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Indoor WiFi Energy Harvester with Multiple Antenna for Low-power Wireless Applications
Abstract
This research proposed a WiFi energy harvester for low-power wireless applications. The proposed system harvests energy using three antennas to cover three ISM (Industrial, Scientific, and Medical) channels with central frequencies at 2.412 GHz, 2.439 GHz, and 2.462 GHz. For each channel, a co-planar waveguide antenna is designed to harvest energy from indoor WiFi transmitters. FR4 substrate with relative permittivity of 4.3 and loss tangent of 0.025 is used to form the antennas. The output from each harvester antenna is then connected to a seven-stage multiplier circuit. The multiplier circuit is to rectify and boost the harvested energy to a higher voltage level and then stored temporarily in a super capacitor. A dc-dc boost-charger circuit with battery management is used to increase the output voltage level to 2 V. An experiment with the proposed system has been conducted using transmitted energy from available WiFi transmitters. The power density at the harvesting antenna front is between -80 dBm and -50 dBm. The proposed harvester system takes about 6 to 7 hours to charge up the first stage super capacitor up to the minimal threshold voltage (0.45V). This minimal threshold will start the boost-charger circuit charging the secondary storage device. This research demonstrates that the proposed system can supply energy for low-power wireless sensors that operate with an input power less than 1 mW.
... Another interesting use case of Wi-Fi is in energy harvesting; compared to RFID or BLE, where the energy harvesting is received, Wi-Fi could act as a transmitter for RF energy harvesting, which could power an ultra-low-power sensor in an indoor environment. There has been research on Wi-Fi energy harvesting [54]; however, the issue is the efficiency of energy harvesting with multiple antennas having an efficiency below 20% and a maximum output of 2V at 1mA output. Another area of research is hybrid Wi-Fi systems; this could be with another LAN protocol such as LIFI [55] or a PAN protocol [56] such as Bluetooth. ...
... The current trend of improvements to hardware power consumption optimization might lead to the development of more software-based power consumption techniques. The development of batteryless and hybrid systems that rely on external power sources are currently being researched as seeming viable to be included in embedded systems [54]. Wi-Fi energy harvesting is an example where direct inclusion into low-power applications that are currently in use, such as TV remotes, clocks, and smoke alarms, will lead to the inclusion of hybrid technology. ...
Wireless short-range communication has become widespread in the modern era, partly due to the advancement of the Internet of Things (IoT) and smart technology. This technology is now utilized in various sectors, including lighting, medical, and industrial applications. This article aims to examine the historical, present, and forthcoming advancements in wireless short-range communication. Additionally, the review will analyze the modifications made to communication protocols, such as Bluetooth, RFID and NFC, in order to better accommodate modern applications. Batteryless technology, particularly batteryless NFC, is an emerging development in short-range wireless communication that combines power and data transmission into a single carrier. This modification will significantly influence the trajectory of short-range communication and its applications. The foundation of most low-power, short-range communication applications relies on an ultra-low-power microcontroller. Therefore, this study will encompass an analysis of ultra-low-power microcontrollers and an investigation into the potential limitations they might encounter in the future. In addition to offering a thorough examination of current Wireless short-range communication, this article will also attempt to forecast future patterns and identify possible obstacles that future research may address.
... In this design, the system efficiency increases by 18.6% at −50 dBm. The advantage of this approach is that it can increase system efficiency by not requiring the receiver antenna to be 100% energized from the transmitted antenna [28]. This means integrating antennas in one structure with rectifier circuits, which reduce cable losses. ...
... Square structure with a hybrid rectenna [36,37] techniques were applied to increase the gain of the receiver. The second part is to design the RF conversion circuit utilizing a full-wave rectifier circuit [28] combined with a voltage multiplier circuit to increase the voltage. This system uses the designed rectenna to receive energy at a frequency of 2.45 GHz, which is the most widely applied frequency in wireless communication in Thailand. ...
In this paper, the design of a resonator rectenna, based on metamaterials and capable of harvesting radio-frequency energy at 2.45 GHz to power any low-power devices, is presented. The proposed design uses a simple and inexpensive circuit consisting of a microstrip patch antenna with a mushroom-like electromagnetic band gap (EBG), partially reflective surface (PRS) structure, rectifier circuit, voltagemultiplier circuit, and 2.45GHz Wi-Fi module. The mushroom-like EBG sheet was fabricated on an FR4 substrate surrounding the conventional patch antenna to suppress surface waves so as to enhance the antenna performance. Furthermore, the antenna performance was improved more by utilizing the slotted I-shaped structure as a superstrate called a PRS surface. The enhancement occurred via the reflection of the transmitted power. The proposed rectenna achieved amaximumdirective gain of 11.62 dBi covering the industrial, scientific, and medical radio band of 2.40.2.48GHz.AWi-Fi 4231 access point transmitted signals in the 2.45GHz band. The rectenna, located 45. anticlockwise relative to the access point, could achieve a maximum power of 0.53 μW. In this study, the rectenna was fully characterized and charged to low-power devices.
