Low-loss differential bandpass filter using TE01δ-mode dielectric resonators

A novel differential bandpass filter (BPF) based on a TE_01δ-mode dielectric resonator (DR) is proposed. By utilising the inherent electromagnetic properties of the TE_01δ-mode ring-shaped DR, the TE_01δ mode, as a dominate mode of the DR, can be differentially excited for constructing the fundamental differential passband of the BPF. To validate the proposed idea, a second-order differential BPF is designed, fabricated and measured. Good agreement is obtained between simulated and measured results, showcasing good performance such as low insertion loss and high common-mode suppression in the differential passband.