RF Energy Harvesting Applications Research Articles

Reconfigurable Antennas for RF Energy Harvesting Application: Current Trends, Challenges, and Solutions from Design Perspective

Due to the widespread use of low-power embedded devices in both industrial and consumer applications, research into the use of alternate energy sources has been sparked by the requirement for continuous power. Due to its accessibility and ability to be implanted, RF energy is always taken into consideration among the traditional energy sources that are currently available. There is a significant necessity for efficient RF front-ends, which must provide effective circular polarization (CP) features, effectiveness, feasibility from a design standpoint, and optimal usage of ambient RF signals accessible in the environment. So, for understanding their utilization in RF energy harvesting, a metasurface reflector-inspired CP-printed reconfigurable antenna integrated with a Greinacher voltage divider (GVD) rectifier circuit is reported. It offers broadband CP with fractional bandwidth > 25%, CP gain > 8.35 dBic, and directional radiation with the 3 dB angular beamwidth > 100° in the 3.5/5 GHz bands. With the integration of the rectifier circuit, a theoretical DC output > 4.8 V at 12 dBm is obtained. The acceptable impedance bandwidth, axial ratio bandwidth, antenna gain, antenna efficiency, and directional radiation with a 3 dB angular beamwidth value are studied and subsequently matched with the trade-offs (usage of diodes, complexity of DC biasing circuits, and attainment of polarization reconfigurability) obtained from the state of the art. A comprehensive study of the reconfigurable antennas is reported to highlight the findings as a widespread solution for these limitations in RF energy harvesting application.

Multiband Microstrip Rectenna Using ZnO-Based Planar Schottky Diode for RF Energy Harvesting Applications.

This paper presents a single-substrate microstrip rectenna for dedicated radio frequency energy harvesting applications. The proposed configuration of the rectenna circuit is composed of a clipart moon-shaped cut in order to improve the antenna impedance bandwidth. The curvature of the ground plane is modified with a simple U-shaped slot etched into it to improve the antenna bandwidth by changing the current distribution; therefore, this affects the inductance and capacitance embedded into the ground plane. The linear polarized ultra-wide bandwidth (UWB) antenna is achieved by using 50 Ω microstrip line and build on Roger 3003 substrate with an area of 32 × 31 mm2. The operating bandwidth of the proposed UWB antenna extended from 3 GHz to 25 GHz at -6 dB reflection coefficient (VSWR ≤ 3) and extended from both 3.5 to 12 GHz, from 16 up to 22 GHz at -10 dB impedance bandwidth (VSWR ≤ 2). This was used to harvest RF energy from most of the wireless communication bands. In addition, the proposed antenna integrates with the rectifier circuit to create the rectenna system. Moreover, to implement the shunt half-wave rectifier (SHWR) circuit, a planar Ag/ZnO Schottky diode uses a diode area of 1 × 1 mm2. The proposed diode is investigated and designed, and its S-parameter is measured for use in the circuit rectifier design. The proposed rectifier has a total area of 40 × 9 mm2 and operates at different resonant frequencies, namely 3.5 GHz, 6 GHz, 8 GHz, 10 GHz and 18 GHz, with a good agreement between simulation and measurement. The maximum measured output DC voltage of the rectenna circuit is 600 mV with a maximum measured efficiency of 25% at 3.5 GHz, with an input power level of 0 dBm at a rectifier load of 300 Ω.