... As can be seen from Fig. 2, GSM 900/1800 bands have high RF power densities. While other RF sources like AM radio stations [12,14] and UHF RFID [48,49] are promising sources they are still very limited. ...
... Alneyadi [49], in 2014 constructed a voltage quadruple Greinacher rectifier with a peak efficiency of 57,8% at 8 dBm input power from a 2.42 GHz WLAN -band for trickle charging of capacitors and powering of wireless sensors. In the same year Kadir [48] and Kellog [24] came up with systems for low power wireless applications. Kellog demonstrated the first ever communication between RF powered devices and off-shelf Wi-Fi devices. ...
This radio frequency (RF) energy harvesting is an emerging technology and research area that promises to produce energy to run low-power wireless devices. The great interest that has recently been paid to RF harvesting is predominantly driven by the great progress in both wireless communication systems and broadcasting technologies that have availed a lot of freely propagating ambient RF energy. The principle aim of an RF energy harvesting system is to convert the received ambient RF energy into usable DC power. This paper presents a state of the art concise review of RF energy harvesting sources for low power applications, and also discusses open research questions and future research directions on ambient RF energy harvesting.
... This emphasis arises due to the relatively low ambient power density, necessitating highly efficient rectifiers to effectively convert available power into usable electrical energy. For instance, a three-stage Dickson rectifier proposed for RFEH operating at 915 MHz achieved a modest PCE of 25% despite efforts to boost the output voltage to 4 V [25]. Similarly, a seven-stage full-wave rectifier intended for RFEH applications at 2400 MHz exhibited a measured PCE of 18.6%, coupled with a maximum output voltage of 2 V [20]. ...
Recently, there has been an increasing fascination for employing radio frequency (RF) energy harvesting techniques to energize various low-power devices by harnessing the ambient RF energy in the surroundings. This work outlines a novel advancement in RF energy harvesting (RFEH) technology, intending to power portable gadgets with minimal operating power demands. A high-gain receiver microstrip patch antenna was designed and tested to capture ambient RF residue, operating at 2450 MHz. Similarly, a two-stage Dickson voltage booster was developed and employed with the RFEH to transform the received RF signals into useful DC voltage signals. Additionally, an LC series circuit was utilized to ensure impedance matching between the antenna and rectifier, facilitating the extraction of maximum power from the developed prototype. The findings indicate that the developed rectifier attained a peak power conversion efficiency (PCE) of 64% when operating at an input power level of 0 dBm. During experimentation, the voltage booster demonstrated its capability to rectify a minimum input AC signal of only 50 mV, yielding a corresponding 180 mV output DC signal. Moreover, the maximum power of 4.60 µW was achieved when subjected to an input AC signal of 1500 mV with a load resistance of 470 kΩ. Finally, the devised RFEH was also tested in an open environment, receiving signals from Wi-Fi modems positioned at varying distances for evaluation.
... RFEH featuring an E-shaped patch RA and a full-wave rectifier, obtained a peak harvested voltage of 2.9 V when receiving energy from a GSM-900 transmitter located 50 m away [103]. The voltage levels obtained as indicated [97][98][99][100], surpass the 2 V threshold. This holds significant potential for their use in low-voltage applications such as wireless sensors and IMDs as outlined in Table 1. ...
The power consumption of portable gadgets, implantable medical devices (IMDs) and wireless sensor nodes (WSNs) has reduced significantly with the ongoing progression in low-power electronics and the swift advancement in nano and microfabrication. Energy harvesting techniques that extract and convert ambient energy into electrical power have been favored to operate such low-power devices as an alternative to batteries. Due to the expanded availability of radio frequency (RF) energy residue in the surroundings, radio frequency energy harvesters (RFEHs) for low-power devices have garnered notable attention in recent times. This work establishes a review study of RFEHs developed for the utilization of low-power devices. From the modest single band to the complex multiband circuitry, the work reviews state of the art of required circuitry for RFEH that contains a receiving antenna, impedance matching circuit, and an AC-DC rectifier. Furthermore, the advantages and disadvantages associated with various circuit architectures are comprehensively discussed. Moreover, the reported receiving antenna, impedance matching circuit, and an AC-DC rectifier are also compared to draw conclusions towards their implementations in RFEHs for sensors and biomedical devices applications.
... Meanwhile, a Leggiero tag can work with existing RF energy harvesting technologies that harvest RF energy. Such an energy harvester can provide more than 30 W of power [32], which is the power consumption of the Leggiero tag. Other energy harvesters such as solar panels can also be considered to power the tag. ...
... Par conséquent, la récupération d'énergie concerne la bande de fréquences supérieure aux Ultra Haute Fréquences (UHF) et concerne en particulier les réseaux Wi ou cellulaires avec des fréquences aux alentours de 2,4 GHz. Plusieurs études sur la récupération d'énergie RF ont été réalisées dans des zones couvertes par un certain nombre d'ondes électromagnétiques [34], [35], [36], [37], [38]. L'un des prototypes réalisé est capable de récolter quelques microwatts pour une tension de sortie de 0,45 V. Ce prototype permet de charger un super-condensateur en 7 heures. ...
