A Hybrid Excitation Method of Finite-gap Port Model in SIE for Electromagnetic Radiation Analysis

In this paper, a finite-gap port model, i.e., combining the current source with the voltage source in surface integral equation (SIE) is proposed to solve the electromagnetic radiation problem. For this model, a small gap region in the domain of analysis is identified as a two-terminal port and the fields in the gap are linked to the voltage or current definition. Two conditions must be enforced. One is the line integral of the electric field along straight paths in the gap are equal to the port voltage. The other is the current conducted into/out of the gap region is identical and equal in magnitude to the port current. The port model is implemented by modifying the traditional method of moments (MoM) solution to use a novel divergence-conforming testing function at the gap as well as half-RWG basis functions connected across the gap. And the half-RWG basis functions are defined on the opposite edge triangles at the two-terminal. Compared to the traditional delta-gap voltage sources with RWG basis functions defined in a pair of triangles, this finite-gap port model with new test functions removes the connecting patch between two terminals, which leads to high solution accuracy to calculate the port parameters of microstrip. When the traditional excitation is used to solve radiation problems with multi-port structures, the same type of excitation source for each port, either voltage or current sources are often chosen. However, in the practical engineering of antenna radiation, the voltage and current sources are often all added to excite antennas. In additional, it is also required to add the simultaneous excitation of multiple current and voltage sources into the ports of interconnection and packaging circuit simulation. To solve this problem, a hybrid excitation method of finite-gap port model with multiple current and voltage sources is combined in SIE. Several numerical results are further provided to demonstrate the validity and efficiency of this proposed method.