Abstract: In order to extend the application area of time reversal theory in the electromagnetic field, a method for electromagnetic wave focusing based on the active detected time reversal theory is proposed. This method accomplishes the refocusing of signal energy by time reversing the reflected waves of targets and searching signal energy in the search area. Firstly, an antenna element in the transducer array emits electromagnetic waves to the target area. And this signal is reflected by targets, and every antenna element receives and records the reflected signals. When the process of emitting and receiving is finished by all antennas, all signals received by an antenna are added and time reversed. Then, retransmitting the time-reversed signals of every antenna to the target area virtually, and the signal energy is refocused in the direction of targets. Based on the propagation characteristics of electromagnetic waves the fundamentals of and the algorithm for active detected time reversal refocusing are given in this paper. Finally, the characteristic that the proposed method can accomplish electromagnetic wave refocusing effectively is validated via simulation.

Key words: time reversal, active detection, electromagnetic waves, focusing, reflection