UWB Microstrip Patch Antenna Design for Energy Harvesting Applications

RF energy harvesting systems, which are the receiver part of Wireless Power Transfer (WPT), have gained significant development in recent years. For maximum energy acquisition over a wide frequency range, such as to provide power to small handheld devices like cell phones, tablets, smart watches, and other smart devices, wideband and compact antennas are desired. RF systems are expected to cover different frequency bands, such as 2.4 GHz, 5.1 GHz, 5.8 GHz (Bluetooth/Wi-Fi), 2.3 GHz, 2.5 GHz, 3.5 GHz, 5 GHz (WiMAX), for energy harvesting. For such an RF harvesting system, the antenna is desired to have a wide bandwidth, good gain, and an omnidirectional radiation pattern. Energy harvesting devices refer to designs that integrate production and storage. For instance, radio frequency energy sources contain a large amount of electromagnetic energy in the environment, and with RF energy harvesting systems, a portion of this electromagnetic energy can be collected and converted into usable DC voltage. Microstrip patch antennas are very good alternatives for energy harvesting applications because they are cost-effective, compact in size and weight, flat in structure, and highly repeatable. This paper presents a microstrip patch antenna with a bandwidth of 3.9 GHz in the 3.4 to 7.3 GHz range for UWB applications. The antenna design has a gain value of 3.28dBi at the numerically calculated resonance frequency of 4.9 GHz and generally covers frequencies used for electronic device communication such as Wi-Fi 5 GHz and WiMAX. The proposed antenna design has gain values that are allowed to be used for RF energy harvesting applications.

Triple‐band metasurface absorber for RF energy harvesting applications

AbstractEnergy harvesting is expected to be ubiquitous and essential to modern‐day life in the future. The limitations of ambient sources, such as thermal, mechanical, and solar, for energy harvesting can be overcome by RF energy harvesting for low‐power devices. With the help of perfect metasurface absorbers, an electromagnetic wave can be used as an ambient source for energy harvesting. In this paper, a simple polarization‐insensitive triple‐band perfect metasurface absorber is proposed for RF energy harvesting applications. The three‐layer (metal–dielectric–metal) meta‐atom of the designed metasurface consists of a cross‐shaped metal patch surrounded by slotted square‐shaped metallic patches and of meta‐atoms. The absorber is typically developed in S‐ and C‐bands with resonant frequencies of 3.06, 3.9, and 5.97 GHz. The absorption is near unity which persists over a wide angle of incidence. The experimental results are in close agreement, within 2%, with the simulation results. The reliability of the proposed absorber has been determined for the RF energy harvesting applications, and a high harvesting efficiency of 94.4% and 84% has been observed at 3.07 and 5.97 GHz, respectively.

High isolated Psi-Shaped 4x4 MIMO UWB antenna for RF energy harvesting applications

A 4x4 Ultra Wide Band Multi Input Multi Output antenna with Ψ (Psi) patch on an elliptical slot defected ground structure designed to be in control of Characteristic Mode Theory Analysis. Utilizing the design of the Ψ-shaped antenna offers good isolation of beneath − 20 dB in the full UWB frequency (3.1 GHz to10.6 GHz). The antenna planned on FR4 with thickness of 1.6 mm, dielectric strength of 4.4 and loss tangent value of 0.02. This antenna compromises worthy impedance bandwidth as of 3.10 GHz to 12.00 GHz through with better isolation. This designing furnishes radiation efficiency of 92%, 115% of bandwidth; and maximum peak gain of 6.50 dBi. The diversity features of DG, ECC, CCL and MEG are 9.998, 0.012, 0.25 bits/s/Hz and − 3.2 dB correspondingly. This antenna stands adequate for RF Energy Harvesting Applications.

Microstrip Patch Antenna Array Design for RF Energy Harvesting Applications

In recent years, with the rapid developments in the field of technology and the development of wireless communication systems; led to a noticeable increase in the number of portable, rechargeable and low-power devices. These electronic devices have become a necessity even in our simplest works, due to the increase in their number and variety; It is desired that the energy needs can be met continuously and quickly at a low cost. Batteries, which are non-renewable generators, provide the energy required for such low-power devices in the world. The increase in the tendency towards non-renewable energy sources leads to negative environmental and economic consequences. Therefore, it becomes important to turn to renewable energy sources and to work on it. Energy harvesting systems, which are an innovative energy source, are the best potential alternatives to collect the energy needed by the mentioned low-power devices. With the increase of different frequency bands such as GSM 900, GSM 1800, UMTS, 3G, Wi-Fi, Wi-Max and LTE, RF energy harvesting is becoming quite common. In this paper, a printed multiband microstrip patch antenna is presented. Antenna design covers numerically calculated frequencies of 1.6dBi at 2.4GHz, 3.95dBi at 5.2GHz, gain values, and frequencies often used for electronic device communication such as Wi-Fi 2.4GHz and WiMAX. The proposed antenna design has allowable gain values to be used for RF energy harvesting applications.

