Broadband Energy Harvesting Using a Metamaterial Resonator Embedded With Non-Foster Impedance Circuitry

TL;DR

This paper introduces a metamaterial resonator antenna embedded with non-foster circuitry to significantly broaden its operational bandwidth, enhancing wireless power transfer efficiency for RFID and biomedical devices.

Contribution

It presents a novel integration of non-foster impedance circuitry with a metamaterial SRR antenna to overcome narrowband limitations, demonstrated through simulations and a prototype at 500 MHz.

Findings

Bandwidth increased by nearly 400 MHz

Effective frequency ratio Δf/fC improved from 0.49 to 1.65

Prototype validated with discrete components at 500 MHz

Abstract

Radio Frequency Identification (RFID) and implantable biomedical devices need efficient power and data transfer with very low profile antennas. We propose a low profile electrically small antenna for near-field wireless power and data telemetry employing a metamaterial Split Ring Resonator (SRR) antenna. SRRs can be designed for operation over wide frequencies from RF to visible. However, they are inherently narrowband making them sensitive to component mismatch with respect to external transmit antenna. Here we propose an embedding of a non-foster impedance circuitry into the metamaterial SRR structure that imparts conjugate negative complex impedance to this resonator antenna thereby increasing the effective bandwidth and thus overcoming the fundamental limit for efficient signal coupling. We demonstrate the concept through extensive numerical simulations and a prototype system at the board level using discrete off-the-shelf components and printed circuit SRR antenna at 500 MHz. We show that the power transfer between SRR receive antenna and the external transmit loop antenna is broadened by almost 400 MHz which corresponds to increase in {\Delta}f/fC from 0.49 to 1.65, before and after non-foster circuit activation.