Homodyne single line phase noise measurement system for microwave oscillators

Proper measurement of phase noise for different oscillators is still a very problematic metrology issue. The most common way of measuring phase noise is the PLL technique, but it is complicated and efficient only when dealing with high stability crystal oscillators, masers, etc. In this article, we present the new concept of measuring phase noise, which is applicable especially for noisy oscillators working within the microwave bands. The whole concept of the measurement system is based on the single line discriminator method developed by Easdale, Dyer, Howes and Pollard. This system, enhanced with homodyne signal detection, significantly improves sensitivity and dynamic range of measurement, keeps the simplicity of the construction and calibration of the measurement system.