Г-Shaped Asymmetrical Monopole Antenna on Truncated DGS For Multiband RF Energy Harvesting Applications

In today's world, through the advancement of technology, wireless communication has become an integral part of our lives with the utilization of versatile electronic devices such as cell phones, tablets, and computers that contain wireless communication modules. The idea of utilizing different frequencies and power of RF signals in the environment has led to the concept of harvesting RF signals to produce DC output voltage. In this paper, a printed multiband monopole antenna is presented. The proposed antenna is composed of two Г-shaped asymmetrically positioned feeding lines which are located on slotted truncated ground plane with three stubs loaded on both ground plane sides. The antenna design covers the frequently used frequencies for electronic device communication, such as GSM 1800, UMTS 2100, WLAN 2450 and LTE 2600 With the numerically computed gain values of 3.89dBi at 1.8GHz, 4.51dBi at 2.1GHz, 5.02dBi at 2.45GHz, and 5.03dBi at 2.6GHz, respectively. The proposed antenna design has permissible gain values to be used for RF energy harvesting applications.

A miniaturized advanced rectenna integrated circuit for implantable applications

This paper presents analysis and design of a new miniaturized advanced rectenna integrated circuit for RF energy harvesting applications. The rectenna circuits consist of (antenna, rectifying circuit) and matching network connected together. The 1 × 4.5 mm2 planar L-shaped dipole antenna implanted inside human ‘s body arm for operation in ISM dual-bands like 1.5GHz and 5.8GHz. The new device quantum well asymmetric spacer tunnel layer (QW-ASPAT) rectifier diodes based on GaAs and InGaAs platforms have been used for the mesa size area of 10 × 10 μm2. The DC, RF, and C-V characteristics of the new rectifier diodes were performed and modelled by using SILVACO ATLAS software. The highest extracted curvature coefficient, kv value of the both QW-ASPAT devices at zero bias was about 33 V−1 compared with the standard structures was 13 V−1. The cut off frequency of the proposed QW-GaAs and QW-InGaAs devices are 26GHz and 46GHz respectively. The fully integrated rectenna circuit was performed by Advanced Design System (ADS) software. The maximum DC output voltage and power of the proposed rectenna system were 0.7 V,1.5 V and 167 μw, 325 μw when used single, and double stage voltage doubler rectifiers respectively at the input RF power of 0 dBm.

New circularly polarized microstrip patch antenna array design for energy harvesting applications

This paper gives an essential contribution to the energy engineering topic, especially the energy harvesting field. Wireless power transmission (WPT) is one of the most widely used methods in this field recently to generate electricity in a clean way for the environment like the rectenna systems. The main component of the rectenna systems is the microstrip patch antenna (MPA). This is the main reason why this article proposes a novel conception of 1×4 circular polarized MPA array to operate in the industrial, scientific, and medical (ISM) band at the resonant frequency of 2.45 GHz for radio frequency energy harvesting (RFEH) systems. The basic MPA element is a square antenna using a center slot and V-slits at the four corners combined with a defected ground structure (DGS) method. This proposed conception is developed in order to improve the antenna’s performance to integrate with a rectifier circuit for the Rectenna systems which are the most used systems in RFEH. The simulation results obtained by CST MWS software and HFSS solver show that this novel design in this paper gives good performances in terms of the reflection coefficient, voltage standing wave ratio, axial ratio, directivity, and gain at 2.45 [GHz]. This developed MPA is suitable for various RFEH applications.

Rectifier Circuits for RF Energy Harvesting and Wireless Power Transfer Applications: A Comprehensive Review Based on Operating Conditions

