Precise Transient Electric Field Shaping With Prescribed Amplitude Pattern by Discrete Time Reversal

Generation of arbitrarily shaped transient electric fields in a prescribed bounded region, especially with high precision and low sidelobes, is a challenging fundamental issue with applications ranging from electromagnetic (EM) switch, microwave chemotherapy to wireless power transfer. In this work, we study for the first time the transmission of the EM field excited by point current sources (PCSs) in time reversal cavity (TRC) or time reversal mirror (TRM) from the view of EM radiation. We first decompose the predefined area into a number of spatial grids, those are all utilized as PCSs here. When the electric field of one PCS is calculated, other PCSs are treated as secondary sources. We can get the whole electric field distribution by calculating these grids one by one. Based on this theory, we choose the closed TRC/TRM as excitation transmitters to construct arbitrarily shaped electric field inside TRC/TRM, whose excitation can be synthesized after all the TRC/TRM elements capture their responses to the known probing signals emitted from probe antennas situated at all grids. Thanks to the spatial and temporal focusing property of time reversal (TR), a set of the TR focusing field is produced simultaneously with their focal spots spaced by grids. We successfully and dynamically demonstrate the simple generation method for different desired transient electric fields, and observe the electric distribution during the process of getting desired shaped electric field with time under different limited given regions.