Les compteurs d’eau intelligents sont des éléments clés pour automatiser les relevés des consommations dans un réseau de distribution et pour optimiser la gestion des consommations. Letravail de cette thèse se concentre sur le développement d’un compteur d’eau intelligent quitransmet les relevés de manière autonome. L’autonomie est définie comme la capacité à transmettreautomatiquement des informations tout en maîtrisant l’aspect énergétique. En effet, lebesoin d’énergie est crucial pour un compteur d’eau communiquant afin d’alimenter l’électroniqueembarquée. Actuellement, les compteurs communicants utilisent une pile pour assurer lamesure, la mise en forme et la transmission des données. La transmission des données représentele poste de dépense énergétique le plus important. Les contributions de cette thèse comportentdeux volets pour tendre vers une optimisation des performances énergétiques des compteurstout en assurant la transmission des consommations d’eau.Dans un premier temps, le compteur d’eau a été équipé d’un récupérateur d’énergie pour rechargersa batterie afin d’améliorer sa durée de vie. Le dispositif de récupération d’énergie est capabled’extraire l’énergie électrique provenant du flux d’eau et l’énergie hydraulique provenant desvariations de pression dans la canalisation. Puis, une nouvelle stratégie de collecte de données aété proposée pour être embarquée dans le compteur. Cette stratégie de communication chercheà économiser l’énergie en réduisant les temps de traitement et de transmission. Un algorithmede compression sans perte et une gestion efficace de l’énergie ont été mis en place pour émettrele maximum de données tout en réduisant la longueur des messages.Les contributions proposées ont été validées par un prototype expérimental. Un bilan énergétiquea été réalisé pour des compteurs en conditions réelles de fonctionnement. Ces compteurs ont étéinsérés dans un réseau de distribution d’eau existant pour transmettre en continu les donnéesde consommations vers une base de données. La validité des données transmises a été vérifiée.
... The authors in the paper [18] proposed a Wi-Fi energy harvester for low-power wireless applications. The proposed system harvests energy using three antennas to cover three ISM (Industrial, Scientific, and Medical) channels with central frequencies at 2.412 GHz, 2.439 GHz, and 2.462 GHz. ...
With the increase in applications related to smart home communication, intelligent health care, environmental monitoring and the Internet of Things (IoT), the demand for low-power electronic devices has increased significantly. Usually, a replaceable battery would be selected as an energy source for these electronic devices, but it is impractical to replace batteries in some areas that may be difficult to reach or potentially dangerous. Also, batteries add to the size, and their disposal causes environmental pollution. This has raised a need for reliable, continuous, and environment-friendly sources of powering and charging these devices. Considering the ubiquitous nature of Wireless Fidelity (Wi-Fi) in terms of its accessibility, widespread availability, and high-speed data access, one of the options of harvesting energy is from Wi-Fi signals. The ability to harvest Wi-Fi energy from ambient or dedicated sources enables wireless charging of low-power devices. This paper develops the framework for a Wi-Fi Energy Harvesting system based on the 7-stage Villard rectifier voltage multiplier circuit, which was analyzed and simulated using Agilent Design Systems (ADS). The design, simulation, and performance evaluation of the circuit are described in the paper. The output of the multiplier circuit is given to the power management circuit, and final simulated output of 3.3 V / 5 V is achieved.
... Thus, Reference [17] presents the design, development, and evaluation of a rectifier circuit prototype to apply the energy collection of 2.45 GHz signals, obtaining an RF/DC conversion efficiency of 68% at −10 dBm in simulation and 33% to −5 dBm of the built prototype. Reference [18] presents the design of an RF energy harvesting system based on three harvesters using three-panel antennas to cover three channels of the 2.4 GHz WiFi band. The output of the three blocks is connected to a voltage multiplier circuit. ...
This paper shows the design process of a simplified harvesting circuit for WiFi at the 2.4 GHz frequency band based on the analysis of the environment available signals. Those signals and their power level define an antenna design to maximize captured energy and select the proper number of stages for a voltage multiplier so that an impedance matching network is no longer required. With this, it is possible to maintain the harvester architecture simple without sacrificing performance. The use of supercapacitors is preferred over batteries due to their high-power capacity, the ability to deliver high peak currents, long-life cycle size, and low cost. Hence, supercapacitor availability allows to devise a novel switching scheme that employs two units that favor energy use and speed up the recharging process. The built harvester exhibits a power conversion efficiency greater than 50% under an incident signal of 0 dBm in the rectenna. The tests are carried out in an academic environment using a multi SSID router, collecting 494 mJ without requiring special modifications in the router used as an energy source.
... Finally, it worth mentioning that WiTAG can be coupled with existing technologies for harvesting RF energy from WiFi signals. Gudan et al. [9] and Abd et al. [13] design WiFi RF harvesting systems that provides 36.6 µW and 43.8 µW of power, respectively, which are more that the energy requirement of WiTAG. Depending on the use case, WiTAG can also utilize alternative energy harvesting technologies such as indoor or outdoor solar harvesting. ...
