Low‐loss differential bandpass filter using TE 01 δ ‐mode dielectric resonators

A novel differential bandpass filter (BPF) based on a TE 01 δ ‐mode dielectric resonator (DR) is proposed. By utilising the inherent electromagnetic properties of the TE 01 δ ‐mode ring‐shaped DR, the TE 01 δ 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.