Design of dual-mode dual-band filter based on multilayer groove gap waveguide

This paper presents a novel dual-mode dual-band filter (DBF) based on multilayer groove gap waveguide (GGW). Unlike other published planar GGW filters, the proposed filter achieves a vertically stacked duplicate topology by introducing a rectangular aperture in the common wall and traditional inductive irises on the same layer, with perfect central symmetry in the overall structure. This reduces machining difficulty while having a smaller size. By optimizing the dimensions of the coupling structure and rectangular cavities, dual-mode resonators (DMRs) including even mode and odd mode are used to accomplish dual-bandpass response. Additionally, an efficient transition is presented and applied to achieve a good impedance matching from rectangular waveguide (RW) to GGW. To better demonstrate, a multilayer DBF with working center frequencies of 67.9 and 69.8 GHz is designed, fabricated and measured. Good consistency can be observed between the simulation result and the measurement result.