An Improvement of Closed-Form Formula for Mutual Impedance Computation

Abstract

In this paper, we present an improvement of a closed-form formula for mutual impedance computation. Depending on the center-to-center spacing between two rectangular microstrip patch antennas, the mutual impedance formula is separated into two parts. The formula based on synthetic asymptote and variable separation is utilized for spacings of more than 0.5 λ0. When the spacing is less than 0.5 λ0, an approximate formula is proposed to improve the computation for closely spaced elements. Simulation results are compared to computational results of mutual impedances and mutual coupling coefficients as functions of normalized center-to-center spacing in both E-and H-plane coupling configurations. A good agreement between simulation and computation is achieved.Key Words: Array Antenna, Closed-Form Formula, Microstrip Patch, Mutual Coupling, Mutual Impedance.