A Noise Doubling Radiometer for the Absolute Calibration of High-Frequency Noise Sources

A switching type radiometer is described in which the comparison of the standard and the unknown noise sources is performed without the physical disconnection of any of the sources. This ensures that no impedance change takes place in the relatively wide frequency band of the measurement. Thus reception of the 'reverse radiation' of the receiver reflected back into the receiver remains constant during the measurement and so may be nulled initially.