Title: Radio Frequency Energy Harvesting for Autonomous Systems
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
ANTENNAS for LOW POWER APPLICATIONS Basic Full
ANTENNAS FOR LOW POWER APPLICATIONS By Kent Smith Introduction: There seems to be little information on compact antenna design for the low power wireless field. Good antenna design is required to realize good range performance. A good antenna requires it to be the right type for the application. It also must be matched and tuned to the transmitter and receiver. To get the best results, a designer should have an idea about how the antenna works, and what the important design considerations are. This paper should help to achieve effective antenna design. Some Terms: Wavelength; Important for determination of antenna length, this is the distance that the radio wave travels during one complete cycle of the wave. This length is inversely proportional to the frequency and may be calculated by: wavelength (cm)=30000 / frequency (Mhz). Groundplane; A solid conductive area that is an important part of RF design techniques. These are usually used in transmitter and receiver circuits. An example is where most of the traces will be routed on the topside of the board, and the bottom will be a mostly solid copper area. The groundplane helps to reduce stray reactances and radiation. Of course, the antenna line needs to run away from the groundplane. dB, or decibel; A logarithmic scale used to show power gain or loss in an rf circuit. +3 dB is twice the power, while -3 dB is one half. It takes 6 dB to double or halve the radiating distance, due to the inverse square law. The Basic Antenna, and how it works. An antenna can be defined as any wire, or conductor, that carries a pulsing or alternating current. -
25. Antennas II
25. Antennas II Radiation patterns Beyond the Hertzian dipole - superposition Directivity and antenna gain More complicated antennas Impedance matching Reminder: Hertzian dipole The Hertzian dipole is a linear d << antenna which is much shorter than the free-space wavelength: V(t) Far field: jk0 r j t 00Id e ˆ Er,, t j sin 4 r Radiation resistance: 2 d 2 RZ rad 3 0 2 where Z 000 377 is the impedance of free space. R Radiation efficiency: rad (typically is small because d << ) RRrad Ohmic Radiation patterns Antennas do not radiate power equally in all directions. For a linear dipole, no power is radiated along the antenna’s axis ( = 0). 222 2 I 00Idsin 0 ˆ 330 30 Sr, 22 32 cr 0 300 60 We’ve seen this picture before… 270 90 Such polar plots of far-field power vs. angle 240 120 210 150 are known as ‘radiation patterns’. 180 Note that this picture is only a 2D slice of a 3D pattern. E-plane pattern: the 2D slice displaying the plane which contains the electric field vectors. H-plane pattern: the 2D slice displaying the plane which contains the magnetic field vectors. Radiation patterns – Hertzian dipole z y E-plane radiation pattern y x 3D cutaway view H-plane radiation pattern Beyond the Hertzian dipole: longer antennas All of the results we’ve derived so far apply only in the situation where the antenna is short, i.e., d << . That assumption allowed us to say that the current in the antenna was independent of position along the antenna, depending only on time: I(t) = I0 cos(t) no z dependence! For longer antennas, this is no longer true. -
Reuters Institute: the Future of Voice and the Implications for News
DIGITAL NEWS PROJECT NOVEMBER 2018 The Future of Voice and the Implications for News Nic Newman Contents About the Author 4 Acknowledgements 4 Executive Summary 5 1. Methodology and Approach 8 2. What is Voice? 10 3. How Voice is Being Used Today 14 4. News Usage in Detail 23 5. Publisher Strategies and Monetisation 32 6. Future Developments and Conclusions 40 References 43 Appendix: List of Interviewees 44 THE REUTERS INSTITUTE FOR THE STUDY OF JOURNALISM About the Author Nic Newman is Senior Research Associate at the Reuters Institute and lead author of the Digital News Report, as well as an annual study looking at trends in technology and journalism. He is also a consultant on digital media, working actively with news companies on product, audience, and business strategies for digital transition. Acknowledgements The author is particularly grateful to media companies and experts for giving their time to share insights for this report in such an enthusiastic and open way. Particular thanks, also, to Peter Stewart for his early encouragement and for his extremely informative daily Alexa ‘flash briefings’ on the ever changing voice scene. The author is also grateful to Differentology andY ouGov for the professionalism with which they carried out the qualitative and quantitative research respectively and for the flexibility in accommodating our complex and often changing requirements. The research team at the Reuters Institute provided valuable advice on methodology and content and the author is grateful to Lucas Graves and Rasmus Kleis Nielsen for their constructive and thoughtful comments on the manuscript. Also thanks to Alex Reid at the Reuters Institute for keeping the publication on track at all times. -
The Study of Electromagnetic Processes in the Experiments of Tesla
