Recycling radio waves with smart wallsRecycling radio waves with smart walls M. Dupr e 1, N. Ka na ,...
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Recycling radio waves with smart walls M. Dupr´ e 1 , N. Ka¨ ına 1 , G. Lerosey 1 , and M. Fink 1 1 Institut Langevin, ESPCI ParisTech & CNRS [email protected] Abstract— We propose to use electronically reconfigurable ultrathin metasurfaces as smart walls to reflect more intelligently the waves in indoor environments. We experimentally prove at 2.47 GHz that it is possible to use these as spatial microwave modulators, using a simple energy feedback. In particular, we show that we can enhance the transmission between two antennas by orders of magnitude or locally conceal a volume from the penetration of waves in a typical office room. We propose to use electronically reconfigurable ultrathin metasurfaces as smart walls to reflect more intelligently the waves in indoor environments. We experimentally prove at 2.47 GHz that it is possible to use these as spatial microwave modulators, using a simple energy feedback. In particular, we show that we can enhance the transmission between two antennas by orders of magnitude or locally conceal a volume from the penetration of waves in a typical office room. An increasing amount of data is nowadays conveyed wirelessly by radio waves in dense environ- ments such as cities or buildings [1]. While propagating, the electromagnetic waves carrying the information are reflected several times off obstacles such as walls and furnitures, thus causing a spread of the associated electromagnetic energy throughout those complex and reverberating me- dia. This raises health issues and wastes energy. Here we show that part of this seemingly lost energy can be recycled by reflecting more intelligently these multiply scattered waves using smart walls rather than bare ones. To do so we propose to use ultrathin metasurfaces [2] that we design to be electronically reconfigurable in real time as spatial microwave modulators [3]. We show that they can be utilized to cover part of the walls of a typical office room, hence transforming these dumb surfaces into smart ones. We demonstrate that, akin to the spatial light modulators which can focus light through complex media [4,5], those spatial microwave modulators can passively turn a random electromagnetic field resulting from reverberated and multiply scattered waves into a shaped one using a simple energy feedback and simple optimization algorithms [6]. Specifically, we prove that such smart walls can, in real time, increase by orders of magnitude the energy of a wireless signal received by any antenna or locally conceal a volume from penetration of microwaves [7]. We will present simulation and experimental results as well as a quantitative estimation of the benefits brought by the approach, by introducing and modeling the notion of wavefront shaping in reverberating media. Our smart walls have applications in green wireless communications and electromagnetic protec- tion. Indeed this approach could be used alongside others [8,9] to develop energy efficient wireless communication systems.but they are also amazing tools for fundamental physics related to the propagation of waves in complex, highly scattering or reverberating media. ACKNOWLEDGMENT This research was partially funded by French ”Ministre de la Dfense, Direction Gnrale de l’Armement”. REFERENCES 1. A. Paulraj, R. Nabar, D. Gore,Introduction to Space-Time Wireless Communications, Cam- bridge University Press, London, 2003. 2. A. V. Kildishev, A. Boltasseva and V. M. Shalaev, “Planar Photonics with Metasurfaces,“ Science, Vol. 339, No. 6125 , 1232009-1232009, 2013. 3. N. Ka¨ ına, M Dupr´ e, M. Fink, G. Lerosey,“Hybridized resonances to design tunable binary phase metasurface unit cells,“ Optics Express, Vol. 22, No. 16, 18881-18888, 2014. 4. A. P. Mosk, A. Lagendijk, G. Lerosey, and M. Fink, “Controlling waves in space and time for imaging and focusing in complex media,“ Nat. Photon., Vol. 6, 283-292, 2012.
Transcript of Recycling radio waves with smart wallsRecycling radio waves with smart walls M. Dupr e 1, N. Ka na ,...
Recycling radio waves with smart walls
M. Dupre1, N. Kaına1, G. Lerosey1, and M. Fink1
1Institut Langevin, ESPCI ParisTech & [email protected]
Abstract—
We propose to use electronically reconfigurable ultrathin metasurfaces as smart walls to reflectmore intelligently the waves in indoor environments. We experimentally prove at 2.47 GHz thatit is possible to use these as spatial microwave modulators, using a simple energy feedback. Inparticular, we show that we can enhance the transmission between two antennas by orders ofmagnitude or locally conceal a volume from the penetration of waves in a typical office room.
