Measuring phase noise at K-hand

This paper investigates the applicability of common methods of phase noise measurement and short-term frequency stability measurement to K-band frequencies. A phase-noise testset was designed and implemented to test a unit with a nominal frequency of 17.86 GHz, a nominal integrated phase noise of 3° rms, and a nominal carrier-to-equivalent-noise-spectral-density of 110 dB-Hz. The object was to build the least expensive manual testset within a three month (or less) period. The testset was implemented using mostly commercial “off-the-shelf” (COTS) instruments. The oscilloscope method was only applicable to measuring instantaneous quantities of phase jitter. The frequency counter method could only be used in an automatic (computer controlled) testset. Although a stand-alone COTS phase noise measurement system was found to be the “best” measurement technique, the system offered much more capability and automation than was needed and was also fairly expensive. A second phase detector method using a superheterodyne receiver, local oscillator signal source, and root mean square voltmeter did not produce the best results; however, the results were attributable to design flaws. The method was still found to be feasible. The SSB phase noise method using a COTS spectrum analyzer was found to be very applicable to K-band testing