Omnidirectional dual-polarized low-profile textile rectenna with over 50% efficiency for sub-μW/cm2 wearable power harvesting

Abstract

Despite the recent advances in textile antennas, in complete systems such as a rectenna, the efficiency of fully-textile solutions has been over 46% lower than hybrid textile/rigid implementations. This paper presents a fully-textile rectenna for ultra-low power sub-W/cm^2 applications. A dual-polarized omnidirectional low-profile textile antenna is presented. The rectenna is based on a compact inductively-matched rectifier. The textile-based rectifier occupies 0.22 cm^2 and achieves a state-of-art Power Conversion Efficiency (PCE) of 41.8% at -20 dBm, at 820 MHz, despite its lossy substrate. A triple-band rectifier is then designed and fabricated to show the scalability of the matching approach. The rectifier is characterized using a new figure of merit “average PCE” over a time period while charging a capacitor. Time-varying s-parameters are used to quantify the impact of the capacitor’s charge on the impedance matching. The rectifier directly charges a 1.32 mF capacitor up to 1 V in 0.41 and 4.5 seconds from 10 and 0 dBm, respectively. Wireless testing of the proposed rectenna demonstrates over 50% and 40% PCE below 1 μW/cm2 in space and on-body, respectively. The rectenna efficiently receives power from mismatched polarization and with a 360-degree half-power beamwidth.

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Identifiers

ORCID for Mahmoud Wagih: orcid.org/0000-0002-7806-4333

ORCID for Alex S. Weddell: orcid.org/0000-0002-6763-5460

ORCID for Steve Beeby: orcid.org/0000-0002-0800-1759

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