Transmitting Antennas and Ground Systems for 1750 Meters
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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). -
Optimization of Low Frequency Litz-Wire RF Coils
Optimization of Low Frequency Litz-wire RF Coils J.A. Croon, II. M. fkJrSbooll1, A. F. Mehlkopf Fi7culty of Applied Physics, DeFt IJniversity of Technology, P.O. Box 5046, 2600 GA Delft, 77zeNetherlands INTRODUCTION Equations ]4] and [5] show that the skin losses are proportional to the In MRI the patient or sample losses increase with the square of the resistivity while the proximity losses are proportional to the conductiv- resonance frequency. This makes coil losses significant at low field ity. The rota1 losses are minimized if the derivative of P,,,, to p is zero. strengths. dP,oss %kin Rprox_ It is well known (1) that for frequencies of several hundreds of l&z - =--- - 0 or Rski,, = R WI stranded or litz wires can have lower losses than conventional wires, do P P PYqX Here we will investigate and present the optimization of copper solenoid coils for room temperature and for liquid nitrogen temperature. Thus the maximum coil quality is achieved if the skin losses equal the For litz wire coils we distinguish three types of losses: proximity losses. 1. losses within each considered strand, 2. proximity losses in the surrounding strands and RESULTS 3. eddy losses the environment of the coil (mainly determined by the The results of table 1 concern solenoids with a single litz wire and with sample losses). The losses within the considered strands are called skin six parallel litz wires. The six parallel wires are placed above each losses. We will show that the maximum coil quality is achieved if the other and twisted such that the losses in each parallel wire are the skin losses are equal to the proximity losses. -
Figure 1 Old Huge Magnetic Receiving Loop Antennas
ANTENTOP- 02- 2004, # 006 Old Receiving Magnetic Loop Antennas Igor Grigorov, RK3ZK [email protected] Receiving magnetic loop antennas were widely used in the professional radio communication from the beginning of the 20 Century. Since 1906 magnetic loop antennas were used for direction finding purposes needed for navigation of ships and planes. Later, from 20s, magnetic loop antennas were used for broadcasting reception. In the USSR in 20- 40 years of the 20 Century when broadcasting was gone on LW and MW, huge loop antennas were used on Reception Broadcasting Centers (see pages 93- 94 about USSRs RBC). Magnetic loop antennas worldwide were used for reception service radio stations working in VLW, LW and MW. The article writes up several designs of such old receiving loop antennas. LW- MW Huge Receiving Loop Fig. 2 shows a typical connection of the above mention Antennas for Broadcasting and huge magnetic receiving loop antennas designed for Direction Finding working on one fixing frequency to the receiver. To a resonance the loop A1 is tuned by lengthening coil L1 In old radio textbooks you can find description of old (sometimes two lengthening coils switched symmetrically magnetic receiving loop antennas. As a rule, old to both side of the loop were used) and variable air- magnetic receiving loop antennas had a triangle or dielectric capacitor C1. T1 did connection with antenna square shape, a side of the triangle or square had feedline. L1, C1 and T1, as a rule, are placed directly length in 10-20 meters. The huge square was put near the antenna keeping minimum length for wires from on to a corner. -
The Gulf of Georgia Submarine Telephone Cable
