Analytical response sensitivities of infinitesimally thin metallic shapes

Recently, a self-adjoint analytical method was proposed to compute the S-parameter sensitivities of microwave structures from the field solution at the object of interest. However, due to field singularities, the method is inapplicable to infinitesimally thin metallic shapes-a case of interest in the analysis and design of printed circuits and antennas. Here, we propose a formulation, which allows for the analytical calculation of the sensitivities with respect to the shape parameters of infinitesimally thin metallic objects. The computation is simulator-independent and is very fast as it involves a numerical integration of the surface current and charge densities along a suitably chosen contour on the metal. The method is validated through comparisons with reference S-parameters sensitivities obtained with a commercial finite-element-method (FEM) simulator. The proposed method enables the much needed analytical response sensitivities for simulators that are not based on the FEM, e.g., the method of moments (MoM) and the finite-difference time-domain (FDTD) method.