This document provides a review of using plasmonic nano-antennas to harvest mid-infrared (MIR) energy from the environment to power nano air vehicles (NAVs). It discusses how NAVs have limited flight times due to battery capacity, and harvesting ambient MIR radiation emitted from the Earth's surface is a potential solution. The document reviews MIR rectennas that could convert this radiation to DC electricity for constant power. Potential applications for powering NAVs include civil security, disaster monitoring, and hazardous environment inspection. It also provides equations to estimate NAV flight times and ranges based on battery and design specifications.
what is air borne wind energy system and how it is work and types of wind energy system history of air borne wind energy system mathematical calculation related to awes all are in this pdf
In this paper, we present the idea of sun based vitality satellites sun oriented cells in the satellite Convert daylight into power, which will transform into radio recurrence vitality, at that point a collector will achieve the site Earth was re jolted by utilizing the reception apparatus with the innovation of remote and accepting it Power transmission is transmitting power i.e., as microwave for lessening transmission and dispersion. In this paper we want to elaborate all the aspect related to the wireless power transmission using solar power satellite by which the overall efficiency, reliability will be increased. Karan Sharma | Prateeek Saini | Naveen Jangid | Dr. Himani Goyal Sharma ""Wireless Power Transmission using SPS"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-3 , April 2019, URL: https://www.ijtsrd.com/papers/ijtsrd21719.pdf
Paper URL: https://www.ijtsrd.com/engineering/electrical-engineering/21719/wireless-power-transmission-using-sps/karan-sharma
This research proposal suggests studying the optimal arrangement of floating offshore wind turbines (FOWT) in a wind farm to minimize costs and improve efficiency. The proposal notes that incoming waves interacting with FOWT structures produce scattered and radiated waves that can interfere destructively with ambient waves at certain points. Arranging FOWT at these intersection points could reduce wave-induced loads, allowing cheaper floating platforms and moorings. The proposal focuses on the semi-submersible 'Trifloater' design and using computational fluid dynamics to model wave interactions and determine an optimal arrangement that minimizes motion for large-scale FOWT arrays.
This document discusses applications and future work regarding nanoantennas. Some potential applications include integrating nanoantennas into consumer electronics to continuously charge batteries, coating buildings to supplement the power grid, and fabricating them into polyester fabric. Future work includes designing nanoantennas to operate at other wavelengths to concurrently collect visible, near-infrared, and mid-infrared energy. Researchers also aim to develop photonic systems and switches that can efficiently handle the absorbed light without converting it to electricity.
This document summarizes the design and testing of a fuel cell powered unmanned aerial vehicle (UAV) for low altitude surveillance missions. The UAV was designed with an aerodynamic glider configuration and powered by a 200 W polymer electrolyte membrane fuel cell system fed by a chemical hydride hydrogen generator, along with lithium polymer batteries. Bench and flight tests showed the hybrid power system enabled flight durations of nearly 4 hours. The document discusses the aircraft design process, onboard power system, results from testing, and lessons learned for optimizing long endurance fuel cell powered UAVs.
The Underwater Sensor Network (UWSN) is main interesting area due to its most valuable
applications like: disaster preventions, distributed tactical surveillance, undersea exploration, seismic
monitoring, environmental monitoring and many more. The design of energy efficient routing protocol
however is a challenging issue because in underwater environment the batteries of the sensor nodes
cannot be recharged easily. Majority of the researchers have adapted the terrestrial WSN methodologies
to overcome this problem but in underwater environment the terrestrial WSN approach is not feasible due
to the acoustic signaling and water current. This research paper focuses the key limitation of the current
energy efficient routing protocols. The simulation results with comparative analysis for energy efficient
routing protocols are also presented in this research article; which helps the researchers to find the further
research gap in the field of energy efficient routing protocols.
A new configuration of patch antenna array for rectenna array applicationsTELKOMNIKA JOURNAL
The performance and advantages of microstrip patch antennas made them a field of interest for wireless power transmission applications, especially for rectenna systems where the choice of the antenna is a crucial step. In this paper, a 5.8 GHz circularly polarized patch antenna has been designed and fabricated, then mounted by using 4 elements to achieve an antenna array to enhance the captured power to be converted by the rectifier circuit. The antenna array is well matched at 5.8 GHz in terms of reflection coefficient and has a directivity of 11 dB and a gain of 6 dB. Results have been confirmed by fabrication.
solar power satellite & microwave power transmissionbhavisha patel
In this seminar topic,I included all the things related SPS system & how microwave power transmission can done through magetron,retro directive beam controlling scheme & all.I also mentioned the design of optical rectenna & economic evolution of the topic.
what is air borne wind energy system and how it is work and types of wind energy system history of air borne wind energy system mathematical calculation related to awes all are in this pdf
In this paper, we present the idea of sun based vitality satellites sun oriented cells in the satellite Convert daylight into power, which will transform into radio recurrence vitality, at that point a collector will achieve the site Earth was re jolted by utilizing the reception apparatus with the innovation of remote and accepting it Power transmission is transmitting power i.e., as microwave for lessening transmission and dispersion. In this paper we want to elaborate all the aspect related to the wireless power transmission using solar power satellite by which the overall efficiency, reliability will be increased. Karan Sharma | Prateeek Saini | Naveen Jangid | Dr. Himani Goyal Sharma ""Wireless Power Transmission using SPS"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-3 , April 2019, URL: https://www.ijtsrd.com/papers/ijtsrd21719.pdf
Paper URL: https://www.ijtsrd.com/engineering/electrical-engineering/21719/wireless-power-transmission-using-sps/karan-sharma
This research proposal suggests studying the optimal arrangement of floating offshore wind turbines (FOWT) in a wind farm to minimize costs and improve efficiency. The proposal notes that incoming waves interacting with FOWT structures produce scattered and radiated waves that can interfere destructively with ambient waves at certain points. Arranging FOWT at these intersection points could reduce wave-induced loads, allowing cheaper floating platforms and moorings. The proposal focuses on the semi-submersible 'Trifloater' design and using computational fluid dynamics to model wave interactions and determine an optimal arrangement that minimizes motion for large-scale FOWT arrays.
This document discusses applications and future work regarding nanoantennas. Some potential applications include integrating nanoantennas into consumer electronics to continuously charge batteries, coating buildings to supplement the power grid, and fabricating them into polyester fabric. Future work includes designing nanoantennas to operate at other wavelengths to concurrently collect visible, near-infrared, and mid-infrared energy. Researchers also aim to develop photonic systems and switches that can efficiently handle the absorbed light without converting it to electricity.
This document summarizes the design and testing of a fuel cell powered unmanned aerial vehicle (UAV) for low altitude surveillance missions. The UAV was designed with an aerodynamic glider configuration and powered by a 200 W polymer electrolyte membrane fuel cell system fed by a chemical hydride hydrogen generator, along with lithium polymer batteries. Bench and flight tests showed the hybrid power system enabled flight durations of nearly 4 hours. The document discusses the aircraft design process, onboard power system, results from testing, and lessons learned for optimizing long endurance fuel cell powered UAVs.
The Underwater Sensor Network (UWSN) is main interesting area due to its most valuable
applications like: disaster preventions, distributed tactical surveillance, undersea exploration, seismic
monitoring, environmental monitoring and many more. The design of energy efficient routing protocol
however is a challenging issue because in underwater environment the batteries of the sensor nodes
cannot be recharged easily. Majority of the researchers have adapted the terrestrial WSN methodologies
to overcome this problem but in underwater environment the terrestrial WSN approach is not feasible due
to the acoustic signaling and water current. This research paper focuses the key limitation of the current
energy efficient routing protocols. The simulation results with comparative analysis for energy efficient
routing protocols are also presented in this research article; which helps the researchers to find the further
research gap in the field of energy efficient routing protocols.
A new configuration of patch antenna array for rectenna array applicationsTELKOMNIKA JOURNAL
The performance and advantages of microstrip patch antennas made them a field of interest for wireless power transmission applications, especially for rectenna systems where the choice of the antenna is a crucial step. In this paper, a 5.8 GHz circularly polarized patch antenna has been designed and fabricated, then mounted by using 4 elements to achieve an antenna array to enhance the captured power to be converted by the rectifier circuit. The antenna array is well matched at 5.8 GHz in terms of reflection coefficient and has a directivity of 11 dB and a gain of 6 dB. Results have been confirmed by fabrication.
solar power satellite & microwave power transmissionbhavisha patel
In this seminar topic,I included all the things related SPS system & how microwave power transmission can done through magetron,retro directive beam controlling scheme & all.I also mentioned the design of optical rectenna & economic evolution of the topic.
This chapter discusses wind resource and site assessment for wind farm projects. It explains that accurate wind speed measurements are crucial for assessing the wind resource and financial viability of a project. On-site wind measurements should be taken for at least one full year using high-quality instruments like cup anemometers. Careful instrument selection, installation, calibration and data analysis are important to obtain reliable wind speed data that can then be used to model the spatial variation of wind across the site.
This document describes a proposed design for a renewable energy quadrotor system (REQS) capable of extended autonomous flight in variable environments. The REQS would combine multirotor drone technology with integrated solar panels and wind turbines to prolong flight time. A scaled proof-of-concept model was built and tested to determine feasibility. Testing showed the design provided sufficient space for electronics and sensors while the renewable components generated adequate power without degrading flight. Future applications discussed include arctic data collection, planetary exploration, and agricultural monitoring.
This document describes the CubeSat High Impulse Propulsion System (CHIPS) being developed by CU Aerospace and VACCO Industries. CHIPS integrates primary propulsion, attitude control, and propellant storage into a single module compatible with CubeSats. It uses a micro-resistojet thruster and cold gas attitude control system. Testing of a prototype showed the resistojet can provide up to 563 N-s of total impulse using R134a propellant. The document discusses propulsion options for CubeSats and why electrothermal propulsion in the 70-400 second specific impulse range is best suited for enabling rapid orbital maneuvers within a day.
The document discusses wave energy technology. It describes three main categories of wave energy converters: oscillating water columns that use air pockets to drive turbines; oscillating body converters that use wave motion to generate electricity; and overtopping converters that use reservoirs to drive turbines. More than 100 pilot and demonstration projects exist worldwide but only a handful are close to commercialization. The document estimates the potential cost of electricity from wave energy and barriers to its development and deployment.
