High Power Low-Loss Terahertz Filter with Higher-Order Mode Suppression

Filters consisting of oversized waveguides need to suppress higher order modes that may propagate due to trapped mode resonances. This research work presents a filtering system consisting of tapers and ultra wide band oversized waveguide filter. The purpose of the filtering system is to pass the desired band while rejecting unwanted band along with suppression of higher order modes. Design includes inductive irises coupled filter section connected between oversized waveguides and used to suppress higher order modes. Filter has pass band from 0.29-0.39 THz. 3rd order direct coupled oversized waveguide filter is designed using all pole chebychev synthesis procedure having inductive irises with waveguide dimensions as a × b = 2000µm × 600µm. Thickness of irises is selected to be 100µm to ensure high power handling capability. Corners of the filters are chamfered with fillet radius 20µm. Taper is designed in order to connect the standard waveguide (710um × 355um) to oversized waveguide (2000um × 600um).