High spectral purity 26 GHz oscillator based on a SiO_2 Whispering Gallery Mode Resonator

摘要

One of the key parameters to achieve high spectral purity microwave oscillators is the resonator Q-factor. Ultra high performances have been already demonstrated in X-band with Sapphire resonator. SiO_2 monocrystal is another dielectric material to be considered. It presents low dielectric losses, is low coast and available in large size and high purity. We present the evaluation of a 26GHz-oscillator using a SiO_2 monocrystal Whispering gallery mode resonator as frequency reference. The SiO_2 resonator features a loaded Q-factor of 23000 leading to a phase noise S_Φ(1kHz) = -73 dB.rad~2.Hz~(-1). This first prototype though not yet completely optimised demonstrates the potentiality of dielectric quartz resonator for the achievement of low phase noise microwave source .