Alternative Surface Integral Equation-Based Characteristic Mode Formulations for Composite Metallic-Dielectric Objects

Abstract

The characteristic modes (CMs) analysis can give physical insights into the intrinsic mechanisms of radiating structures. To obtain the CMs of composite metallic-dielectric objects is a very challenging task. Existing formulations encounter some problems in calculating the CMs of multiple and multi-layer composite structures. In this paper, we present two new surface integral equation (SIE) formulations for the calculation of CMs of composite metallic-dielectric objects. Employing the contact-region modeling (CRM) technique and the inherent dependent relationships between various kinds of equivalent sources, we propose two new SIE-based CM formulations wherein the electric or magnetic currents on the surfaces of dielectric regions are alternatively involved to suppress spurious modes. Compared to the existing formulations, the proposed formulations are easier to be extended to multiple and multi-layer composite structures. Numerical results of five representative structures are presented to validate the accuracy of the proposed formulations. INDEX TERMS Surface integral equation (SIE), characteristic modes (CMs), contact-region modeling (CRM), composite metallic-dielectric objects.