Electrically tunable half mode substrate integrated waveguide resonator

This paper presents a novel electronically tunable half mode substrate integrated waveguide (HMSIW) cavity resonator at microwave frequency. The resonant frequency of the cavity is tuned with different DC biasing voltages applied over a varactor coupled to the cavity. This structure has been analyzed with a full-wave software Ansoft-HFSS12. To validate our analyses, an X-band reflective tunable HMSIW cavity resonator is designed and fabricated as an experimental example. According to simulated and measured results, an equivalent circuit of the resonator with the varactor is obtained. Measured results show that the tuning range of the resonator is about 360 MHz with the loaded Q_L of 85 and the unloaded Q_U of 150. The proposed resonator can be used to design tunable devices such as microwave and millimeter-wave voltage controlled oscillator (VCO).