RF Energy Harvesting Research Articles

Interference-assisted energy harvesting short packet communications with hardware impairments

Radio frequency energy harvesting offers a promising solution to provide low power Internet of Things (IoT) devices with convenient and perpetual energy supply. In this work, we investigate the reliable performance of an energy-constrained transmitter communicating with a receiver over Nakagami-m channel, where the effects of transceiver hardware impairments and finite blocklength coding are jointly considered. Specifically, the communication link between the transmitter and receiver operates within the coverage of an existing wireless system, with radio frequency signal from the existing system serving as an energy signal for the transmitter while acting as an interference signal for the receiver. By utilizing the finite-blocklength information theory, we first derive average block error rate (BLER) and asymptotic average BLER in closed-form expressions, which enable us to quantify the extent of reliability loss. Then, we analyze effective throughput of the system, and determine the optimal blocklength that maximizes the effective throughput. Computer simulations are employed to validate the accuracy of our analytical findings, demonstrating the presence of an outage threshold solely due to hardware impairments. Furthermore, if transmission rate exceeds the outage threshold defined by the level of hardware impairments, reliable communication within the system under consideration cannot be achieved, regardless of the transmit signal-to-noise ratio (SNR).

Proposal of a 2.4 GHz Rectifier With Temperature Range Trimming for Low-Power RF Energy Harvesting

Proposal of a 2.4 GHz Rectifier With Temperature Range Trimming for Low-Power RF Energy Harvesting

A Compact Loop-shaped Dual-band Omnidirectional Rectenna for RF Energy Harvesting

A Compact Loop-shaped Dual-band Omnidirectional Rectenna for RF Energy Harvesting

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

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

A Versatile RF Energy Harvester for IoT Sensors in 5G Network With Extended Input Power Range

A Versatile RF Energy Harvester for IoT Sensors in 5G Network With Extended Input Power Range

Omnidirectional Flexible Tri-Band Rectenna With Eliminated Matching Circuit for Ambient RF Energy Harvesting

Omnidirectional Flexible Tri-Band Rectenna With Eliminated Matching Circuit for Ambient RF Energy Harvesting

Radio-frequency Energy Harvester for a Hybrid Power Supply with Constant Voltage Output to a Water Meter

Radio-frequency Energy Harvester for a Hybrid Power Supply with Constant Voltage Output to a Water Meter

Simulation based Comparative Review on a Metasurface based Perfect Absorber

In this paper, the different research papers are studied and comparatively analyzed to carry out the simulation based survey of various proposals for improvement to design Metarsurface based Perfect Absorber for GHz and THz frequency band for RF Energy Harvesting applications. Using a structure that can effectively absorb the most radiation is one of the biggest obstacles in reducing the impact of EM wave radiation. A perfect absorber may be created using variety of structures and materials with various specifications. Various structures are designed and simulated by different authors in variety of simulation softwares using useful parameters. Three distinct structures have been created, two of which were created using CST Microwave Studio and the third using HFFS for comparative study. A perfect absorber can be constructed for GHz and THz for dual band and multiband since the operating frequency range and band are not limited.

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 Survey on Challenges of Millimeter Wave Communications for Fifth-Generation Wireless Networks

Abstract-Cellular networks rely heavily on downlink beamforming; however, calculating beamformers that maximize the weighted sum rate (WSR) under power constraints is an NP-hard problem. A weighted minimum mean square error (WMMSE) algorithm variant is suggested for a MU-MISO downlink channel in order to address this trade-off between complexity and performance. This variation avoids bisection searches, eigendata compositions, and matrix inversions—all of which are challenging to implement as conventional network layers. With a reduced complexity, the suggested network architecture outperforms the WMMSE algorithm truncated to the same number of iterations and adapts well to variations in the channel distribution. Many use cases for vehicles that demand high capacity, extremely low latency, and high reliability can be made possible by 5G. To facilitate this, 5G For a MU-MISO downlink channel, a variation of the weighted minimum mean square error (WMMSE) algorithm is proposed to address this trade-off between complexity and performance. This variation avoids complex network layer implementations such as matrix inversions, eigendata compositions, and bisection searches. The suggested network architecture generalizes well to changes in the channel distribution and performs comparably to the WMMSE algorithm truncated to the same number of iterations, but at a lower complexity. Numerous automotive use cases requiring high capacity, extremely low latency, and high reliability can be made possible by 5G. 5G suggests using highly directed mm Wave system deployment and dense small cell technology to support this. To reduce the cost of signaling, however, enabling vehicular communication necessitates strong mobility management strategies. KEYWORD: Millimetre wave communications, propagation, channel measurements, channel models, MIMO, hybrid precoding, non-orthogonal multiple access (NOMA), multiple access techniques, simultaneous wireless information and power transfer (SWIPT), RF energy harvesting.

