Compact Planar Integrated Rectenna for Batteryless IoT Applications

Alexandru Takacs (1) , Abderrahim Okba (1) , Hervé Aubert (1)

1 LAAS-MINC - Équipe MIcro et Nanosystèmes pour les Communications sans fil

This paper addresses a new topology of compact rectennas in which the rectifier is integrated directly on the radiating surface. The rectenna is designed for wireless power transmission or microwave energy harvesting application in ISM 900 MHz band and exhibits a very good measured conversion efficiency (>25%) on a non-optimal load (10kΩ) for very low microwave power densities (>0.18 µW/cm 2). The measured DC voltage (>330 mV for microwave power density of at least 0.22 µW/cm 2) obtained from this planar rectenna is in the range of the cold turn-on/start-up voltage of modern commercial off-the-shelf DC-to-DC boost converters and power management units. The proposed rectenna is also very compact: its physical surface (10.5 x 6 cm 2) is only 5% of the square wavelength at the operating frequency (860 MHz). Keywords-wireless power transmission, microwave energy harvesting, rectenna, internet of things. I. INTRODUCTION The rise of the Internet of Things (IoT) applications faces to a new challenge: how to power efficiently an enormous number of wireless sensors, intelligent tags, and devices? Nowadays, the use of a battery is almost a standard but, the topic of the self-powered/batteryless devices excites from longtime the scientific community and becomes recently an industrial reality for emerging innovative start-up and companies [1][2]. One solution to implement self-powered and/or batteryless devices is to use a wireless power transmission approach: an intentionally microwave transmitter (energy shower) will energize at distance a rectenna module (rectifier + antenna). The energy shower should operate in the ISM bands and is then subject to regulations. ISM 868/915 MHz band provides a good trade-off in terms of free-space losses (fixing the maximum operating range of such a system) and wavelength (fixing the size of receiving antenna of the rectenna module). Many rectenna designs operating in the ISM 868/915 MHz band were proposed in the past with a focus mainly on the measured intrinsic performances (e.g., efficiency, harvested DC power, etc.) [3]-[5]. From an industrial point of view, a successful rectenna design for IoT applications should be compact, low-profile and low-cost. The size of the rectenna module is determined mainly by the receiving antenna. Electronic devices should be also integrated with the antenna, e.g., the rectifier including its matching circuit, the Power Management Unit (PMU), the energy

Domaines: Electromagnétisme

Alexandru Takacs, Abderrahim Okba, Hervé Aubert. Compact Planar Integrated Rectenna for Batteryless IoT Applications. European Microwave Week (EuMW), Sep 2018, Madrid, Spain. ⟨hal-02066082⟩