Green's Function Retrieval with Absorbing Probes in Reverberating Cavities.
The cross-correlation of a diffuse wave field converges toward the difference between the anticausal and causal Green's functions between two points. This property has paved the way to passive imaging using ambient noise sources. In this Letter, we investigate Green's function retrieval in electromagnetism. Using a model based on the fluctuation dissipation theorem, we demonstrate theoretically that the cross-correlation function strongly depends on the absorption properties of the receivers. This is confirmed in measurements within a reverberation chamber. In contrast to measurements with noninvasive probes, we show that only the anticausal Green's function can be retrieved with a matched antenna. Finally, we interpret this result as an equivalent time-reversal experiment with an electromagnetic sink.
Institut d'Electronique et de Télécommunications de Rennes, UMR CNRS 6164, Université de Rennes 1, Rennes 35042, France.
Matthieu
M
Davy
ESPCI ParisTech, PSL Research University, CNRS, Institut Langevin-1 rue Jussieu, F-75005 Paris, France.
Julien
J
de Rosny
Institut d'Electronique et de Télécommunications de Rennes, UMR CNRS 6164, INSA de Rennes, Rennes 35708, France.
Philippe
P
Besnier