Frequency-domain and finite-difference, time-domain solutions to a nonlinearly-terminated dipole: theory and validation

Both a frequency-domain and finite-difference time-domain solution to scattering by a dipole terminated in a nonlinearity are described and evaluated with respect to measured data. The objective of this work is to estimate externally generated intermodulation product interference levels. The frequency-domain solution models the scattering dipole by its Thevenin equivalent, and then applies Kirchhoffs voltage law to find the current through the nonlinear load; because the current-voltage relationship across the load is nonlinear, an iterative approach is used to solve the KVL equation. Model output is the dipole current at intermodulation product frequencies of interest. In the finite-difference, time-domain approach, a computational space is divided into small cells, with the constitutive parameters of each cell set separately. Most cells contain free space, but some contain the wire antennas, and others contain the voltage source, a resistive load, or the nonlinear diode load. In the FDTD cell which contains the nonlinear load, a nonlinear equation is solved at each time step