Dielectric Resonators With High $Q$ -Factor for Tunable Low Phase Noise Oscillators

This paper demonstrates the realization of tunable microwave low phase noise oscillators. A ceramic-based dielectric resonator enclosed in a metallic cavity with an unloaded $Q$ of 13000 is proposed. The relationship between geometric parameters and resonant frequency is determined. The dielectric puck is then incorporated into multilayer printed circuit boards by using substrate-integrated waveguide techniques. The results show that the resonator resonates at ${\rm TE}_{01\delta }$ mode with a frequency of 13.3 GHz. Therefore, 13.3 GHz dielectric resonator oscillators with both mechanic and electronic tuning are built. The oscillator includes a pseudomorphic high-electron-mobility transistor low-noise amplifier and an electronic phase shifter. The measured phase noise of the oscillator is ${-}{\rm 121.7}~{\rm dBc}/{\rm Hz}$ at a 10-kHz offset. The calculated and measured phase noise results show a difference of 3 dB.