Thermal Noise Measurements in a Reverberation Chamber

Two models describing properties of the thermal noise power emerging from an antenna mounted in a reverberation chamber are described. The first compares the reverberation chamber to an over-moded cavity acting as a black-body source; the second describes the noise in terms of the antenna noise temperature. Measurements based on the antenna noise temperature model show the noise power to be dependent on the position of the rotating mechanical stirrer. The correlation of the antenna noise temperature with the stirrer position dependent antenna mis-match factor is shown. When a signal is injected into the chamber measurements of the signal to noise power ratio show that this ratio is dependent on the stirrer position and also the position of the signal source within the chamber. These results have significant consequences for the detection of weak signals from radiating sources in a reverberation chamber.