Novel Dual-Mode Dielectric-Filled Waveguide Filters

A novel dual-mode rectangular dielectric-filled cavity is proposed. By applying dual blind holes in a silver plated dielectric cavity, the cavity generates a pair of TE
₂₀₁
modes, whose resonant frequencies can be controlled by the depth of the blind holes. The capacitive effect of the blind holes can also reduce the resonant frequencies of the modes. The proposed cavity is applied to dual-mode dielectric-filled waveguide filters. The coupling between the two modes is controlled by the slot between the two blind holes. A single-cavity dual-mode filter, a three-cavity fourth-order filter and a six-cavity seventh-order filter are designed. The results show that the second-order filter reduces size by 49%, the fourth-order filter by 29% and the seventh-order filter by 14% comparing to conventional single-mode filters with similar performance.