This document discusses solar power satellites (SPS). It begins by introducing SPS as a renewable energy source that could transmit power to Earth via microwave beams from satellites in geosynchronous orbit. It then discusses the need for alternative energy sources due to increasing demand and environmental issues from fossil fuels. The document outlines the history and concepts behind SPS, including their structure and use of klystron transmitters, beam control systems, and rectennas to convert and transmit power. It notes both advantages such as a constant power supply and disadvantages including high costs. The conclusion states that while large-scale wireless power transmission must still be proven, SPS could help solve energy issues in the coming decades.
The document discusses an airborne wind energy system called an energy kite. An energy kite system replaces traditional wind turbines by using kites equipped with turbines or DC motors. These kites fly in a circular trajectory hundreds of meters above the ground, harnessing stronger winds and generating electricity through the motors on board. The kites are tethered to the ground by strong carbon fiber cables that transmit the generated electricity. Energy kite systems have advantages over traditional wind turbines like access to stronger winds, lower costs, and greater power generation potential. They could significantly reduce air pollution if widely adopted.
IRJET- Transmission of Ac Power from Offshore to Onshore by using Low Frequen...IRJET Journal
This document discusses the transmission of AC power from offshore wind farms to onshore grids using low frequency AC transmission. Some key points:
1) Offshore wind farms generate power at medium voltage DC which is converted to low frequency AC (e.g. 20Hz) using cycloconverters for transmission through undersea cables.
2) At the receiving end, the low frequency AC is converted back to standard grid frequency AC using phase shift transformers before connecting to the onshore grid.
3) Low frequency AC transmission allows use of the same undersea cable designs as used for standard frequency but increases transmission capacity and distance. It provides an alternative to HVAC and HVDC transmission for medium length offshore connections.
Fusion Energy: When might it become economically feasible?Jeffrey Funk
These slides discuss the technological trends that might make fusion energy economically feasible in the future. Steady improvements in superconductors are improving the economic feasibility of magnetic confinement, which can be measured by the "triple product." this triple product includes temperature, plasma density, and controlled reaction time. these superconductors are currently being improved for other applications such as MRI and energy transmission. Improvements in inertial laser confinement are also occurring through improvements in lasers, which are also being used in other applications. What does this mean for policy?
Wind energy is a promising energy source. Modern wind power industry officially started in 1979 in Denmark with a
turbine of few KW and its evaluation brought up to now, devices of which rated power is higher than 20 MW.
The size of wind turbine’s massively increased and their design achieved a common standard device: Horizontal axis,
Three blades, Upwind, Pitch controlled blades, Active yaw system.
Design of Lattice Wind Turbine Towers With Structural OptimizationIJERA Editor
This article aims to study the self-supporting truss towers used to support large wind turbines in areas with high altitude. The goal is to evaluate and validate numerically by finite element method the structural analysis when the lattice structures of the towers of wind turbines are subjected to static loads and these from common usage. With this, it is expected minimize the cost of transportation and installation of the tower and maximize the generation of electricity, respecting technical standards and restrictions of structural integrity and safety, making vibration analysis and the required static and dynamic loads, thereby preventing failures by fractures or mechanical fatigue. Practical examples of towers will be designed by the system and will be tested in structural simulation programs using the Finite Element Method. This analysis is done on the entire region coupling action of the turbine, with variable sensitivity to vibration levels. The results obtained for freestanding lattice tower are compared with the information of a tubular one designed to support the generator with the same characteristics. At the end of this work itwas possible to observe the feasibility of using lattice towers that proved better as its structural performance but with caveats about its dynamic performance since the appearance of several other modes natural frequency thus reducing the intervals between them in low frequency and theoretically increase the risk of resonance.
A Systematic Review of Renewable Energy Trend.pdfssuser793b4e
This paper systematically and successfully reviewed the renewable energy trend from 2010 to 2023. This review
detailed the difference renewable energy and conclusion was drawn that solar photovoltaic (PV) energy has the
leading trend in power generation growth and innovation. This research work explained in detail the most recent
solar photovoltaic optimization techniques and it was observed from the review that hybridization of intelligent and
non-intelligent maximum power point tracking technique has the best tracking power conversion efficiency. The
advantages and disadvantage of solar PV together with the solar optimization and innovational growth trends were
examined. This research showed that clean and renewable energy sources will continue to grow and the solar energy
industry is expected to experience significant growth and rapid innovation in the next 10 years. From the observed
rapid growth and innovation trend in solar energy, the world will have a very cheap, abundant and clean energy
before 2050.
The SpaceDrive Project - First Results on EMDrive and Mach-Effect ThrustersSérgio Sacani
Propellantless propulsion is believed to be the best option for interstellar travel. However, photon rockets or solar sails have thrusts so low that maybe only nano-scaled spacecraft may reach the next star within our lifetime using very high-power laser beams. Following into the footsteps of earlier breakthrough propulsion programs, we are investigating different concepts based on non-classical/revolutionary propulsion ideas that claim to be at least an order of magnitude more efficient in producing thrust compared to photon rockets. Our intention is to develop an excellent research infrastructure to test new ideas and measure thrusts and/or artefacts with high confidence to determine if a concept works and if it does how to scale it up. At present, we are focusing on two possible revolutionary concepts: The EMDrive and the Mach-Effect Thruster. The first concept uses microwaves in a truncated cone-shaped cavity that is claimed to produce thrust. Although it is not clear on which theoretical basis this can work, several experimental tests have been reported in the literature, which warrants a closer examination. The second concept is believed to generate mass fluctuations in a piezo-crystal stack that creates non-zero time-averaged thrusts. Here we are reporting first results of our improved thrust balance as well as EMDrive and Mach-Effect thruster models. Special attention is given to the investigation and identification of error sources that cause false thrust signals. Our results show that the magnetic interaction from not sufficiently shielded cables or thrusters are a major factor that needs to be taken into account for proper μN thrust measurements for these type of devices.
Iaetsd rf controlled sailing robot for oceanic missionsIaetsd Iaetsd
This document discusses a proposed sailing robot that can be controlled remotely using RF wireless communication. The robot would use sensors like depth sensors, obstacle sensors, and metal detectors to perform tasks like measuring ocean depths and locating sunken ships. It would also use a GPS module for navigation and tracking and a camera to send video back to the controller. The robot's movements would be controlled from a laptop using an RF module, and sensor data would also be transmitted back to the laptop. The goal is to develop a robot that can perform dangerous oceanic missions without risking human lives onboard.
This document summarizes the feasibility study of the WindFloat technology, a three-legged floating foundation designed to support offshore wind turbines in water depths from 30-50 meters. Key advantages of the floating foundation include flexibility in site location, access to stronger wind resources further offshore, and simpler offshore installation procedures compared to fixed foundations. The design draws on offshore oil and gas platform technologies while accounting for the different requirements of wind turbines. Hydrodynamic analysis and testing were performed to understand platform motions under wave and wind loads. Coupling of aerodynamic and hydrodynamic models allows for a more accurate analysis of interactions between the turbine and floating platform.
Adaptive maximum power point tracking using neural networks for a photovoltai...Mellah Hacene
Adaptive Maximum Power Point Tracking Using Neural Networks for a Photovoltaic Systems According Grid
Electrical Engineering & Electromechanics, (5), 57–66, 2021. https://doi.org/10.20998/2074-272X.2021.5.08
Advanced weather forecasting for RES applications: Smart4RES developments tow...Leonardo ENERGY
Recording at: https://youtu.be/45Zpjog95QU
This is the 3rd Smart4RES webinar that will address technological and market challenges in RES prediction and will introduce the Smart4RES strategy to improve weather forecasting models with high resolution.
Through wind and solar applications, Innovative Numerical Weather Prediction and Large-Eddy Simulation approaches will be presented.
LBRP: A RESILIENT ENERGY HARVESTING NOISE AWARE ROUTING PROTOCOL FOR UNDER WA...ijfcstjournal
Underwater detector network is one amongst the foremost difficult and fascinating analysis arenas that open the door of pleasing plenty of researchers during this field of study. In several under water based
sensor applications, nodes are square measured and through this the energy is affected. Thus, the mobility of each sensor nodes are measured through the water atmosphere from the water flow for sensor based protocol formations. Researchers have developed many routing protocols. However, those lost their charm with the time. This can be the demand of the age to supply associate degree upon energy-efficient and ascendable strong routing protocol for under water actuator networks. During this work, the authors tend to propose a customary routing protocol named level primarily based routing protocol (LBRP), reaching to offer strong, ascendable and energy economical routing. LBRP conjointly guarantees the most effective use of total energy consumption and ensures packet transmission which redirects as an additional reliability in compare to different routing protocols. In this work, the authors have used the level of forwarding node, residual energy and distance from the forwarding node to the causing node as a proof in multicasting technique comparisons. Throughout this work, the authors have got a recognition result concerning about
86.35% on the average in node multicasting performances. Simulation has been experienced each in a wheezy and quiet atmosphere which represents the endorsement of higher performance for the planned protocol.
LBRP: A RESILIENT ENERGY HARVESTING NOISE AWARE ROUTING PROTOCOL FOR UNDER WA...ijfcstjournal
Underwater detector network is one amongst the foremost difficult and fascinating analysis arenas that
open the door of pleasing plenty of researchers during this field of study. In several under water based
sensor applications, nodes are square measured and through this the energy is affected. Thus, the mobility
of each sensor nodes are measured through the water atmosphere from the water flow for sensor based
protocol formations. Researchers have developed many routing protocols. However, those lost their charm
with the time. This can be the demand of the age to supply associate degree upon energy-efficient and
ascendable strong routing protocol for under water actuator networks. During this work, the authors tend
to propose a customary routing protocol named level primarily based routing protocol (LBRP), reaching to
offer strong, ascendable and energy economical routing. LBRP conjointly guarantees the most effective use
of total energy consumption and ensures packet transmission which redirects as an additional reliability in
compare to different routing protocols. In this work, the authors have used the level of forwarding node,
residual energy and distance from the forwarding node to the causing node as a proof in multicasting
technique comparisons. Throughout this work, the authors have got a recognition result concerning about
86.35% on the average in node multicasting performances. Simulation has been experienced each in a
wheezy and quiet atmosphere which represents the endorsement of higher performance for the planned
protocol.
