LoRaWAN Battery-Free Wireless Sensors Network Designed for Structural Health Monitoring in the Construction Domain.

This paper addresses the practical implementation of a wireless sensors network designed to actualize cyber-physical systems that are dedicated to structural health monitoring applications in the construction domain. This network consists of a mesh grid composed of LoRaWAN battery-free wireless sensing nodes that collect physical data and communicating nodes that interface the sensing nodes with the digital world through the Internet. Two prototypes of sensing nodes were manufactured and are powered wirelessly by using a far-field wireless power transmission technique and only one dedicated RF energy source operating in the ISM 868 MHz frequency band. These sensing nodes can simultaneously perform temperature and relative humidity measurements and can transmit the measured data wirelessly over long-range distances by using the LoRa technology and the LoRaWAN protocol. Experimental results for a simplified network confirm that the periodicity of the measurements and data transmission of the sensing nodes can be controlled by the dedicated RF source (embedded in or just controlled by the associated communicating node), by tuning the radiated power density of the RF waves, and without any modification of the software or the hardware implemented in the sensing nodes

Transmission d'énergie sans fil et collecte/récupération d'énergie RF

National audienceA synthesis of research and research support work will be presented with a special focus on the theme and results concerning wireless energy transfer and RF energy recovery/collection for various applications including connected objects, wireless and energy autonomous sensor networks.Une synthèse de travaux de recherche et d'encadrement recherche sera présentée avec un focus spécial sur la thématique et les résultats concernant le transfert d'énergie sans fil et la récupération/la collecte d'énergie RF pour des applications diverses incluant les objets connectés, les réseaux de capteurs sans fils et autonomes en énergie

Contribution à la conception de circuits passifs à faibles pertes d'insertion en ondes millimétriques

Ce travail présente notre contribution à la conception de circuits passifs à faibles pertes en ondes millimétriques en utilisant un substrat à membrane de silicium. Premièrement nous proposons une topologie originale à iris résonants pour des filtres diplexeurs à très faibles pertes utilisables dans les télécommunications spatiales. Nous proposons également deux méthodes d'optimisation (par approximation successive et une méthode évolutive basée sur les algorithmes génétiques) pour ces filtres. Puis en utilisant une structure combinant deux transitions progressives (guide rectangulaire-guide nervuré et microruban-coplanaire) avec une discontinuité microruban-coplanaire nous concevons une transition guide d'onde - ligne coplanaire à la fois large bande et faibles pertes. Enfin la conception d'un répartiteur de puissance pour un réseau d'antenne montre la faisabilité de la réalisation intégrée d'un élément rayonnant très compact à polarisation circulaire.TOULOUSE-ENSEEIHT (315552331) / SudocSudocFranceF

Energy efficient wireless sensors networks

International audienc

Implementation of a Wireless Sensor Network Designed to Be Embedded in Reinforced Concrete

International audienceThis paper presents the McBIM project (Material communicating with the Building Information Modelling) which aspires to provide a communicating reinforced concretes, thus, addresses the design and an implementation of a wireless sensor network devoted to be embedded in reinforced concrete in order to assure structural health monitoring tasks during its entire lifetime. This wireless sensor network is composed of communicating nodes-collecting, processing and sharing with other communicating materials and with virtual models the generated data, and wirelessly powering and controlling the sensing nodes-and sensing nodes-measuring their internal or environmental parameters, pre-processing and transmitting these to the communicating nodes-. The sensing nodes are battery-free and wirelessly powered by a far-field (radiative) wireless power transmission system. Experiments in the air and from a reinforced concrete beam provide encouraging results

900 MHz Miniaturized Rectenna

International audienceThis paper addresses the design and the characterization of a new topology of compact rectenna used for electromagnetic energy harvesting of low incident electromagnetic power densities. The rectenna uses a broadband miniaturized flat dipole antenna with a single diode rectifier. The experimental results demonstrate that the efficiency of the proposed compact rectenna is up to 38% at 900MHz for electromagnetic power density of 0.26µW/cm²

Compact Planar Integrated Rectenna for Batteryless IoT Applications

International audienceThis 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 energ

Ultra-compact Ku band rectenna

International audienceThis paper addresses an innovative and ultra-compact rectenna designed for energy harvesting or wireless power transfer applications. The presented rectenna uses a printed cross dipoles antenna array and a rectifier implemented with only one silicon Schottky diode. Experimental results show that 1.15 mW of DC power can be obtained for an optimal load impedance of 500 Ω using a compact rectenna (2.5 cm 2 or 0.6 square wavelength) illuminated by an electric field of 60 V/m at 14.7 GHz

Compact Flat Dipole Rectenna for IoT Applications

International audienceA new compact topology of rectenna, which combines a miniaturized wideband printed antenna and a rectifier integrated on the radiating surface, is reported in this paper. The rectenna is designed for ISM 900 MHz band and applied to wireless power transmission and energy harvesting to supply Ultra-Wideband tags for 3D indoor localization. The rectenna allows activating a DC-DC boost converter that supplies power to the tags. It exhibits a minimum conversion efficiency of 25% for very low microwave power densities (> 0.18 µW/cm 2) on the non-optimal loading impedance (of about 10 kΩ) of a commercial DC-to-DC boost converter and power management unit. The harvested DC voltage obtained from this novel rectenna exceeds 330 mV for microwave power density of 0.22 µW/cm 2. This measured DC voltage is in the range of the cold turn-on/start-up voltage of nowadays commercial off-the-shelf DC-to-DC boost converters and power management units. The proposed rectenna is also very compact, as its surface (11 × 6 cm 2) is of 0.05λ 2 at the operating frequency (860 MHz)

Compact Rectennas for Ultra-Low-Power Wireless Transmission Applications

International audienceThis paper addresses the design and characterization of compact rectennas for wireless power transmission application in the industrial, scientific, and medical 868-MHz/915-MHz band. These rectennas are designed for supplying power to a dc-to-dc boost converter. The proposed low-profile rectenna exhibits a good tradeoff between compactness (0.06λ² at 900 MHz) and RF-to-dc conversion efficiency, which is higher than 25% for RF power densities of at least 0.25 μW/cm² and 37% for 2.1 μW/cm². It is shown that this rectenna can activate the standard Bq25504 dc-to-dc boost converter for an RF power density higher than 0.6 μW/cm². Moreover, through using a storage capacitor of 220 μF, a light emitting diode (LED) can be turned on for a duration of 60 ms with power consumption of 9.45 mW and a dc voltage of 3 V. The LED allows emulating the dc consumption of the QN908x ultra-lower-power Bluetooth 5 module which operates in the transmission mode with -4 dBm of output power