Advances in the adjoint variable method for time-domain transmission line modeling

In this paper, we review recent advances in the adjoint variable method (AVM) technique for time-domain transmission-line modeling (TLM). The AVM theory is applied to estimate objective function sensitivities with respect to designable dimensions of dielectric discontinuities. Using only two simulations, the sensitivities with respect to all designable parameters can be calculated efficiently. Analytical derivatives of system matrices may also be exploited to derive an exact adjoint system.