Enhanced topology for the design of bandpass elliptic filters employing inductive windows and dielectric objects

This work presents a new topology for the design of bandpass elliptic filters employing inductive windows and dielectric objects. The proposed filtering structure combines, for the first time, the modified TE
102
resonating mode with the modified TE
201
mode. The TE
201
mode is excited by placing a wide dielectric post inside a waveguide cavity. The main advantage of the new topology is that two transmission zeros can be synthesized in the insertion loss response of the filter, for a second order structure. Also there is a high flexibility on the location of the transmission zeros. They can be synthesized along the frequency axis for maximum selectivity, or as a pair of complex poles for phase equalization.