Analytical dielectric constant sensitivity of ridge waveguide filters

Sensitivity of the scattering parameters of ridge waveguide filters with respect to the relative dielectric constant is evaluated analytically. These scattering parameters are obtained with the full-wave mode matching technique. Using only the mode matching simulation of the original structure, the sensitivity of the scattering parameters is obtained. The adjoint network method (ANM) is applied to the generalized scattering matrices (GSMs) of the different filter components. The derivatives of these GSMs are obtained analytically instead of being evaluated using finite differences. This guarantees good accuracy of the calculated sensitivity. Excellent agreement is obtained between ANM calculated sensitivity and that obtained using the more expensive central finite differences.