LBRP: A RESILIENT ENERGY HARVESTING NOISE AWARE ROUTING PROTOCOL FOR UNDER WA...ijfcstjournal
Underwater detector network is one amongst the foremost difficult and fascinating analysis arenas that open the door of pleasing plenty of researchers during this field of study. In several under water based sensor applications, nodes are square measured and through this the energy is affected. Thus, the mobility of each sensor nodes are measured through the water atmosphere from the water flow for sensor based protocol formations. Researchers have developed many routing protocols. However, those lost their charm with the time. This can be the demand of the age to supply associate degree upon energy-efficient and ascendable strong routing protocol for under water actuator networks. During this work, the authors tend to propose a customary routing protocol named level primarily based routing protocol (LBRP), reaching to offer strong, ascendable and energy economical routing. LBRP conjointly guarantees the most effective use of total energy consumption and ensures packet transmission which redirects as an additional reliability in compare to different routing protocols. In this work, the authors have used the level of forwarding node, residual energy and distance from the forwarding node to the causing node as a proof in multicasting technique comparisons. Throughout this work, the authors have got a recognition result concerning about 86.35% on the average in node multicasting performances. Simulation has been experienced each in a wheezy and quiet atmosphere which represents the endorsement of higher performance for the planned protocol.
Remote Monitoring and Control of Boat Using Lora TechnologyIJAEMSJORNAL
This work is a prototype boat that can travel in water. This robot is powered by rechargeable battery. The direction of the robot can be precise by an RF remote. This can be moved forward and reverse direction by using geared motors, also this robot can take sharp turnings towards left and right directions. In this work the LPC2148, DC Servomotors, RF Technology; L293D H-Bridge is used to drive the DC Servomotor. A high sensitive camera is also interfaced to capture the surrounding things and also to transmit to the remote place. The RF modules used here are STT-868 MHz Transmitter, STR-868 MHz Receiver. The three switches are connected to the RF transmitter through RF Encoder. The encoder constantly recites the position of the switches and permits the data to the RF transmitter and the transmitter transmits the data for further process.
Software Engineering and Project Management - Software Testing + Agile Method...Prakhyath Rai
Software Testing: A Strategic Approach to Software Testing, Strategic Issues, Test Strategies for Conventional Software, Test Strategies for Object -Oriented Software, Validation Testing, System Testing, The Art of Debugging.
Agile Methodology: Before Agile – Waterfall, Agile Development.
This chapter discusses wind resource and site assessment for wind farm projects. It explains that accurate wind speed measurements are crucial for assessing the wind resource and financial viability of a project. On-site wind measurements should be taken for at least one full year using high-quality instruments like cup anemometers. Careful instrument selection, installation, calibration and data analysis are important to obtain reliable wind speed data that can then be used to model the spatial variation of wind across the site.
This document describes a proposed design for a renewable energy quadrotor system (REQS) capable of extended autonomous flight in variable environments. The REQS would combine multirotor drone technology with integrated solar panels and wind turbines to prolong flight time. A scaled proof-of-concept model was built and tested to determine feasibility. Testing showed the design provided sufficient space for electronics and sensors while the renewable components generated adequate power without degrading flight. Future applications discussed include arctic data collection, planetary exploration, and agricultural monitoring.
This document describes the CubeSat High Impulse Propulsion System (CHIPS) being developed by CU Aerospace and VACCO Industries. CHIPS integrates primary propulsion, attitude control, and propellant storage into a single module compatible with CubeSats. It uses a micro-resistojet thruster and cold gas attitude control system. Testing of a prototype showed the resistojet can provide up to 563 N-s of total impulse using R134a propellant. The document discusses propulsion options for CubeSats and why electrothermal propulsion in the 70-400 second specific impulse range is best suited for enabling rapid orbital maneuvers within a day.
The document discusses wave energy technology. It describes three main categories of wave energy converters: oscillating water columns that use air pockets to drive turbines; oscillating body converters that use wave motion to generate electricity; and overtopping converters that use reservoirs to drive turbines. More than 100 pilot and demonstration projects exist worldwide but only a handful are close to commercialization. The document estimates the potential cost of electricity from wave energy and barriers to its development and deployment.
This document discusses solar power satellites (SPS). It begins by introducing SPS as a renewable energy source that could transmit power to Earth via microwave beams from satellites in geosynchronous orbit. It then discusses the need for alternative energy sources due to increasing demand and environmental issues from fossil fuels. The document outlines the history and concepts behind SPS, including their structure and use of klystron transmitters, beam control systems, and rectennas to convert and transmit power. It notes both advantages such as a constant power supply and disadvantages including high costs. The conclusion states that while large-scale wireless power transmission must still be proven, SPS could help solve energy issues in the coming decades.
The document discusses an airborne wind energy system called an energy kite. An energy kite system replaces traditional wind turbines by using kites equipped with turbines or DC motors. These kites fly in a circular trajectory hundreds of meters above the ground, harnessing stronger winds and generating electricity through the motors on board. The kites are tethered to the ground by strong carbon fiber cables that transmit the generated electricity. Energy kite systems have advantages over traditional wind turbines like access to stronger winds, lower costs, and greater power generation potential. They could significantly reduce air pollution if widely adopted.
IRJET- Transmission of Ac Power from Offshore to Onshore by using Low Frequen...IRJET Journal
This document discusses the transmission of AC power from offshore wind farms to onshore grids using low frequency AC transmission. Some key points:
1) Offshore wind farms generate power at medium voltage DC which is converted to low frequency AC (e.g. 20Hz) using cycloconverters for transmission through undersea cables.
2) At the receiving end, the low frequency AC is converted back to standard grid frequency AC using phase shift transformers before connecting to the onshore grid.
3) Low frequency AC transmission allows use of the same undersea cable designs as used for standard frequency but increases transmission capacity and distance. It provides an alternative to HVAC and HVDC transmission for medium length offshore connections.
Fusion Energy: When might it become economically feasible?Jeffrey Funk
These slides discuss the technological trends that might make fusion energy economically feasible in the future. Steady improvements in superconductors are improving the economic feasibility of magnetic confinement, which can be measured by the "triple product." this triple product includes temperature, plasma density, and controlled reaction time. these superconductors are currently being improved for other applications such as MRI and energy transmission. Improvements in inertial laser confinement are also occurring through improvements in lasers, which are also being used in other applications. What does this mean for policy?
Wind energy is a promising energy source. Modern wind power industry officially started in 1979 in Denmark with a
turbine of few KW and its evaluation brought up to now, devices of which rated power is higher than 20 MW.
The size of wind turbine’s massively increased and their design achieved a common standard device: Horizontal axis,
Three blades, Upwind, Pitch controlled blades, Active yaw system.
Design of Lattice Wind Turbine Towers With Structural OptimizationIJERA Editor
This article aims to study the self-supporting truss towers used to support large wind turbines in areas with high altitude. The goal is to evaluate and validate numerically by finite element method the structural analysis when the lattice structures of the towers of wind turbines are subjected to static loads and these from common usage. With this, it is expected minimize the cost of transportation and installation of the tower and maximize the generation of electricity, respecting technical standards and restrictions of structural integrity and safety, making vibration analysis and the required static and dynamic loads, thereby preventing failures by fractures or mechanical fatigue. Practical examples of towers will be designed by the system and will be tested in structural simulation programs using the Finite Element Method. This analysis is done on the entire region coupling action of the turbine, with variable sensitivity to vibration levels. The results obtained for freestanding lattice tower are compared with the information of a tubular one designed to support the generator with the same characteristics. At the end of this work itwas possible to observe the feasibility of using lattice towers that proved better as its structural performance but with caveats about its dynamic performance since the appearance of several other modes natural frequency thus reducing the intervals between them in low frequency and theoretically increase the risk of resonance.
A Systematic Review of Renewable Energy Trend.pdfssuser793b4e
This paper systematically and successfully reviewed the renewable energy trend from 2010 to 2023. This review
detailed the difference renewable energy and conclusion was drawn that solar photovoltaic (PV) energy has the
leading trend in power generation growth and innovation. This research work explained in detail the most recent
solar photovoltaic optimization techniques and it was observed from the review that hybridization of intelligent and
non-intelligent maximum power point tracking technique has the best tracking power conversion efficiency. The
advantages and disadvantage of solar PV together with the solar optimization and innovational growth trends were
examined. This research showed that clean and renewable energy sources will continue to grow and the solar energy
industry is expected to experience significant growth and rapid innovation in the next 10 years. From the observed
rapid growth and innovation trend in solar energy, the world will have a very cheap, abundant and clean energy
before 2050.
The SpaceDrive Project - First Results on EMDrive and Mach-Effect ThrustersSérgio Sacani
Propellantless propulsion is believed to be the best option for interstellar travel. However, photon rockets or solar sails have thrusts so low that maybe only nano-scaled spacecraft may reach the next star within our lifetime using very high-power laser beams. Following into the footsteps of earlier breakthrough propulsion programs, we are investigating different concepts based on non-classical/revolutionary propulsion ideas that claim to be at least an order of magnitude more efficient in producing thrust compared to photon rockets. Our intention is to develop an excellent research infrastructure to test new ideas and measure thrusts and/or artefacts with high confidence to determine if a concept works and if it does how to scale it up. At present, we are focusing on two possible revolutionary concepts: The EMDrive and the Mach-Effect Thruster. The first concept uses microwaves in a truncated cone-shaped cavity that is claimed to produce thrust. Although it is not clear on which theoretical basis this can work, several experimental tests have been reported in the literature, which warrants a closer examination. The second concept is believed to generate mass fluctuations in a piezo-crystal stack that creates non-zero time-averaged thrusts. Here we are reporting first results of our improved thrust balance as well as EMDrive and Mach-Effect thruster models. Special attention is given to the investigation and identification of error sources that cause false thrust signals. Our results show that the magnetic interaction from not sufficiently shielded cables or thrusters are a major factor that needs to be taken into account for proper μN thrust measurements for these type of devices.
Iaetsd rf controlled sailing robot for oceanic missionsIaetsd Iaetsd
This document discusses a proposed sailing robot that can be controlled remotely using RF wireless communication. The robot would use sensors like depth sensors, obstacle sensors, and metal detectors to perform tasks like measuring ocean depths and locating sunken ships. It would also use a GPS module for navigation and tracking and a camera to send video back to the controller. The robot's movements would be controlled from a laptop using an RF module, and sensor data would also be transmitted back to the laptop. The goal is to develop a robot that can perform dangerous oceanic missions without risking human lives onboard.
