Designs of miniaturized differential bandpass filters using dual-mode dielectric resonators

In this paper, two types of dual-mode dielectric resonators (DRs) are utilized to design miniaturized differential bandpass filters (BPFs). According to the boundary conditions of the electromagnetic fields, inserting a metal plate on the electric field's symmetry plane doesn't disturb the original field distributions. Thus, the structure of each employed DR is introduced by cutting off along the electric field's symmetry plane and inserting a metal plate on the section, resulting in significant size reduction compared with the conventional one. Meanwhile, a pair of orthogonal half-cut modes of each dual-mode DR can be differentially excited and coupled for constructing the differential-mode (DM) passband of differential dual-mode DR BPF. For demonstration, two differential BPFs employing the proposed dual-mode DRs are designed and simulated, showing good DM and common-mode (CM) responses as well as offering a significant size reduction in comparison with the conventional differential filters.