RF Energy Harvesting System Research Articles

Enhanced RF Energy Harvesting System Utilizing Piezoelectric Transformer

RF energy harvesting converts ambient signals into electrical power, providing a sustainable energy source. This study demonstrates the use of a piezoelectric transformer for efficient RF energy harvesting. In this work, a piezoelectric transformer (PT) is employed as a high-gain, efficient inverting amplifier to enhance RF wireless energy harvesting. The PT, composed of lead zirconate titanate (PZT), is placed after the receiving loop antenna, with its output connected to an AC-to-DC converter circuit. Maximum harvested power was observed at the PT’s resonance frequency of 50 kHz, with an optimal load of 40 kΩ. The system, comprising the antenna, transformer, and rectifier circuit, continues to resonate at 50 kHz, as confirmed by input impedance measurements, demonstrating stable and effective performance. The overall system efficiency was characterized to be 88%.

High-efficiency quad-band RF energy harvesting system with improved cross-coupled differential-drive rectifier

Abstract RF energy harvesting technology has garnered significant attention from researchers in recent years. This paper presents a high-efficiency quad-band RF energy harvesting (RFEH) system. It introduces an improved cross-coupled differential-drive rectifier designed for ambient wireless powering, capable of harnessing power from four distinct ambient RF sources: FM-100, DTV-600, GSM-1800, and WiFi-2400 frequency bands. The proposed RFEH system demonstrates notable advancements, achieving a high RF to DC conversion efficiency of over 80 % within an input power range of −5 dB m to +13 dB m, with a 5 kΩ resistance load. This power output is deemed sufficient for energizing low-power micro-devices autonomously, without reliance on external power sources. Notably, the DC output voltage of the proposed RFEH system exhibits a high level of stability against variations in input power, a characteristic not adequately addressed in existing systems.

Advancements and Challenges in Antenna Design and Rectifying Circuits for Radio Frequency Energy Harvesting.

The proliferation of smart devices increases the demand for energy-efficient, battery-free technologies essential for sustaining IoT devices in Industry 4.0 and 5G networks, which require zero maintenance and sustainable operation. Integrating radio frequency (RF) energy harvesting with IoT and 5G technologies enables real-time data acquisition, reduces maintenance costs, and enhances productivity, supporting a carbon-free future. This survey reviews the challenges and advancements in RF energy harvesting, focusing on far-field wireless power transfer and powering low-energy devices. It examines miniaturization, circular polarization, fabrication challenges, and efficiency using the metamaterial-inspired antenna, concentrating on improving diode nonlinearity design. This study analyzes key components such as rectifiers, impedance matching networks, and antennas, and evaluates their applications in biomedical and IoT devices. The review concludes with future directions to increase bandwidth, improve power conversion efficiency, and optimize RF energy harvesting system designs.

An automatic matching high-sensitivity RF energy harvesting system with tuning power consumption of 2.4nW

An automatic matching high-sensitivity RF energy harvesting system with tuning power consumption of 2.4nW

Efficient rectifier with wide input power range for 5G applications

This article presents three efficient rectifiers for radio frequency energy harvest-ing (RFEH) systems operating at the fifth generation (5G) band (3.5 GHz). Eachrectifier operates at various input power levels (high, low, and across a widepower range). The high and low-power rectifiers feature a single serial topologyusing HSMS-2860 and SMS-7630 Schottky diodes, respectively, along with mi-crostrip lines to implement the input and output filters and the impedance match-ing network. At an radio frequency (RF) power level of 15 dBm, the high-powerrectifier harvests 67.4% to direct current (DC) power with a 300Ωload resistorand an output voltage of 2.5V. The low-power rectifier achieves its maximumpower conversion efficiency (PCE) at -2 dBm, reaching 45% efficiency with a1200Ωload. The rectifier with a extended input power range comprises twobranches of subrectifiers functioning at both high and low power levels. De-pending on the power level, the considered subrectifier harvests radio frequencypower into DC power, while the other subrectifier is deactivated. Across a powerspan of 32.5 dB (ranging from -13 to 19.5 dBm), the rectifier maintains an effi-ciency above 30%. The proposed rectifiers are efficient and suitable for imple-mentation in 5G-enabled RFEH systems.

