Noise source calibration in the decimetre band

This paper discusses the problems involved in the design ofnoise comparators and standards for the frequency range 300¿3000 MHz.The problems are illustrated by reference to an existing noise comparatorbuilt for the frequency range 300-1000 MHz, and to an experimental system for the range 1¿2 GHz. Thermal noise standards are considered with reference to an existing 1000°C coaxial design, employed at the lower frequencies. A projected 400°C model, more suitable for the higher frequencies, is also discussed. Experimental results are given for the calibration of various types of broadband coaxial noise sources, demonstrating the need for accurate calibration facilities.