Design of Compact Bandpass Filters Using Novel Dual-Mode Dielectric Patch Resonator

This paper introduces a new dual-mode dielectric patch resonator (DPR), which consists of a thin square dielectric patch with high permittivity and a low-permittivity substrate with bottom ground plane. A pair of TM
₁₁
degenerate modes can act as the dominate mode by fusing the dielectric patch and the substrate with the ground plane, whose resonant frequency is derived by using the combination of mixed magnetic wall method and mirror theory. It can be found that the constructed dual-mode DPR owns both merits of the planar transmission line and the dielectric resonator at the same time, i.e., low-profile configuration and high unloaded quality factor (Q
_u
). Based on the proposed dual-mode DPR, a single-ended bandpass filter (BPF) and a differential BPF is designed respectively. Good agreement can be observed between their respective simulated and measured results. Both of them showcase several advantages such as low passband loss, low profile, and compact size.