... With the harvester an output voltage of 1.8 V was produced which is used to charge a capacitor in reasonable time. A similar study reported a Wi-Fi energy harvester [16]by using three different antennas which are then experimentally tested. The results show that harvester is capable to harvest a voltage of 0.45 V with an output power of 10 µW, similarly the maximum efficiency of 19% has been achieved. ...
... In [44] 900MHz and 1800MHz bands of Global System for Mobile Communications (GSM) were used for energy harvesting. In [45] WiFi routers is used. In [46] cellular base stations is used, and finally, in [47], [48] satellites' electromagnetic waves are used for energy harvesting. ...
Over 115 years ago Tesla invented the concept of wireless power transfer. Many industrial applications based on this technology have been developed ever since. This technology is of interest especially where the interconnecting wires are inconvenient, or even impossible. This paper provides a survey that describes the history of wireless power technology. Specifically two types of wireless power transfer, radiative and non-radiative, are studied. Additionally the formation of the first standard (Qi) and other standards are mentioned. Finally, the main challenges and future prediction of this technology are presented too.
... Similarly, an ambient RF energy harvesting sensor node requiring a minimum input power of −18dBm (15.8 µW) was operated at 10.4km from a 1MW UHF TV station, and over 200m from a cellular BS [29]. Combinations utilising multiple antennas at multiple locations and at multiple bands connected initially in series (to increase voltage and cold-start the harvester) and then in parallel to maintain efficiency have been addressed by multiple authors [9], [39]. Recently, the first battery-free camera sensors and wearable temperature sensors that are solely powered using off-the-shelf Wi-Fi chipsets at 2.4 GHz were demonstrated in [31] and [40], respectively. ...
The global move toward wireless access point (AP) densification has alluded toward the possibility of harvesting the unused ambient RF energy, especially in the 2.4-GHz unlicensed band, in order to power useful electronic devices, which collectively make up the so-called low energy Internet of Things (LE-IoT). Despite the huge market demand for free ambient energy and the research community's efforts in prototyping efficient rectifiers, there is, however, little knowledge about the available power densities in dense indoor and outdoor AP deployments. Obtaining this information is, therefore, vital for engineering the power requirements of LE-IoT devices and managing expectations for their subsequent commercialization. In this paper, we present power density measurements in a controlled indoor ultra-dense deployment corresponding to approximately one AP per square meter. We detail our methodology and hardware and offer a variety of ambient RF measurement results suggesting that Wi-Fi AP densification cannot solely power personal devices such as wearables, but at best can trickle charge them in the hopes of extending battery life, the main hurdle being the small form factor of such mobile devices. In contrast, our measurements suggest that household devices, such as smoke detectors, can be powered by ambient RF harvesting. To this end, AP densification aids in increasing the total available power density, but also in distributing a smooth blanket of available RF energy thus minimizing harvesting-holes.
... However, because the battery capacity of sensor nodes is limited, users have to replace batteries frequently, which reduces the economic competitiveness of networks. One of the key technologies to solve the battery problem in sensor nodes is the radio frequency (RF) energy harvesting, the process of capturing electromagnetic waves from the ambient environment and charging battery of sensor nodes [1].Fig. 1 shows a schematic of the RF energy harvesting system. Since the system consists of antennas and a rectifying circuit, called " rectenna " , research interests have been divided into the design of each. ...
Energy harvesting is an essential technology for future Internet of Things (IoT) networks. In this letter, the advantage of the mutual coupling effect for radio frequency (RF) energy harvesting is presented by analyzing the equivalent circuit model and conducting two half-wavelength dipole antenna array experiments. When mutual coupling exists with the spacing of antennas near half a wavelength, the total received power can be as much as 5.10 μW, 1.47 times larger than the value without mutual coupling, showing that the received power of the half-wavelength dipole antenna can be increased by exploiting mutual coupling. In addition, based on theoretical analysis, we attempt to generalize the mutual coupling effect for more than two dipole antennas. Analytical results show that the received power gain with mutual coupling can be more than 50%, compared to the uncoupled case.
... Instead of relying on dedicated wireless charger, wireless charging systems based on ambient energy harvesting have also been developed. Literature has demonstrated the development of self-recharging sensors platform harvesting environmental RF signals from TV broadcast [149]- [152], amplitude modulated (AM) radio broadcast [153], Global System for Mobile Communications (GSM) bands (900/1800) [154], [155], WiFi routers [156], [157], cellular base stations [158] and satellite [159]- [161]. ...
... Instead of relying on dedicated wireless charger, wireless charging systems based on ambient energy harvesting have also been developed. Literature has demonstrated the development of self-recharging sensors platform harvesting environmental RF signals from TV broadcast [147]- [150], amplitude modulated (AM) radio broadcast [151], Global System for Mobile Communications (GSM) bands (900/1800) [152], [153], WiFi routers [154], [155], cellular base stations [156] and satellite [157]- [159]. ...