.4 paper presented at the 285th Meeting of the American Institute of Electrical Engineers, Vancouver, B. C., September 10, 1913. Copyright 1913. By A.I.EE. THE GULF OF GEORGIA SUBMARINE TELEPHONE CABLE BY E. P. LA BELLE AND L. P. CRIM The recent laying of a continuously loaded submarine tele- phone cable, across the Gulf of Georgia, between Point Grey, near Vancouver, and Nanaimo, on Vancouver Island, in British Columbia, is of interest as it is the only cable of its type in use outside of Europe. The purpose of this cable was to provide such telephonic facilities to Vancouver Island that the speaking range could be extended from any point on the Island to Vancouver, and other principal towns on the mainland in the territory served by the British Columbia Telephone Company. The only means of telephonic communication between Van- couver and Victoria, prior to the laying of this cable, was through a submarine cable between Bellingham and Victoria, laid in 1904. This cable was non-loaded, of the four-core type, with gutta-percha insulation, and to the writer's best knowledge, is the only cable of this type in use in North America. This cable is in five pieces crossing the various channels between Belling- ham and Victoria. A total of 14.2 nautical miles (16.37 miles, 26.3 km.) of this cable is in use. The conductors are stranded and weigh 180 lb. per nautical mile (44. 3 kg. per km.). By means of a circuit which could be provided through this cable by way of Bellingham, a fairly satisfactory service was maintained between Vancouver and Victoria, the circuit equating to about 26 miles (41.8 km.) of standard cable. -
Wireless Energy Transfer by Resonant Inductive Coupling
Wireless Energy Transfer by Resonant Inductive Coupling Master of Science Thesis Rikard Vinge Department of Signals and systems CHALMERS UNIVERSITY OF TECHNOLOGY Göteborg, Sweden 2015 Master’s thesis EX019/2015 Wireless Energy Transfer by Resonant Inductive Coupling Rikard Vinge Department of Signals and systems Division of Signal processing and biomedical engineering Signal processing research group Chalmers University of Technology Göteborg, Sweden 2015 Wireless Energy Transfer by Resonant Inductive Coupling Rikard Vinge © Rikard Vinge, 2015. Main supervisor: Thomas Rylander, Department of Signals and systems Additional supervisor: Johan Winges, Department of Signals and systems Examiner: Thomas Rylander, Department of Signals and systems Master’s Thesis EX019/2015 Department of Signals and systems Division of Signal processing and biomedical engineering Signal processing research group Chalmers University of Technology SE-412 96 Göteborg Telephone +46 (0)31 772 1000 Cover: Magnetic field lines between the primary and secondary coil in a wireless energy transfer system simulated in COMSOL. Typeset in LATEX Göteborg, Sweden 2015 iv Wireless Energy Transfer by Resonant Inductive Coupling Rikard Vinge Department of Signals and systems Chalmers University of Technology Abstract This thesis investigates wireless energy transfer systems based on resonant inductive coupling with applications such as charging electric vehicles. Wireless energy trans- fer can be used to power or charge stationary and moving objects and vehicles, and the interest in energy transfer over the air has grown considerably in recent years. We study wireless energy transfer systems consisting of two resonant circuits that are magnetically coupled via coils. Further, we explore the use of magnetic materials and shielding metal plates to improve the performance of the energy transfer. -
VK4YE Compact End-Fed 5 Band HF Antenna
