Optimizing test source polarization in time reversal electromagnetic focusing

Time Reversal (TR) is a well known simple time/spatial refocusing based on the time invariance of wave equation in lossless media, which is performed in a two phases process (M. Fink, IEEE Trans. Ultrason. Ferroelec. Freq. Contr., 39, 1992, pp. 555–566). The first (sensing) step consists in sensing the field radiated by a point source located in the point where one wants to refocus the field. In the second (back-propagation) step, the signal collected by a set of receivers (Time Reversal Mirror) is time reversed and back-propagated. By virtue of the time invariance of the wave equation which governs the propagation phenomenon, the wave will undergoes the same path focusing in the point where the original point source was located.