New Tunable Substrate Integrated Waveguide Bandstop Resonator

This letter presents a new trade-off between tuning range and Q-factor for a tunable substrate integrated waveguide resonator used to give a bandstop response. The originality of this work lies in the use of an electrically-controlled short-circuit condition that closes the substrate integrated waveguide cavity. Frequency shift is obtained with a varactor diode whereas the substrate integrated waveguide cavity makes it possible to maintain a high Q-factor. This leads to a new trade-off between tuning range (about 2.1%) and electrical performances (unloaded Q-factor around 130-140). An X-band bandstop tunable substrate integrated waveguide resonator was designed, fabricated and measured.