Passive Antenna Characterization Through Impedance Correlations in a Diffuse Field

Abstract

Ambient noise correlations allow the passive recovery of Green’s functions between two probes. Recently, the same approach has been applied to electromagnetism, but by correlating diffuse fields in mode-stirred chambers. Until now, only the correlation of S-parameters has been studied. However, it has very recently been shown that the result can be difficult to interpret. To overcome this limitation, a new approach is proposed in this article to directly estimate the self- and mutual impedances of two coupled antennas from impedance correlations. The theoretical developments presented are validated experimentally in a reverberation chamber (RC) excited by a single antenna where mechanical and source stirring techniques are combined to generate a sufficiently diffuse field environment. It is shown, with antennas of different properties, that this approach allows reconstructing with good accuracy the complex impedance matrix between two receiving antennas as well as the transmission coefficient between them. The extracted gain pattern, in good agreement with that measured in an anechoic chamber, shows the good sensitivity of the proposed passive characterization technique.