This document summarizes the feasibility study of the WindFloat technology, a three-legged floating foundation designed to support offshore wind turbines in water depths from 30-50 meters. Key advantages of the floating foundation include flexibility in site location, access to stronger wind resources further offshore, and simpler offshore installation procedures compared to fixed foundations. The design draws on offshore oil and gas platform technologies while accounting for the different requirements of wind turbines. Hydrodynamic analysis and testing were performed to understand platform motions under wave and wind loads. Coupling of aerodynamic and hydrodynamic models allows for a more accurate analysis of interactions between the turbine and floating platform.
Adaptive maximum power point tracking using neural networks for a photovoltai...Mellah Hacene
Adaptive Maximum Power Point Tracking Using Neural Networks for a Photovoltaic Systems According Grid
Electrical Engineering & Electromechanics, (5), 57–66, 2021. https://doi.org/10.20998/2074-272X.2021.5.08
Advanced weather forecasting for RES applications: Smart4RES developments tow...Leonardo ENERGY
Recording at: https://youtu.be/45Zpjog95QU
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LBRP: A RESILIENT ENERGY HARVESTING NOISE AWARE ROUTING PROTOCOL FOR UNDER WA...ijfcstjournal
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sensor applications, nodes are square measured and through this the energy is affected. Thus, the mobility of each sensor nodes are measured through the water atmosphere from the water flow for sensor based protocol formations. Researchers have developed many routing protocols. However, those lost their charm with the time. This can be the demand of the age to supply associate degree upon energy-efficient and ascendable strong routing protocol for under water actuator networks. During this work, the authors tend to propose a customary routing protocol named level primarily based routing protocol (LBRP), reaching to offer strong, ascendable and energy economical routing. LBRP conjointly guarantees the most effective use of total energy consumption and ensures packet transmission which redirects as an additional reliability in compare to different routing protocols. In this work, the authors have used the level of forwarding node, residual energy and distance from the forwarding node to the causing node as a proof in multicasting technique comparisons. Throughout this work, the authors have got a recognition result concerning about
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LBRP: A RESILIENT ENERGY HARVESTING NOISE AWARE ROUTING PROTOCOL FOR UNDER WA...ijfcstjournal
Underwater detector network is one amongst the foremost difficult and fascinating analysis arenas that
open the door of pleasing plenty of researchers during this field of study. In several under water based
sensor applications, nodes are square measured and through this the energy is affected. Thus, the mobility
of each sensor nodes are measured through the water atmosphere from the water flow for sensor based
protocol formations. Researchers have developed many routing protocols. However, those lost their charm
with the time. This can be the demand of the age to supply associate degree upon energy-efficient and
ascendable strong routing protocol for under water actuator networks. During this work, the authors tend
to propose a customary routing protocol named level primarily based routing protocol (LBRP), reaching to
offer strong, ascendable and energy economical routing. LBRP conjointly guarantees the most effective use
of total energy consumption and ensures packet transmission which redirects as an additional reliability in
compare to different routing protocols. In this work, the authors have used the level of forwarding node,
residual energy and distance from the forwarding node to the causing node as a proof in multicasting
technique comparisons. Throughout this work, the authors have got a recognition result concerning about
86.35% on the average in node multicasting performances. Simulation has been experienced each in a
wheezy and quiet atmosphere which represents the endorsement of higher performance for the planned
protocol.
LBRP: A RESILIENT ENERGY HARVESTING NOISE AWARE ROUTING PROTOCOL FOR UNDER WA...ijfcstjournal
Underwater detector network is one amongst the foremost difficult and fascinating analysis arenas that open the door of pleasing plenty of researchers during this field of study. In several under water based sensor applications, nodes are square measured and through this the energy is affected. Thus, the mobility of each sensor nodes are measured through the water atmosphere from the water flow for sensor based protocol formations. Researchers have developed many routing protocols. However, those lost their charm with the time. This can be the demand of the age to supply associate degree upon energy-efficient and ascendable strong routing protocol for under water actuator networks. During this work, the authors tend to propose a customary routing protocol named level primarily based routing protocol (LBRP), reaching to offer strong, ascendable and energy economical routing. LBRP conjointly guarantees the most effective use of total energy consumption and ensures packet transmission which redirects as an additional reliability in compare to different routing protocols. In this work, the authors have used the level of forwarding node, residual energy and distance from the forwarding node to the causing node as a proof in multicasting technique comparisons. Throughout this work, the authors have got a recognition result concerning about 86.35% on the average in node multicasting performances. Simulation has been experienced each in a wheezy and quiet atmosphere which represents the endorsement of higher performance for the planned protocol.
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The document further emphasizes on the importance of checking the connection between the Windows and WSL environments, providing instructions on how to ensure that the connection is optimal and ready for remote debugging.
It also offers an in-depth guide on how to configure the WSL interpreter and files within the PyCharm environment. This is essential for ensuring that the debugging process is set up correctly and that the program can be run effectively within the WSL terminal.
Additionally, the document provides guidance on how to set up breakpoints for debugging, a fundamental aspect of the debugging process which allows the developer to stop the execution of their code at certain points and inspect their program at those stages.
Finally, the document concludes by providing a link to a reference blog. This blog offers additional information and guidance on configuring the remote Python interpreter in PyCharm, providing the reader with a well-rounded understanding of the process.
Home security is of paramount importance in today's world, where we rely more on technology, home
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important. Home security is important for the occupant’s safety. In this paper, we came up with a low cost,
AI based model home security system. The system has a user-friendly interface, allowing users to start
model training and face detection with simple keyboard commands. Our goal is to introduce an innovative
home security system using facial recognition technology. Unlike traditional systems, this system trains
and saves images of friends and family members. The system scans this folder to recognize familiar faces
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Optimizing Gradle Builds - Gradle DPE Tour Berlin 2024Sinan KOZAK
Sinan from the Delivery Hero mobile infrastructure engineering team shares a deep dive into performance acceleration with Gradle build cache optimizations. Sinan shares their journey into solving complex build-cache problems that affect Gradle builds. By understanding the challenges and solutions found in our journey, we aim to demonstrate the possibilities for faster builds. The case study reveals how overlapping outputs and cache misconfigurations led to significant increases in build times, especially as the project scaled up with numerous modules using Paparazzi tests. The journey from diagnosing to defeating cache issues offers invaluable lessons on maintaining cache integrity without sacrificing functionality.
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Blood Finder is an emergency time app where a user can search for the blood banks as
well as the registered blood donors around Mumbai. This application also provide an
opportunity for the user of this application to become a registered donor for this user have
to enroll for the donor request from the application itself. If the admin wish to make user
a registered donor, with some of the formalities with the organization it can be done.
Specialization of this application is that the user will not have to register on sign-in for
searching the blood banks and blood donors it can be just done by installing the
application to the mobile.
The purpose of making this application is to save the user’s time for searching blood of
needed blood group during the time of the emergency.
This is an android application developed in Java and XML with the connectivity of
SQLite database. This application will provide most of basic functionality required for an
emergency time application. All the details of Blood banks and Blood donors are stored
in the database i.e. SQLite.
This application allowed the user to get all the information regarding blood banks and
blood donors such as Name, Number, Address, Blood Group, rather than searching it on
the different websites and wasting the precious time. This application is effective and
user friendly.
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advent of technology has also increased the traffic hazards and the road accidents take place
frequently which causes huge loss of life and property because of the poor emergency facilities.
Many lives could have been saved if emergency service could get accident information and
reach in time. Our project will provide an optimum solution to this draw back. A piezo electric
sensor can be used as a crash or rollover detector of the vehicle during and after a crash. With
signals from a piezo electric sensor, a severe accident can be recognized. According to this
project when a vehicle meets with an accident immediately piezo electric sensor will detect the
signal or if a car rolls over. Then with the help of GSM module and GPS module, the location
will be sent to the emergency contact. Then after conforming the location necessary action will
be taken. If the person meets with a small accident or if there is no serious threat to anyone’s
life, then the alert message can be terminated by the driver by a switch provided in order to
avoid wasting the valuable time of the medical rescue team.
Height and depth gauge linear metrology.pdfq30122000
Height gauges may also be used to measure the height of an object by using the underside of the scriber as the datum. The datum may be permanently fixed or the height gauge may have provision to adjust the scale, this is done by sliding the scale vertically along the body of the height gauge by turning a fine feed screw at the top of the gauge; then with the scriber set to the same level as the base, the scale can be matched to it. This adjustment allows different scribers or probes to be used, as well as adjusting for any errors in a damaged or resharpened probe.
1. See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/314866067
Nano Energy Harvesting with Plasmonic Nano-Antennas: A review of MID-IR
Rectenna and Application
Article in Advanced Electromagnetics · March 2017
DOI: 10.7716/aem.v6i2.462
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2. Nano Energy Harvesting with Plasmonic Nano-Antennas:
A review of MID-IR Rectenna and Application
Rocco Citroni1
, Alberto Leggieri1
, Davide Passi1
, Franco Di Paolo1
, Aldo Di Carlo1
1
Department of Electronic Engineering, University of Rome Tor Vergata, Italy
*corresponding author, Email: (rocco.citroni@uniroma2.it)
Abstract
Drones, a technical nickname for unmanned aerial
vehicles (UAVs) are gaining more and more interest and
popularity. Supported by the miniaturization and cost
reduction of electronic components, a new class of
UAVs called Nano-air vehicles or NAVs represent the
future technology for indoor and outdoor mission. One
of the main considerations when building or buying a
drone is the flight time and range. The flight time is
nowadays a drawback for miniature unmanned aerial
vehicles (UAVs). It is limited to a few minutes before
requiring a forced recovery to replace exhausted
batteries. Currently the batteries are the dominant
technology, which possess limited operation in time and
energy. The real viability to extending flight time (FT)
of NAVs is possibly exploring new and more disruptive
alternative solution able either to recharge a battery, or
even to directly power the NAVs during the flight. A
Plasmonic Nano Energy harvester is an attractive
technology to extending the FT extracting the energy in
mid-infrared radiation emitted from Earth’s surface with
Rectenna tuned to mid-infrared wavelengths
(7 –14 )
m
µ with a peak wavelength of about10 m
µ . In
this review the concepts emerging from this work
identify and suggest how this novel harvester can
constantly supply these flying objects for the whole day.
