A novel port extraction technique for coupling circuits with full wave time domain integral equation solvers

Fully coupled transient analysis of electromagnetic-circuit systems is highly desirable for a number of applications. Over the last decade or so, there have been several papers that present effective solutions to this problem within the context of full-wave differential or integral equation solvers. The method typically espoused is as follows: discretize the underlying electromagnetic (EM) system, couple with the circuit subsystem self-consistently, and then solve the coupled system. Within this framework, non-linearities are easily accounted for in the solution process. This is in direct contrast to frequency domain analysis, wherein one defines ports that couple the electromagnetic and circuit subsystems, i.e., representation of the EM system using an effective impedance. This approach permits: (a) solution only at the circuit level, and (b) one can readily incorporate different circuits without having to solve the coupled system repeatedly. In this paper, we present a technique that helps realize the same efficiency in the time domain. We will prescribe the means to effectively represent the EM subsystem in terms of a transient admittance, thus facilitating a solution to the coupled system via a circuit-level solve. Several results are presented that serve to validate the proposed approach and demonstrate its effectiveness.