Analysis of Symmetric Two-Layer Discontinuity in Microstrip Line: Capacitive Section in Microstrip Line And Comb Slot Resonator in Ground Plane

A technique for calculating the scattering characteristics of a symmetric two-layer discontinuity in a microstrip transmission line is proposed. The discontinuity consists of a capacitive section of a microstrip line and a comb-shaped slot resonator in its ground plane. The technique is based on the transverse resonance method. Electromagnetic field distribution in the comb-slot resonator is described in terms of basis functions of TE-waves of a complex cross-section waveguide. It is shown that proposed structure enables a design of passive devices (filters) with a complex scattering characteristic. The latter covers both bandwidths and wide stop bands with at least three frequencies of the resonant interaction with the microstrip transmission line.