Q-band dual-mode substrate integrated waveguide filter and diplexer with circular cavity

摘要

This paper proposes novel dual-mode substrate integrated waveguide (SIW) filterand diplexer with circular cavities, in which a pair of symmetrical metallicvia perturbations is placed at different positions in a single cavity combiningdifferent angle of feeding lines to obtain flexible transmission response. So thatmultiple transmission zeros can be obtained on one or both sides of the passband.Compared with traditional structure, the proposed dual-mode circularcavity filter and diplexer not only reduce the number of resonators and the volumeof filters, but also realize the transmission in higher frequency with theexisting machining precision. For verify the structure mentioned above, thedual-mode SIW filter and diplexer are designed, fabricated, and measured in astandard printed circuit board (PCB) process at Q-band. The filter is measuredat a central frequency(CF) of 44.86 GHz with a 3 dB fractional bandwidth(FBW) of 10.2%, insertion loss (IL) is 1.9 dB, meanwhile the measured diplexerinsertion losses (IL) are 2.1 and 2.4 dB in the lower and upper passbands centeredat 38.3 and 44.8 GHz with the fractional bandwidths of 10.7% and 10.1%.The isolation is lower than -40 dB. The measured results show good agreementswith the simulated ones.