Researchers from North Carolina State University and Carnegie Mellon University have found that adding a magnetic resonance field enhancer (MRFE) – which can be as simple as a copper loop – to a wireless charging system can boost transfer efficiency by at least 100 percent, and possibly as much as 5,000 percent.
“Our experimental results show double the efficiency using the MRFE in comparison to air alone,” says NC State Associate Professor David Ricketts.
By placing the MRFE between the transmitter and the receiver (without touching either) as an intermediate material, the researchers were able to significantly enhance the magnetic field, increasing its efficiency.
“We realized that any enhancement needs to not only increase the magnetic field the receiver ‘sees,’ but also not siphon off any of the power being put out by the transmitter,” Ricketts says. “The MRFE amplifies the magnetic field while removing very little power from the system.”
The researchers conducted an experiment that transmitted power through air alone (figure 3), through a metamaterial (figure 2), and through an MRFE made of the same quality material as the metamaterial (figure 3). The MRFE significantly outperformed both of the others. Also, the MRFE is less than one-tenth the volume of metamaterial enhancers.
A pre-proof draft of the paper, “Magnetic field enhancement in wireless power with metamaterials and magnetic resonant couplers,” has been published in the journal IEEE Antennas and Wireless Propagation Letters.