of power is converted to radiation at the higher frequencies, it is shown that at least within the working volume the electric field maintains a reasonably constant level.