The study of electromagnetic processes in the experiments of Tesla B. Sacco1, A.K. Tomilin 2, 1 RAI, Center for Research and Technological Innovation (Turin, Italy), [email protected] 2National Research Tomsk Polytechnic University (Tomsk, Russian Federation), [email protected] The Tesla wireless transmission of energy original experiment, proposed again in a downsized scale by K. Meyl, has been replicated in order to test the hypothesis of the existence of electroscalar (longitudinal) waves. Additional experiments have been performed, in which we have investigated the features of the electromagnetic processes between the two spherical antennas. In particular, the origin of coils resonances has been measured and analyzed. Resonant frequencies calculated on the basis of the generalized electrodynamic theory, are in good agreement with the experimental values found. Keywords: Tesla transformer, K. Meyl experiments, electroscalar waves, generalized electrodynamics, coil resonant frequency. 1. Introduction In the early twentieth century, Tesla conducted experiments in which he demonstrated unusual properties of electromagnetic waves. Results of experiments have been published in the newspapers, and many devices were patented (e.g. [1]). However, such work has not received suitable theoretical explanation, and so far no practical application of the results have been developed. One hundred years later, Professor K. Meyl [2] aimed to reproduce the same experiments using a miniature, laboratory version of the Tesla setup, arguing that it can help to detect unusual phenomena that are explained by the presence of electroscalar (longitudinal) waves, namely: • the reaction on the transmitter of the presence of the receiver; • the transmission of scalar waves with a speed of 1,5 times the speed of light; • the inefficiency of a Faraday cage in shielding scalar waves, and • the possibility of wireless transmission of electrical energy. -
Download (PDF)
Nanotechnology Education - Engineering a better future NNCI.net Teacher’s Guide To See or Not to See? Hydrophobic and Hydrophilic Surfaces Grade Level: Middle & high Summary: This activity can be school completed as a separate one or in conjunction with the lesson Subject area(s): Physical Superhydrophobicexpialidocious: science & Chemistry Learning about hydrophobic surfaces found at: Time required: (2) 50 https://www.nnci.net/node/5895. minutes classes The activity is a visual demonstration of the difference between hydrophobic and hydrophilic surfaces. Using a polystyrene Learning objectives: surface (petri dish) and a modified Tesla coil, you can chemically Through observation and alter the non-masked surface to become hydrophilic. Students experimentation, students will learn that we can chemically change the surface of a will understand how the material on the nano level from a hydrophobic to hydrophilic surface of a material can surface. The activity helps students learn that how a material be chemically altered. behaves on the macroscale is affected by its structure on the nanoscale. The activity is adapted from Kim et. al’s 2012 article in the Journal of Chemical Education (see references). Background Information: Teacher Background: Commercial products have frequently taken their inspiration from nature. For example, Velcro® resulted from a Swiss engineer, George Mestral, walking in the woods and wondering why burdock seeds stuck to his dog and his coat. Other bio-inspired products include adhesives, waterproof materials, and solar cells among many others. Scientists often look at nature to get ideas and designs for products that can help us. We call this study of nature biomimetics (see Resource section for further information). -
The Self-Resonance and Self-Capacitance of Solenoid Coils: Applicable Theory, Models and Calculation Methods
1 The self-resonance and self-capacitance of solenoid coils: applicable theory, models and calculation methods. By David W Knight1 Version2 1.00, 4th May 2016. DOI: 10.13140/RG.2.1.1472.0887 Abstract The data on which Medhurst's semi-empirical self-capacitance formula is based are re-analysed in a way that takes the permittivity of the coil-former into account. The updated formula is compared with theories attributing self-capacitance to the capacitance between adjacent turns, and also with transmission-line theories. The inter-turn capacitance approach is found to have no predictive power. Transmission-line behaviour is corroborated by measurements using an induction loop and a receiving antenna, and by visualising the electric field using a gas discharge tube. In-circuit solenoid self-capacitance determinations show long-coil asymptotic behaviour corresponding to a wave propagating along the helical conductor with a phase-velocity governed by the local refractive index (i.e., v = c if the medium is air). This is consistent with measurements of transformer phase error vs. frequency, which indicate a constant time delay. These observations are at odds with the fact that a long solenoid in free space will exhibit helical propagation with a frequency-dependent phase velocity > c. The implication is that unmodified helical-waveguide theories are not appropriate for the prediction of self-capacitance, but they remain applicable in principle to open- circuit systems, such as Tesla coils, helical resonators and loaded vertical antennas, despite poor agreement with actual measurements. A semi-empirical method is given for predicting the first self- resonance frequencies of free coils by treating the coil as a helical transmission-line terminated by its own axial-field and fringe-field capacitances. -
