Iterative adjoint technique for sensitivity analysis

This paper presents an accurate and efficient full-wave method, combined with iterative adjoint technique, for analyzing sensitivities of planar microwave circuits with respect to design parameters. The method of moments (MoM) in spatial domain is utilized, and the generalized conjugate residual (GCR) iterative scheme is applied to solve the linear matrix equations with fast convergence. Green's functions for multilayer planar structures in the discrete complex image method (DCIM) form are employed to simplify the spatial domain manipulation. In the present method, a conventional integration model and the corresponding adjoint model are solved by the MoM, respectively. The adjoint technique, with the aid of iterative schemes, could considerably reduce the computational requirements, especially for the electrically large-size device with many perturbing design parameters. Numerical results of S-parameter sensitivities of a low pass microstrip filter by the present method are presented.