The repeatability of insertion loss of the most commonly used coaxial connector pairs was tested between 100 MHz and 12 GHz. The resolution of the measurements was better than 0.0001 dB. With carefully performed connections the repeatability expressed in standard deviation varied between 0.0002 and 0.002 dB. These values are some 2–3 times smaller than those published by Bergfried and Fisher.¹ The method described is particularly suitable for measuring the attenuation of small-loss elements such as adapters, air-spaced lines, etc.