Pocketbook for You, in Any Print Style: Including Updated and Filtered Data, However You Want It
Hello Since 1994, Media UK - www.mediauk.com - has contained a full media directory. We now contain media news from over 50 sources, RAJAR and playlist information, the industry's widest selection of radio jobs, and much more - and it's all free. From our directory, we're proud to be able to produce a new edition of the Radio Pocket Book. We've based this on the Radio Authority version that was available when we launched 17 years ago. We hope you find it useful. Enjoy this return of an old favourite: and set mediauk.com on your browser favourites list. James Cridland Managing Director Media UK First published in Great Britain in September 2011 Copyright © 1994-2011 Not At All Bad Ltd. All Rights Reserved. mediauk.com/terms This edition produced October 18, 2011 Set in Book Antiqua Printed on dead trees Published by Not At All Bad Ltd (t/a Media UK) Registered in England, No 6312072 Registered Office (not for correspondence): 96a Curtain Road, London EC2A 3AA 020 7100 1811 [email protected] @mediauk www.mediauk.com Foreword In 1975, when I was 13, I wrote to the IBA to ask for a copy of their latest publication grandly titled Transmitting stations: a Pocket Guide. The year before I had listened with excitement to the launch of our local commercial station, Liverpool's Radio City, and wanted to find out what other stations I might be able to pick up. In those days the Guide covered TV as well as radio, which could only manage to fill two pages – but then there were only 19 “ILR” stations. -
Antenna Theory and Matching
Antenna Theory and Matching Farrukh Inam Applications Engineer LPRF TI 1 Agenda • Antenna Basics • Antenna Parameters • Radio Range and Communication Link • Antenna Matching Example 2 What is an Antenna • Converts guided EM waves from a transmission line to spherical wave in free space or vice versa. • Matches the transmission line impedance to that of free space for maximum radiated power. • An important design consideration is matching the antenna to the transmission line (TL) and the RF source. The quality of match is specified in terms of VSWR or S11. • Standing waves are produced when RF power is not completely delivered to the antenna. In high power RF systems this might even cause arching or discharge in the transmission lines. • Resistive/dielectric losses are also undesirable as they decrease the efficiency of the antenna. 3 When does radiation occur • EM radiation occurs when charge is accelerated or decelerated (time-varying current element). • Stationary charge means zero current ⇒ no radiation. • If charge is moving with a uniform velocity ⇒ no radiation. • If charge is accelerated due to EMF or due to discontinuities, such as termination, bend, curvature ⇒ radiation occurs. 4 Commonly Used Antennas • PCB antennas – No extra cost – Size can be demanding at sub 433 MHz (but we have a good solution!) – Good performance at > 868 MHz • Whip antennas – Expensive solutions for high volume – Good performance – Hard to fit in many applications • Chip antennas – Medium cost – Good performance at 2.4 GHz – OK performance at 868-955 -
Investigating Energy Harvesting Technology to Wirelessly Charge Batteries of Mobile Devices
Investigating energy harvesting technology to wirelessly charge batteries of mobile devices By Neetu Ramsaroop (19751797) Submitted in fulfilment of the requirements of the Master of Information and Communications Technology degree In the Department of Information Technology in the Faculty of Accounting and Informatics Durban University of Technology Durban, South Africa July, 2017 DECLARATION I, Neetu Ramsaroop, declare that this dissertation represents my own work and has not been previously submitted in any form for another degree at any university or institution of higher learning. All information cited from published and unpublished works have been acknowledged. ________________________ ____________________________ Student Date Approved for final submission Supervisor: ___________________________ ____________________________ Prof. O. O. Olugbara Date Co-supervisors: ___________________________ ____________________________ Esther D. Joubert Date i DEDICATION To My family and my supportive friends ii ACKNOWLEDGMENTS I am grateful to God for embracing me with the strength and inspiration all through this research journey. My sincere gratitude is accorded to my Supervisor, Professor O.O. Olugbara, for his dedication, academic knowledge, expertise, guidance, patience, direction, feedback, comments and meticulous checking of this study. Not to mention his “reminder” phone calls to keep me in check. I would also like to express my deepest appreciation to my Co-Supervisor, Mrs Esther Joubert, for her dedication, constant encouragement, guidance, motivation, outstanding academic writing, patience with my messages at odd hours, dealing with my panic moments and the pleasant manner in which she provided direction in this study. I am thankful to all my friends, DUT colleagues and work colleagues for their support, motivation and advice during this work. -
Tesla's Coil. a Toy Or Useful Thing in the Life of Radio Engineering?
