Time Reversal in Reverberation Chambers: Application to Lossy Media

The capability of the time reversal technique (TR) to focus in time and in space a signal is analyzed when the wanted focusing point is immersed in a lossy medium, a saline solution adopted for physiological purposes. A loop probe is immersed in the saline solution located inside a reverberation chamber. The procedure starts from the measured transfer function between the loop and an antenna, and the TR entire procedure is carried out post-processing the measured transfer function due to the absence of an adequate signal generator for the creation of the TR mirrored signal. In spite of an expected amplitude reduction due to losses, the final reconstructed signal in the saline solution has a good shape and good focalization. Losses are also augmented by adding absorbers in the chamber showing the robustness of the procedure. Finally, the sensitivity to small chamber state variations, stirrer small angular step variations, is checked computing the amount of acceptable changes for a 50% amplitude reduction.