DOCSLIB.ORG

Infusing Radio-Based Communications Tools

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Infusing Radio-Based Communications Tools INFUSINGINFUSING RADIO-BASEDRADIO-BASED COMMUNICATIONSCOMMUNICATIONS TOOLSTOOLS INTOINTO THETHE CURRICULUMCURRICULUM EDITED BY GREG JONES PUBLICATION DESIGN BY SAVANEE BANGPIPOB COVER ILLUSTRATION & DESIGN BY PIJARN CHAROENSRI TCET COPYRIGHT © 1995 ALL RIGHTS RESERVED Infusing Radio-Based Communications Tools into the Curriculum Contents i C O N T E N T S Foreword ..................................................................................................... iii Overview ...................................................................................................... v Acknowledgment ........................................................................................ ix This Manual’s Content ............................................................................... xi Part I: Proposed Applications of Radio-Based Communications Tools in K-12 Curricula............................................................... 1 K-12 Amateur Radio in the Classroom. By Greene ..................... 3 Amateur Radio in the Writing Curriculum. By Herod ........ 9 Use of Amateur Radio to Provide Telecommunications in Texas Education. By Wade ............................................ 13 Pre-K/K Radio Communications for Pre-K/K Students. By Adams ....................................................................... 17 Elementary An Affordable Approach to Telecommunications in the Elementary School. By Lucas ....................................... 21 A Proposal for Radio Equipment for Elementary School. By Embry........................................................................ 27 Middle School/Junior High A Proposal to Create a Global Communications Center. By Hadley and Raymond................................................ 31 Use of Packet Radio in Junior High Computer Literacy. By Rowe ......................................................................... 39 Using Weather Satellite Images in Middle School Science. By Bennett ...................................................................... 45 Integrating Packet Radio into the Computer Literacy Curriculum. By Griffin .................................................. 49 Using Packet Radio to Teach Telecommunications. By Case ........................................................................... 53 ii Infusing Radio-Based Communications Tools into the Curriculum Junior High/High School A Proposal for Establishing Amateur Radio in Secondary School Curricula. By Hubbard ...................................... 57 Special Education Implementation of Radio Technology in Classrooms for the Hearing Impaired. By Reeder .................................. 67 Gifted and Talented Integration of Packet Radio into K-12 Gifted and Talented Programs. By Tuma ........................................ 73 Part II: Lesson Plans for Use of Radio Communications to Expand the Walls of the Classroom ........................................... 77 Elementary ATS-3 Satellite: Linking 6th Graders and Pacific Islanders. By Embry........................................................................ 79 Amateur Radio Pen Pals. By Embry ................................... 83 Uses of Packet Radio in Teaching 3rd Grade Social Studies. By Tubbs ......................................................................... 87 Using Weather Satellites with 3rd Grade Students. By Tubbs .. 91 Introducing Students to the Packet Radio Communications Tool. By Lucas .................................. 95 4th Grade Language Arts, Writing, and Packet Radio. By Tuma ......................................................................... 99 Packet Radio and 6th Grade Science: Land Biomes. By Hootman.................................................................... 103 Middle School/Junior High Weather Patterns Using Satellite Images. By Bennett ......... 107 Computer Literacy and Packet Radio. By Griffin ............... 115 Making Texas Geography Come Alive. By Greene ............ 119 A Database Application Using Packet Radio to Collect the Data. By Willis......................................................... 121 A Collaborative Physical Science Project Using Packet Radio Telecommunications. By Wade ........................... 125 Gifted and Talented Using Amateur Radio Technology with Gifted Students. By Rowe ......................................................................... 129 Additional References ................................................................................ 133 Foreword iii F O R E W O R D Two trains of thought have converged in this publication. First, educators of the 90’s are constantly searching for new ways to make school more interesting and relevant to the real world. At the same time, many telecommunications engineers fondly recall the construction of a crystal radio as the event that triggered their lifelong enthusiasm for the field. Packet radio, as a form of computer-based communication, is so affordable and yet so intriguing that it may have the potential for motivating the next generation of would-be telecommunications scientists. The second school of thought is that it is best to ask educators themselves how they might like to see amateur radio-based communications integrated into education. This booklet contains several examples of technology integration proposals and lesson plans produced by educators who accepted precisely that task. All authors had 45 hours of study in radio applications and theory, and many went on to receive an amateur radio license. It is hoped that other educators will find their work useful and