A Stable Time-Domain Integral Equation Formulation for Composite Structures

The electromagnetic scattering from composite structures is analyzed using a new (CC)PMCHWT formulation that constitutes the time-domain extension of a recently introduced improved combined-field integral equation (CFIE) formulation. This approach yields "second-kind integral equations" that have well-tested identity operators. Hence, in the frequency-domain the resulting matrix equations exhibit better conditioning and faster convergence than those resulting from the traditional formulation. The proposed time-domain formulation yields stable results without resorting to special stabilization schemes. Specifically, the results from (CC)PMCHWT formulation are demonstrated stable even when those from the (EH)PMCHWT formulation are not. The proposed scheme, however, outperforms the Muller formulation for multi-region problems and composite structures