Low-power wireless sensors will play a big role in smart city applications. These sensors require a power supply to function. Batteries are not optimal for such numerous sensor networks because of their limited life and need for regular maintenance; hence, they are not a universal solution. RF energy harvesting (RFEH) and wireless power transfer (WPT) techniques have the potential to be a green and sustainable solution for supplying power to various low-power devices by capturing ambient RF energy. The ubiquitous nature of RF energy makes it available to exploit and reutilize in power wireless sensor nodes, wireless body area networks, wireless charging systems, RFID tags, and the Internet of Things <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> , <xref ref-type="bibr" rid="ref2" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[2]</xref> . <xref ref-type="fig" rid="fig1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Figure 1(a)</xref> displays a conceptual diagram of an RFEH/WPT system. To capture power from free space that is transmitted by the base station, the harvesting node needs a receiving antenna and rectifier to convert the power into dc signals. This dc output is then further utilized to feed a low-power device. <xref ref-type="fig" rid="fig1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Figure 1(b)</xref> shows that at 10-m distance from the cellular tower, a digital batteryless watch was powered by a rectenna operating at 1.8 GHz. This LCD watch (low-power device) required 1.5 V to function and was successfully powered up using the RFEH system <xref ref-type="bibr" rid="ref3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[3]</xref> .

A Dual-Band Rectifier Using Half-Wave Transmission Line Matching for 5G and Wi-Fi Bands RFEH/MPT Applications

A dual-band rectifier is presented for RF energy harvesting (RFEH) and microwave power transfer (MPT) applications. Starting with a single-band rectifier, the second band is added by utilizing a half-wavelength transmission line (HWTL) in the matching network (MN). A series diode topology using HSMS-2860 Schottky diode is used for power conversion. The rectifier simultaneously harvests the RF energy with power conversion efficiency (PCE) of 54.9% and 42.3% and output voltage of 1.4 and 1.242 V at 0-dBm input power for 3.5-GHz 5G band and 5.8-GHz Wi-Fi band, respectively.

Design of a High-Efficiency DC-DC Boost Converter for RF Energy Harvesting IoT Sensors.

In this paper, an optimal design of a high-efficiency DC-DC boost converter is proposed for RF energy harvesting Internet of Things (IoT) sensors. Since the output DC voltage of the RF-DC rectifier for RF energy harvesting varies considerably depending on the RF input power, the DC-DC boost converter following the RF-DC rectifier is required to achieve high power conversion efficiency (PCE) in a wide input voltage range. Therefore, based on the loss analysis and modeling of an inductor-based DC-DC boost converter, an optimal design method of design parameters, including inductance and peak inductor current, is proposed to obtain the maximum PCE by minimizing the total loss according to different input voltages in a wide input voltage range. A high-efficiency DC-DC boost converter for RF energy harvesting applications is designed using a 65 nm CMOS process. The modeled total losses agree well with the circuit simulation results and the proposed loss modeling results accurately predict the optimal design parameters to obtain the maximum PCE. Based on the proposed loss modeling, the optimally designed DC-DC boost converter achieves a power conversion efficiency of 96.5% at a low input voltage of 0.1 V and a peak efficiency of 98.4% at an input voltage of 0.4 V.

A New Compact Triple-Band Triangular Patch Antenna for RF Energy Harvesting Applications in IoT Devices.

This work proposes a new compact triple-band triangular patch antenna for RF energy harvesting applications in IoT devices. It is realized on Teflon glass substrate with a thickness of 0.67 mm and a relative permittivity of 2.1. Four versions of this antenna have been designed and realized with inclinations of 0°, 30°, 60° and 90° to study the impact of the tilting on their characteristics (S11 parameter, radiation pattern, gain) and to explore the possibilities of their implementation in the architectures of electronic equipment according to the available space. The antenna is also realized on waterproof paper with a thickness of 0.1 mm and a relative permittivity of 1.4 for biomedical domain. All the antennas (vertical antenna, tilted antennas and antenna realized on waterproof paper) have a size of 39 × 9 mm2 and cover the 2.45 GHz and 5.2 GHz Wi-Fi bands and the 8.2 GHz band. A good agreement is obtained between measured and simulated results. Radiation patterns show that all the antennas are omnidirectional for 2.45 GHz and pseudo-omnidirectional for 5.2 GHz and 8.2 GHz with maximum measured gains of 2.6 dBi, 4.55 dBi and 6 dBi, respectively. The maximum measured radiation efficiencies for the three antenna configurations are, respectively, of 75%, 70% and 72%. The Specific Absorption Rate (SAR) for the antenna bound on the human body is of 1.1 W/kg, 0.71 W/kg and 0.45 W/kg, respectively, for the three frequencies 2.45 GHz, 5.2 GHz and 8.2 GHz. All these antennas are then applied to realize RF energy harvesting systems. These systems are designed, realized and tested for the frequency 2.45 GHz, −20 dBm input power and 2 kΩ resistance load. The maximum measured output DC power is of 7.68 µW with a maximum RF-to-DC conversion efficiency of 77%.