Highly Sensitive RF Energy Harvesting System for Wireless Protocol in IoT Devices

Highly Sensitive RF Energy Harvesting System for Wireless Protocol in IoT Devices

Novel two-dimensional radio frequency energy harvesting system: Design and implementation

Novel two-dimensional radio frequency energy harvesting system: Design and implementation

Development of 2400-2450 MHz Frequency Band RF Energy Harvesting System for Low-Power Device Operation.

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.

Design of High-Efficiency Microwatt RF Energy Harvesting System

Design of High-Efficiency Microwatt RF Energy Harvesting System

Energy Harvesting Fractal Antenna for Charging Low Power Devices

Radio frequency energy harvesting (RFEH) is a prospective technique that uses electromagnetic waves which waste in the air to create energy. This cutting-edge technology offers the ability to wirelessly charge battery-free gadgets, making it a potential alternative energy source for use in the future. Fractal antenna systems are a type of antenna that is characterized by their self-similarity and ability to operate over a wide range of frequencies. The proposed design combined two popular fractal shapes in one design. This one design combines the advantages of the other two designs. This research presents a novel multi-band fractal slot antenna design and optimization method for RFEH systems. The fractal antenna designs that were simulated using the CAD design suite, as well as the final design and performance that captured multiple bands are described. The rectifying and matching networks are next evaluated, and the ADS (Advanced Construct System) software is used to construct and simulate each circuit. Additionally, the voltage regulator, energy storage, and application are addressed along with the required voltage to completely function a wireless sensor node, which may be utilized in many applications including wearable technology and intelligent traffic systems (ITS) that control roads to improve environmental quality. Finally, experimental results demonstrated good agreement with simulations that had a high radiation efficiency and gain.

Design and investigation of small-scale long-distance RF energy harvesting system for wireless charging using CNN, LSTM, and reinforcement learning

Introduction: The energy supply challenge in wireless charging applications is currently a significant research problem. To address this issue, this study introduces a novel small-scale long-distance radio frequency (RF) energy harvesting system that utilizes a hybrid model incorporating CNN, LSTM, and reinforcement learning. This research aims to improve RF energy harvesting and wireless charging efficiency.Method: The methodology of this study involves data collection, data processing, model training and evaluation, and integration of reinforcement learning algorithms. Firstly, RF signal data at different distances are collected and rigorously processed to create training and testing datasets. Next, the CNN-LSTM model is trained using the prepared data, and model performance is enhanced by adjusting hyperparameters. During the evaluation phase, specialized test data is used to assess the accuracy of the model in predicting RF energy harvesting and wireless charging efficiency. Finally, reinforcement learning algorithms are integrated, and a reward function is defined to incentivize efficient wireless charging and maximize energy harvesting, allowing the system to dynamically adjust its strategy in real time.Results: Experimental validation demonstrates that the optimized CNN-LSTM model exhibits high accuracy in predicting RF energy harvesting and wireless charging efficiency. Through the integration of reinforcement learning algorithms, the system can dynamically adjust its strategy in real time, maximizing energy harvesting efficiency and charging effectiveness. These results indicate significant progress in long-distance RF energy harvesting and wireless charging with this system.Discussion: The results of this study validate the outstanding performance of the small-scale long-distance RF energy harvesting system. This system is not only applicable to current wireless charging applications but also demonstrates potential in other wireless charging domains. Particularly, it holds significant prospects in providing energy support for wearable devices, Internet of Things (IoT), and mobile devices.

