Authors: Yakir Hadad, Jason Soric, Dimitrios Sounas and Andrea Alù
Source: FERMAT, Volume 21, Communications 8, May-Jun., 2017
Abstract: Time-reversal symmetries impose stringent constraints on antennas, radiating and scattering systems. In telecommunications, we are bound to transmit and receive signals equally well from the same point in space, making a directive antenna prone to receive echoes and reflections. In a similar fashion, while metasurfaces have shown large flexibility in manipulating transmissions and reflections from interfaces, they are bound to transmit from opposite directions with the same strength. Recent works have shown that weak temporal modulation or mechanical motion in suitably designed metamaterial structures may largely break reciprocity and time-reversal symmetry, providing a way to overcome these constraints. Here we show theoretically and experimentally radiating and scattering systems with drastically different transmission and reception properties. The proposed concept may provide a route towards compact and efficient radio-frequency communication systems, as well as open new directions in nanophotonics, energy harvesting, and thermal management, when translated to different frequency ranges.
Index Terms: Antennas, Metamaterials, Reciprocity, Spatio-temporal modulation.
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Time-Modulated Antennas and Metasurfaces