Transient Response of Nonlinearly Loaded Antennas Above a Lossy Dielectric Half-Space: A Modified MoM-AOM Approach

This paper proposes an entirely frequency-domain technique for the transient analysis of electromagnetic systems involving nonlinearly loaded wire antennas over a lossy dielectric half-space. The analysis involves two stages. In the first stage, the problem is transformed into a nonlinear microwave equivalent circuit with the circuit parameters of antenna extracted by the method of moment (MoM). The effect of lossy dielectric half-space is considered by proper implementation of the Sommerfeld asymptotic method in the MoM. In the second stage, 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 respective spectra is introduced. To construct the transformation matrix for a transient excitation involving a large number of excitation frequencies, a fast algorithm is developed. The algorithm is based on the frequency arrangement of transformation matrix obtained by matrix multiplication property. The proposed technique is well suited for direct inclusion in the kernel of computational tools for solving problems involving the electric field integral equation. The accuracy of the proposed method is confirmed by comparing the simulation results of several case studies with those obtained using the time-domain methods available in the literature.