Wireless charging is a technology of transmitting power through an air gap to electrical devices for the purpose of energy replenishment. The recent progress in wireless charging techniques and development of commercial products have provided a promising alternative way to address the energy bottleneck of conventionally portable battery-powered devices. However, the incorporation of wireless charging into the existing wireless communication systems also brings along a series of challenging issues with regard to implementation, scheduling, and power management. In this article, we present a comprehensive overview of wireless charging techniques, the developments in technical standards, and their recent advances in network applications. In particular, with regard to network applications , we review the mobile charger dispatch strategies, static charger scheduling strategies and wireless charger deployment strategies. Additionally, we discuss open issues and challenges in implementing wireless charging technologies. Finally, we envision some practical future network applications of wireless charging.
This research presents a proposed quad-band antenna design aimed at fulfilling the requirements of antenna rectifiers operatingwithin the operating range of 0.5 - 3 GHz. In order to enhance the functionality of Internet of Things (IoT) nodes in real-worldambient settings, a hybrid methodology is used that integrates power from both radio frequency (RF) and direct current (DC)sources. This strategy utilizes certain frequency bands, including GSM 900, GSM 1800, Wi-Fi 2.4 and LTE 2600 GHz bands, toprovide the desired power supply. A circularly polarized bowtie-log periodic antenna with a ring-like central framework andasymmetric slots facilitates more accurate matching in the top four frequency bands and multiband consequence, whereascircular shapes loaded within an open rectangular antenna are used in the lower frequency bands. The proposed approachfor achieving consistent rectenna output under numerous levels of input power and resistances to loads involves the use of amodified π- network with microstrip matching elements. The dc rectification efficiency is highest at 73.30% (at 0.9, 1.8, 2.1, and2.44 GHz for - 17.5 dBm input power level), and 61.8% (at 0.9, and 1.84 GHz for - 14 dBm input power level), individually for thevalue of load resistance at 6.1 kΩ. The DC output voltage that is generated in the system is 464.5 mV to 492.2 mV for indoorand ambient environments, respectively. The encouraging outcomes in both indoor and outdoor environments are great forpowering IoT devices that consume low-power.
This paper presents a fully-integrated adaptive dual-output power management system with storage capability for thermoelectric energy harvesting applications. The first output delivers the load power and is regulated at 1.6 V. This output is provided by the primary path of the system that is implemented using a 5-stage reconfigurable Dickson charge pump. In case of the presence of more available power than the load demand, a secondary path is enabled to store the excess amount of energy on a supercapacitor. This provides the second output of the system that is capable of charging up to about twice the voltage of the first output. Besides storing the excess energy, a new technique using the secondary path is proposed for regulating the first output and achieving the maximum power point tracking of the input source. The proposed system is automatically reconfigured to maximize the end-to-end efficiency with the aid of a finite state machine. The system is implemented in 180nm CMOS technology. It utilizes a total on-chip flying capacitance of 2.1 nF, and operates across an input voltage range from 0.35 V to 1 V. Measurement results show that the system achieves an end-to-end efficiency of 72% at a total output power of 1.24 mW.
Wearable sensors have been implemented widely to provide comfortable and continuous long-term monitoring in many applications. Minimal requirements on maintenance is a main characteristic of wearable sensors, but unfortunately, many of them are still powered by battery with limited capacity which need to be charged or replaced regularly. Energy harvesting technologies are applied to provide a reliable solution to this issue. This paper presents several design considerations for self-powered wearable sensors. Suitable energy sources are discussed, such as ambient energy sources (solar, RF, and ultrasonic energy), human body energy (mechanical, piezoelectric, triboelectric, electromagnetic, electrostatic, and thermal energy), and the subcutaneous energy harvesting technique for implantable sensors. Moreover, power management integrated circuits, energy storage options, and the material selection and conditioning circuit of triboelectric nanogenerator (TENG) are discussed. Five case studies utilizing different energy harvesting techniques are discussed and evaluated in terms of their system implementation and performance to provide some deeper understandings of wearable sensors.
The usage of conductive cables is always preferred as the first choice to power electrical loads. It is appropriate and efficient especially for most of the stationary loads that support our daily applications, whether in our homes or in industry. On the other hand, with the rapid evolution of technology, products are becoming smaller and portable so depending on wired connection to gain energy may not be an applied solution for many applications.
Radio frequency (RF) energy harvesting is the process by which radiative electro-magnetic waves, typically from 3 kHz to 300 GHz, are captured, converted, stored and used to operate usually low-energy consumption devices ranging from wearable electronics to sensor networks. RF signals can be primarily generated from two sources: dedicated and ambient RF sources. The former can be deployed to provide energy when predictable supply is expected, usually from license-free frequency bands of radio spectrum. The latter refer to RF transmitters originally not intended for energy transfer, such as TV towers, radio towers, and Wi-Fi routers. Until recently, most implementations of networks powered by RF energy were demonstrated through experiments and prototype setups as proof-of-principles and to show potential practical applications. Now, with the ubiquitousness of Wi-Fi and the advance in CMOS technology and supercapacitors, RF-powered devices have found various applications and are now used or offered in commercial products. The aim of this book chapter is to provide a basic understanding of RF energy harvesting (RFEH) techniques, describe the underlying electronics hardware design, show the current state-of-the-art applications and commercially available products, and finally expand to future applications and challenges ahead.