will continue to build upon the initial collection of ideas produced by these pioneers. Gerald Knezek, Ph.D. Texas Center for Educational Technology Department of Technology and Cognition College of Education University of North Texas iv Infusing Radio-Based Communications Tools into the Curriculum Overview v O V E R V I E W For the past few years, technology educators at the University of North Texas in conjunction with the Texas Center for Educational Technology (TCET) have initiated activities designed to increase K-12 educators’ awareness of the potential for using low cost radio and satellite technology to enhance traditional education. Initiatives focus on three areas: 1) evaluation of existing low cost communication technologies, 2) research and development of integrated curricu- lar-radio/satellite technology models to demonstrate feasible scenarios for use by teachers and learners to enhance education, and 3) dissemination and training activities intended to convey the lessons learned to technology coordinators and classroom teachers. Research has shown that students learn better when motivated by an interest in their subjects. It is generally agreed by teachers who use radio/satellite technology in the classroom that this curricular enhancement can provide students with a fun and practical way to learn traditional content. Radio/satellite technol- ogy can be used in many curricular areas, such as General Science, Algebra, Geometry, Physics, Industrial Technology, Language Arts, Computer Literacy, and many others. This radio infusion guide is a continued effort to disseminate the concepts of using radio/satellite technology in education. The guide is based on selected papers which were submitted by graduate students in a summer institute covering Educational Radio/Satellite Communications which was taught by Gerald Knezek, KB5EWV, Greg Jones, WD5IVD, and Mike Maner, WI5H, at the Uni- versity of North Texas in the summer of 1991. Additional papers were selected from those submitted in a similar class held the following summer (1992). The information published in this guide was built upon the following general model of using radio/satellite technology in the classroom. The three modes of the general model are: 1. Monitor Mode (Receive Only) The teacher and students receive only; they do not transmit. Satellite Telemetry, Weather Imaging, Short Wave Listening, etc. 2. Teacher Licensed The teacher acts as the facilitator/operator for transmitting. Participation in real-time communication using the radio. ATS-3 Satellite Communications vi Infusing Radio-Based Communications Tools into the Curriculum 3. Teacher and Student(s) Licensed * The teacher and students are licensed for communications. Packet Radio connections to other schools. Amateur TV * This mode allows more freedom and flexibility; the teacher does not have to spend time monitoring student communications. Each mode builds on the previous in knowledge and expertise. The monitor mode encompasses the largest group of the model since anyone can receive communications without a license. Any teacher with minimal support and technology can introduce a wide variety of radio/satellite technology in the moni- tor mode. Educators sometimes do not realize that their classroom and schools are bombarded by millions of information sources daily. The secret is knowing which are useful for education. With a receiver and a way of decoding and displaying the information, these sources can be used directly in the classroom. Examples of the monitor mode might include: Voice of America broadcasts for language arts, reception of NOAA for physical sciences, or the reception of the low-earth satellites for data information that can be used in math and physics courses. In K-12 education, radio/satellite technology is beginning to spread with the reception of weather satellite images. There are now over twenty amateur radio satellites and a score of weather satellites readily available to educators
Load more

Recommended publications
  • Crystal Radio Set Systems: Design, Measurement, and Improvement Volume II a Web Book by Ben Tongue
    Crystal Radio Set Systems: Design, Measurement, and Improvement Volume II A web book by Ben Tongue First published: 10 Jul 1999; Revised: 01/06/10 i NOTES: ii 185 PREFACE Note: An easy way to use a DVM ohmmeter to check if a ferrite is made of MnZn of NiZn material is to place the leads of the ohmmeter on a bare part of the test ferrite and read the The main purpose of these Articles is to show how resistance. The resistance of NiZn will be so high that the Engineering Principles may be applied to the design of crystal ohmmeter will show an open circuit. If the ferrite is of the radios. Measurement techniques and actual measurements are MnZn type, the ohmmeter will show a reading. The reading described. They relate to selectivity, sensitivity, inductor (coil) was about 100k ohms on the ferrite rods used here. and capacitor Q (quality factor), impedance matching, the diode SPICE parameters saturation current and ideality factor, #29 Published: 10/07/2006; Revised: 01/07/08 audio transformer characteristics, earphone and antenna to ground system parameters. The design of some crystal radios that embody these principles are shown, along with performance measurements. Some original technical concepts such as the linear-to-square-law crossover point of a diode detector, contra-wound inductors and the 'benny' are presented. Please note: If any terms or concepts used here are unclear or obscure, please check out Article # 00 for possible explanations. If there still is a problem, e-mail me and I'll try to assist (Use the link below to the Front Page for my Email address).
