Antenna reciprocity and the theory of electromagnetic time reversal

In this paper, the theory of electromagnetic time reversal mirrors is examined in the light of antenna reciprocity relations in time domain. The single antenna relation is used to disprove the fallacious view of electromagnetic time reversal as a back propagation mechanism of waves. Then, the two-antenna reciprocity relation is used to explain the observed behavior of wireless channels under time reversal procedures. The time domain impulse responses of 175% bandwidth wireless channels are measured to test the spatial and temporal focusing of TR.