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

Cangialosi, Frank; Grover, Tyler; Healey, Patrick L.; Furman, Tim; Simon, Andrew; Anlage, Steven M.

doi:10.1109/wpt.2016.7498832

Cited by 23 publications

(10 citation statements)

References 32 publications

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“…The first is long-range wireless electromagnetic power transfer technologies that seek to deliver significant electromagnetic power to a single designated object located inside a complex scattering enclosure many wavelengths away from the source. Current approaches utilize multiple scattering and interfering wave trajectories connecting power source and target through either TR 56,57 or phase conjugation of microwave signals 58 that involve either large bandwidth or a large numbers of channels. These methods suffer from low efficiency as well as radiation safety concerns.…”

Section: Discussionmentioning

confidence: 99%

Perfect absorption in complex scattering systems with or without hidden symmetries

Chen

Anlage

2020

Nat Commun

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Wavefront shaping (WFS) schemes for efficient energy deposition in weakly lossy targets is an ongoing challenge for many classical wave technologies relevant to next-generation telecommunications, long-range wireless power transfer, and electromagnetic warfare. In many circumstances these targets are embedded inside complicated enclosures which lack any type of (geometric or hidden) symmetry, such as complex networks, buildings, or vessels, where the hypersensitive nature of multiple interference paths challenges the viability of WFS protocols. We demonstrate the success of a general WFS scheme, based on coherent perfect absorption (CPA) electromagnetic protocols, by utilizing a network of coupled transmission lines with complex connectivity that enforces the absence of geometric symmetries. Our platform allows for control of the local losses inside the network and of the violation of time-reversal symmetry via a magnetic field; thus establishing CPA beyond its initial concept as the time-reversal of a laser cavity, while offering an opportunity for better insight into CPA formation via the implementation of semiclassical tools.

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Section: Discussionmentioning

confidence: 99%

Perfect absorption in complex scattering systems with or without hidden symmetries

Chen

Anlage

2020

Nat Commun

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“…strong, medium and weak multipath. Using (16), PRPR is calculated for these threes representative cases. The array element number N is set to 4 as used in the experiment and T is varied for each case depending on the decay level.…”

Section: Appendixmentioning

confidence: 99%

“…From these transfer functions, PRPR can be calculated for each multipath case using (16) and their values are shown in Table 1. These PRPR results are directly associated with the signal characteristics in Figs.…”

Section: Appendixmentioning

confidence: 99%

Investigation of Time-Reversal Based Far-Field Wireless Power Transfer From Antenna Array in a Complex Environment

Park

Hong

2020

IEEE Access

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The performance of time-reversal (TR) based far-field wireless power transfer (WPT) from an antenna array in a complex propagation environment is investigated in comparison with conventional arraybased beamforming (BF). A two-step experiment is performed, namely 1) the propagation stage and 2) rectification stage. In the propagation stage, signal transmission is measured between the transmit array and receive antenna in an indoor multipath environment, for line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios. The results demonstrate that TR results in higher peak voltage compared to BF given the same average transmit power. In addition, while BF loses its ability to selectively send waves at the receiver due to impairment of the beam from multipath, TR can selectively focus waves at the receiver by inherently taking advantage of multipath. In the rectification stage, the resulting signals from the propagation stage are fed into a broadband rectifier for RF-to-DC conversion. It is shown that the signals received using TR lead to higher rectified DC voltage and rectification efficiency. The overall results suggest that TR can outperform BF with higher rectification efficiency given the same average transmit power. Through optimization of the TR pulse interval, array configuration and transmit power, further improvement in the performance of TR based WPT in a complex propagation environment is possible.INDEX TERMS Time-reversal, complex propagation environment, wireless power transfer, antenna array, beamforming, broadband rectifier, rectification efficiency.

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“…It is proven that TR can achieve an energy gain of 30 dB, and when continuous wave is used, the TR scheme can avoid indoor fading phenomenon. In [3], it explores the spatial profile of TR-WPT for energy reception at the vertical direction of the focus point in a metal cavity and gives a closed-form expression. In [4], it uses the temporal-spatial focusing effect of TR, combined with coils containing metamaterials, to illuminate centimeter-level LED lamps, thus demonstrating the precise control of near-field electromagnetic waves.…”

Section: Introductionmentioning

confidence: 99%

Long-Distance Wireless Power Transfer Based on Time Reversal Technique

Hu¹,

Lin²,

Liao³

2020

Recent Wireless Power Transfer Technologies

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Wireless power transfer (WPT) using microwave irradiation can set human free from the annoying wires. However, WPT has low energy efficiency due to electromagnetic wave diffraction in the case of indoor non-line-of-sight (NLOS) and causes electromagnetic radiation pollution around the room in the case of indoor line-of-sight (LOS). Time reversal (TR) technique is an inverse operation of timedomain signals and makes full use of the multipath effect. TR technique can improve the efficiency and reduce the pollution due to its unique temporal-spatial focusing effect. We will detail the principles of TR with the finite TR arrays. What's more, we propose a sequential convex programming (SCP) algorithm based on diode circuit to obtain the optimal frequency point amplitude to further improve energy efficiency. The simulation result shows that the TR-SCP-WPT system model will get the significant energy gain.

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

Cited by 23 publications

References 32 publications

Perfect absorption in complex scattering systems with or without hidden symmetries

Perfect absorption in complex scattering systems with or without hidden symmetries

Investigation of Time-Reversal Based Far-Field Wireless Power Transfer From Antenna Array in a Complex Environment

Long-Distance Wireless Power Transfer Based on Time Reversal Technique

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