    [Show full text]
  • Before Valve Amplification) Page 1 of 15 Before Valve Amplification - Wireless Communication of an Early Era
    (Before Valve Amplification) Page 1 of 15 Before Valve Amplification - Wireless Communication of an Early Era by Lloyd Butler VK5BR At the turn of the century there were no amplifier valves and no transistors, but radio communication across the ocean had been established. Now we look back and see how it was done and discuss the equipment used. (Orininally published in the journal "Amateur Radio", July 1986) INTRODUCTION In the complex electronics world of today, where thousands of transistors junctions are placed on a single silicon chip, we regard even electron tube amplification as being from a bygone era. We tend to associate the early development of radio around the electron tube as an amplifier, but we should not forget that the pioneers had established radio communications before that device had been discovered. This article examines some of the equipment used for radio (or should we say wireless) communications of that day. Discussion will concentrate on the equipment used and associated circuit descriptions rather than the history of its development. Anyone interested in history is referred to a thesis The Historical Development of Radio Communications by J R Cox VK6NJ published as a series in Amateur Radio, from December 1964 to June 1965. Over the years, some of the early terms used have given-way to other commonly used ones. Radio was called wireless, and still is to some extent. For example, it is still found in the name of our own representative body, the W1A. Electro Magnetic (EM) Waves were called hertzian waves or ether waves and the medium which supported them was known as the ether.
    [Show full text]
  • DESIGNING a DX CRYSTAL SET Equipment
    DESIGNING A DX CRYSTAL SET by Mike Tuggle 46-469 Kuneki St. Kaneohe, HI 96744-3536 E-Mail: [email protected] Long distance reception with crystal radios is once again becoming a serious pursuit among hams and other radio hobbyists. They are discovering that the DX capabilities of these receivers have been greatly underrated. I've been particularly interested in crystal sets since 1959, when I first discovered you could actually DX with them. The Internet has aided crystal set DX activity by making exchange of ideas between like- minded enthusiasts much, much easier. This article only touches the surface from a personal perspective. The reader is encouraged to pursue the online resources, described below, covering all aspects and providing further examples of this fascinating hobby. In this article I'll cover general design considerations for building DX crystal sets, but will leave the actual construction specifications up to you. Equipment Figures 1 and 2 show an example of a DX crystal set. I call it the "Lyonodyne-17." The design evolved from an earlier version described in the November, 1978 OTB. As you can see, this is not your grandfather's crystal set. Antenna (right) and detector (left) tuners are mounted on the middle board. Wave traps are located fore and aft on separate boards, making it possible to adjust the coupling by moving the boards. The antenna coil (L1) is wound on a short ferrite rod. The matching transformer unit for my RCA "Big Cans" sound powered phones is at front, left. So, what makes a crystal radio a "DX" set? Well, this one is double-tuned (L1-C1 and L2-C2) for selectivity to tune weak DX stations in the RF jungle we now live in.
    [Show full text]
  • The Crystal Radio
    The Crystal Radio: An Inexpensive Form of Mass Communication Christopher Manxhari Massachusetts Academy of Math & Science at Worcester Polytechnic Institute Manxhari 1 Introduction Technology has always been developing, and with it so have methods and access to communication. One such example is the internet, which has been rapidly growing in the past years. Yet, despite all of these advancements, there is still a large population that lacks internet. During distraught times, such as the coronavirus pandemic, having access to information is important, but not everyone is able to access urgent information. Roughly 10% of the United States population does not have access to the internet (Anderson, Perrin, Jiang, & Kumar, 2020). This proportion translates to over 30 million United States citizens, which is quite a substantial population size. In fact, there appears to be a correlation between income level and the proportion of those in a certain economic bracket that have internet. At an annual income of less than $30,000, 18% of citizens lack access to the internet. Withal, 7% of those making between $30,000 and $50,000 annually, 3% of those making $50,000 to $75,000 annually, and 2% of those making anything upwards annually lack that access (Anderson ​ ​ et al., 2020). See Figure 1 for more data on the ​ ​ ​ ​ demographics of those using the internet. It is evident that one’s income level is positively correlated with higher frequencies of internet usage. The internet is but one of many mediums of mass communication, and it is certainly one dominating form. As of 2018, roughly 41% of U.S.
