Wideband microstrip-to-air-filled substrate integrated waveguide transition with controllable band-pass performance

摘要

A novel wideband back-to-back microstrip-to-air-filled substrate integrated waveguide (AFSIW) transition with controllable band-pass performance is presented. The wideband transition is constructed by a gradient microstrip and a section of widened partially dielectric-filled AFSIW. The sharp rejection performance above the pass band is achieved by taking advantage of the notch characteristics of the widened partially dielectric-filled AFSIW section. The lower stop band is determined by the cut-off characteristic of the intermediate AFSIW between the back-to-back transitions. The relationship between the band-pass response and the dimensional parameters of the transition is investigated. A prototype is designed, manufactured and measured. The measured fractional bandwidth (FBW) is 57.63% centered at 14.75 GHz. The suppression over 20 similar to 25 GHz is better than 25 dB, and a transmission zero with a suppression of 51.7 dB is introduced at 1 GHz away from the upper-edge frequency of the pass band.