Dual Band Rectenna for Wireless Energy Harvesting in the 2.40 GHz and 5.38 GHz

The objective of this study, reflected in this document, was to implement a rectenna for 2.45 GHz and 5.38 GHz wireless local area applications. For this purpose, the antenna dimensions were set to 18 mm × 44 mm, which is simulated using the optimization software CST Studio, manufactured on FR4 substrate with a thickness of 1.6 mm, where the conductive material has a thickness of 0.035 mm. Likewise, the rectangular slot technique was used to improve the bandwidth of the antenna; this technique consists of inserting slots in the structure to modify the displacement of the surface current. The above presented a gain of 2.49 dB at the 2.45 GHz frequency and 4.01 dB at the 5.38 GHz frequency. The proposed antenna for RF energy harvesting applications exhibits a dipole type radiation pattern, which enhances the capture of RF energy from various directions. The triple slotted-band rectifier with T-shaped impedance matching network was designed in FR4, using a Schotkky HSMS-286C diode for AC to DC RF control switching. A tp-link TL-WR940N wireless router was used as the RF emitting source at 30 cm separation between it and the proposed rectenna. The DC output of the rectenna is 3 volts with a generated signal power of 20 dBm at 2.4 GHz. The low-cost rectenna can be used for power-charging applications in the Internet of things (IoT) systems.

Investigation of a high-gain and broadband circularly polarized monopole antenna for RF energyharvesting application

AbstractIn this research article, a metasurface (MTS)-loaded high-gain and broadband circularly polarized (CP) monopole antenna is reported. The proposed antenna configuration consists of a symmetric Y-shaped radiating monopole over a partial ground plane with extended twin parasitic conducting strips (PCS) loaded with a MTS reflector. To achieve left-hand circular polarization characteristics, a metallic copper strip is utilized to short the partial ground plane with one of the twin PCS [PCS(L)]. By using the grid-slotted sub patches on a rectangular MTS a reflector of 2λfa × 1.65λfa × 0.02λfa is placed just below the monopole radiator at a height of 0.33λfa, which provides broadened impedance (IBW) and 3 dB axial ratio bandwidth (ARBW) responses with high gain. The proposed prototype with an volumetric dimension of 1.33λfa × 0.9λfa × 0.02λfa at fa = 5 GHz is designed and characterized. It exhibits a measured IBW of 48.45% (3.57–5.89 GHz), ARBW of 25.25% (4.21–5.42 GHz), and CP gain of &gt; 8.35 dBic with the antenna efficiency of &gt; 75% in the desired operating frequency bands. The obtained performances of the proposed MTS antenna confirm its suitability for RF energy harvesting application.

Patch antenna with multi-cell EBG for RF energy harvesting applications

AbstractIn this paper, a ring patch antenna with 1 GHz of bandwidth and three resonances is designed for the RF energy harvesting application. Two complementary split-ring resonators (CSRR) is etched out from the patch, designed at 6.8 GHz, near feed to enhance the bandwidth from 267 MHz to 1 GHz. Due to the introduction of CSRR, two additional resonances at 6.4 and 7.4 GHz are obtained with gain 5.5 and 0.2 dB respectively. The gains at 6.8 and 7.4 GHz are enhanced to 8.3 and 2 dB respectively by cascaded circular mushroom electromagnetic bandgap structures (EBGs) with circular symmetry designed around the antenna. This ring patch antenna with cascaded EBG is integrated with a rectifier circuit based on voltage doubler topology (rectenna). The results of the rectenna show that, for an input power of 7 dBm to the rectifier circuit, a DC output voltage of 1.2 V with a power conversion efficiency of 40% is achieved.