Keywords—NAV; Nano Energy Harvesting;
Plasmonic Harvester; MIM-MIIM
1. Introduction
Designed to provide short range “over-the-hill”, or
“around-the corner” information, today the task of
unmanned air vehicles (UAVs) is to support
reconnaissance, surveillance, and target acquisition
(RSTA) mission. Thanks to miniaturization and ultralow
power technique, a new class of unmanned named
NAVs (Nano Air Vehicles) is emerging. The class of
NAVs is lightweight, man-portable and hand launch-
able. Nano-drones are minuscule Nano flight robots split
into two sub-sections: autonomous aircraft and remotely
piloted aircraft. They are capable of transferring data,
such as live footage, back to base, designed for quick
assembly and disassembly during field deployment [1].
Figure 1 shows an example of black UAV Hornet Nano
helicopter.
Figure 1: Black UAV Hornet Nano helicopter "photo on
courtesy by Proxdynamics"[3]
Designed for short range utility, the unit measures about
10 (length) ×2.5(width) cm, has maximum flight altitude
around 100 m, with a 10m/s maximum speed and
maximum takeoff weight (MTOW= Mass + Payload) of
20 g (battery included). The maximum flight time is
approximately 20 minutes, powered by high energy
density lithium-ion or lithium polymer batteries [2]. The
Nano-robot can be operated almost anywhere at any
time without prior airspace coordination. The small size
and electric motors makes it virtually inaudible and
invisible beyond short distances particularly at night.
Nevertheless, one of the main drawbacks faced today is
the flight time, directly limited by the on-board battery
capacity [4]. The other key drawbacks are the weight
and size of the NAV, which restrict the mounting of
larger payloads or extra batteries. The design challenge
is to generate and store enough energy to maximize
flight time. Currently for unmanned systems, batteries
represent the dominant technologies. They represent a
significant fraction of the total size and weight of the
system. The battery’s energy density (energy per mass)
is the essential parameter in this context. A higher
energy density enables longer flight times and lighter
aircraft [5]. However, the batteries are not very efficient
in particular mission where recharging them is
impossible for example in toxic and radiation
ADVANCED ELECTROMAGNETICS, VOL. 6, NO. 2, MARCH 2017
3. 2
environments. We accept their limitations (such as short
lifetime, long recharge time, etc.) simply because there
are no real alternatives [4]. Currently when the battery
is running low, we need to force some robots to return
to change their batteries. One possibility to overcome
these power limitations is to extract (harvest) energy
from the environment. These forms of energy will allow
creating a highly efficient and self-powered system able
to provide unlimited energy supply to NAVs. This is a
newly emerging field of Nano-energy [6]. Although
particular harvester as photovoltaics (PV) technologies
has improved the flight time, PV is not an “always-on”
power source, in fact it is limited in two major ways: by
the availability of light and the absorbed wavelengths
[7,8]. A new idea is proposed. As with any object in
thermal equilibrium, Earth absorbs solar energy from
the sun during daytime and then continuously re-emits it
at day and night. At thermal equilibrium, the Earth
absorbs and re-emits the same amount of energy. The
peak wavelength of this re-radiation spectrum falls at
around 10 µm [9, 10]. So if an antenna could detect this
wavelength, it could also convert it into electricity.
Assuming the antenna is not in thermal equilibrium with
its surroundings it is possible to scavenge energy from
the environment without violating the second law of
thermodynamics [11]. Rectennas (Nano antennas
coupled to a tunneling diode) that use excited localized
surface plasmons tuned to the Mid-IR can harvest IR
energy from the sun at night and day and convert it into
DC electricity to energize Nano-drones all day. The
principal advantage of the proposed technique is that it
employs plasmonic Rectennas that absorb the incident
IR radiation treating it as electromagnetic waves
inducing a AC current in the antenna surface. The
antennas rely on natural resonance [12]. Subsequently
the AC current will be rectified to energize the load. The
paper is organized as follows: Section 2 presents the
equations to estimate flight time and range for NAVs.
Section 3 presents a circuit model of the IR antenna
coupled to rectifying diode. A review of wideband Nano
Antennas tuned to the Mid-IR that uses excited localized
surface plasmons, is reported in subsection of Section 3.
Section 4 shows the status of rectifiers, the challenge in
Mid-IR range and the proposed solution. Finally,
Section 5 provides concluding remarks.
1.1 Possible Area of Applications
In today’s world, civil security is of major importance.
In protecting the public from threats such as terrorist
attacks and in successfully identifying crimes,
appropriate air support can be a decisive advantage.
Helicopters can be an important source of support to
teams on the ground. However, as a form of air support
they are expensive and can take time to be ready for
engagement. The UAV are less expansive, in particular
Nano-drones have a quick assembly and disassembly
during field deployment. A Nano-drone can be instantly
ready for action, allowing for immediate air support. In
disaster monitoring inside tunnels or buildings while
large UAV cannot be deployment, a Nano-drone can act
immediately, without any loss of time. In several
scenarios, where the human intervention is not possible,
e.g., in toxic and radiation small area using NAVs can
provide a useful support. It is important to be able to
obtain a rapid overview of the situation that is often only
possible from the sky. In the future, using the optional
waypoint navigation function will allow to Nano-drones
to inspect the relevant installation autonomously,
without the need for navigation instructions from a pilot
[13, 14, 15, 16].
2.0 Equations to Estimate Flight Time and
Range of NAV
One of the main considerations when building or buying
a drone is the flight time and range. Batteries currently
power all components on board NAV as electronic
circuits, sensors, actuators, and the communication
devices. Factors as capacity and energy density of
battery allows longer flight time. However, to increase
the flight time is necessary to increase the capacity with
resulting in increased battery size. Many factors affect
the correct calculation of the flight time as hovering or
sportive flying, cable, turbulence, battery type. [17, 18,
19]. The table 1 shows the materials list of a commercial
NAV and their weight budget.
Table 1: materials list of NAV and their weight budget.
To estimate the flight time the author considers two
flight conditions, full throttle and hovering. The force
generated by the rotor must be more than the weight (at
least 2:1) of the NAV otherwise, would not be able to
take off vertically. Smaller UAVs (usually the size of
the palm of your hand) tend to use small-brushed
NAV Helicopter
Components
Weight (g)
Flight Control
Board
3
Battery 1.5
Camera Board 1
Antenna 2
Motor /propellers 4.9/2.5
TX/RX 2
Speed Controller 0.70
Actuator 3
Cables 1
Frame 2
Total Weight 21
4. 3
motors. Let’s assume a helicopter‘s weight (including
frame, motors, electronics, battery, accessories etc.) to
be 20g. Each motor should therefore be capable of
providing (20g/1 motor) x 2:1 = 40g of thrust (or more).
The figure 2 shows the required current that the motor
needs to Full Throttle:
0,0 0,1 0,2 0,3 0,4 0,5 0,6
0
20
40
60
80
100
120 Thrust
Thrust
[g]
I [A]
Current vs Thrust Engine
Figure 2: Curve shows the correlation between engine
thrust and current battery
Assume user is using 75% throttle of the time to fly
around, and the rest of the time hovering, the current
draw in throttle for 40 g of thrust will be 0.20 A, in the
hovering time the current will be supposed 10 % less
(This is purely estimation). What will be the maximum
flight time and range assuming a single battery on board
Nano robot with a minimum capacity of 90 mAh?
[17,18,19]. To calculate the flight time in both flight
condition we should consider the following losses
(wind, hovering or sportive flying, cable,
turbulence...) for this reasons we estimate ~10% losses
[20].
1000
0.90 60 ( )
batt
Throttle
tot
C
N
t
I
⋅
= ⋅ ⋅ Full throttle flight
time based on the battery capacity and motor current
with margin of error due to the exclusion of electronics,
accessories (1)
1000
0.90 60 ( )
batt
Hover
Htot
C
N
t
I
⋅
= ⋅ ⋅ Hover flight time based
on the battery capacity and motor current with margin of
error due to the exclusion of electronics, accessories (2)
( )
2
hover throttle
average
t t
t
+
= Average flight time
(3)
Where:
C is the capacity of battery = 90 mAh
batt
N is the number of battery on board NAV = 1
tot motor motor
I I N
= ⋅ Total Full throttle UAV current
(4)
Htot Hmotor motor
I I N
= ⋅ Total hover UAV current
(5)
motor
N is the number of motor on board NAV=1
The results for Throttle and hover condition are
presented in table 2 and table 3below.
Table 2: Results for NAV in Throttle condition
Table 3: Results for NAV in Hover condition
The simulation in figure 3 shows the results of flight
time vs battery capacity respectively in throttle and
hover condition
Throttle Equation Results Unit
Thrust / 40 g
mot
I Figure 2 0.20 A
tot
I 4 0.20 A
Throttle
t 1 24.3 min
Range 7 2.035x10^3 m
average
t 3 25.65 min
Hover Equation Results Unit
Thrust / 40 g
Hmot
I Figure 2 0.18 A
Htot
I 5 0.18 A
Hover
t 2 27 min
Range 7 / m
average
t 3 25.65 min
5. 4
Figure 3: Flight time in Throttle and Hover condition vs
Battery Capacity
The figure 3 shows that the flight time in both conditions
increases as a function of the battery capacity. However,
as the capacity of battery gets larger, the increase in
flight time becomes ineffective. In fact there will be a
point where it just does not gain any more flight time
with bigger battery (even lose flight time). The figure 3
shows that the advantage in hover condition is only of
three minutes on throttle condition.
2.1 Range of NAV
The equation 7 shows, known the motor efficiency and
specific energy of the battery, how the payload’s weight
could affect the range of a UAV. D’Angelo estimates the
energy requirement to be [21]:
( )
1 370
p v
r c
m m
d p
v r v
η
+
+
−
(6)
The range d in km is:
2 (1 )
( )
370
b r
p v
c
E v
d
m m p
r v
η
⋅ −
=
+
+
(7)
Where b
E is the source specific energy of the battery
(for Li-Po 100-265 Wh/Kg), p
m = payload mass in g,
v
m = vehicle mass in g, r = lift-to-drag ratio, =
power transfer efficiency for motor and propeller, p =
power consumption of electronics in W, r
v = ratio of
headwind to airspeed and c
v = cruising velocity of the
aircraft in m/sec. We assume to be 0.5, and r to be 3.
