Abstract: In the calculation of transmission line systems response to electromagnetic pulse (EMP), the frequency-dependent effect of terminated loads should be considered. A numerical algorithm for a transmission line system terminated with frequency-dependent loads exposed to EMP is proposed. Firstly, the amplitude-frequency characteristics and phase-frequency characteristics of frequency-dependent loads are captured by vector network analyzer. Then the measured data are expressed by a series of rational formulas based on residuals and poles derived by vector fitting (VF) method. Lastly discrete equations for the system are derived based on finite-difference time-domain (FDTD) method. In the proposed algorithm, piecewise linear recursive convolution technique is employed to simplify the computation of convolution formulas. The simulated results show a well consistency with the theory. Compared the other algorithm, this method increases the efficiency and accuracy, and has a broad application prospect in frequency-dependent systems.

Key words: electromagnetic pulse, frequency-dependent transmission line system, transmission line model, vector fitting method, finite-difference time-domain method