УДК 537 Ільчук Д.Р. Tesla's coil. A toy or useful thing in the life of radio engineering? Вінницький національний технічний університет Аннотація. У цій статті, подан опис такого приладу як Котушка Тесли. Наведені її характеристики, принцип роботи, історія створення та значення в сучасному житті. Також описані процеси створення власноруч та розсуди про практичність даного виробу у реальному житті. Ключові слова: Котушка індуктивності, висока напруга, Нікола Тесла, радіотехніка, електрична дуга. Abstract. This article contains a description of the device as a Tesla coil. These characteristics of the principle of history and value creation in modern life. Also describes the process of creating his own judge and practicality of this product in real life. Keywords: Inductor, high voltage, Nikola Tesla, radio, electric arc. I.Introduction Perhaps in the life of every student comes a time when it begins to be interested in their field. In some it comes in the first year, someone on last. At the beginning of the 3rd year I finally decided to solder something with their hands. The choice immediately fell on Tesla coil. But is this thing so important, whether it is only a toy, which is impossible to do anything useful? Let us know about it. II. Summary The Tesla coil is an electrical resonant transformer circuit designed by inventor Nikola Tesla around 1891 as a power supply for his "System of Electric Lighting".It is used to produce high-voltage, low-current, high frequency alternating-current electricity. Tesla experimented with a number of different configurations consisting of two, or sometimes three, coupled resonant electric circuits. -
THE ULTIMATE Tesla Coil Design and CONSTRUCTION GUIDE the ULTIMATE Tesla Coil Design and CONSTRUCTION GUIDE
THE ULTIMATE Tesla Coil Design AND CONSTRUCTION GUIDE THE ULTIMATE Tesla Coil Design AND CONSTRUCTION GUIDE Mitch Tilbury New York Chicago San Francisco Lisbon London Madrid Mexico City Milan New Delhi San Juan Seoul Singapore Sydney Toronto Copyright © 2008 by The McGraw-Hill Companies, Inc. All rights reserved. Manufactured in the United States of America. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher. 0-07-159589-9 The material in this eBook also appears in the print version of this title: 0-07-149737-4. All trademarks are trademarks of their respective owners. Rather than put a trademark symbol after every occurrence of a trademarked name, we use names in an editorial fashion only, and to the benefit of the trademark owner, with no intention of infringement of the trademark. Where such designations appear in this book, they have been printed with initial caps. McGraw-Hill eBooks are available at special quantity discounts to use as premiums and sales promotions, or for use in corporate training programs. For more information, please contact George Hoare, Special Sales, at [email protected] or (212) 904-4069. TERMS OF USE This is a copyrighted work and The McGraw-Hill Companies, Inc. (“McGraw-Hill”) and its licensors reserve all rights in and to the work. Use of this work is subject to these terms. Except as permitted under the Copyright Act of 1976 and the right to store and retrieve one copy of the work, you may not decompile, disassemble, reverse engineer, reproduce, modify, create derivative works based upon, transmit, distribute, disseminate, sell, publish or sublicense the work or any part of it without McGraw-Hill’s prior consent. -
Langley Bath Clearwater Middle
Together Forward—Full Steam Ahead! PURPOSE: DIRECTION: TOGETHER FORWARD Full STEAM Ahead! Together We Stand Future Leaders Science Open-Minded Original Thinkers Technology Global Thinkers Responsible Citizens Engineering Encouraging Work Career College Ready Arts Teaching Integrity Advocates for Life-Long Learning Mathematics High Expectations Real World Problem Solvers Enriching Experiences Devoted to Kindness Respect for All ELA Doesn’t Meet ELA Approaches ELA Meets ELA Exceeds South Carolina College andCareer Ready Carolina College South Grade 2018 Grade 2018 Grade 2018 Grade 2018 6 34.6 6 35.7 6 21.1 6 8.6 ELA 7 36.9 7 34.8 7 17.6 7 10.7 8 42.0 8 27.8 8 17.2 8 13.0 ELA Not Met ELA Approaches ELA Met ELA Exemplary Grade 2016 2017 Grade 2017 Grade 2016 2017 Grade 2016 2017 6 22.1 39.6 6 40.6 6 22.1 16.0 6 7.6 3.7 7 29.7 43.2 7 37.9 7 21.3 14.2 7 6.9 4.7 8 31.7 40.5 8 11.8 4.5 8 34.5 8 24.5 20.5 Math Doesn’t Meet Math Approaches Math Meets Math Exceeds Grade 2018 Grade 2018 Grade 2018 Grade 2018 MATH 6 44.8 6 24.6 6 18.6 6 12.0 7 41.5 7 38.8 7 13.8 7 5.9 8 30.2 8 47.9 8 10.7 8 11.2 — SC Ready Math Not Met Math Approaches Math Met Math Exemplary Grade 2016 2017 Grade 2017 Grade 2016 2017 Grade 2016 2017 6 30.8 45.5 6 36.9 6 10.5 12.3 6 7.6 5.3 7 30.9 34.9 7 36.7 7 22.5 15.4 7 6.9 13.0 8 40.5 39.0 8 39.5 8 11.7 14.5 8 11.8 7.0 Langley Bath Clearwater Middle Paul Spadaro Principal Marlee Calloway Catherine Neal Emily Harvey & Myasha Witherspoon Casey Rogers Guidance Counselors Assistant Principals Catherine Corbett Charish Saunders Secretary/Bookkeeper