Ultra-Wideband Electromagnetic Space-Frequency Time Reversal Beamforming in a Rectangular Metal Tube

This paper has designed a structural health monitoring system to localize a defect on the wall of a rectangular tube by using space-frequency time reversal beamforming. The propagated electromagnetic wave in a metal rectangular tube is distorted by intermodal and intramodal dispersions. Time reversal beamforming is a novel signal processing technique which can alleviate the channel dispersions by back-propagating the time reversed signal in the problem medium by means of the exact Green's function. We use four ultrawideband printed quasi-Yagi antennas with the bandwidth of 4GHz at the central frequency 10GHz to excite several different wavemodes of an infinite rectangular metal tube. Finally, we show that the range resolution of the space-frequency time reversal and DORT time reversal are in good agreement.