1,721,050 research outputs found
Energy harvesting for smart city applications
No full textThe 'smart cities' concept is now becoming a reality: cities are increasingly connected and intelligent, with rapid advances in diverse areas including transportation, utilities, and municipal services. These can allow services to be delivered more efficiently and reliably, enriching residents' and visitors' experiences, and the data generated can be used for innovative new applications. While many sensors enabling these applications can be grid-powered, there is an increasing need for autonomous distributed or wearable sensing devices, which may also perform edge analytics. While these systems are typically powered by batteries so that they can be deployed quickly and cheaply, this comes with the cost of periodic battery replacement. This paper surveys the state-of-the-art in smart city sensing applications and considers their future directions, focusing on the power demands of sensors, and considerations for using energy harvesting.</p
Meshed high-impedance matching network-free rectenna optimized for additive manufacturing
No full textAdditive manufacturing using direct-write or screen printing represents low-waste methods for fabricating antennas on low-cost flexible substrates. To realize rectennas using low-resolution printing methods, high-impedance antennas with simple printable geometries are required. This paper proposes an electrically-small (0.212×0.212λ2) folded dipole antenna design with a scalable impedance for directly matching energy harvesting rectifiers. The antenna is demonstrated in a high-efficiency sub-1 GHz rectenna, with varying mesh fill-factors for optical transparency. The proposed solid (non-transparent) and meshed (70%-transparent) rectennas achieve a Power Conversion Efficiency (PCE) of over 70% and 60% from sub-1 μW/cm2 power densities, at 940 and 920 MHz, respectively. This represents a 37% improvement in the PCE over state-of-the-art flexible rectennas while maintaining the smallest electrical size and simplest design by not requiring a matching network. The 70%-transparent rectenna’s performance is investigated in real-life use-cases showing its suitability for ambient RF energy harvesting with over 500 mV DC output from a phone-call
Using environmental data for IoT device energy harvesting prediction
No full textThere has been significant innovation in the domain of Internet of Things (IoT) as nowadays wireless data transmission is playing an essential role in various organizations like agriculture, defence, transportation, etc. Batteries are the most common option to power wireless devices. However, using batteries to power IoT devices has drawbacks including the cost and disruption of frequent battery replacement, and environmental concerns about battery disposal. Solar energy harvesting is a promising solution for long-term operation applications. However, solar energy harvesting varies drastically over location and time. Due to fluctuating weather conditions and the environmental effects on PV surface condition, output could be reduced and become insufficient. Environmental conditions including temperature, wind, solar irradiance, humidity, tilt angle and the dust accumulated over time on the photovoltaic (PV) module surface affects the amount of energy harvested. To address this issue, a novel solution is required to autonomously predict the harvested energy and plan the IoT device tasks accordingly, to enhance its performance and lifetime. Using Machine Learning (ML) algorithms could make it possible to predict how much energy can be harvested using weather forecast data. This research is ongoing, and aims to apply ML algorithms on historical weather data including environmental factors to generate solar energy predictions for IoT device energy budget planning
Millimeter-wave textile antenna for on-body RF energy harvesting in future 5G networks
No full textMillimeter-Wave (mmWave) bands will be a key part of future 5G networks, with the 26 and 28 GHz bands being introduced first. The wide bandwidth aims to solve traffic-related issues. The projected high base-station density, highly directive transmitters, and the wide bandwidth make it a very promising RF energy harvesting (RFEH) source. Broadband antennas are necessary to harvest power efficiently from the full spectrum.This work presents the first antenna on textile for wearable ambient RFEH in the 26 GHz and 28 GHz bands. The antenna has an impedance bandwidth from 20 to 30 GHz, and exhibits a peak on-body gain of 7 dB with an omnidirectional radiation pattern for capturing ambient RF energy. The radiation efficiency on- and off-body was observed to be at least 40% and 60% respectively, between 24 and 30 GHz. A two-line microstrip dielectric characterization of the textile substrate in the mm Waveband has been performed. The antenna has been fabricated on a 310 μm woven polyester substrate using etched ultra-thin Polyimide copper laminates with a minimum feature size of 150μm. A high robustness against human proximity has been demonstrated with a stable bandwidth and improved gain
Dispenser printed flexible rectenna for dual-ISM band high-efficiency supercapacitor charging
No full textThis paper presents a dual-band sub-1 GHz rectenna for near and far-field powering of Internet of Things(IoT) nodes. The rectifier is based on a coplanar waveguide (CPW) voltage doubler with inductive matching, achieving over 80% power conversion efficiency (PCE) at 10 dBm and 915 MHz.The rectifier is designed to directly charge a 6.8 mF supercapacitor with no DC power management circuitry or load tracking, achieving the highest reported average charging efficiency of47.2% and 33.3%, at 433 and 915 MHz respectively. From6 dBm input power, a 1.5-2.8 mA dummy load can be RF-powered with over 30% duty-cycle at 915 MHz. A dual-band single-layer antenna is designed and fabricated using dispenser printing on a flexible polyimide substrate. The antenna maintains over 2.1 dBi gain at 915 MHz with omnidirectional patterns, whileoccupying under 10×10 cm. The integrated rectenna is evaluatedin two real-world applications: energy harvesting from a 915MHz transmitter showing a 49% wireless charging efficiency for a 7.4μW/cm2incident power density; and ambient energy harvesting generating 47 mJ in 5 seconds at 3 to 5 cm from ahandheld two-way radio
Dataset for the journal article "Impact of dust and tilt angle on the photovoltaic performance in a desert environment"
No full textDataset supporting the journal article "Impact of dust and tilt angle on the photovoltaic performance in a desert environment", published in: Solar Energy (Elsevier).
