Researchers from the University of Waterloo in Canada have developed a novel design for electromagnetic energy harvesting, using metamaterials.

The metamaterials that can be designed so that they don’t reflect or re-transmit power — enabling almost full absorption of incident waves at a specific range of frequencies and polarizations.

Metasurface-based antennas

KurzweilAI has reported a variety of schemes for harvesting electromagnetic energy, using classical (“dipole”) antenna designs.

“Our technology introduces ‘metasurfaces’ that are much better energy collectors than classical antennas,” explained co-author Omar M. Ramahi, professor of electrical and computer engineering.

Metasurfaces are formed by etching the surface of a material with an elegant pattern of periodic shapes. The particular dimensions of these patterns and their proximity to each other can be tuned to provide “near-unity” (almost complete) energy absorption.

Applications include wireless power transfer to power remote devices such as RFID and remote devices, and even to beam “space solar power” down from space, Ramahi noted.

The technology can also be extended to the infrared and visible spectra. “We’ve already extended our work into the infrared frequency regime and we hope to report very soon about near-unity absorption in those higher-frequency regimes,” added Ramahi.

The open-access article appeared today (April 14) in the journal Applied Physics Letters. The authors are affiliated with the University of Waterloo.

Abstract of Metamaterial electromagnetic energy harvester with near unity efficiency

We present the design of a metamaterial medium for electromagnetic energy harvesting based on the full absorption concept. A metamaterial slab was designed comprising 13 × 13 electrically small cells, each loaded with an 82 Ω resistor which mimics the input impedance of arectification circuitry. Unlike earlier designs of metamaterial absorbers, here the power absorption is mostly dissipated across a resistive load instead of the dielectric substrate. This implies that effective electromagnetic energy harvesting can be achieved. The power is channeled through a via connected to each cell. For a design optimized at 3 GHz, simulation and experimental results show power absorption efficiency of 97% and 93%, respectively.