Design and Measurement of a Zero-Index Metasurface for Microwave Power Transmission Applications

In practical microwave power transmission (MPT) applications, the oblique incident angle always influences the captured power of the moving receiver. To mitigate this issue, a near-zero index metasurface (ZIM) is designed and investigated, the results prove that it can correct the wave vector direction for a wide range of the incident angle, and guarantee all outgoing waves propagate at the same angle (perpendicular to the receiver). Therefore, the harvested power at the receiving terminal can be enhanced in the MPT system. A system-level result indicates that, after loading a designed ZIM in the MPT system, the reception efficiency (RE) increased from 51.6% (without ZIM) to 63.8% at a working frequency of 5.8 GHz. In addition, although the received power inevitably decreases when the incidence angle increases, the fabricated ZIM retains a higher RE of the system than that without it.