Novel Coupling Mechanism for In-line Pseudoelliptic TE01δ Mode Dielectric Resonator Filter Design

In this paper, a novel in-line dielectric resonator (DR) filter with pseudoelliptic response is proposed. The basic configuration is a triplet, which is implemented by three TE01 delta single-mode resonators oriented along orthogonal directions and cascaded along an evanescent mode waveguide. By shifting the middle DR puck horizontally or vertically to exploit a pair of orthogonal evanescent modes that can excite alternatively the first or the last resonator. Bypass- or cross-coupling between nonadjacent DR pucks can be established and properly controlled unless the middle DR puck shifts both horizontally and vertically. Base on this novel mechanism, pseudoelliptic filters can be implemented with in-line structure instead of utilizing conventional cumbersome cross-coupled architectures. A 6th order filter cascaded double triplets with two transmission zeros (TZs) at the lower and upper skirt has been investigated and designed to validate the proposed approach.