Time reversal experiments in the microwave range: Description of the radar and results

Abstract

We present a new RADAR system able to perform Phase Conjugation experiments over the ultrawideband [2-4] GHz. The system is equipped with a transmit/receive linear array made of eight antennas connected to a 2-port Vector Network Analyzer through eight independent couples of digitally-controlled RF attenuators and phase shifters. Thus, each channel can selectively transmit or receive and can as well attenuate and phase shift the RF signal. For each frequency, either the Phase Conjugation or the Decomposition of the Time Reversal Operator (DORT) is applied to the received signal and the appropriate amplitude and phase law is coded into the prototype; the focusing wave is then experimentally re-emitted by the array. The quality of the achieved backpropagation is evaluated both in frequency and time domain: In this sense we can speak of Time Reversal. The excellent agreement between measured and theoretical results validates the potential of our system.