Miniaturized Dielectric Waveguide Bandpass Filter Using Strongly Coupled Resonator Quintuplet

This letter proposes a miniaturized dielectric waveguide bandpass filter (BPF) using strongly coupled resonator quintuplet (SCRQt). The SCRQt is formed by five quarter-wavelength resonators on the top surface of a dielectric block coated with silver. The five resonators are strongly coupled, resulting in five resonance modes. Four of these modes form the filter’s passband, while one mode is functioning as a redundant mode (RM) with a resonance frequency significantly lower than the passband. A fourth-order BPF utilizing the proposed SCRQt is designed and measured at the center frequency of 3.5 GHz. Compared with other dielectric waveguide filter, it significantly reduces the overall size.