Dual-band RF Energy Harvesting Research Articles

3-D-Printed Dual-Band Rectenna System for Green IoT Application

This paper describes the novel fully 3D-printed dual-band RF energy harvester suitable for wireless sensor network green IoT applications. The proposed energy harvesting system is composed of a dual-band circular omnidirectional monopole antenna array with a T-junction power divider, RF rectifier, and an impedance matching network. The circular monopole antenna array is conformed to a cylindrical substrate to achieve the compact system. The Villard multiplier-based rectifier has been used for the conversion of RF signal to DC voltage. The presented rectenna is fabricated using a 3D printable, biodegradable, conformal and an economical substrate. The test is performed in an RF ambient environment. The manufactured configuration obtained conversion efficiencies of 67.29% with output voltage of 1.39 V and 42.16% with output voltage of 1.1 V at 0 dBm RF input power in 2.4 GHz and 5.2 GHz frequency bands respectively. The proposed configuration’s simulated and measured results are in concordance with each other. The study emphasizes the potential of 3D-printed rectenna in terms of cost-effective prototyping.

A Fully-Integrated CMOS Dual-Band RF Energy Harvesting Front-End Employing Adaptive Frequency Selection

A Fully-Integrated CMOS Dual-Band RF Energy Harvesting Front-End Employing Adaptive Frequency Selection

Dual-band rectenna system for biomedical wireless applications

- This paper proposes a dual-band RF energy harvester to power biomedical wireless devices for various health applications. Biomedical devices may be implantable medical devices or wearable devices. The proposed system's novelty is that it can work in widespread operating power ranges with good conversion efficiencies. The Pi impedance matching network is used in the projected dual-band rectifier that is practicable for RF energy harvesting within the existing band of frequencies. The proposed antenna is simulated and designed using CST MW Studio 2018, while for the designing and simulation of the rectifier, ADS 2020 is used. Also, for the DC pass filter and matching network, ADS 2020 is used. For fabrication, an FR-4 lossy substrate having a dielectric constant of 4.4 and dielectric height of 1.6 mm is used. The projected result shows that the conversion efficiency is greater than 50% (capable of 78%), with an input power range of 8.5–10 dBm. At an input power of 8 dBm, the typical DC voltage was increased to 1.8 V. With the use of matching circuits, the maximum conversion efficiency is 78%, while without a matching circuit, the maximum conversion efficiency is only 37%. The matching circuit was critical for conversion efficiency.

A Novel Dual-band Ambient RF Energy Harvesting System for Autonomous Wireless Sensor Node Application

This paper presents a novel dual-band ambient Wi-Fi energy harvesting system for an autonomous wireless sensor node (AWSN) which operates independently without other external power source. While conventional wireless sensor nodes employing batteries with limited lifespans, an AWSN is supplied by harvested energy and does not require frequent battery replacement. Due to that reason, research on the energy harvesting aspect of AWSNs has been carried out intensively in recent years. By optimizing the matching network, the proposed ambient Wi-Fi energy harvesting system achieves a relatively good efficiency in dual-band at 2.45 GHz and 5.8 GHz. The efficiency reaches a peak at 47.45 % and 42 % at 2.45 GHz and 5.8 GHz, respectively. The proposed idea is numerically and experimentally demonstrated with the Wi-Fi source in building.

A high-sensitivity, low-noise dual-band RF energy harvesting and managing system for wireless bio-potential acquisition

This paper proposes a high-sensitivity, low-noise dual-band RF energy harvesting and managing system for wireless bio-potential acquisition. The proposed system consists of a dual-band RF energy harvester, a voltage monitor, and a power management unit (PMU). The proposed dual-band RF energy harvester adopts the hybrid threshold voltage self-compensation technology, which effectively reduces the equivalent threshold voltage of transistors and improves the power conversion efficiency (PCE). To match the input power and the load power with the minimum current consumption, a low-power voltage monitor is proposed in this paper. Moreover, the proposed PMU combines a voltage bootstrap circuit and a low-noise high-PSRR LDO to avoid the use of off-chip inductors and suppress output ripple. The proposed chip was implemented in a 0.18-μm deep n-well CMOS process, occupying a core area of 1.30 mm✕2.06 mm. The measured results show the dual-band RF energy harvester outputs a DC voltage of 1 V in two different frequency bands at the input power as low as −18.5 dBm. The PMU outputs stable DC voltages of 1 V and 1.8 V in working mode. In sleep mode, only the voltage monitor is working, and the average quiescent current is only 0.6 μA.

Resistance Compression Dual-Band Differential CMOS RF Energy Harvester Under Modulated Signal Excitation

This paper proposes a resistance compression dual-band differential CMOS RF energy harvester for harvesting power at dual frequencies. The use of resistance compression dual-band matching network minimizes the sensitivity of the RF-DC converter for the variation in the input power and the rectifier load. The proposed system can work at 914 MHz and 2.4 GHz for arbitrary complex impedance simultaneously. The design is fabricated in a standard CMOS $0.18~\mu \text{m}$ technology and provides a regulated output voltage of 1 V. The cumulative efficiency in the presence of two frequencies shows an improvement of 14.2% with concern to single frequency (914 MHz at −14 dBm). Also maintains the efficiency of >20% for the input power range of −16 ~ 0 dBm. Also studied and analysed the implication of Wi-Fi bandwidth (72 MHz), OFDM modulation, and 64-QAM modulation on the efficiency and sensitivity of the system concerning continuous input signal. Observed the improvement in the efficiency with the peak-to-average power ratio.

