Efficient Radio Frequency Energy Harvesting Research Articles

Charging and Wake-Up of IoT Devices using Harvested RF Energy with Near-Zero Power Consumption

Sixth generation (6G) wireless systems are envisioned to support ubiquitous connection of a massive number of battery-powered Internet-of-Things (IoT) devices. Radio frequency (RF) energy harvesting and wake-up radio have been extensively considered as standalone technologies to extend the battery lifetime of IoT devices. In this article, we present a general framework for designing efficient combined RF energy harvesting and wake-up circuits to further reduce the energy consumption of IoT devices and allow them to operate nearly self-sustainably. Specifically, we propose two address detector designs: a dual-power-mode pulse width detector (PWD) and a multi-power-mode pulse width modulation (PWM) detector that can be integrated in combined architectures with a single shared antenna and rectifier. Furthermore, we validate the practicality of the presented framework by testing sample designs under real operational conditions. Finally, we conclude the article by introducing future research directions for realizing large IoT networks with combined RF energy harvesting and wake-up radio.

Concomitance of radio frequency energy harvesting and wearable devices: A review of rectenna designs

Passing through the transformation of wood to coal then to oil and gas, we find ourselves fortunate to witness the next major transformation, which will lead us to the “New Energy Era.” Due to advancements in the field of electronics, energy harvesting has attracted great attraction from researchers and scientists to enhance portability and reliability with reduction in battery wastes. Moreover, wearable electronic devices are also becoming quite popular these days because of their usage in a broad range of applications like sports, health sciences, emergency, and so forth. In order to make sure smooth operation and to increase the working time span of these devices, it has become really important to bring wearable devices and radio frequency (RF) energy harvesting to the same platform. RF energy harvesting is one of the best suitable technology for wearable devices. The abundance of RF energy in surroundings and the ability of RF signal to penetrate buildings play an important role to empower wearable devices. One of the major challenges is to improve power conversion efficiency of wearable rectenna for energy harvesting due to requirements of less efficient bio-compatible materials for such antennas with conformability issues. This article mainly aims to present different wearable rectenna design techniques, reported over the years. It also presents a tabular comparison of rectenna performance in terms of power conversion efficiency and gains for diverse frequency bands, substrate materials, and conducting materials. In addition, this article also includes the challenges and obstacles in designing an efficient RF energy harvesting rectenna for wearable devices.

Design of a compact and efficient 2.4 GHz rectenna system for energy harvesting

his communication presents a coplanar waveguide fed rectenna system implemented for efficient Radio frequency energy harvesting at 2.4 GHz Bluetooth/WLAN applications engrossing an overall dimension of 40 × 35 mm2. The antenna is designed on a rectangular patch having four slots etched on the radiator. Also, the ground is introduced with edge slots that are close to the feed line to improve the overall impedance bandwidth providing a gain of 4.12dBi. The E-plane corresponding to the radiation showcases dipole characteristics while the H-plane follows an omnidirectional pattern. The rectifying part comprises a hybrid Tripler circuit which is well matched with the L-shaped input impedance such that most of the received power could be deliberated. The results have demonstrated that the designed rectenna exhibits high conversion efficiency of 66.7% and output DC voltage of 3.47 V for load values of 3 kΩ at 2.4 GHz under the input power of 5 dBm.

A Novel RF Energy Harvester for Event-Based Environmental Monitoring in Wireless Sensor Networks

Perpetual energy source is the major research issue in the research community for energy-constrained wireless sensor network (WSN) and IoT applications. Radio-frequency (RF) energy harvesting has become a technology available round the clock due to increased communication activities. However, efficient RF energy harvesting for low-power regions [ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$PRF \leq (0 {\mathrm{ dBm}})$ </tex-math></inline-formula> ] is still a challenge. This article proposes a novel RF energy harvesting technique along with an intelligent dynamic energy flow control algorithm. The algorithm works with dedicated energy flow control hardware. It is also able to provide perpetual life time to the ultralow power sensor nodes. A close approximation of the size of the RF energy harvester array is proposed for the perpetual lifetime of the WSN node deployed with wake-up radio for event-based monitoring applications. The model is verified by mathematical analysis, simulation, and fabricated prototype results for the operability in the given system. It is found that the circuit provides improved dc output voltage over the previous benchmark at low power in the range of −20 to 0 dBm. The system can charge a 2.7 V, 350 F supercapacitor with the rate <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.16~\mu \text{V}$ </tex-math></inline-formula> /s at 0 dBm, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.125~\mu \text{V}$ </tex-math></inline-formula> /s at −6 dBm, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.08~\mu \text{V}$ </tex-math></inline-formula> /s at −20 dBm. To prove the utility of the proposed idea, an RF field survey is also conducted and found that the proposed circuit can harvest energy from high power region (≥ −6 dBm) for LTE850 and LTE 900 bands.

