A Novel Hardware Architecture to Time-Reverse Electromagnetic Signals with Low Cost

West Virginia University Research Corporation, Morgantown WV

Investigators

Abstract

Time-reversal technique is capable of focusing waves in space and time. It has the potential to enable a wide range of revolutionary apparatuses, as shown by extensive prior research. Particularly, "time-reversal of acoustic signals" has been successfully implemented for underwater communication and sonar. However to date, no practical systems for "time-reversal of electromagnetic signals" have been reported; the major pertinent bottleneck is the expensive/bulky hardware required by time-reversing electromagnetic signals. This research proposes a novel frequency-domain architecture to time-reverse electromagnetic signals with low cost. It is expected to fundamentally resolve the "high-cost difficulty" associated with "time-reversal of electromagnetic signals," and in turn, to accomplish an efficient and robust hardware solution to space-time focusing of electromagnetic waves. This project's outcome can be readily employed in numerous challenging applications such as wireless communication in extreme environments, high-resolution imaging radars, tracking of wireless sensors/tags, and medical diagnosis. The proposed research will make constructive impacts on the science and engineering curriculum at West Virginia University Institute of Technology. The proposed research activities will support both graduate and undergraduate students and provide them with excellent research opportunities in the areas of electromagnetic modeling, antennas, microwave circuits, and wireless systems. Existing collaborations with local high school districts enables high school students/instructors to participate in the proposed research activities and gain practical engineering experiences. This project is intended to impact both research and educational aspects of local industries by providing novel system/circuit solutions for wireless systems, supplying exceptionally well-trained students, and organizing industrial seminars, short courses, and workshops. Research findings of this project will be disseminated by the means of journal publications, conference presentations, patents, project webpage, newspapers, and radio. This research proposes a novel architecture to time-reverse wideband microwave signals with low cost. It exploits detour in the frequency domain to avoid high-speed analog-to-digital conversion in time, via three steps: (i) "Fourier transform," to obtain discrete spectrum of the input signal; (ii) "Digital signal processing," to carry out complex conjugate operation for the spectral samples obtained in Step (i); and (iii) "Inverse Fourier transform," to synthesize the time-reversed signal using discrete continuous-wave elements. This novel time-reversal architecture is comprised solely of common semi-conductor components like oscillators, multipliers/mixers, band-pass-filters, amplifiers, and switches. As a result, it embodies a compact and low-cost system-on-a-chip implementation. Its success would establish an efficient and robust hardware solution to space-time focusing of electromagnetic waves. Specifically, this research has the following three major tasks: first, prove the feasibility of time-reversing microwave signals with inexpensive circuitries; second, investigate antennas with large bandwidth and omni-directional pattern; and third, demonstrate space-time focusing of electromagnetic waves by integrating the circuits from the first task and antennas from the second task