Precision Microwave Waveguide Loss Calibrations

Precision microwave insertion-loss measurements are an important part of the evaluation and calibration of the Jet Propulsion Laboratory-NASA low-noise deep-space communication systems. A study of cooled transmission-line components was initiated with the Rantec Corporation in July 1966. The preliminary work at Rantec involved WR 430 waveguide insertion-loss calibrations using a microwave cavity Q technique. JPL verified the technique by repeating the calibration using a direct insertion-loss measurement technique between matched components. The JPL measurements are described in detail, and the critical areas identified. The difference between the reported JPL (0.00427 dB) and Rantec (0.00414 dB) measurements of 0.00013 dB is within experimental accuracies and adds to the confidence factor of both measurement techniques.