A study of uncertainty models in a reverberation chamber at NIST

The reverberation chamber has become a good alternative for over-the-air (OTA) testing of small antennas. Here the uncertainty of total radiated power measurements is evaluated for a reverberation chamber at National Institute of Standards and Technology (NIST), Boulder, Colorado. A procedure for measuring the uncertainty based on the standard deviation of nine different antenna orientations in the RC has been used. A model for the uncertainty, developed at Chalmers University of Technology, has been evaluated for measurements in this chamber. The model is based on the standard deviation of a Gaussian distribution for both the non-line-of-sight and the line-of-sight components together with an average Rician K-factor. It is found that the agreement between theoretical and experimental values are good and that the model describes the uncertainty well for both various loading in the chamber and various amount of platform stirring.