A Finite-gap Port Model in SIE with CRWG Basis Functions for Radiation Analysis

This paper presents a novel finite-gap port model of method of moments (MoM) solution for the surface integral equation (SIE), which is developed for the analysis of electromagnetic (EM) radiation from metallic structures. For the finite-gap port model, a small gap region is identified as a two-terminal port and the fields in the gap are linked to the voltage or current definition. Two conditions should be enforced. The one is the line integral of the electric field along straight paths in the gap being equal to the port voltage. The other is the current conducted into/out of the gap region being identical and equal to the port current. This port model is implemented by modifying the traditional MoM solution to use RWG basis at the gap as well as half RWG basis connected across the gap. Compared to the traditional delta-gap with RWG basis defined in a pair of triangles, this finite-gap port model with new test functions removes the connecting patch between two terminals, which results in more accurate in solving the port parameters of microstrip. Moreover, this scheme utilizes curved triangular patches for geometric modeling, and the curved Rao-Wilton-Glisson (CRWG) basis functions for surface current modeling to further improve computational efficiency. Several numerical results are provided to illustrate that in comparison with the conventional SIE for simulating S parameters of microstrip antennas, our scheme obtains higher solution accuracy, and requires much less memory and computational time. Thus, it demonstrates the accuracy and efficiency of this method for radiation analysis of metal radiative structures., etc.