Time reversal of electromagnetic signals with time-varying transmission lines

A new method to realize time reversal of electromagnetic signals by using time-varying transmission lines is reported in this paper. The corresponding theory is studied and discussed. It is developed using distributed modulated PIN diodes of two arrays between a microstrip line. The circuit architecture is presented and simulated using a RF/microwave circuit simulator, Agilent ADS. A saw signal to be time reversed here has a time duration of 8 ns and peak value of 200mV, and it is amplitude modulated by a sinusoidal carrier with an operation frequency of 5.2 GHz. The PIN diodes are on-and-off controlled by an 8-ns square wave signal with a peak value of 7 V. Results show that an 8-ns electromagnetic signal can be time reversed efficiently with this method.