Next-Generation IoT: Harnessing AI for Enhanced Localization and Energy Harvesting in Backscatter Communications

Ongoing backscatter communications and localisation research have been able to obtain incredibly accurate results in controlled environments. The main issue with these systems is faced in complex RF environments. This paper investigates concurrent localization and ambient radio frequency (RF) energy harvesting using backscatter communication systems for Internet of Things networks. Dynamic real-world environments introduce complexity from multipath reflection and shadowing, as well as interference from movements. A machine learning framework leveraging K-Nearest Neighbors and Random Forest classifiers creates robustness against such variability. Historically, received signal measurements construct a location fingerprint database resilient to perturbations. The Random Forest model demonstrates precise localization across customized benches with programmable shuffling of chairs outfitted with RF identification tags. Average precision accuracy exceeds 99% despite deliberate placement modifications, inducing signal fluctuations emulating mobility and clutter. Significantly, directional antennas can harvest over −3 dBm, while even omnidirectional antennas provide −10 dBm—both suitable for perpetually replenishing low-energy electronics. Consequently, the intelligent backscatter platform localizes unmodified objects to customizable precision while promoting self-sustainability.

A reconfigurable wideband MIMO antenna combines RF energy harvesting

SummaryThis article introduces a novel and groundbreaking approach combining multiple‐input‐multiple‐output (MIMO) technology with radio frequency (RF) energy harvesting. The proposed antenna consists of two semi‐circular monopole antenna components, optimized with dimensions of 89 × 51.02 × 1.6 mm3, that share a common ground plane to achieve MIMO characteristics. A series of split‐ring resonators on the ground plane significantly enhances the isolation between the two radiating components. Band‐notched features are performed in the 3.5 GHz WiMAX and 5.5 GHz WLAN bands through modified C‐shaped slots in the radiating patch and two rectangular split‐ring resonators serving as parasitic devices near the feed line. The reconfiguration of band‐notching is made possible by controlling the modes of the embedded PIN diodes. The two antenna elements maintain mutual coupling below −18 dB from 1.5–13 GHz, achieving an impressive 158.62% impedance bandwidth. The antenna's efficiency and gain experience significant drop, indicating effective interference suppression at the center frequencies of the notch bands, and its performance in MIMO systems is assessed through parameters including envelope correlation coefficient, port isolation, radiation patterns, efficiency, gain, and diversity gain. The simulated properties of the designed antenna closely align with the measured outcomes, demonstrating its reliability and consistency. Moreover, the article evaluates the antenna's potential for RF energy harvesting, achieving a maximum harvested energy of 4.88 V. This proposed antenna can be used in multiple applications, like wideband, band‐notching MIMO, and RF energy harvesting. This proposed antenna is an efficient, reconfigurable wideband MIMO antenna with novel RF energy harvesting capability.

Multi-objective optimization for energy efficient cooperative communication in energy-constrained overlay Cognitive Radio Networks

With the rapid proliferation of wireless devices, energy efficiency and addressing spectrum scarcity have become critical global concerns. To address these challenges, this paper explores radio-frequency energy harvesting in Cognitive Radio Networks (CRNs) as a solution which can significantly extend the battery life of mobile devices. In this setup, energy-constrained secondary users (SUs) use Simultaneous Wireless Information and Power Transfer (SWIPT) technology to harvest energy from primary signals and aid primary transmission. We propose a joint time-switching and power-splitting technique to maximize energy harvesting, achieving a 97.7% accurate sub-optimal solution compared to the optimal (benchmark) result. Furthermore, we investigate optimal power allocation during cooperative communication and secondary transmission, resulting in a near-optimal solution with 98.5% accuracy. We also introduce a cooperative communication framework using the Hedonic game concept, enabling SUs to establish preferred partnerships with suitable primary users (PUs). Numerical results indicate that this cooperative framework enhances the secondary network’s overall utility, average SU satisfaction, and SU participation when compared to the non-cooperative approach.

