Spurious-Free Characteristic Mode Formulation Based on Surface Integral Equation for N Lossy/Lossless Penetrable Objects and N PECs

A novel surface integral equation (SIE)-based theory of characteristic modes (TCM) for arbitrarily shaped
N
lossy/lossless penetrable objects and
N
perfect electric conductors (PECs) is proposed in this letter. Compared to previous work, the novel SIE-based generalized eigenvalue equation (GEE) is valid for any number of objects and valid for objects that contact with each other by employing the contact-region modeling (CRM) technique. Moreover, a novel combined field integral equation (CFIE)-based TCM has been proposed in this letter to deal with the internal resonance and decrease the condition numbers.