Mechanically Tunable Oscillator Based on Air-filled Folded Substrate Integrated Waveguide Cavity

A compact tunable low phase noise oscillator is presented by taking advantage of air-filled substrate integrated waveguide (SIW) resonator with high quality factor. A relative tuning bandwidth of 1.81% is realized by employing two screws to perturb the folded air-filled cavity. The proposed oscillator in which reflection-type topology is applied is fabricated through a multilayer printed circuit board (PCB) process operating from 8.728~8.886GHz. The measured phase noise is -101.77dBc/Hz~-102.11dBc/Hz at an offset frequency of 100kHz and high output power exceeding 10dBm is available during the whole tuning range.