We propose to use electronically reconfigurable ultrathin metasurfaces as smart walls to reflectmore intelligently the waves in indoor environments. We experimentally prove at 2.47 GHz thatit is possible to use these as spatial microwave modulators, using a simple energy feedback. Inparticular, we show that we can enhance the transmission between two antennas by orders ofmagnitude or locally conceal a volume from the penetration of waves in a typical office room.
An increasing amount of data is nowadays conveyed wirelessly by radio waves in dense environ-ments such as cities or buildings [1]. While propagating, the electromagnetic waves carrying theinformation are reflected several times off obstacles such as walls and furnitures, thus causing aspread of the associated electromagnetic energy throughout those complex and reverberating me-dia. This raises health issues and wastes energy. Here we show that part of this seemingly lostenergy can be recycled by reflecting more intelligently these multiply scattered waves using smartwalls rather than bare ones. To do so we propose to use ultrathin metasurfaces [2] that we designto be electronically reconfigurable in real time as spatial microwave modulators [3]. We show thatthey can be utilized to cover part of the walls of a typical office room, hence transforming thesedumb surfaces into smart ones. We demonstrate that, akin to the spatial light modulators whichcan focus light through complex media [4,5], those spatial microwave modulators can passivelyturn a random electromagnetic field resulting from reverberated and multiply scattered waves intoa shaped one using a simple energy feedback and simple optimization algorithms [6]. Specifically,we prove that such smart walls can, in real time, increase by orders of magnitude the energy of awireless signal received by any antenna or locally conceal a volume from penetration of microwaves[7]. We will present simulation and experimental results as well as a quantitative estimation of thebenefits brought by the approach, by introducing and modeling the notion of wavefront shaping inreverberating media.
Our smart walls have applications in green wireless communications and electromagnetic protec-tion. Indeed this approach could be used alongside others [8,9] to develop energy efficient wirelesscommunication systems.but they are also amazing tools for fundamental physics related to thepropagation of waves in complex, highly scattering or reverberating media.
ACKNOWLEDGMENT
This research was partially funded by French ”Ministre de la Dfense, Direction Gnrale de l’Armement”.
REFERENCES
1. A. Paulraj, R. Nabar, D. Gore,Introduction to Space-Time Wireless Communications, Cam-bridge University Press, London, 2003.
2. A. V. Kildishev, A. Boltasseva and V. M. Shalaev, “Planar Photonics with Metasurfaces,“Science, Vol. 339, No. 6125 , 1232009-1232009, 2013.
3. N. Kaına, M Dupre, M. Fink, G. Lerosey,“Hybridized resonances to design tunable binaryphase metasurface unit cells,“ Optics Express, Vol. 22, No. 16, 18881-18888, 2014.
4. A. P. Mosk, A. Lagendijk, G. Lerosey, and M. Fink, “Controlling waves in space and time forimaging and focusing in complex media,“ Nat. Photon., Vol. 6, 283-292, 2012.
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Figure 1: (a) Scheme of the unit cell (up) and picture of the metasurface. Average transmission spectra fora field maximization (b) and field minimization (c). Average maps of the field after maximization (d) andminimization (e).
5. J. Aulbach, B. Gjonaj, P. M. Johnson, A. P. Mosk, and A. Lagendijk, “’Focusing and ScanningMicroscopy with Propagating Surface Plasmons,“ Phys. Rev. Lett., Vol. 106, 103901, 2010.
6. I. M. Vellekoop, A. P. Mosk, “Focusing coherent light through opaque strongly scatteringmedia,“ Opt. Lett. Vol. 32, No. 16, 2309-2311, 2007.
7. M. Dupre, N. Kaına, G. Lerosey, and M. Fink, “Shaping complex microwave fields in rever-berating media with binary tunable metasurfaces,“ Sci. Rep., Vol. 4, 6693, 2014.
8. L. Subrt, P. Pechac,“Controlling propagation environments using Intelligent Walls,“ 6th Eur.Conf. Antennas Propag, IEEE, 1-5, 2012.
9. L. Subrt, P. Pechac,“Intelligent walls as autonomous parts of smart indoor environments,“ ETCommun., Vol. 6, 1004, 2012.
