Measuring antenna noise parameters using a set of Wheeler caps

The noise correlation matrix and noise parameters are parameters of interest for antennas, and antenna arrays, particularly in the radio-astronomy context. For a passive network, such as an antenna, 2-port scattering parameters can be used to establish a noise correlation matrix and consequently the antenna noise parameters. In this paper we show how the 2-port scattering parameters of an antenna can be completely determined by measuring its reflection coefficient inside two specifically sized Wheeler caps, in addition to a free space measurement. We use the measurement to determine the noise correlation matrices and noise parameters of an antenna.