Graphene-Based Materials for Energy Harvesting at Microwave Frequencies: A Comprehensive Review

Harvesting energy from microwave frequency is one of the key areas of research in the past decade to provide an alternative power source for wireless devices and sensor networks. The increase in the employment of Internet of Things (IoT) devices as well as sensors in order to support technological advancement leads to an increase in the energy demand. This in turn leads to environmental pollution due to the large amount of batteries being disposed. As such, in order to support the current demand for clean and sustainable energy that can reduce environmental pollution, various approaches to reduce the usage of conventional batteries in these systems are being researched. One of the approaches is the usage of the antenna to harvest radio frequency energy. The appearance of graphenebased material further sparked the interest of researchers due to its exciting properties. Therefore, this paper aims to provide a comprehensive review on the advancement of the usage of graphene-based material in the field of harvesting ambient radio frequency energy. Graphene material is first introduced in order to understand its characteristics and properties as a replacement for the conventional copper material. Current state-of-the-art approaches on graphene-based radio frequency energy harvesting systems were then reviewed and compared. The future prospect of graphene-based material in energy harvesting systems was also presented and discussed, shedding light on the future potential areas for research and development.

A Compact RF Energy Harvesting System With an Improved Impedance Matching Network

A Compact RF Energy Harvesting System With an Improved Impedance Matching Network

RF energy harvesting for intraoral orthodontic force monitoring

Optimal orthodontic forces need to be applied to induce appropriate biological and mechanical reactions in the periodontium, thus leading to proper tooth movements, while excessive orthodontic forces could harm the tooth roots and periodontal tissues during treatment. However, estimating orthodontic forces currently relies on clinical experience, lacking objective data and analysis; thus monitoring the in-vivo orthodontic force is essential to reducing side effects and improving orthodontic treatment. Unfortunately, in-vivo orthodontic force sensor systems are currently not available, and in-vitro ones are mostly bulky and costly. Here, we report a battery-free and wireless orthodontic force sensing system (BWS) designed for in-vivo, contactless, and real-time measurement of the orthodontic force. We developed a 915 MHz far-field RF energy harvesting system to power the intraoral BWS, and achieved an in vivo wireless measurement distance of 220 mm. This system allows in-vivo orthodontic force monitoring at anytime and anywhere, so it can be applied to improve clinical treatments and orthodontic research. Besides, in vivo experiments demonstrate that the system can harvest a voltage of 2 V even at a 350 mm distance, which highlights the device's potential to serve as a versatile platform for monitoring various oral environmental parameters through different sensors.

A 915 MHz Closed-Loop Self-Regulated RF Energy Harvesting System for Batteryless Devices

Batteryless devices are essential for hard-to-reach applications such as implantable biomedical devices.Powering such devices is a difficult task, and energy harvesting from the environment is mandatory. Among the power sources available in urban areas, RF signals stand out. However, the RF power at the receiving antenna is not constant, and energy-harvesting circuits should provide a stable DC output voltage. In this paper, we present an RF energy harvestingbased power management system that provides a stable 0.4-V DC supply voltage to power low-voltage systems. A closed-loop impedance matching tuning system is used to automatically regulate the system DC output voltage by tuning the input impedance matching network. The proposed circuit is implemented at schematic level in a 65-nm standard CMOS process.The entire system power efficiency (PCE) is 48.28% at the input power level of -14.92 dBm. The proposed solution is demonstrated for powering low-voltage devices with a regulated output voltage of 0.4 V and 16 uW resistive load.

A Fully Integrated CMOS Tri-Band Ambient RF Energy Harvesting System for IoT Devices

A Fully Integrated CMOS Tri-Band Ambient RF Energy Harvesting System for IoT Devices

Investigation of a Circularly Polarized Metasurface Antenna for Hybrid Wireless Applications.