Linear/Non-Linear Energy Harvesting Models via Multi-Antenna Relay Cooperation in V2V Communications

Vehicle-to-vehicle (V2V) communications is a part of next-generation wireless networks to create smart cities with the connectivity of intelligent transportation systems. Besides, green communications is considered in V2V communication systems for energy sustainability and carbon neutrality. In this scope, radio-frequency (RF) energy harvesting (EH) provides a battery-free energy source as a solution for the future of V2V communications. Herein, the employment of RF-EH in V2V communications is considered where the bit error probability (BEP) of a dual-hop decode-and-forward relaying system is obtained depending on the utilization of antennas at the relay. The multiple antenna power-constraint relay harvests its power by applying dedicated antenna (DA)/power splitting (PS) EH modes and linear (L)/nonlinear (NL) EH models. Moreover, the links between nodes are exposed to double-Rayleigh fading. Finally, the performance of different system parameters is compared using theoretical derivations of BEP. The results provide a comprehensive analysis of the proposed system considering PS/DA-EH modes and L/NL-EH models, as well as deterministic/uniformly distributed placement of nodes. It is observed that PS-EH outperforms DA-EH assuming a placement of an equal number of antennas and distances. Moreover, optimal performance of PS/DA-EH is achieved by allocating more power and increasing the number of antennas for EH, respectively.

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

Miniaturized Broadband Bi-Yagi Antenna Array for Ambient RF Energy Harvesting.

This paper presents a miniaturized broadband Bi-Yagi antenna array that covers a bandwidth from 1.79 GHz to 2.56 GHz. The proposed antenna achieves a tradeoff between maximizing bandwidth, effective area, and gain while minimizing physical dimensions. The antenna design considers the coupling between the radiator and director elements, resulting in increased bandwidth as the resonating modes shift apart. Additionally, the proposed design optimizes element spacing and dimensions to achieve high gain, wide bandwidth, efficient radiation, and a minimum aperture size. The proposed antenna, with physical dimensions of 138.6 mm × 47.7 mm × 1.57 mm, demonstrates gains ranging from 6.2 dBi to 9.34 dBi across the frequency range, with a total efficiency between 88% and 98%. The proposed design is experimentally validated by measuring the reflection coefficients, input impedance, gain, and normalized radiation pattern. These features make the antenna well suited for capturing and harvesting electromagnetic waves in mobile wireless and Wi-Fi applications.

Dualband rectenna for RF energy harvesting using metamaterial reflect array and novel matching technique

Harvesting energy from multiple sources, antenna gain, rectifier power conversion efficiency, and rectenna size are essential properties to consider while designing an antenna for ambient energy harvesting. This paper represents two high-gain, dualband antennas using a metamaterial Artificial Magnetic Conductor array. Both antennas are designed to harvest energy from GSM-1800, and the 2.45 GHz Industrial, Scientific, and Medical (ISM) frequency bands. The first antenna achieves a gain of 6.85 dB and 6.57 dB at 1.8 GHz and 2.45 GHz, respectively. The second configuration shows a gain of 7.11 dB at 1.8 GHz and 6.79 dB at 2.45 GHz. The antennas are circularly polarized at 2.45 GHZ.A dualband rectifier is designed based on a novel matching procedure to complete the energy harvesting system. The measured peak conversion efficiency is 72 % at 1.8GHz and 65 % at 2.45GHz with an area of 33 ×55 mm2.

Double elliptical resonator based quad-band incident angle and polarization angle insensitive metamaterial absorber for wireless applications

In this article, a double elliptical split ring resonator-based quad band metamaterial absorber (MMA) is demonstrated for applications in the microwave range. The resonator is made up of four squares outside split rings and two elliptical split rings positioned in the middle of the structure. The resonating patch is placed over an FR-4 dielectric layer with a thickness of 1.6 mm. The unit cell has an electrical size of 0.103λ0 × 0.103λ0, where λ0 is the wavelength determined at 2.576 GHz. The MMA shows maximum absorption of 99.83% at 2.576 GHz, 99.98% at 5.648 GHz, 99.56% at 8.32 GHz, and 99.15% at 13.456 GHz with TE mode. For TM mode, at 2.576 GHz, 5.632 GHz, 8.304 GHz, and 13.44 GHz, corresponding absorptions are 99.21%, 99.67%, 99.5%, and 99%, respectively. The MMA is polarisation and incidence angle (0° to 90°) insensitivity for both TM and TE modes. The unit cell provides single negative characteristics including an EMR (effective medium ratio) of 9.71 and a Q factor (quality factor) over 25. The proposed MMA provides high harvesting efficiencies of 92.87%, 76.9%, 94.12%, and 90.97% for frequencies of 2.57 GHz, 5.64 GHz, 8.32 GHz, and 13.45 GHz, correspondingly. The equivalent circuit is modeled to understand the resonance behavior of the MMA and the circuit parameters are determined and validated using Advanced Design Systems (ADS) software. The performance of the MMA is examined using the prototype of the array of the unit cells in an experimental setup. The experimental outcome provides a close similarity with simulation outcomes indicating the good performance of the MMA. The metamaterial absorber's high performance makes it suitable for many applications, such as RF energy harvesting applications, image technologies, stealth technologies, and radar systems as well as minimizing electromagnetic interference in satellites.

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.