An Alternative Sub-Structure Generalized Eigenvalue Equation for Characteristic Modes

A new type surface integral equation (SIE)-based sub-structure generalized eigenvalue equation (GEE) for composite objects has been proposed in this paper. The obtained eigenvalues can reflect the radiation efficiency of each mode directly. These mode solutions can provide more flexible guidance for the design of antennas in lossy environments. Numerical results validate the validity and veracity of the proposed GEE for characteristic mode (CM).