VK4YE Compact End-Fed 5 Band HF Antenna INTRODUCTION End-fed antennas are increasingly popular again, at least partly because of compact ferrite toroid cores. Small cores facilitate easy-to-build low-power RF transformers and networks. The combination of lightweight matching systems, combined with the installation simplicity of NOT hanging a heavy coaxial feeder from a long span of thin antenna wire, has rekindled interest in end-fed half-wave antennas. The 25m long antenna described here will get you on air without an ATU on 80m, 40m, 20m, 15m & 10m. It has been purposely reduced in length compared to a full sized 80m dipole by the insertion of a 70uH loading coil. At 7MHz, the impedance of the loading coil is about 3kΩ, and this effectively disconnects the tail of the antenna at 40m and above. The reason for reducing the size of the antenna is to enable operation on smaller house allotments as well as being compact enough for portable work. The length of the antenna from the feed point to the loading coil is 20.2m and this sets the 40m resonance at 7.1MHz, which in turn dictates the responses of the harmonically related bands 14MHz, 21MHz and 28MHz. As the length of the antenna is around 2/3 of the span of a half-wave dipole on 80m, there are two compromises. Firstly, bandwidth on 80m is restricted to about 80 kHz at the 2:1 SWR points, and secondly, there will be a reduction of around 1.5 S points in both transmitted and received signals. -
APRIL 1939 Vol. 17, No. 4
APRIL 1939 Vol. 17, No. 4 www.americanradiohistory.com ELECTRICAL COMMUNICATION A Journal of Progress in the Telephone. Telegraph and Radio Art H. T. KOHLHAAS, EDITOR EDITORIAL BOARD E. A. Brofos G. Deakin E. M. Deloraine P. E. Erikson F. Gill W. Hatton R. A. Mack H. M. Pease Kenneth E. Stockton C. E. Strong Issued Quarterly by the /nf-l!rnuil'1nu/ Sruunurd Elec/-ric Corpora/ion 67 BROAD STREET, NEW YORK, N.Y., U.S.A. Volume XVII April, 1939 Number 4 PAGE PUBLIC ADDRESS SYSTEM AT THE THIRTY-FOURTH INTERNATIONAL EUCHARISTIC CONGRESS, BUDAPEST, MAY 22�29, 1938.......... 319 By G. A. de Czegledy ULTRA-SHORT WAVE OSCILLATORS ........... .............. ... 325 By D. H. Black ULTRA-SHORT WAVE POLICE RADIO TELEPHONE INSTALLATIONS IN OSLO AND STOCKHOLM. .. .. .. .. .. .. .. .. .. .. 335 By G. Weider R-6 AUTOMATIC SYSTEM...................................... 346 By F. Gohorel and R. Lafon }AMES LAWRENCE McQuARRIE .................................. 358 }AMES LAWRENCE McQuARRIE-AN APPRECIATION................ 359 By F. B. Jewett THE BUCHAREST-PLOESTI TOLL CABLE .........•................ 360 By A. C. Nano SOME INDUSTRIAL APPLICATIONS OF SELENIUM RECTIFIERS. .. .. .. 366 By S. V. C. Scruby and H. E. Giroz A LONG DISTANCE AUTOMATIC TELEPRINTER EXCHANGE WITH MANUAL PRIORITY SERVICES ........................................ 375 By G. A. M. Hyde THE EIFFEL TOWER TELEVISION TRANSMITTER. .. .. .. .. .. .. .. 382 By S. Mallein and G. Rabuteau RECENT TELECOMMUNICATION DEVELOPMENTS OF INTEREST. .. .. .. 398 www.americanradiohistory.com Jam es L. McQuarrie 1867-1939 www.americanradiohistory.com Public Address System at the Thirty-Fourth International Eucharistic Congress Budapest, May 22-29, 1938 By G. A. DE CZEGLEDY, A.M.I.R.E., Chief Engineer, Standard Electric Company Limited, Budapest, Hungary NTERNATIONAL Eucharistic Congresses fully for the benefit of multitudes, both at the I rank amongst the outstanding events in Congresses themselves and at distant points, the Catholic world of modern times. -
Analytical Model for Effects of Twisting on Litz-Wire Losses
Analytical Model for Effects of Twisting on Litz-Wire Losses Charles R. Sullivan Richard Y. Zhang Thayer School of Engineering at Dartmouth Dept. Elec. Eng. & Comp. Sci., M.I.T. 14 Engineering Drive, Hanover, NH 03755, USA Cambridge, MA, USA Email: [email protected] Email: [email protected] Abstract—Litz wire uses complex twisting to balance currents allows answering these questions for any litz-wire construc- between strands. Most models are not helpful for choosing the tion in any transformer or inductor winding application. The twisting configuration because they assume that the twisting ultimate goal is a practical goal, to verify existing design works perfectly. A complete model that shows the effect of twisting on loss is introduced. The model can predict loss for guidelines, such as those provided in [12], and to extend a precise configuration, but in practice, it is difficult to achieve them to provide guidance on all aspects of litz-wire design. sufficient manufacturing precision to use this approach. More In particular, many design methods provide guidance on the practically, the model can predict worst-case loss over the range number and diameter of strands to use. The method in [12] of expected production variation. The model is useful for making is particularly recommended because it provides a simple-to- design choices for the twisting configuration and the pitch of the twisting at each level of construction. use method that takes into account trade-offs between cost and loss in choosing the number and diameter of strands. I. INTRODUCTION Also provided in [12] is a simple and systematic method for Litz wire uses complex twisting configurations to balance choosing some of the construction details— the number of currents between strands. -
Privateline Magazine-November-December-1995.Pdf
Volume 2, No. 6 Nov ember/December $4.50 rivate line a journal of inquiry into the telephone system Alexander Graham Bell CABLE STATION ... OPERATIONS J • > , t f CANADIAN i TELECOM, - PART2 DIGITAL TELEPHONY BILL UPDATE MICROWAVE PROPAGATION BASICS DEF CON Ill REVIEW INDEX TO PR/VA TE LINE, VOLUME2 As reported oo CBS "60 Mlnu111•: How cortaln de vices can slowd own - 1v1nslop - watthour mel11I- Damien Thorn's ceLLULAR+co MPUTERS+TELco+sEcuRrrv :!'~:~d:,,~r~~Jro~: :ii~~~/!l!~~~~~:~ scrlbesm eler creep, overload droop, elc. Plans $29. 1,0, MANUAL,Exte rnal maoneUcwa ys (applled lo the melerlts eH)l o slow down and slopwaltllo ur melers 1 ULTIMATE HACKER 2011 Cruc en t Dr ., P.O . Drawer 537 ;l'~Ed~s ~'io~ ~~~~~r ~e~~~s :~~ ~ Alamogordo , NM 8831 o error modes( many), ANSI Standards, etc.Dem and and ~ (5051 439-1776 439 -8551 · Polyphan Melen. E,perlmcntalresulls l o slow and 8A M _ 7PM MST, Mon_ sai stop metersby others. $19. Any 2, $38. All 3, $59. Ell.!G (5051 434-0234, 434 -1778 (orde,s FILE ARCHIVE ON CD-ROM only;W you g el voice,enler• 111 111· anyUme): 24-hr ATMcrlm11 , abuses,,u ln111blllUn and dalHls 11- Fcea Te c h Byooo n; (relates dlrecUy1 0 your posedl1 00+ methodsd eta!ed, Include:Physka l, Reg. orderor prospectiveOfde~: Tu••· and Thurs. only. E. cipher, PINcompromise. card counterteltino, mao lili.lllunJJ tdlltlJl~ ZJ!ll±.AddS5 neticslrlpe, fa lse froo~ TEMrEST, Van Ed<.tapping , 10131s;lffOS: Canada) . Al aemsIn slock. VI SA.M C11dOK. spoollng,Inside lob , •~r-<ool, vfbrallon,pulse, high The entire underground NoCODs °' 'bill me•s.Ne w Catalog (200+ olfersl $2 voltage- olhers.C ase his1<>f1es,law, comlermeasures, order $5'N1! (check or MO).li!l..d.Qlru. -
Winding Resistance and Winding Power Loss of High-Frequency Power Inductors
Wright State University CORE Scholar Browse all Theses and Dissertations Theses and Dissertations 2012 Winding Resistance and Winding Power Loss of High-Frequency Power Inductors Rafal P. Wojda Wright State University Follow this and additional works at: https://corescholar.libraries.wright.edu/etd_all Part of the Computer Engineering Commons, and the Computer Sciences Commons Repository Citation Wojda, Rafal P., "Winding Resistance and Winding Power Loss of High-Frequency Power Inductors" (2012). Browse all Theses and Dissertations. 