The increasing prevalence of the Internet of Things (IoT) as the primary networking infrastructure in a future society, driven by a strong focus on sustainability and data, is noteworthy. A significant concern associated with the widespread use of Internet of Things (IoT) devices is the insufficient availability of viable strategies for effectively sustaining their power supply and ensuring their uninterrupted functionality. The ability of RF energy-harvesting systems to externally replenish batteries serves as a primary driver for the development of these technologies. To effectively mitigate concerns related to wireless technology, it is imperative to adhere strictly to the mandated limitations on electromagnetic field emissions. A TA broadband polarization-reconfigurable Y-shaped monopole antenna that is improved with a SADEA-tuned smart metasurface is one technique that has been proposed in order to accomplish this goal. A Y-shaped printed monopole antenna is first taken into consideration. To comprehend the process of polarization reconfigurability transitioning from linear to circular polarization (CP), a BAR 50-02 V RF PIN Diode is employed to shorten one of the parasitic conducting strips to the ground plane. A SADEA-driven metasurface, which utilizes the artificial intelligence-driven surrogate model-assisted differential evolution for antenna synthesis, is devised and positioned beneath the radiator to optimize performance trade-offs while increasing the antenna's gain and bandwidth. The ultimate prototype achieves the following: an impedance bandwidth of 2.58 GHz (3.27-5.85 GHz, 48.45%); an axial bandwidth of 1.25 GHz (4.19-5.44 GHz, 25.96%); a peak gain exceeding 8.45 dBic; and when a highly efficient rectifier is integrated, the maximum RF-DC conversion efficiency of 73.82% and DC output of 5.44 V are obtained. Based on the results mentioned earlier, it is considered appropriate to supply power to intelligent sensors and reduce reliance on batteries via RF energy-harvesting mechanisms implemented in hybrid wireless applications.

An integrated thermal and RF energy harvesting system with rectifying combination and storage controller for IoT devices

This work presents an integrated thermal/RF energy harvester. The harvesting system can combine energy from two sources simultaneously (one DC and one AC) and deliver a regulated combined voltage of 1.75 V to a load and a storage controller. The output power of the harvester is in the range of hundreds of μWatts which is suitable for low-power wireless sensor networks. Maximum power point tracking (MPPT) is achieved by reconfiguring the number of stages of the DC path, the frequency driving the charge pump, and the capacitors of the matching network in the RF-path. The storage controller charges a supercapacitor to 3.5 V to power up the system during power shortage periods. The system is implemented in a 180 nm CMOS technology and utilizes a total on-chip capacitance of 2.4 nF. The peak end-to-end efficiency of the system reaches 60.3 % at output load power of 1.275 mW.

A Hybrid Solar-RF Energy Harvesting System Based on an EM4325-Embedded RFID Tag

This paper presents the deployment of a hybrid energy harvesting system that combines a wireless energy harvesting (EH) system and a 6 V, 170 mA monocrystalline solar energy derived from the Sun’s rays. The hybrid energy harvesting (HEH) system comprises the rectifier, the solar cell panel, the charging circuit, and the EM4325 embedded RFID tag. This study aims to design an efficient EH system capable of increasing the read range of an active RFID tag. The proposed approach integrates a meandered line radio frequency identification (RFID) tag with an EM4325 IC chip as the receiver antenna. A halfwave doubler RF rectifier circuit is connected to the antenna using a 50 Ω SMA connector to convert the captured RF waves into usable electrical power. A solar energy charging module equipped with a Maximum Power Point Tracking (MPPT) system, a rechargeable lithium-ion battery, and a DC-DC converter is configured to manage and store the harvested energy efficiently. The UHF tag antenna operates at 919 MHz, achieving a peak gain of 3.54 dB. The proposed rectenna achieves a maximum measured harvested power conversion efficiency (PCE) of 55.14% for an input power (Pin) of 15 dBm at a distance of 5.10 cm, while the solar cell panel realizes 3.92 W of power. Experimental results demonstrate the hybrid harvester system’s effectiveness, achieving a PCE of 86.49% at an output voltage (VDC) of 5.35 V. The main advantage of this approach is the creation of a compact hybrid RF and solar EH system by combining the solar cell panel with the antenna, thus enabling multi-functionality.

Rectenna structure analysis for ambient RF Energy Harvesting

The paper proposes an efficient structure of RF Energy Harvesting (RFEH) system that can improve efficiency of the system. The paper analysis and indicate relationships between characteristics of the RFEH system such as: center frequency, bandwidth, Q factor, passive gain, and number of rectifier stages. After that, paper proposes design steps to design the RFEH system in which high enough Q and wide bandwidth are guaranteed. The RFEH system is designed and tested to proved the effectiveness of the proposed method. Mesurement results show that a sensitivity of 1V output DC voltage reaches at -20 dBm input power of 950 MHz signal. The power conversion efficiency (PCE) of the system is 57% at -10 dBm input level. The system can generate 3.58 output power when input power of the LTE signal is -19.4 dBm.