Graphene found to efficiently absorb radio waves

February 25, 2014

Graphene model (credit: Wikimedia Commons)

Add “secure wireless communications” to the growing list of applications for graphene, according to scientists at Queen Mary University of London and the Cambridge Graphene Centre.

Publishing in the journal Scientific Reports (open access), the scientists demonstrated that stacked graphene layers increased the absorption of millimeter waves by 90 per cent over a wide bandwidth (125 — 165 GHz, which could be extended down to microwave frequencies) without blocking visibility (monolayer graphene is ~98% transparent).

For example, graphene could be added as a coating to buildings or windows to block radio waves, said Yang Hao, co-author of the study and Professor of Antennas and Electromagnetics at Queen Mary’s School of Electronic Engineering and Computer Science. “This could be used to [improve the security of] wireless networks, for example.”

Abstract of Scientific Reports paper

The development of transparent radio-frequency electronics has been limited, until recently, by the lack of suitable materials. Naturally thin and transparent graphene may lead to disruptive innovations in such applications. Here, we realize optically transparent broadband absorbers operating in the millimetre wave regime achieved by stacking graphene bearing quartz substrates on a ground plate. Broadband absorption is a result of mutually coupled Fabry-Perot resonators represented by each graphene-quartz substrate. An analytical model has been developed to predict the absorption performance and the angular dependence of the absorber. Using a repeated transfer-and-etch process, multilayer graphene was processed to control its surface resistivity. Millimetre wave reflectometer measurements of the stacked graphene-quartz absorbers demonstrated excellent broadband absorption of 90% with a 28% fractional bandwidth from 125–165 GHz. Our data suggests that the absorbers’ operation can also be extended to microwave and low-terahertz bands with negligible loss in performance.