A Preliminary Analysis on RF Antenna Simulation comparison based on UHF and 5G for Energy Harvest Application

The goal of this research is to look at the performance of RF antennas in the UHF and 5G frequencies for energy harvesting applications. Energy harvesting is the method of gathering and storing external sources in a wireless autonomous device. The focus of this simulation is on two design parameters for a meander dipole antenna that can be utilised for energy harvesting in the UHF and 5G bands. The antenna design is based on FR4 material with a dielectric constant of 4.4 and thicknesses of 3.5 mm and 1.15 mm for the initial simulation. As a result, the CST Studio Suite Software was used to model the meander dipole type. To test performance, S11 passes below -25.79 dB for UHF and -25.7idB for 5G ranges are typically utilised. At these frequencies, the antenna bandwidths are 44.5 MHz and 450 MHz, respectively Finally, the developed Meander dipole antenna can be employed in RF energy harvesting applications, such as wireless sensor networks, by combining rectifier and matching circuits.

Design and Implementation of Multi-Band Fractal Slot Antennas for Energy Harvesting Applications

This paper introduces a design and optimization procedure of multiband fractal slot antennas for RF energy harvesting applications. The antennas were simulated using CST Studio Suite. A parametric study is conducted to determine the critical structural parameters that influence the antenna performance. The parametric study included varying the size ratio of the structure, the shape of the ground plane and the length of the feeding inset. Simulation results showed that the proposed antennas in this work exhibit multiband performance and they offer the possibility of controlling the resonant frequency at any specific frequency band. The optimized antenna has seven resonant frequencies at 1.8 GHz, 2.4 GHz, 3.45 GHz, 3.6 GHz, 4 GHz, 4.6 GHz and 5.3 GHz covering several ambient communication networks (GSM, UMTS and 5G), Bluetooth and WLAN systems. Simulation results shows that Antenna 1 has achieved a gain of more than 4.5 dBi at all the resonant frequencies with a radiation efficiency ranged between 87%–95%; whereas Antenna 2 has achieved more than 3 dBi gain at lower frequencies while reaching around 7 dBi at higher frequencies with a radiation efficiency ranged between 80%–97%. Finally, two fractal slot antennas were fabricated and tested in the lab to validate the simulation results and to proof the concept of the feasibility of this type of antennas for this application. Experimental results showed a good agreement with simulations.

Design and Analysis of Polarization-Independent, Wide-Angle, Broadband Metasurface Absorber Using Resistor-Loaded Split-Ring Resonators

Metasurface (MS) absorbers with polarization-insensitivity and wide-angle reception features have attracted much attention due to their unique absorption property. A polarization-insensitive broadband MS absorber structure, having wide-angle reception based on square split-ring resonators (SSRRs) and loaded with lumped resistors, is proposed in this paper. The proposed MS unit cell consists of a fixed-thickness FR4 dielectric substrate and a variable air-thickness substrate. The simulation results show that the proposed MS absorber is stable across a wide angular range for both normal and oblique incidences. Furthermore, the simulated results show that some parameters, such as unit-cell geometry and lumped resistors, can be varied to improve the performance of the MS absorber. The experimental results indicate that the proposed MS absorber can be achieved an absorption higher than 90% across the frequency range from 1.89 GHz to 6.85 GHz with a relative bandwidth of 113%, which is in agreement with simulation results. Thus, the proposed MS absorber can be more suitable in RF energy harvesting or wireless power transfer applications.

A wide‐band antenna with dual open rings resonator for RF energy harvesting

AbstractIn this letter, a wide‐band antenna with dual open rings resonator (DORR) is presented for ambient radio frequency (RF) energy harvesting applications. The proposed antenna is designed to harvest RF energy at DCS1800, UMTS/LTE, and Wi‐Fi bands (1.7–2.65 GHz). The DORR produces a strong coupling effect and leads to more current paths, thus contributing to a wider bandwidth. The measured bandwidth is from 1.68 to 2.80 GHz with 50% fractional bandwidth. The measured gains are 3.5, 5, and 5 dBi at 1.83 GHz (DCS1800), 2 GHz (UMTS/LTE), and 2.45 GHz (Wi‐Fi), respectively. Moreover, over 90% radiation efficiency and larger than 3 dBi gain are achieved for the operating bands. The antenna can be used for RF energy harvesting and various communication applications.