It is clear that advances in battery source specific energy
will drastically increase flight time and range. The table
4 shows the values used in (7) to calculate the maximum
range of NAV.
Table 4: Summaries of values used in (7) to calculate the
maximum range of NAV.
b
E
(Wh/kg)
r
V p
m
(g)
v
m
(g)
η r p
(W)
c
V
(m/sec)
(100-
265)
0.3 1 19 0.5 3 0.74 5
The Figure 4 shows the range as a function of payload
mass. The aircraft’s range is roughly proportional to the
payload mass. As payload mass is increased, the total
weight of the aircraft increases. Increasing the weight
raises the minimum speed of the aircraft and reduces the
throttle range.
Figure 4: Range NAV vs Payload mass
The Figure 5 plots the range as a function of cruising
velocity and motor efficiency. The variation of motor
efficiency with cruising velocity leads to increase the
range. This will involve the power will have increase
because the motor will have to spin faster, and thus pull
more current.
Figure 5: Range of NAV as a function of motor
efficiency and cruising velocity
0 20 40 60 80 100
0
10
20
30
Flight Time vs Battery Capacity
(mAh)
(min)
tThrottle C
( )
tHover C
( )
C
6. 5
3.0 Energy Harvesting Principles
Figure 6 shows the block diagram of a self-powered
system that harvests energy from the environment. The
classic (high-efficiency) energy-harvester system
consists of an energy generator,
capture/storage/management electronics and a load
designed to be powered by the harvester. The first block
of diagram below, the transducer is a plasmonic
harvester. It is shown as the energy generator. The
plasmonic generator transforms IR electromagnetic
wave, into electrical voltage/current. The energy-
conditioning block is used to properly charge the storage
unit. The power-conditioning block provides the
appropriate power supply to the load. A second key
component of energy management is storage and
retention, with minimal leakage or loss. When the
source is minimum, there may be extended time
intervals before sufficient energy has been captured and
stored. Therefore, the harvester's electronic design must
possess extremely high retention when the energy-
generator function is randomly available or interrupted
for long periods of time [22,23].
Transducer
Energy
Conditioning
Storage
Power
Conditioning
Load
Environmental
Energy
Figure 6: Block diagram of a self-powered system. The
blocks inside the dashed red box form the energy
harvester subsystem.
The capturing, accumulating and storing of small
packets of electrical energy requires high efficiency.
The circuit must stay in the active mode and be ready to
perform the capture whenever harvestable energy
becomes available. The device must be ready to provide
an output as the application design requires it. The
efficiency must be high enough so that the energy
consumed by the load is much smaller than the energy
provided by the generating source. At any instant of time
t the amount of energy consumed at node i (NAV) is
[24]:
0
( , ) [ ( , ) ( , )]
t
s c
t
E i t P i t P i t dt
= −
∫ (8)
Where ( , )
s
P i t and ( , )
c
P i t represents respectively the
power of energy harvester and energy being consumed
at that time t from node i . Therefore, a node is self-
contained if:
( , ) 0
E i t > 0
t
∀ > (9)
In fact, by formula 8 any energy received when
( ) ( )
, ,
s c
P i t P i t
< is wasted. Also, when
( ) ( )
, ,
s c
P i t P i t
≥ , the energy ( ) ( )
, ,
s c
P i t P i t
− is
wasted. Due to the variability of environmental energy
sources, a storage unit (battery or an ultra-capacitor) is
needed to provide a constant power flow to the load.
However, an energy storage mechanism is not ideal and
present any criticality: the energy capacity is limited, the
charging efficiency η is strictly less than 1 and some
energy is lost through leakage. The conditions of energy
conservation and buffer size limit are discussed below.
First define a rectifier function [x]+
as follows [25]:
_ 0
[ ]
0 _ 0
x x
x
x
+ ≥
=
<
Energy conservation leads to:
0
0 0 0
[ ( , ) ( , )] [ ( , ) ( , )] ( ) 0
T T T
s c c s leak
B P i t P i t dt P i t P i t dt P t dt
η + +
+ − − − − ≥
∫ ∫ ∫
[0, )
T
∀ ∈ ∞ (10)
Where, 0
B is the initial energy stored in the ideal energy
buffer and ( )
,
leak
P i t is the leakage power for the energy
buffer. The buffer size limit requires the following
additional constraint to be satisfied:
0
0 0 0
[ ( , ) ( , )] [ ( , ) ( , )] ( , )
T T T
s c c s leak
B P i t P i t dt P i t P i t dt P i t dt B
η + +
+ − − − − ≤
∫ ∫ ∫
[0, )
T
∀ ∈ ∞ (11)
B is the size of the energy buffer.
The eq. (10) is a sufficient and necessary condition to be
satisfied by all allowable ( )
,
s
P i t and ( )
,
c
P i t instead
the condition (11) is only sufficient but not necessary.
This happens because excess energy not used or stored
in the buffer can be dissipated as heat from the system.
In this case, the left-hand side of Eq. (10) will be strictly
greater than zero, by the amount of energy wasted. The
condition (11) becomes necessary if wasting energy is
not allowed.
3.1 Proposed Novel Energy Harvester
Currently, the batteries represents the only dominant
technology to energize the NAVs. However, batteries
present several disadvantages: the need to replace or
recharge them periodically and their big size and weight.
To maximize the flying time weight and power budget
should be carefully monitored. One possibility to
overcome these power limitations is to extract (harvest)
energy from the environment. These technologies can be
7. 6
used to possibly replace or at least extend the lifetime of
a battery. By using the energy from environment, our
goal is therefore to make the system self-powered and
energy independent. The idea therefore is to add an
energy scavenging unit on board which would provide
an unlimited source of power over the NAVs’ lifetime.
The mission period would no longer be limited by the
power source, and no additional maintenance would be
required for recharging or replacing the battery. To
maximize the flying time, is of primary importance to
investigate which harvesting technology is the most
promise in terms of energy source availability, ease of
implementation, and useful levels of output power. Each
configuration has its own advantages and limitations,
and in general, it is not possible for an energy harvester
to perform well in all applications. For this reason,
energy harvesters are normally designed for a specific
application and a particular frequency range of
operation. From state of the art, it became clear that
some of these ambient energy sources are not always
available in unlimited quantities. They fluctuate from
time to time and from place to place depending on what
time of day or season. They change from one season to
another and from one region to another. For example
traditional photovoltaics is not “always-on” power
source, two major limits can be identified: the
availability of light and the wavelengths that can be
absorbed. Vibration (electromagnetic, electrostatic,
piezoelectric, transducers) and triboelectric harvesters
can generate power as soon as the aircraft start running.
The RF is “always on “, however it has lowest energy
density in an outdoor/indoor environment moreover, the
power decreases with inverse square law
2
1 r . Finally,
thermal energy can generate power if there is a
temperature gradient during the flight between for
example electric engine and external air. On the NAV,
temperature gradients may not occur straight away after
take-off or there are few or no temperature gradients
during the cruise. With an accurate knowledge of the
environment, one could combine two or more energy
harvesters to provide perpetual sources of electrical
energy to Nano robot. Combining two or more sources
increases the chance of having constant power supply at
all times such that when one form is not available in
sufficient quantity, the other will complement the
temporary shortage. This technique is presented as
hybrid energy harvesting techniques. Unfortunately,
this technique is ideal in this context; in fact, it is
impossible to add extra weight to Nano flight robots
[26,27]. This author et al. have investigated the concepts
and possibility of harvesting plasmonic energy in a mini
UAV. Earth receives solar radiation only during the
daylight hours; but emits mid-infrared (Mid- IR 7-14
m
µ ) radiation during both the day and the night hours
with a peak wavelength of about 10 m
µ [8,9]. The
proposed technique employs plasmonic Rectennas that
absorb the incident IR radiation treating it as
electromagnetic waves. Particular Nano Antennas (used
as Nano generators) tuned in Mid-IR and integrated to
rectifiers (Rectennas) can harvest IR energy from the
sun night and day and convert it into electricity.
Plasmonic Nano-Generator can operate round the clock,
independently of weather conditions such as humidity
and cloud cover and without restriction of orientation
towards the sun.
3.2 Rectenna architecture and circuit model of
IR antenna coupled to rectifying diode.
LPF
(Prerectification
Filter)
Rectification
Circuit
LPF
(Post
Rectification
Filter)
Load
Antenna
Figure 7: Rectenna equivalent circuit.
The sun emits shortwave radiation (visible light and near
infrared) because it is extremely hot and has a lot of
energy to give off. Once in the Earth’s atmosphere,
clouds and the surface absorb the solar energy. The
ground heats up and re-emits energy as longwave
radiation in the form of infrared rays (LWIR) [12]
because Earth is cooler than the sun and has less energy
available to give off. Typical rectenna block diagram is
presented in Figure 7. The word “rectenna” is the result
of joining “rectifying circuit” and “antenna”. The
rectenna is a passive element with a diode that can
receive and rectify MID- IR power to DC, it can operate
without any power source. The first block are the
nanoantennas. They are small structures that capture the
incident electromagnetic re-emitted from Earth’ surface
causing an AC current onto the antenna surface. For the
nanoantenna is required to capture MID-IR radiation.
For this purpose, a wide acceptance angle is essential.
