An Experimental Study of Frequency and Power Stability of Phase-Locked Microwave Signal Sources

Abstract

In setting up of microwave measurement standards of power attenuation, impedance, noise, etc. at the highest level of accuracy, high stability of frequency and power of the microwave signal source is an essential requirement. For this purpose, experimental investigations of frequency and power stabilization of microwave signals derived from klystrons and other sources under phase-locked and unlocked conditions have been carried out. The signals both locked and unlocked have been analyzed for their spectral purity, frequency drift etc. using microwave counter and spectrum analyzer. Phase-locked signals show better frequency stability, less residual FM and low noise-side bands. Source warm-up time is an important factor to achieve better frequency and power stability. Stability of the output power under locked condition improves to better than 0.1% as compared to 0.7 to 1.0% under unlocked condition. Such phase-locked microwave signal sources have been utilized for precision measurement of power, attenuation, impedance, frequency etc.