    [Show full text]
  • Construction and Operation of a Simple Homemade Radio Receiving Outfit
    Construction and Operation of a Simple Homemade Radio Receiving Outfit The 1922 Bureau of Standards publication, Construc- tion and Operation of a Simple Homemade Radio Receiving Outfit [1], is perhaps the best-known of a series of publications on radio intended for the general public at a time when the embryonic radio industry in the U.S. was undergoing exponential growth. While there were a number of earlier experiments with radio broadcasts to the general public, most histori- ans consider the late fall of 1920 to be the beginning of radio broadcasting for entertainment purposes. Pittsburgh, PA, station KDKA, owned by Westinghouse, received its license from the Department of Commerce just in time to broadcast the Harding-Cox presidential election returns. In today’s world where instant global communications are commonplace, it is difficult to appreciate the excitement that this event generated. Fig 1. The crystal radio described in Circular 120. News of the new development spread rapidly, and interest in radio soared. By the end of 1921, new broad- casting stations were springing up all over the country. Radios were selling faster than companies could manu- facture them. The demand for information on this new technology was almost insatiable. The Radio Section of the Bureau of Standards provided measurement know- how to the burgeoning radio industry as well as general information on the new technology to the public. Letters to the Bureau seeking information on radio technology began as a trickle, and then soon became a flood. Answering them became a burden. Circular 120, published in April 1922, began: “Frequent inquiries are received at the Bureau of Standards for information regarding the construction of a simple receiving set which any person can construct in the home from materials which can be easily secured.
    [Show full text]
  • A Stable, Low-Noise Crystal Oscillator for Microwave and Millimeter-Wave Transverters
    A Stable, Low-Noise Crystal Oscillator for Microwave and Millimeter-Wave Transverters Would you like to try narrow-band modes in the gigahertz bands? If so, you’ll need a very stable and ultra-clean local oscillator. This project fills that need. By John Stephensen, KD6OZH mateurs are using narrow- than at lower microwave frequencies. commercial equipment on nearby fre- band modulation—including On SSB, the indicated frequency quencies or amateur beacons operating ACW, SSB and NBFM—on ever- should be within 500 Hz at both the at the same site. higher frequencies. In the US, SSB is transmitter and receiver, or you may I decided to replace the LO in my commonplace on all microwave bands not hear the station calling you. Dur- 24-GHz transverter and solve both the through 10 GHz and is spreading to ing a microwave contest, you don’t phase-noise and stability problems. the 24- and 47-GHz millimeter-wave want to adjust both the antenna and This article describes the crystal oscil- bands. In Europe, narrow-band opera- the frequency while trying to make a lator and multiplier designs that re- tion has taken place as high as contact. I wasted many hours during sulted. They work nicely with existing 411 GHz.1 the last 10-GHz-and-Up contest be- transverters using the KK7B LO The local oscillator (LO) used at cause the LO in my transverter was design2 with a few modifications and these higher, millimeter-wave fre- 85 kHz off frequency at 24.192 GHz. can be adapted to others.
    [Show full text]
  • Build a Crystal Radio: Electronics Series - Part I
    The University of Maine DigitalCommons@UMaine General University of Maine Publications University of Maine Publications 1965 Build a Crystal Radio: Electronics Series - Part I University of Maine Cooperative Extension Service Follow this and additional works at: https://digitalcommons.library.umaine.edu/univ_publications Part of the Higher Education Commons, History Commons, and the Radio Commons Repository Citation University of Maine Cooperative Extension Service, "Build a Crystal Radio: Electronics Series - Part I" (1965). General University of Maine Publications. 286. https://digitalcommons.library.umaine.edu/univ_publications/286 This Monograph is brought to you for free and open access by DigitalCommons@UMaine. It has been accepted for inclusion in General University of Maine Publications by an authorized administrator of DigitalCommons@UMaine. For more information, please contact [email protected]. UNIVERSITY OF MAINE LIBRARY COOPERATIVE EXTENSION SERVICE • UNIVERSITY OF MAINE, O r o n o ELECTRIC GUIDE SHEET OUTLINE A-21 (Advanced) BUILD A CRYSTAL RADIO ELECTRONICS SERIES - PART I lectronics is a fascinating hobby or a prof­ E itable lifetime occupation. Radio, apart of electronics, had its begin- ning about 1895 when Marconi succeeded in transmitting a "wireless" message over a distance of a mile and a half. Marconi did not invent radio, nor was he alone in its early work. However, from that small beginning radio has advanced until to- day its influence is felt in every phase of our lives. Through radio and television the world's greatest entertainers, educators, and poli­ ticians virtually step into our living room. Electronics provides communications across continents, oceans and into outer space.
