Compact triple-mode microwave dielectric resonator filters

This paper presents a novel and compact triple-mode dielectric resonator (DR) bandpass filter (BPF) based on a single waveguide cavity. A triple-mode resonator can be achieved by pairing the degenerate EH11 modes with a TM01δ mode. The DR structure is composed of two slitted pieces of dielectric pucks that are placed in the middle of a cylindrical metallic cavity. The resonator offers a size reduction ratio of about 15.6% compared with equivalent air-filled coaxial filters. A coaxial probe is used to excite the degenerate EH11 modes while the TM01 mode is excited using a vertical hole etched in the ceramic pucks. Finally, a, third-order generalised Chebyshev BPF is simulated using HFSS software. The filter has finite transmission zeros (TZ) on the high or low side of the passband.