This paper presents a muli-input multi-output battery-less energy harvesting system for microscale wireless sensor nodes that combines piezoelectric and photovoltaic energy sources. The system undergoes four states of operation to achieve two voltage levels at the output of 1.2V and 3V. It is a dual path system that uses a single inductor for both boost and buck converter. A maximum power point tracking technique is introduced to lock to the maximum power voltage of the photovoltaic transducer. The system was implemented in UMC CMOS 130nm technology. It achieves an efficiency up to 74% at 10mW of harvested power.
RF energy harvesting is a novel technology which is used for harvesting energy from the ambient RF resources. In energy harvesting, harvested energy is converted into useful electrical energy to recharge battery of electronic devices. With energy harvesting scheme, there is no need to replace battery, and the device can be recharged without cable line. Although the energy harvesting technique brings the convenience for recharging the devices, the amount of harvested energy is too small to operate device without supplying energy from the wired resource. In this paper, we consider Wi-Fi signals as energy harvesting resource, where Wi-Fi nodes can harvest energy from ambient signals that are being transmitted by the other users. Not only energy harvesting but also data transmission is considered in this paper. In order to achieve simultaneous wireless information and power transfer (SWIPT) switching circuit is proposed. We
measure the received signal strength of Wi-Fi signals in the real environment, and our simulation results show harvested energy and throughput of the nodes in Wi-Fi network.
This paper is based on the experimental approaches of designing whole block of RF (Radio Frequency) energy harvester for powering low power devices. So includes worked done, results obtained, conclusions and suggestions for further improvements. This design consists of three main parts transducer, energy conditioning unit and energy storage unit. The transducer converts RF energy into electrical form which is then easier to condition and store. Three types of antennas used as transducer. Before store energy into a storage unit, conditioning subsystem rectifies and increases the voltage level up to a desired level. In reality available RF energy varies with the time. So store energy into a storage unit which is a super capacitor is done as far as harvesting. Devices such as wireless sensor nodes, calculators, remote controllers and phone chargers which consume extremely low energy during its employment are the most suitable devices to energize. Using sufficiently efficient system it is possible to energize selected low power devices using RF energy.
The present letter describes the design of an energy harvesting circuit on a one-sided directional flexible planar antenna. The circuit is composed of a flexible antenna with an impedance matching circuit, a resonant circuit, and a booster circuit for converting and boosting radio frequency power into a dc voltage. The proposed one-sided directional flexible antenna has a bottom floating metal layer that enables one-sided radiation and easy connection of the booster circuit to the metal layer. The simulated output dc voltage is 2.89 V for an input of 100 mV and a 50 Ω power source at 900 MHz, and power efficiency is 58.7% for 1.0 × 107 Ω load resistance.
We have demonstrated wireless power transfer by coupling RF power from a microwave oven magnetron RF source using a dipole at optimum position within the cavity. A 40dBm coupled power is transmitted using a monopole corner reflector antenna having gain of 14.97dBi and a half power beam width of 22 : At the receiving end a patch antenna is placed at variable distances ranging from 0.307 meters (1 foot) to 4 meters (13 feet). The measured power received varies from 25dBm to 3dBm which is in close agreement with the theoretically calculated value using Friis transmission equation. The received RF power is simulated on Multisim with a rectifier circuit and it is shown that an efficiency of 5.5% to 0.2% with respect to the transmitted power can be achieved as the distance is varied from 0.307 meters to 4 meters.
In this paper, a feasibility study of the ambient radio frequency (RF) as an energy source to be harvested and converted into electrical energy is presented. This study is to investigate the ability to harvest the ambient RF power density produced by the GSM telecommunication tower for very low power device usage. To capture the RF signal, a normal mode helical rectenna is designed and fabricated. The reason of choosing the normal mode helical antenna in this study is to solve the major problem of a microstrip patch antenna array where the overall size is very large. Experimental results showed that with-10dBm input power, a voltage of 0.3V is generated at the distance 2.5 meters. Hence, this proved that the ambient RF energy can be a suitable candidate as an energy harvesting source.
In this letter, a high efficiency RF‐DC conversion circuit for RF energy harvesting system (EHS) is proposed.The proposed circuit consists of Villard voltage doubler, the input and output termination networks which can suppress the unwanted RF signals produced by Schottky diodes. The fabricated circuit operating at 2.45 GHz has a maximum RF‐DC conversion efficiency of 83.37% and output voltage of 11.30 V at an input RF power of 140 mW. The proposed circuit has an advantage of simple design which helps to reduce the design cost of EHSs. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2330–2335, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27087
Electromagnetic wave radiation is an extremely important and has long been a telecommunications research experts. But in nature there are a lot of electromagnetic source of free that has not been used for the benefit of further. On paper was devised a system called ambient electromagnetic harvesting. The system is aimed to catch a source of free in the electromagnetic waves from the transmitter uhf (tv) to a later tillable and used as a source of alternative energy. A device that takes in these systems among others are antennæ accepter and power harvester. Antennæ accepter made is a log periodic dipole array, serves to receives electromagnetic waves and turn it into an electrical signal fire. Being power harvester serves to change an electrical signal ac of antennæ be dc and fastens it. For location near the source of transmitter sctv (tv) obtained maximum tension 1766 mv. If the measurement of being done in our free (the lab b.301) the maximum voltage is produced by 591 mv. Obtained from various experiments that closer to the station and the more stable condition of equipment, the bigger the voltage is produced. With arus produced range from 0.008 ma it is expected that this system is able to distribute battery with 600 mah specifications, 1.2 v for 21 hours.