    [Show full text]
  • 25 Cents February 1923
    CIRCULATION OF THIS ISSUE OVER 225,000 COPIES ,psyymems_ DIO 25 Cents February 1923 NEWS Over 175 I Ilustrations Edited by H.GERNSBACK `A LOOSE COUPLE THE 100% WIRELESS MAGAZINE CIRCULATION LARGER THAN ANY OTHER PUBLICATION www.americanradiohistory.com CUNNINGHAM TYPE C 300 PATENTED AMPLIFIES AS IT DETECTS Patent Notice Cunningham tubes are covered by pat- enta dated 11 -7 -05. 1- 15 -07, 2 -18 -08 and others issued and pending. Licensed only for amateur or experimental uses in radio communication. Any other use will be an infringement. TYPE C -300 Super - Sensitive DETECTOR $ 500 TYPE C -301 Give Clearest Reception Distortioaless AMPLIFIER Cunningham Tubes used in any standard receiving set tvill enable you and your friends to listen to news reports at breakfast, stock market quotations at lunch, $650 and in the evening sit in your comfortable living -room by the fireside and enjoy the finest music and entertainment of the day. Send 5c for new 32 -page Cunningham Tube catalog, containing detailed instruc- tion for the operation of Cunningham Tubes as well as numerous circuit diagrams and graphic illustrations of tube action. The Cunningham Technical Bureau is at your Service. Address your problems to Dept. R. The trade mark GE Eastern is the guarantee of these quality Home Office:- Representatives: - tubes. Each tube is built to most rigid specifica- 248 First Street 154 West Lake Street tions. San Francisco, Calif. Chicago, Illinois www.americanradiohistory.com Radio News for February, 1923 $ 00 2000Ohm 75o 30000hm Their Deep, Natural- Voiced Pitch Is Rapidly Selling Thousands ACTUALLY-thousands are being snapped up on the strength of their pleasing voice tone and keen sensitive- ness.
    [Show full text]
  • Crystal Radio Engineering
    Crystal Radio Engineering A web book by Kenneth A. Kuhn updated Apr. 17, 2008 i ii A SIMPLE CRYSTAL RADIO PREFACE ADVANCED TOPICS This is a collection of articles that form a text book on designing crystal radios. The primary focus is to illustrate to A chapter on making various measurements of your system is engineering students how to apply concepts of engineering to planned. Some other chapters or additional information is solve a problem. It takes a lot of in-depth research to be good planned to connect all the chapters together smoothly. Right at what one does. The main part of this book deals with now the connections are rough -- but this is a work in progress. understanding the required concepts to build a good basic crystal radio. Advanced concepts (to be written and posted last) will deal with a number of improvements that can be made to the basic design. Here is a link to an excellent site for crystal radio information: http://www.crystalradio.net/crystalplans/index.shtml http://www.1n34a.com/ This is an excellent site with links to other crystal radio sites. Be sure to check the Ben Tongue link for a number of practical articles. Here is a source for parts I found using a Google search http://www.midnightscience.com/catalog5.html#part2 This company specializes in parts for crystal radios and sells variable capacitors, diodes, crystal earphones, etc. I have not bought from them before so I do not know how good they are but I might try them someday. The following are links to the pdfs for each chapter.
