A Combined MoM-AOM Approach for Frequency Domain Analysis of Nonlinearly Loaded Antennas in the Presence of a Lossy Ground

A modeling technique based on the frequency-domain spectral balance method is proposed for analyzing nonlinearly loaded antennas in the presence of a lossy ground. The modeling involves two stages. First, the problem is transformed into a nonlinear microwave equivalent circuit with the circuit parameters of the antenna extracted by the method of moments. Then, the nonlinear microwave equivalent circuit is treated using the arithmetic operator method. To efficiently perform basic arithmetic operations in the frequency-domain, a linear matrix transformation of the spectra is introduced. The main feature of the proposed technique is its efficiency in dealing with problems involving strongly nonlinear loads, the presence of a lossy ground, and multitone excitations. It is also suited for the analysis of array antennas, considering the mutual effects between array elements. The accuracy of the proposed model is confirmed by comparing the simulation results of several case studies with those obtained using the conventional methods available in the literature. Mutual coupling effects, multi-frequency excitation, strong nonlinear loads, and the presence of a lossy ground are included in the simulations to cover all of the asserted aspects of the paper.