Nanoantennas, should be able to concentrate the
incoming radiation, therefore a wideband antenna is
favorited. The matching between the antenna and the
rectifier is provided by low-pass filter [28]. Its aim is
suppressing possible unwanted higher harmonics
rejected by the nonlinear diode. These could come back
to the nanoantenna resulting in power losses [29]. The
diode is the most important device to achieve high-
energy conversion efficiency. These types of rectifier
should be coplanar and coupled to the nanoantenna. The
requirements for an ultra-high speed diode used to
obtain a DC signal are responsivity, small size, small
turn on voltage and efficient performance at MID-IR
frequency. Impedance matching between the rectenna
system and the load is required to transfer the maximum
power to load. This is possible when the load impedance
is the conjugation of the rectenna impedance. Finally,
the last block DC pass filter between diode and load
provides a DC path to the load by separating the high-
frequency components from the DC signal. The energy
conversion efficiency of a rectenna structure essentially
it depends on two elements, the nanoantenna and the
8. 7
diode [29] which implies nanoantenna efficiency,
impedance matching between nanoantenna and
rectifying element and the coupling efficiency of the
rectifier to the load. Therefore, the product of the
efficiencies of each step determines the rectification
efficiency (η) of a Rectenna as follows [11, 30, 31]:
a s c q
η η η η η
= (12)
The antenna efficiency, which corresponds to the total
power coupled by the antenna per unit of intercepted
power, is represented by a
η . An antenna designed for IR
harvesting operates as a receiving antenna that interacts
with the incident EM wave. The incident wave induces
current on the metal antenna surface, which constitutes
the power coupled by the antenna. Figure 8 shows the
equivalent circuit of the antenna coupled to rectifying
diode. The receiving antenna, when operating at its
resonant frequency, can be modeled by a voltage source,
A
V , and an impedance in series, A A A
Z R jX
= + . A
V is
the open circuit voltage occurring at the end of the
antenna when no load is connected and A
Z is the
antenna impedance, where A
X is the antenna reactance
and A
R is the antenna resistance which is a combination
of the radiation resistance rad
R (radiated power by
antenna), in series with the loss resistance ohmic
R
(conductive and dielectric losses of antenna)[12].
A
R
A
V
A
X
D
C ( )
D D
R V D
V L
Z
LWIR
gap
C
IR Antenna Rectifying Diode
Figure 8: Circuit model of IR antenna coupled to
rectifying diode.
Air-gap between two-arm antenna is modeled with the
capacitance gap
C . The MIM tunnel diode is modeled
with a voltage dependent resistor ( ( ))
D
R V in parallel
with a capacitor ( )
D
C and a resistor (r) in series for the
conductive losses on the antenna arms. The cutoff
frequency c
f , characterizing the frequency response of
the diode, depends on both the diode resistance and
capacitance as follows [12]:
1
2
c
D D
f
R C
π
= (13)
When resistance D
R depends on the fabrication
process, the cutoff frequency can be tuned by adjusting
the capacitance D
C . The diode capacitance is given by:
0
r
D
A
C
d
ε ε
= (14)
where r
ε represents the relative permittivity of the
insulator layer of the MIM diode, 0
ε is the permittivity
of free space, A is the diode junction area (overlapping
area), and d is the thickness of the insulator layer. The
MIM diode cut-off frequency is determined by the time
constant, D D D
R C
τ = [12]. When the antenna is coupled
to the diode, the cutoff frequency of the rectenna is
rewritten as [12]:
2 ( )
A D
c
A D gap D
R R
f
R R C C
π
+
=
+
(15)
The total power provided by this voltage source is
determined by the antenna efficiency a
η . The next
efficiency component considers the losses that occur
while the currents at the antenna surface flow onto the
antenna node where the tunnel junction is formed. It is
represented by s
η . This parameter strictly depends on
the material conduction property at the operating
frequency. The impedance matching between the
antenna radiation resistance and the diode resistance
forms a very crucial component of the total efficiency,
represented by c
η (equation 16). The tunnel diode is
characterized with a capacitive and a voltage dependent
resistor in this circuit model. In order to achieve efficient
coupling with the input power it is important to keep the
diode resistance D
R value as close as possible to the
antenna resistance A
R . Here the junction resistance
value should be the value at the operating bias voltage,
which is zero-bias (0)
D
R for IR harvesting applications
and ( )
D bias
R V for IR detecting case. ( )
D bias
R V is
always lower than (0)
D
R due to the nonlinear I-V
characteristic of tunnel diodes. Lastly, q
η is the
quantum efficiency derived in equation 17:
D
c
D A
R
R R
η =
+
(16)
1
2
q S
e
ω
η = ⋅
ℏ
(17)
9. 8
The rectenna’s responsivity “S” measured in A/W, is the
quantification of the diode’s ability to rectify a Terahertz
signal. It is defined as:
''
'
( )
( )
bias
bias
I V
S
I V
= , '
( )
bias
I V and
''
( )
bias
I V are the first and the second derivative of the
electric current passing through the diode at a certain
bias voltage. The incident electric field rms
E can be
related to the Poynting vector using the vacuum
impedance 0
Z .
0
0
0
377
Z
µ
ε
= = Ω (18)
The incident power intensity or Poynting vector (ξ ) is
the time averaged power per unit area A of the incident
radiation:
2
2
0 0
2
p
inc rms
E
P E
A Z Z
ξ = = =
⋅
2
[ / ]
W m (19)
The amplitude of the coupled potential across the
antenna arms A
V is related to the incident electric field
( p
E ) and the effective antenna length eff
l as in
Equation 20. The effective antenna length ( eff
l ) is a
function of the incident wave direction and the antenna
length ant
L as formulated in Equation 21. When the
beam is incident perpendicularly 90
θ °
= , eff
l can be
approximated as the antenna physical length ant
L :
A eff p
V l E
= ⋅ (20)
sin( )
eff ant
l L θ
= (21)
Here an important parameter called antenna aperture
efficiency or antenna fill factor comes into play.
Antenna fill factor f can be defined as in Equation 22.
It is a dimensionless parameter and is equivalent to
product between antenna coupling efficiency a
η and the
losses s
η by material. Conceptually, it describes how
well the antenna can couple the incident radiation:
2
eff ant
a S
A L
f
A A
η η
= = = (22)
eff
A is the effective area of the antenna defined as :
2
4
eff
G
A
λ
π
= (23)
where is the antenna gain and is the free-space
wavelength.
Thus, the coupled voltage A
V can be expressed in terms
of the incident power as:
2
0
0
2
2
inc ant
A inc
P Z L
V P Z f
A
⋅ ⋅
= = ⋅ ⋅ (24)
Therefore, the induced voltage in the equivalent circuit
is proportional to the square root of the radiation
resistance and the maximum effective aperture. When
the AC electric field excites surface electrons, their
motion on the antenna surface induces an electric field
and a fraction of the coupled power is re-radiated. This
loss in the re-radiated power is represented by a virtual
resistance called “antenna radiation resistance A
R ” and
it is determined by the geometry of the antenna. The
antenna coupling efficiency can also be formulated by
circuit representation where the total radiation power is
shared between the vacuum impedance 0
Z and antenna
radiation resistance A
R as in Equation 25:
0
A
A
R
f
R Z
=
+
(25)
Once the antenna potential is defined in terms of the
incident radiation, the impedance matching efficiency
c
η should be used to define the power across the diode
as in Equation 26:
2
2 2
2[( ) ( ) ]
A D
D
rad ohmic D A D
V R
P
R R R X X
=
+ + + +
(26)
and the power dissipated in the antenna is given by:
2
2 2
2[( ) ( ) ]
A ohmic
ohmic
rad ohmic D D A
V R
P
R R R X X
=
+ + + +
(27)
2
2 2
2[( ) ( ) ]
A rad
rad
rad ohmic D A D
V R
P
R R R X X
=
+ + + +
(28)
Note that rad
P is the scattered (or re-radiated) power by
antenna. This scattered power does not exist as a
separate measurable independent quantity of real power
that enters into any statement of power conservation.
10. 9
However, the scattered wave determines the amount of
captured power by the antenna through interference with
the incident wave. The first component of total
efficiency is defined as power transfer efficiency ( )
t
η .
This term determines the fraction of the incident power
that can reach the diode from the antenna section. It can
be derived as in Equation 29 using Equations 26 and 24:
0
2 2
2
( ) ( )
D
D
t a s c
inc A D A D
f Z R
P
P R R X X
η η η η
⋅ ⋅ ⋅
= ⋅ ⋅ = =
+ + +
(29)
When 0
2
:
D A t
D
f Z
R R
R
η
⋅ ⋅
>> = .
The total efficiency, which is the ratio of the detected
DC power and the incident radiation power, can be
defined as in Equation 30:
0
2 2
2 1
2
( ) ( )
D
t q
A D A D
f Z R
S
e
R R X X
ω
η η η
⋅ ⋅ ⋅
= ⋅ = ⋅ ⋅
+ + +
ℏ
(30)
3.3 Nano Antennas tuned in MID-IR
There are two important aspects of the antenna design:
geometry and material. The need of a broadband antenna
is mandatory. An antenna pattern that can accommodate
wide polarization angle span of the incident wave is
necessary to increase the total coupled power. Ideally,
the material used in the construction of the Nano-
Antenna should exhibit no losses during the collection
of electromagnetic radiation. However, this is hardly
achievable due to the finite conductivity of metals at
THz frequencies [31]. In this paper, three broadband
antennas tuned to the Mid-IR region of the spectrum are
analyzed, as potential systems for harvesting thermal
radiation.
3.3.1 Log Periodic Antenna (LPA)
Rumsey’s principle suggests that the impedance and
pattern properties of an antenna will be frequency
independent (will have a constant impedance at all
frequencies) if the antenna shape is specified only in
terms of angles. To satisfy the equal-angle requirement,
the antenna configuration needs to be infinite in
principle, but is usually truncated in size in practice [32].
Rumsey’s principle has been verified in spiral antennas,
and some log periodic antennas. DuHamel and Isbell
[32] first introduced the Log-periodic antenna. It is
designed to work among a wide range of frequencies.
Larger bandwidth is obtained by means of the insertion
of a set of teeth, whose lengths are suitably chosen to be
resonant in some frequencies inside the desired
bandwidth. Gonzàlez et al. [33] designed a log periodic
antenna for IR application with a scale factor of 2
τ = ,
coupled to a niobium microbolometer. The materials
and fabrication of this antenna is reported on [33]. If
1 2 90
β β °
+ = the antenna becomes self-complementary
in which case it will have a constant impedance of 189
Ω at all frequencies [33]. The log-periodic antenna was
designed to have a frequency coverage of 18–70 THz
which corresponds to a wavelength coverage of 4-16 µ
m. For IR application the wavelength measured were at
10.6 µ m and the radiation efficiency for log periodic IR
antennas was 46%.