This dataset evaluates the performance of photovoltaic (PV) modules with different tilt angles under varying environmental conditions, focusing on the impact of dust accumulation in desert environments. It includes power output measurements for clean and dusty modules. The data is presented in .xlsx file that support figures in the publication.</span
Millimeter-wave textile-based monopole antenna for wearable wireless power transmission
No full textWith a wide bandwidth and a high potential for antenna miniaturization, the millimeter-wave (mmWave) bands have attracted interest for a range of wearable applications. In this paper, a textile-based end-fire monopole is proposed for wireless power transmission (WPT) applications. The proposed Yagi-inspired antenna bandwidth covers the 24 GHz license-free band. The antenna achieves 73% total efficiency, a 2.5 dB improvement over a microstrip patch on the same textile substrate. The antenna has a peak gain over 4 dBi with a wide 80 half-power beamwidth both in space and on a layered human tissue model. The antenna is experimentally characterized for line-of-sight WPT showing a 7 dB forward transmission improvement compared to 2.45 GHz WPT, for 55 cm separation, between two symmetric antennas with sub-cm2 area. Given the antenna’s 0.4 cm2 area, it is shown that mmWaves enable high-efficiency WPT to miniaturized antennas in future 5G networks
Rectennas for radio-frequency energy harvesting and wireless power transfer: A review of antenna design [Antenna applications corner]
No full textRadio-frequency (RF) energy harvesting (RFEH) and radiative wireless power transfer (WPT) have attracted significant interest as methods of enabling battery-free sustainable wireless networks. Rectifying antennas (rectennas) are the cornerstone of WPT and RFEH systems and critically affect the amount of dc power delivered to the load. The antenna element of the rectenna directly impacts the radiation-to-ac harvesting efficiency, which can vary the harvested power by orders of magnitude. In this article, antenna designs employed in WPT and ambient RFEH applications are reviewed. Reported rectennas are categorized based on two main criteria: the antenna-rectifier impedance bandwidth and the antenna's radiation properties. For each criterion, the figure of merit (FoM) is identified for different applications and reviewed comparatively.</p
Towards multi-mode millimeter wave body area networks for information and power transmission: a co-existence study
No full textWhile millimeter-wave (mmWave) technologies are often associated with costly applications using large arrays, several inexpensive implementations promise mmWave connectivity closer to the user in Body Area Networks (BANs) applications. Here, we evaluate the potential for multi-mode mmWave links for information and power transfer applications. The co-existence of off-body radiative and on-body wave-guiding mechanisms is experimentally investigated based on state-of-the-art transmission lines and antennas. First, a body-to-body link with at least -50 dB channel gain is demonstrated based on wide-beam microstrip and reflector-backed broadband antennas. Co-existence is then studied experimentally by measuring the coupling between the off-body communication/power transfer antenna and a wearable Single Wire Transmission Line (SWTL), with an ultra-low on-body attenuation of below -0.8 dB/cm around 28 GHz. Less than -40 dB coupling is demonstrated for clearances as low as 1 cm between the antenna and SWTL. The measured results indicate that co-located textile-based antennas and transmission lines can enable multi-mode high-performance body-centric mmWave networks, and highlight the need for interference-countering mechanisms in future high-density BANs
High-efficiency sub-1 GHz flexible compact rectenna based on parametric antenna-rectifier co-design
No full textThis work presents a high-efficiency, high-sensitivity, compact flexible rectenna based on a high-impedance folded dipole antenna, for sub-1 GHz license-free applications. A voltage-doubler rectifier is studied parametrically, using Electromagnetic-Harmonic Balance co-simulation, to extract the optimal load and source impedances for maximum power conversion efficiency (PCE), using an iterative source and load tuning approach. The proposed antenna is then studied parametrically and designed to directly conjugate the rectifier’s impedance eliminating the matching network and its associated losses. The integrated rectenna is ultra-compact (area = 0.0122 λ2) and is fabricated on a 25 µm-thick flexible low-cost polyimide substrate. The proposed rectenna achieves a remarkable PCE of 43% and 83% at -20 and -4 dBm, respectively. Furthermore, a 1-V DC output is achieved across a 20 kΩ load (optimal impedance) from -9 dBm input. The rectenna demonstrates a -3 dB (50% relative PCE) fractional-bandwidth of 7.9% (813–880 MHz), covering the 868 MHz license-free band
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