An Efficient RF Energy Harvesting System for low power applications

Next generations energy sources of Radio frequency [3MHz-300GHz] are the (QoS).The QoS is going to presents a on the progress of RF energy harvesting techniques. RF based wireless charging methodology are presenting the key to overcome the current issues in harvesting system Radio wave creates the radio frequency (RF) which is one of the sources of energy. The combination of electric and magnetic fields moving together in space forms the electromagnetic energy. The region in which these waves are found is called an electromagnetic field. In this modern electronic era radio waves can be used for many applications in according to the user requirements. Electromagnetic energy can travel through wireless medium so it can be used in a wide range of wireless applications.

Design and performance analysis of broadband rectenna for an efficient RF energy harvesting application

This article proposes the design of coplanar waveguide (CPW) fed broadband rectenna for radio frequency (RF) energy harvesting application. The rectenna is designed to operate in the industrial, scientific, and medical (ISM) frequency band of 5.8 GHz. For designing the proposed rectenna, polytetrafluoroethylene (PTFE) dielectric material was used to design, fabricate the CPW fed slot antenna. It was observed that the proposed antenna exhibits the |S11| of −23.43 dB and achieves the peak antenna gain of 8.56 dBi at 5.8 GHz. Secondly, the CPW fed rectifier circuit which comprises of the matching circuit, rectifying unit, and filter was designed. The measured results showed that the |S11| of −19 dB and it was perfectly matched with 50 Ω impedance. Finally, the rectenna was designed by integration of antenna with rectifier circuit. The simulated results showed the maximum RF to direct current (DC) conversion efficiency and the output DC voltage of 88% and 445 mV at the load resistance of 1 kΩ. The measured results show the maximum RF to DC conversion efficiency of 73.4% with the output DC voltage of 540 mV at the load resistance of 1 kΩ.

Frequency changing technique for efficient fast start-up RF energy harvesting

PurposeThe purpose of the paper is to present a frequency-changing technique to realize a fast start-up radio frequency (RF) energy harvester.Design/methodology/ApproachFirst, a simple analysis of the input impedance of the rectifier circuit is presented, and based on the analysis, it is shown how the input impedance of the rectifier is changed during the rectifier charging. Then, the frequency-changing technique is presented in which the variation of the rectifier input reactance (capacitance) is partly compensated by changing the frequency of the transmitted RF signal. A harvester consisting of a four-stage rectifier and a simple series matching inductor, implemented based on Schottky diode, is employed to verify the technique.FindingsWith the input available power of −12 dBm, the simulated and the measured results prove that the proposed frequency-changing method compared to the typical fixed-frequency method shows more than 30 per cent decrease in the transient time to reach 0.5 V output voltage, while the final harvested output voltage is unchanged.Originality/ValueA frequency-changing technique is presented.

Tri-Stepped Rectangular Antenna for Efficient RF Energy Harvesting

Although the worldwide demand for energy is increasing rapidly, the availability of current traditional resources (such as atomic and thermal power) is insufficient. Hence, artificial (man-made) energy sources are required. Advancements in wireless technology have raised the radio frequency (RF) levels in the environment. These RF waves are available at all times, unlike natural resources such as solar, hydro, and wind energy. The energy requirement and consumption of electronic devices have also been reduced over last decade. Hence, harvesting energy from RF waves and driving low-power devices are the simplest solutions. In the current work, a simplified monopole antenna, called a tri-stepped rectangular antenna for RF harvesting, is proposed. Here, the regular rectangular structure is modified to a step-like structure to achieve impedance matching and maximize the omni-directional gain at all mobile frequencies. This antenna functions with the LTE B5 (850), GSM 900, GSM 1800, 3G, 4G, and ISM (2.4 GHz) systems. We have also demonstrated a proof-of-concept of energy harvesting using RF waves generated by mobile towers and Wi-Fi devices. The system can generate up to 12 mV (14.4 mW) and could charge a battery of rating 3.7 V, 500 mAh. We anticipate this harvested energy to be used in driving the WSN node, Bluetooth devices, and mobile charging.

Current Developments of RF Energy Harvesting System for Wireless Sensor Networks

Energy harvesting or energy scavenging is basically a conversion process of the ambient energy into the electrical energy. The ambient energy exists around us in many different forms including thermal, chemical, electrical and radio frequency (RF). This technique significantly reduces the costs of replacing batteries periodically. Hence, energy harvesting offers various environmental friendly alternative energy sources, which include the vibration, electromagnetic wave, wind energy and solar power. This study will focus on RF energy harvesting that involves the generating of a small amount of the electrical power to drive circuits in wireless communication electronics devices. Recently, wireless sensor network (WSN) has been a crucial part of our daily life. The importance of WSN can be described by the use of sensors in many devices for home security including light sensors, room thermostat and alarm systems. This paper presents an overview and the progress achieved in RF energy harvesting, which involves the integration of antenna with rectifying circuit. Different combinations of antenna and rectifier topologies yield diverse results. Therefore, this study is expected to give an indication on the appropriate techniques to develop an efficient RF energy harvesting system.