3.3.2 Spiral Nano-antenna
Spiral Nano Antenna is a planar structure frequency
independent [32]. Two types of Nano antennas are
presented: Archimedean spiral geometries and square
spiral geometries. Both good resonators they can be
polarized with linearly and circularly waves. The
electric field is concentrated in the gap between two
metallic arms. Increasing the number of arms increases
the electric field and its aperture area. The square spiral
Nano-Antenna proposed by Sabaawi et al [34] has 6
arms with an arm width of 50 nm, a gap of 50 nm, and
overall dimensions of 1.25 1.25
m m
µ µ
⋅ . At resonance of
13 µm the electric field E into the gap is 3
6.2 10 /
V m
µ
−
⋅
. Sabaawi et al [35] designed also a square spiral Nano-
Antenna with dimension of 750 750 nm
⋅ , and a gap size
of 30 nm. The max electric field E captured into the gap,
at the resonance of about 13µm is -3
0.575 10 V / m
µ
⋅ .
The Archimedean spiral Nano-Antenna consists of two
identical arms with a shift of 180°
with respect to each
other. Ahmed M. A. Sabaawi et al [34] showed the
configuration of the Archimedean-Spiral Nano-
Antennas. The configuration is designed to resonate
around 13µm. The electric field E in the gap of the single
Archimedean Spiral Nano-Antennas is 3
5.8 10 V / m
µ
−
⋅ .
With the MIM diode, embedded in the feeding gap the
efficiency has a value about 12
10−
for spiral antennas.
With Esaki diode, a device that consists of an insulating
layer between two thin electrodes and it based on the
tunnel effect is obtained an efficiency about 9
10−
[29].
Sabaawi et al [34] show also a Nano-array made with
two Archimedean spiral antennas with one common
gap. The electric field presented has been of 3
1.84 10−
⋅
/
V m
µ . A Nano-array made with four Archimedean
spiral antennas with one common gap presets an electric
field of 3
6.58 10−
⋅ /
V m
µ . Although is not easy building
an array of these antennas some advantage are: one only
rectifier embedded in the feeding gap, improvement of
equivalent area and largest value of Electric field
compared to single antenna.
3.3.3. Bowtie Nano-antenna
The Bow-Tie Nano-Antenna consists of two triangular
flat metal plates with a gap between the apexes of the
triangles. This structure produces a stronger electric
field in the gap where a rectifier can be embedded. The
main advantages of bowtie antennas are simple design,
broadband impedance and only defined by the bow
11. 10
angleθ . This configuration gives the designer the
freedom to vary several antenna parameters. Gap size,
apex angle and antenna dimensions could be tuned in
order to increase the captured electric field in the gap
[32]. This nanoantenna allows building an array by
coupling each element in one configuration. The total
electric field at feeding point will be the sum of electric
field of each single bow tie antenna. To achieve an
output DC signal, the bowtie nanoantenna is coupled
with an MIM (Metal Insulator Metal) [36]. Gadalla et al
[37] proponed the structure with Au/Al2O3/Pt. MIM
diode is overlapped with antenna arms, the utilization of
different electrodes produces a higher value of tunneling
current. The tunneling current can be improve
increasing the work function difference between the two
different metal and reducing the contact area of the
tunnelling junction; as a consequence, it is obtained a
better impedance matching between antenna and diode.
The Au/TiOx/Ti MIM diode is chosen because gold and
titanium are characterized by a large difference in the
work function and so a strong rectifying effect is
achieved [29,38,39]. A. Haque et al [40] present the
geometric effect (slot) on the performance of the circular
edge bow-tie nano antenna in the IR frequency range.
The proposed antenna is designed to receive induced
electric field at the central gap. The electric field is then
transferred via a feeding line and converted into electric
current to supply the load. The materials and fabrication
of this antenna are reported in [40]. Antenna with double
slot provides better electric field compared to the
antennas without slot or with single slot. Resonance
frequency also changes with the change of the number
of slots.
4.0 Rectifying Element
The diode represent the essential component of
rectenna. The rectenna is limited by the cut-off
frequency (fc) of the diode, fc changes with the type of
rectifier used due to the physical nature of the diode.
However, for MID-IR application a low RC time
constant is mandatory. Two types of diodes are
presented. Schottky barrier diodes where electron moves
across the barrier by a thermal activation and MIM
(metal-insulator-metal) and MIIM (metal-insulator-
insulator-metal) diodes where electron moves across the
barrier for tunneling effect [41,42]. Schottky barrier
diodes are theoretically limited to frequencies of a few
THz, due to relatively higher resistance of
semiconductors compared to metals. MIM/MIIM diodes
have fast electron switching speeds, of the order of 10 fs
[37], and use metal electrodes, thus providing a low
resistance. Therefore, they can be used at higher
frequencies than Schottky barrier diodes and are shown
to be operational at up to 150 THz [41, 42,43,44]. To
improve the rectenna efficiency, the diode must satisfied
several parameters [41]:
( )
( ) ;
( )
F
asym
R
I V
f V
I V
= Asymmetry>1 (31)
( )
( ) ;
( )
NL
dI
V
dV
f V
I V
V
= Nonlinearity>3 (32)
2
2
( )
( ) ;
( )
RES
d I
V
d V
f V
dI
V
dV
= Responsivity> 1
7V −
(33)
The asymmetry FOM (Figure of Merit), defined in
Equation 31, is the absolute ratio of forward to reverse
current at a bias, a value of 1 indicating full symmetry
and hence no rectification. The non-linearity FOM, as
defined by Equation 32, is the ratio of the differential
conductance to the conductance and is a measure of the
deviation from a linear resistor. Finally, the responsivity
FOM defined in Equation 33 is the ratio of the second
derivative of the I-V curve and the differential
conductance and is a measure of the rectified signal as a
function of input power. The rectification process will
be more efficient if the diode will exceeds the values in
equations 31,32,33. Moreover, the MIM diode must be
very fast to IR regime therefore 1) the insulator layer
should be on the order of a few nanometers, by doing so,
it is possible to allow sufficiently large electrical current
and to ensure the tunneling effect 2) diode capacitance
must be small, as consequence, the device area must be
small below 1 2
m
µ (equation 14). To respect the MID-
IR regime (30 THz) however, the diode must have also
a low resistance close to the nanoantenna resistance (to
provide a good impedance matching antenna-diode and
an efficient power transfer), it must pass a large current
at low voltage, as consequence should have a large area.
Currently this tread-off restricts the use of MIM diode
[29]. In this review are presented two types of diodes:
low voltage tunnel diodes and ultralow-voltage diodes
[29]. An example of low voltage tunnel diode in MID-
IR rectennas is the metal-insulator- metal (MIM) diode.
The performance of MIM and MIIM diodes as infrared
detectors are reported in the literature. For MIM
Donchev [41] shows a Nb/Nb2O5/Ag device, the results
are 35.6 asymmetry, 4.0 nonlinearity and 7.9 V-1
responsivity. Yaksh Rawal et al [45] show a new type of
MIM diode Ti/TiO2/Al (21287
2
m
µ area) with 9nm-
thickness dielectric layer, 18 sensitivity ( )
1
V−
and 6.5
asymmetry. The Ni/NiO/Ni system is widely used for
detection and mixing up to 30 THz infrared radiation
due to its significantly low resistance-area product of
1Ω 2
( )
m
µ [41, 46,47,48, 49, 50], which indicates the
potential for a low RC constant. However due to a lack
of asymmetry, the second Ni electrode must be replaced
with a metal of different work function in order to
achieve rectification. This has been investigated by
12. 11
Hoofring et al [51], Krishnan et al [52, 53] and
Esfandiari et al [54] with Au, Cr and Pt contacts
respectively, all displaying good asymmetrical I-V
response. Other structures of dissimilar materials which
have shown promising results are Al/Al2O3/Ni [55,56],
Nb/Nb2O5/Pt [57, 58, 59], ZrCuAlNi/Al2O3/Al [60]
and also Nb/Nb2O5/Ag [61]. More tested metal-
insulator combinations are listed in [57]. The highest
FOMs were observed for Nb/Nb2O5/Pt, which
displayed 1500 asymmetry, 4 nonlinearity and 20 1
V −
responsivity meeting the criteria outlined in Equations
31, 32 and 33. An MIM diode can have asymmetric I–V
if different metals are used on the two sides of the
insulator with great work function difference between
them, giving unequal barrier heights. High barrier
asymmetric diodes provide a large responsivity.
However, keeping the diode resistance low requires low
barrier heights on both sides, which limits the
asymmetry. To achieve a high responsivity, requiring
substantial nonlinearity while maintaining low
resistance, one can resort to a multi-insulator tunnel
barrier (MIIM) [62,63]. With MIIM asymmetry can be
achieved even with similar metal electrodes, as long as
the electron affinity of both insulators is different. The
performance of MIM and MIIM diodes as infrared
detectors was compared by Hegyi et al [64]. It was
shown that the MIIM diode has 10 times higher
responsivity than a derivative MIM diode. This was
experimentally shown by Maraghechi et al [65] who
recorded up to 10 times better nonlinearity for a
Cr/Al2O3/HfO2/Cr diode compared to Cr/Al2O3/Cr
and Cr/HfO2/Cr diodes. A more applicable example is
by Grover & Moddel [66], who compared their
W/Nb2O5/Ta2O5/W structure to an MIM Diode with
equivalent barriers as that of a W/Nb2O5 on one side
and a W/Ta2O5 on the other side, again clearly showing
improved response from the MIIM device. Finally,
ultralow-voltage diodes we call geometric diode is
presented. A geometric diode consists of a thin film with
an asymmetric structure no greater in size than the
MFPL (mean-free path length) in which charge carriers
move more easily to the left than to the right. This planar
structure avoids the capacitance/resistance tradeoff
because it is not a sandwich structure. Made out of a
conductive material, it can have both low resistance and
ultra-low capacitance [67].
5.0 Conclusion Remarks
The progress and challenges of Rectennas to harvest
energy from Earth long-wave infrared emission have
been reviewed. However the accurate design of the
antenna, and in particular rectifiers, remains a key topic.
The use of broadband antennas for collecting MID-IR
infrared Earth’s energy has a big potential advantage.
Even though the tunneling process is femtosecond fast,
MIM tunnel diodes are frequency limited due to their
large RC time constant. Searching for a diode suitable
for solar rectification, in addition to high speed and
responsivity, the goal must be a device that has a
combination of lower resistance and lower capacitance
than the existing MIM diodes. Moreover, further
research activities have to be fulfilled to identify the
suitable materials and technology for the design and
fabrication of efficient THz rectifiers.
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