In-line eighth-order pseudoelliptic filter using dielectric resonator quadruplets implemented using bypassing evanescent modes

A new quadruple-resonator configuration for the design of in-line pseudoelliptic dielectric resonator filters is proposed in this paper. The proposed configuration uses waveguide evanescent modes bypassing the resonators to generate cross coupling between the non-adjacent ring-shaped TE_01δ mode resonators. Specifically, fourth-order filtering functions with a pair of symmetric transmission zeros can be generated by this configuration. An in-line eighth-order C-band filter comprising a couple of cascaded quadruple-resonator configurations for the generation of four symmetric transmission zeros is presented. The experimental results of a manufactured prototype validates the feasibility of the proposed filter structure.