Design and simulation of dual-band RF energy harvesting antenna for WSNs

Radio frequency energy harvesting is attracting an increasing deal of attention in order to provide power to the electronic devices, including Wireless Sensor Networks. In this context, we focus on ambient radiofrequency energy available in the ambient environment. The receiving antenna is the main element of radiofrequency harvester, as it has to capture the RF energy from the radiating sources. Our work provides a new design of the receiving antenna to harness RF energy more effectively. Several simulations and optimizations are performed in order to maximize the antenna gain around the Wi-Fi bandwidth (2.45 GHz and 5 GHz). Variation of the return loss passes below -29 dB for 5 GHz frequencies and the radiation shape shows a quasi-omnidirectional pattern in Wi-Fi bands. The dual band antenna proposed is very interesting for the RF harvesting energy system, meeting the desired criteria to maximize the ambient harvested RF energy.

A dual-band RF energy harvesting circuit using 4th order dual-band matching network

A novel compact rectifier for dual-band operation in the RF energy harvesting is presented. The circuit comprises a 4th order dual-band impedance matching and a single-series circuit with one double diode, both are integrating into a compact shape to occupy a small area of 30×35mm2. The merit of the proposed rectifier circuit is that it can be extended to n number of the frequency band by using only 2×n matching elements. To validate the design method experimentally, a prototype of a dual-band rectifier is fabricated for two public telecommunication bands of GSM-900 and 1800. In order to reduce the circuit complexity and sensitivity arising due to lumped elements, the meander line and the open stub are used to realize the proposed circuit. A good agreement is obtained between the simulation and the measurement. The measured results show that the proposed rectifier circuit exhibits the conversion efficiency of 25.7 and 65% for an input power of -20 and 0 dBm, respectively. In addition, diode nonlinearity w...

A Dual Band RF Energy Harvester with Hybrid Threshold Voltage Self-Compensation

Threshold voltage self-compensation technology (TVSC) has been widely used in RF energy harvester. In this paper, the influence of the size of rectifying transistors, the stages and compensation orders of the rectifier, and the impedance matching network on the performance of RF energy harvester has been studied. A dual band RF energy harvester with hybrid threshold voltage self-compensation (HTVSC) is proposed in this paper in 65-nm CMOS process according to the distribution characteristic of the ambient RF energy. By combining TVSC and the technology of weak forward bias between the source and body of the rectifying transistor, the threshold voltage of MOSFET can be dramatically decreased. The performance of the RF energy harvester has been improved using this new technology. The simulation results show that the proposed dual band RF energy harvester can acquire energy at the band of 900[Formula: see text]MHz and 2.4[Formula: see text]GHz. At 900[Formula: see text]MHz-band (825–960[Formula: see text]MHz), with 1[Formula: see text]M[Formula: see text] load resistor, the output voltage of the energy harvester can be over 1.0[Formula: see text]V with a minimum [Formula: see text]18[Formula: see text]dBm RF input power and a maximum 13.8% power conversion efficiency (PCE). At 2.4[Formula: see text]GHz-band (2.4–2.485[Formula: see text]GHz), the minimum input power can be as low as [Formula: see text]19[Formula: see text]dBm with a maximum efficiency of 16.8%.

Loop Antenna Over Artificial Magnetic Conductor Surface and Its Application to Dual-Band RF Energy Harvesting

This paper studies loop antennas over artificial magnetic conductor (AMC) surfaces with the objective of designing a dual-band RF energy harvesting antenna. The AMC surface is well known to achieve low-profile and higher gain wire antennas. From a practical point of view, impedance matching is of paramount importance to achieve highly efficient reception of weak ambient RF energy. First, the driving-point impedance of a loop antenna over an AMC surface was studied, where a conventional method using image theory to estimate the impedance was found to be not always useful for loop antennas. As the AMC surface is within the reactive near field, mutual coupling between the antenna and the AMC unit cells is significant, which the conventional method does not take into account. Then, we proposed a novel use of a polarization-dependent AMC surface for dual-band RF energy harvesting. An AMC surface with a rectangular unit cell was adopted for two orthogonal polarizations with different frequencies. Finally, the AMC surface and the loop antennas were successfully implemented as a dual-band energy harvesting panel together with RF-to-dc conversion circuits and a power management circuit.

An Antenna Co-Design Dual Band RF Energy Harvester

RF energy is widely available in urban areas and thus presents a promising ambient energy harvesting source. In this paper, a CMOS harvester circuit is modeled and analyzed in detail at low environmental power levels. Based on the circuit analysis, a design procedure is given for a narrowband energy harvester. The antenna and harvester co-design methodology is discussed to improve RF to DC energy conversion efficiency. We demonstrate that it is difficult to harvest RF energy over a wide frequency band if the ambient RF energy sources are weak, owing to the voltage requirements. Since most ambient RF energy lies in a few narrow bands, a dual/multi-band energy harvester architecture should be able to harvest much of the available RF energy. A dual-band CMOS energy harvester is designed and fabricated using an IBM 0.13 μm process. The simulated and measured results demonstrate a dual-band energy harvester that obtains over 9% efficiency for two different bands (around 900 MHz and around 1900 MHz) at an input power as low as -19.3 dBm. The DC output voltage of this harvester is over 1 V, which can be used to recharge the battery to form an inexhaustibly powered communication system.