Efficient Method of Moments for Numerical Analysis of Antennas With Variable Load Impedance

A computationally efficient method which is based on the method of moments (MoM) for numerical analysis of antennas with variable load impedance is proposed. The proposed method deals with both of the variable load impedance and its current as equivalent voltage source. Current distribution of antennas with the variable load impedance is obtained directly from their unloaded full-admittance matrix and the block impedance matrix corresponding to the variable load impedance. The proposed method is quite computationally efficient because inversion of the full-impedance matrix of the antennas is unnecessary when their load impedance varies. Moreover, the proposed method does not include any approximation and its result shows perfect agreement with that of the full-wave analysis. Numerical results of the proposed method are compared with those of conventional MoM using our in-house code and its performance is demonstrated.

I. Introduction

Method of moments (MoM) is well-known as one of the powerful techniques for numerical analysis of antennas or scatterers [1]. The MoM has been applied to numerical analysis of wire antennas [2], [3], planar antennas [4], and dielectric materials [5]. The MoM is computationally efficient because unknown currents to be obtained are only distributed on antennas or scatterers themselves, while unknown electric/magnetic fields to be obtained are distributed on entire region including antennas and scatterers for finite-element method (FEM) or finite-difference time-domain (FDTD) method.