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.