Nonlinear Electromagnetic Time Reversal in an Open Semireverberant System

Abstract

We consider nonlinear electromagnetic time reversal (TR) applied to a semireverberant complex enclosure containing a discrete passive nonlinear circuit. Unlike closed reverberant systems used for the previous demonstrations of nonlinear electromagnetic TR, the experimental system used here better represents realistic environments that are often far more lossy. Moreover, we demonstrate the use of pulse inversion to extract nonlinear responses for electromagnetic time reversal, which could help overcome potential practical-implementation issues. Concentrating on the application of this technique as an efficient power-delivery method, we evaluate the peak power enhancement resulting from TR focusing at the location of the nonlinear circuit.PHYSICAL REVIEW APPLIED 2, 044013 (2014) 2331-7019=14=2(4)=044013 (8) 044013-1

Detection and Location of Nonlinear Scatterers Using Dort Applied With Pulse Inversion

“…DORT (French acronym for decomposition of time-reversal operator) is a technique that utilizes multistatic scattered responses obtained with an array of antennas by means of the eigenvalue decomposition (EVD) to separate the detected targets in terms of the eigenvalues and their eigenvectors, which contain the information necessary to perform selective focusing (beamforming) towards a target of interest [8,9]. PI is a technique that allows either even-or odd-ordered harmonics to be extracted from the linear combination of the scattered responses due to excitation by two transmit pulses, with one an inverted version of the other but otherwise identical [10,11]. Our previous work in [7] has proposed PI-DORT for nonlinear devices by providing examples via a two-dimensional numerical simulation.…”

Leveraging Chaos for Wave-Based Analog Computation: Demonstration with Indoor Wireless Communication Signals

“…The reflections off the irregular cavity walls interfere and give rise to a speckle-like wave field [35], very much like scattering events in multiply scattering optical media such as thin paint layers or biological tissue [21,36]. Furthermore, complex microwave cavities are leveraged in fundamental research on quantum chaos [37] as well as in applications ranging from security screening [38,39] and biomedical imaging [40], via sensing [41,42] and wireless power transfer [43][44][45][46] to electromagnetic compatibility tests [47].…”

Time reversed electromagnetic wave propagation as a novel method of wireless power transfer

“…In our numerical simulations; however, the sonas were only recorded for 30-35 ns and the discretized nature of the data on this time scale led to distortion of the sona signals. The team also explored using pulse inversion, another method of sona extraction that has been well documented in the literature [32,39].…”

“…Hong et al have used this method for numerous time-reversal experiments, citing its computational simplicity as a benefit for using it in physical experiments [32].…”