This paper demonstrates a highly efficient radio frequency (RF) energy harvester to scavenge 2.45 GHz Wi-Fi energies from commercial available wireless routers. The measured Wi-Fi signal strength available in the normal working space is -44 to -18 dBm. In order to harvest and utilize such small signals, a complete system is designed to include a high gain antenna array, a high efficiency rectifier and a boost converter for voltage conditioning. The system can harvest a final DC power of 76.35 μW at a distance of 40 cm away from the wireless router. As the distance increases, the harvested power decreases gradually. A maximum working distance of 2.4 m is measured. The total RF to DC power conversion efficiency is measured to be from 9.76% at 2.4 m to 33.7% at 40 cm away from the router. The output DC voltage are in the range of 1.5 to 7.36 V, which is sufficient to supply various applications such as portable calculators, LED arrays and energy storage devices such as super-capacitors and batteries.
This paper presents a new type of wake-up receiver, called a clock-harvesting receiver, which extracts a 21 Hz clock embedded within the GSM standard for the wake-up of a wireless sensor network. The receiver was fabricated in 0.13 μm CMOS and harvests a 21 Hz clock from the 1900-MHz GSM band. It was designed for heavily duty-cycled operation to reduce the energy required for synchronization of a network. In active mode, the receiver achieves a sensitivity of -87 dBm with 57 μs of jitter while consuming 126 μW. In sleep mode, the power consumption is 81 pW. Experiments conducted in the lab verify the functionality of the receiver with a real local GSM cellular signal.
This study is focused on equipping wireless devices (including sensors) with novel, high-efficiency circuitry to harvest and convert ambient radio frequency (RF) power to direct current (dc). Key components of this technology are (a) miniaturised antenna and (b) high-efficiency rectifying circuit. The first is responsible for capturing the RF waves, and the latter converts the RF energy to dc. A major challenge is the design of novel circuitry to generate a battery-like voltage from very low incoming RF energy. Under this study, the authors designed a novel RF power harvesting front-end whose conversion efficiency is significantly improved at low RF power levels (<;-20 dBm) as compared to existing technologies. Thus, the new circuitry can harvest ambient and widely available RF energy, making a game changing technology for powering mobile devices. In this study, the authors demonstrate this technology by using it to power a commercially available temperature and humidity meter with an LCD display. The latter is powered using nothing more than ambient WiFi signals in an office environment.
The experimental results of a micro-powered 2.45 GHz voltage multiplier with and without the charge-pump integrated circuit (IC) driving a microcontroller on FR-4 are presented. Five different rectifier designs are built and compared under different input power levels. Results show that a multi-stage voltage multiplier delivers higher voltage levels to the microcontroller without the need for the charge-pump IC. However, a single-diode design performs best when the charge-pump IC is present. The measurement results show that the energy harvesting system can provide 2 V to turn on the microcontroller with only 15.6 dBm (27.5 W) radio frequency input power and that the battery-less microcontroller can be wirelessly powered when located up to a distance of 57 cm from a transmitter supplying a total of just 100 mW of microwave power.
This letter presents a high-efficiency 2.45-GHz rectenna that can harvest low input RF power effectively. A new antenna with a simple structure and high gain of 8.6 dBi is proposed for the rectenna. The antenna is designed to directly match the rectifying circuit at 2.45 GHz and mismatch it at the second and third harmonics so that the use of bandpass filter between the antenna and rectifying circuit can be eliminated. The rectenna shows a maximum conversion efficiency of 83% with a load resistance of 1400 Ω. Furthermore, the overall conversion efficiency can remain 50% for the low, -17.2 dBm (corresponding power density 0.22 μW/cm2 ) input power level.
The main challenge for the far field energy harvesting is to overcome the losses due to the long distance between the transmitter and the harvesting location. To compensate for the path losses, antenna arrays or high gain antennas should be used at the receiving part. This paper introduces a novel broadband high gain Yagi-Uda antenna. The design is based on integrating a wide-band strip dipole into a Yagi-Uda antenna. The antenna consists of a reflector and a single director placed nearby the driven dipole. The length of the director, the distance between the feed and the director, and the distance between the feed and the reflector are investigated and optimized in order to reach the widest bandwidth possible for receiving DTV broadcasting signals (475-810 MHz). Detailed design optimization steps, return loss, antenna gain and front-to-back ratio for the new configuration are discussed. The antenna operating band reached 61.2 % in 2.0:1.0 VSWR, and consequently overcame the state of the art by an increased bandwidth of 11.2 %. The simulated results are validated by measurements.