    [Show full text]
  • Radio Electronics, July 1986 with an Article That
    7A 3v7 Most us believe that the age of solid- MARTIN CLIFFORD DID YOU KNOW: TI IAT SOLID-STATE ELEC- of tronics can trace its roots back to 1835? state electronics began with the invention In this, the first installment That radio signals can be demodulated of the transistor; Bardeen and Brattain of using sulfuric acid or nitric acid? That oil - Bell Laboratories produced that first crys- of our new, occasional series filled variable capacitors were once used tal triode in 1948. However, lost in the about the early days of radio, in radio receivers? That a single crystal mists of history is the fact that true solid- detector can be used as a radio receiver? state receivers have been with us since we look at the original That there are some radio receivers that about 1918. "solid-state" receivers. never need to be turned off, have no on/off In more recent times, the term solid- switch, and do not require battery or AC state has been so firmly associated with power? Or that lenzite, zincite, bornite, germanium, and subsequently with sil- tellurium, and chalcopyrite are all semi- icon, that no one should be blamed for conductors? thinking that those are the only materials The Early Days o 1 i I y m y,o- .. J' -, - suitable for use in semiconductors. Yet least some improvement over those with there are numerous materials that are just no tuning at all. as suitable. Among them are carhorun- Another problem was that the output of dum (silicon carbide): galena (a crystal the crystal detector consisted of both an sulphide of lead); molybdenum: lenzite: audio signal and an RF carrier: both were ¿incite (an oxide of zinc): tellurium: bar- passed directly to the headphones.
    [Show full text]
  • ED426693 1999-03-00 Radios in the Classroom: Curriculum Integration and Communication Skills
    ED426693 1999-03-00 Radios in the Classroom: Curriculum Integration and Communication Skills. ERIC Digest. ERIC Development Team www.eric.ed.gov Table of Contents If you're viewing this document online, you can click any of the topics below to link directly to that section. Radios in the Classroom: Curriculum Integration and Communication Skills. ERIC Digest........................................................... 2 TEACHING THE HISTORY OF COMMUNICATION..................... 2 AM-FM RADIO: HANDS-ON GEOGRAPHY AND LANGUAGE ARTS ACTIVITIES................................................................ 2 INTERNATIONAL SHORTWAVE BROADCASTS: HEARING THE WORLD ON A RADIO....................................................3 NOAA NATIONAL WEATHER SERVICE BROADCASTS.............. 3 AMATEUR RADIO: PRACTICING HANDS-ON COMMUNICATION SKILLS...................................................................... 4 SUMMARY.......................................................................4 REFERENCES.................................................................. 4 ERIC Identifier: ED426693 Publication Date: 1999-03-00 Author: Ninno, Anton Source: ERIC Clearinghouse on Information and Technology Syracuse NY. Radios in the Classroom: Curriculum ED426693 1999-03-00 Radios in the Classroom: Curriculum Integration and Page 1 of 8 Communication Skills. ERIC Digest. www.eric.ed.gov ERIC Custom Transformations Team Integration and Communication Skills. ERIC Digest. THIS DIGEST WAS CREATED BY ERIC, THE EDUCATIONAL RESOURCES INFORMATION CENTER. FOR MORE
    [Show full text]
  • Iridescent Lesson Plan
    Iridescent Lesson Plan OBJECTIVE KEY CONCEPTS AND VOCABULARY What will your students be able to do? What three-five key points will you emphasize? Understand the basics of amplitude Amplitude modulation: carrier signal, modulating signal, modulation (AM) and build a crystal radio modulated signal that can receive AM broadcast stations. Crystal radio (Foxhole radio) CONNECTION TO THE BIG IDEA How does the objective connect to the big idea? Learning about amplitude modulation and how crystal radios work will enable them understand how radio PLANNING - receivers work. PRE ASSESSMENT How will you know whether your students have made progress toward the objective? How and when will you assess mastery? Exit slips and concept maps will enable us to check for student understanding. OPENING (2 min) MATERIALS How will you communicate what is about to happen? How will you communicate how it will happen? What materials will you need How will you communicate its importance? How will you communicate connections to previous lessons? for your lesson? Good morning everyone! Let us review quickly what we have learnt so far. Do you (for each experiment) remember what fields interact to produce light? Right, the electric and magnetic A sturdy plastic fields. Do you remember the names of different kinds of waves that we learnt in last bottle or a toilet class? (Radio waves, infrared, visible light, ultra violet, x-rays, and gamma rays.) paper roll, should be How do these waves differ from each other? Right, in terms of wavelengths. We at least 2-3 inches in also made a very simple device to produce electromagnetic waves; do you diameter remember how it worked? It is called a spark gap transmitter.
    [Show full text]