A closed time-reversal cavity for electromagnetic waves in transmission line networks

Wang, Zhaoyang (Electromagnetic Compatibility Laboratory and the Distributed Electrical Systems Laboratory, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland) ; Rachidi, Farhad (Electromagnetic Compatibility Laboratory and the Distributed Electrical Systems Laboratory, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland) ; Paolone, Mario (Electromagnetic Compatibility Laboratory and the Distributed Electrical Systems Laboratory, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland) ; Rubinstein, Marcos (School of Management and Engineering Vaud, HES-SO // University of Applied Sciences Western Switzerland) ; Razzaghi, Reza (Department of Electrical and Computer Systems Engineering, Monash University, Australia)

A closed time-reversal cavity has been considered a purely theoretical concept whose experimental realization was assumed to be impossible. In this paper, we demonstrate that it is, in fact, possible to realize a closed time-reversal cavity using a network of transmission lines. The network is excited by either lumped voltage or current sources at arbitrary locations, and it is terminated on matched impedances. This system is an exact closed time-reversal cavity in the sense that, in the backward-propagation stage, by back-injecting time-reversed measured responses (voltage or current) generated by a source at each line terminal, a time-reversed copy of the current and voltage distribution in the forward-propagation stage is obtained. We report for the first time an experimental realization of a time-reversal cavity formed by a network of inhomogeneous transmission lines, in which the spatial and temporal signal distribution along the network is reproduced as in a sequence of the system state (i.e., voltages and or current along the lines) being played in reverse. We also discuss the interfering effect of the so-called diverging wave for observation points in the vicinity of the source. An active realization of a time-reversal sink is proposed to effectively overcome the interfering effect caused by the diverging waves.


Keywords:
Article Type:
scientifique
Faculty:
Ingénierie et Architecture
School:
HEIG-VD
Institute:
IICT - Institut des Technologies de l'Information et de la Communication
Date:
2020-08
Pagination:
9 p.
Published in:
IEEE Transactions on Antennas and Propagation
Numeration (vol. no.):
early access
DOI:
ISSN:
0018-926X
Appears in Collection:



 Record created 2020-09-15, last modified 2020-10-27

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