Time reversal of RF signals via cascaded time-to-frequency and frequency-to-time mapping in frequency-shifting loops

Time reversal of radio-frequency or microwave signals has important applications applications in telecommunications and electronic warfare. All-digital techniques are intrinsically limited in bandwidth by the speed of the converters, which necessitate the emergence of alternative analog techniques for future implementations. We demonstrate a new, to our knowledge, microwave-photonics architecture in this context, offering integration prospects. The system we propose is based on a pair of frequency-shifting loops, where the first loop transfers the input signal from the time domain into the frequency domain. In contrast, the second loop performs the opposite process, thus achieving the desired time-reversal process. The technique is particularly versatile, allowing the time reversal of signals with bandwidths of the order of tens of MHz, durations on the order of tens of microseconds, and with arbitrarily small latency. The system can also act as a temporal buffer for the reversed signal, a promising feature for photonic-based beamforming.