In-line pseudoelliptic TE01d mode dielectric resonator filters

A new configuration for dielectric resonator filters with in-line structure and pseudoelliptic response is presented in this paper. The proposed concept is realized through the use of TE01δ single-mode resonators with different orientations cascaded along an evanescent mode waveguide. By exploiting a pair of orthogonal evanescent modes that can alternatively by-pass or excite the resonators, cross-coupling between nonadjacent pucks can be established and properly controlled. Pseudoelliptic filters can indeed be designed without using cumbersome cross-coupled architectures or reduced spurious performance dual-mode resonators. The experimental result of a 6^th order filter with two transmission zeros in the lower stopband validates the proposed approach.