We have developed a new battery-less bit-error-rate modulated (BERM) data transmission technology that can directly send data to a WiFi-equipped PC without affecting WiFi communication on the PC. BER modulated data at a 5.5kbps data-rate has been successfully transmitted at a 30-cm distance between a test chip and measurement equipment. The chip also has an energy harvesting function with an active ambient-radio power searching (AAPS) architecture that enhances harvest efficiency. Harvested power was 30.8μW at a 30cm-distance from a 250mW (24dBm) emission WiFi access point (AP), and the operational frequency had a very wide range, 1.9 to 2.4GHz.
A microwave power beaming system was developed to realize wireless power supply to a Micro Aerial Vehicle. This system consists of transmitting, tracking, and receiving systems. In the transmitting system, a 5.8GHz microwave beam was irradiated from an active phased array antenna. Transmitting power was 4W and the beam divergence angle was 9deg. In the tracking system, a 2.45GHz pilot signal was detected by a two-dimensional tracking antenna and the position was deduced though the software retro-directive function. The maximum tracking error was 1.97deg in the azimuth direction and 1.79deg in the traverse direction. Then, FM/AM wireless camera signal was used the pilot signal for tracking. The maximum error was 3.22deg in the traverse direction and was 4.97deg in azimuth direction that were slightly larger than those without modulation.
This paper presents a feasibility study of energy harvesting from ambient radio frequency (RF) sources. A preliminary assessment of the ambient RF energy was carried out by calculation of power spectrum density and measurement of received power in a common suburban area. The results showed that the median value of received power obtained −25dBm from 800 MHz band mobile telephone base station (BS) was averagely 13dB stronger than that from Digital TV broadcasting. A prototype multi-stage RF-DC conversion circuit was designed and tested. Experimental results showed that a 1.0 F electric double layer capacitor can be charged up to 320 mV in 3900 minutes at common suburban area. We confirm that the possibility of energy harvesting from ambient RF sources in suburban area, and clarify the problems in devices for the future energy harvesting systems.
This paper presents a rectenna (rectifier + antenna) design to harvest electrical energy for powering RFIDs from ambient electromagnetic radiation at the 2.45 GHz ISM band (WiFi, Bluetooth, RFID, etc.). The rectenna structure is formed by a miniaturize 2nd iteration Koch fractal patch antenna and two stage Dickson charge pump voltage-doubler rectifier circuit. The proposed rectenna achieves a small size with relatively high realized gain (4 dBi) and good RF to DC conversion efficiency (up to 70%). As a result, the proposed rectenna harvests enough energy from a commercial RFID interrogator 3.1 meters away (4W EIRP at 2.45 GHz ISM band) to power up a 1.6 V LED, enough voltage to enable some RFID chips.
An implantable rectenna with stacked PIFA structure has been developed for wireless power transmission for medical implants in 402-405 MHz (MICS Band). The antenna has dimension of 450 mm<sup>3</sup> measured operating frequency of 402 MHz with broad bandwidth of 50 MHz at return loss -10 dB. Experimental prototype of the compact stacked rectenna was fabricated on Roger 3210 substrate. The rectenna has a conversion efficiency of 80% is achieved when 2dBm microwave power is received at 402 MHz with 20K- Omega load.
RF energy harvesting holds a promise able future for generating a small amount of electrical power to drive partial circuits in wirelessly communicating electronics devices. This paper presents the overview and progress achieved in RF energy harvesting field. A modified form of existing CMOS based voltage doubler circuit is presented to achieve 160% increase in output power over traditional circuits at 0 dBm input power. A schottky diode based RF energy harvesting circuit performance is also studied with practical and simulations results.
In this paper, the suitability of using a printed circuit board (PCB) microstrip patch receiving antenna for a novel application - RF energy harvesting to power a wireless soil sensor network deployed in an outdoor environment - is investigated. The performance of a conventional circular microstrip patch antenna using different microwave laminate substrates is evaluated in terms of return loss, radiation efficiency, and gain. Based on a chosen PCB material as the antenna substrate, an enhanced gain circular patch with a ring shaped parasitic radiator is presented. Simulations have been carried out using CST microwave studio to examine the antenna's performance both in free air and in the presence of different soil conditions.
Antennas and Wireless Propagation Letters
- G Monti
- L Tarricone
- M Spartano
G. Monti, L. Tarricone, and M. Spartano, "X-Band
Planar Rectenna," Antennas and Wireless Propagation
Letters, IEEE, vol. 10, pp. 1116-1119, 2011.
Wireless power harvesting with planar rectennas for 2.45 GHz RFIDs
- U Olgun
- C Chi-Chih
- J L Volakis
U. Olgun, C. Chi-Chih, and J. L. Volakis, "Wireless
power harvesting with planar rectennas for 2.45 GHz
RFIDs," in Electromagnetic Theory (EMTS), 2010 URSI
International Symposium on, 2010, pp. 329-331.