The Comparison and Calibration of Power-Measuring Equipment at Wavelengths of 3 CM and 10 CM

A description is given of recent experiments which have resulted in the production of substandard power-measuring equipment for wavelengths in the 3cm and 10cm wavebands. The equipment consists of two calibrated thermistor bridges measuring up to 1 mW of microwave power, and these may be regarded as the present United Kingdom substandards. The accuracy of the final calibration carried out at wavelengths of 3.18 and 10.77cm is estimated at ±2% and ±1% respectively. Good agreement was obtained in a comparison of the two standards used in the 3cm calibration, the water calorimeter and the torqueoperated vane wattmeter developed by Cullen and Stephenson.