1095. https://corescholar.libraries.wright.edu/etd_all/1095 This Dissertation is brought to you for free and open access by the Theses and Dissertations at CORE Scholar. It has been accepted for inclusion in Browse all Theses and Dissertations by an authorized administrator of CORE Scholar. For more information, please contact [email protected]. WINDING RESISTANCE AND WINDING POWER LOSS OF HIGH-FREQUENCY POWER INDUCTORS A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy By Rafal Piotr Wojda B. Tech., Warsaw University of Technology, Warsaw, Poland, 2007 M. S., Warsaw University of Technology, Warsaw, Poland, 2009 2012 Wright State University WRIGHT STATE UNIVERSITY GRADUATE SCHOOL August 20, 2012 I HEREBY RECOMMEND THAT THE DISSERTATION PREPARED UNDER MY SUPERVISION BY Rafal Piotr Wojda ENTITLED Winding Resistance and Winding Power Loss of High-Frequency Power Inductors BE ACCEPTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Doctor of Philosophy. Marian K. Kazimierczuk, Ph.D. Dissertation Director Ramana V. Grandhi, Ph.D. Director, Ph.D. in Engineering Program Andrew Hsu, Ph.D. Dean, Graduate School Committee on Final Examination Marian K. -
Chapter 4 Inductive Loading
Chapter 4 Inductive Loading 4.0 Introduction This chapter explores the use of inductive loading to increase Rr and to enable excitation of a grounded tower. Chapter 3 demonstrated the utility of capacitive top- loading where the increase in Rr was primarily due to beneficial changes in the current distribution on the vertical. However, top-loading is not the only means for increasing Rr. We can move the tuning inductor or even only a portion of it, from the base up into the vertical. We can also move the feedpoint higher in the vertical. This chapter includes a discussion of multiple-tuning, a technique using inductors to manipulate the feedpoint impedance and distribution of current between multiple parallel wires. 4.1 Loading inductor location Figure 4.1 - Current distribution on a 50' vertical at 475 kHz. 1 In HF mobile verticals it has long been standard practice to move the loading inductor from the base up into the vertical to increase Rr[1]. We can do the same for LF/MF verticals. Figure 4.1 compares the current distribution on a 50' vertical with the tuning inductor at the base and just above midpoint. With the inductor near the midpoint the current below it remains essentially equal to Io. Increasing the current along the lower part of the vertical increases the Ampere-degree area A' (see section 3.3) which translates to increased Rr: 0.22Ω → 0.57Ω. Figure 4.2 - Efficiency as a function of loading inductor location and value. To keep the antenna resonant as we move the coil its value (XL) must be increased, 3411Ω → 6487Ω. -
Highlights of Antenna History
~~ IEEE COMMUNICATIONS MAGAZINE HlOHLlOHTS OF ANTENNA HISTORY JACK RAMSAY A look at the major events in the development of antennas. wires. Antenna systems similar to Edison’s were used by A. E. Dolbear in 1882 when he successfully and somewhat mysteriously succeeded in transmitting code and even speech to significant ranges, allegedly by groundconduction. NINETEENTH CENTURY WIRE ANTENNAS However, in one experiment he actually flew the first kite T is not surprising that wire antennas were inaugurated antenna.About the same time, the Irish professor, in 1842 by theinventor of wire telegraphy,Joseph C. F. Fitzgerald, calculated that a loop would radiate and that Henry, Professor’ of Natural Philosophy at Princeton, a capacitance connected to a resistor would radiate at VHF NJ. By “throwing a spark” to a circuit of wire in an (undoubtedly due to radiation from the wire connecting leads). Iupper room,Henry found that thecurrent received in a In Hertz launched,processed, and received radio 1887 H. parallel circuit in a cellar 30 ft below codd.magnetize needies. waves systematically. He used a balanced or dipole antenna With a vertical wire from his study to the roof of his house, he attachedto ’ an induction coilas a transmitter, and a detected lightning flashes 7-8 mi distant. Henry also sparked one-turn loop (rectangular) containing a sparkgap as a to a telegraph wire running from his laboratory to his house, receiver. He obtained “sympathetic resonance” by tuning the and magnetized needles in a coil attached to a parailel wire dipole with sliding spheres, and the loop by adding series 220 ft away.