Efficient Broadband Circuit-Modeling Approach for Parallel-Plane Structures of Arbitrary Shape

A methodology for creating highly efficient and inherently stable equivalent-circuit models for arbitrarily shaped parallel-plane pairs is presented. Based on Green's function with accelerated convergence, a general impedance expression is derived for circular ports, comprising the static capacitance and inductances and a small number of resonant terms. It can be directly cast into an equivalent multiport circuit for arbitrary number of ports, enabling the application in a SPICE circuit-simulation environment for broadband system analysis with active, passive, and nonlinear components. The equivalent-circuit elements are determined by a simple finite-difference scheme in combination with an analytical port model, which allows us to perform the required modal and the quasi-static analysis with a uniform mesh. Validation by numerical full-wave field simulations demonstrates the versatility of the suggested approach and the high computational savings of several orders of magnitude in frequency and time domain.