A Q-band low-profile waveguide BRF with built-in open-ended λ/2 microstrip resonators

Summary form only given, as follows. A new waveguide band-rejection filter (BRF) is proposed. In the waveguide BRF, two dielectric substrates with open-ended λ/2 mictostrip resonators are employed, and they are simply inserted in a waveguide. For this simple configuration, the BRF is low-profile and easy to be fabricated compared with a conventional one, which employs waveguide cavities outside the waveguide and needs costly machining processes. A Q-band prototype waveguide BRF is fabricated using alumina substrates and the measured results showed more than 50 dB attenuation at 47 GHz in 2 % fractional bandwidth.