Compact bandpass filter based on one-third equilateral triangular resonator of substrate integrated waveguide

A one-third triangular resonator with two electric walls and two virtual magnetic walls is proposed for the design of a broadband filter. The structure is realised by taking out one-third of an equilateral or isosceles triangular resonator of the substrate integrated waveguide and therefore it is called the one-third-mode substrate integrated resonator (OTMSIR). The characteristics of the OTMSIR cavity are studied. Based on this resonator, a filter composed of six OTMSIR cavities is designed, fabricated and tested. The measured results agree well with the simulated ones.