136kHz technical literature
ON7YD
Literature about 136kHz and related topics
 last updated on 5 May 2003
disclaimer
Here you will find a list of literature on 136kHz and related topics. Please respect copyright regulations when downloading or copying. Where ever links are shown and/or sources are mentioned this is only for your information. This pages are strictly non-commercial. Books, articles and magazines are placed on this list based on their relevance.
Do you know any other books, articles or magazines that are interesting to add to this list ?
Share your knowledge with others and inform me by e-mail.
Note : in the list below you will find articles about antennas, propagation and related topics. Articles about transmitters, receivers and home-brew projects can be found here. A practical overview about 136kHz antennas can be found here.
Index

Books

Articles

Magazines

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Books

The Low Frequency Experimenter's Handbook
Language:English
Author(s):P. Dodd (G3LDO)
Editor:Radio Society of Great Britain
References:
Year:2000
Source(s):RSGB Books
The LF Experimenter's Handbook has been written to meet the needs of amateurs and experimenters who have an interest in low power radio techniques below 200kHz. Most of the techniques described are targeted at those using the 136kHz band, but they are also of great interest to readers in New Zealand and Australia with the 183kHz band and the Lowfers in the USA on 180kHz.
The bulk of the material in the book comprises contributions from experimenters world wide and covers antennas, propagation, transmitters, special modes and test equipment, and discusses some applications such as communication with caving enthusiasts.
All those interested in exploring the new frontier of the LF bands will welcome this invaluable and unique reference, whether they tend to transmitting or are content just to receive.

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Taschenbuch der Hochfrequenztechnik
Language:German
Author(s):H. Meinke and F.W. Gundlach
Editor:Springer-Verlag (Berlin / Heidelberg / New York)
References:Library of Congres 67-29831
Year:1968
Source(s):
Chapters H (Antennen) and J (Wellenausbreitung) discuss the topics of antennas and propagation in general and for longwave in particular.

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The LF Experimenter's Source Book
Language:English
Author(s):P. Dodd (G3LDO)
Editor:Radio Society of Great Britain
References:
Year:1998
Source(s):RSGB Books
The LF Experimenter's Source Book brings together source material from all over the world covering antennas, propagation, receivers, transmitters, special modes and test equipment, and also discusses some applications such as communication with caving enthusiasts.The articles are written by the experimenters themselves, giving the reader the feeling of learning direct from those at the sharp end of development.

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VLF Engineering
Language:English
Author(s):A.D. Watt
Editor:Pergamon Press
References:Library of Congres 67-018166
Year:1967
Source(s):
A book about professional VLF engineering, i.e. below 30 kHz, written at university standard. Large sections of the book are mathematical, but includes plenty of graphs and line drawings and general descriptions. plenty of information can be extrapolated from the data provided. It has a large section covering all aspects, theoretical and practical, of VLF radiators including vertical monopoles,"T" and "L" wires , electric and magnetic fields, capacity of wires, top loading, radiation resistance, antennae bandwidth and ground systems.
There is a section on commercial installations and a large section on propagation. Ground wave, ray theory and sky field calculations, Including effects of ionosphere, earths magnetic field, phase anomalies, long distance effects, sunspots and solar flares. Further a smaller section on receiving antennae, a section on Trade offs Tx power, antennae and cost and coverage for commercial stations and a section on Thunderstorms and noise levels.
The book concentrates on the true VLF band, but a lot of the graphs can be extrapolated to suit our requirements.
(information provided by Peter Cleall, G8AFN)

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The Scientist and Engineer's Guide to Digital Signal Processing
Language:English
Author(s):S.W. Smith
Editor:California Technical Publishing
References:ISBN : 0-9660176-3-3
Year:1997
Source(s):free download (PDF files) and purchase information
Digital Signal Processing is one of the most powerful technologies that will shape science and engineering in the twenty-first century. Revolutionary changes have already been made in a broad range of fields: communications, medical imaging, radar, sonar, high fidelity music reproduction, and oil prospecting, to name just a few. Each of these areas has developed a deep DSP technology, with its own algorithms, mathematics, and specialized techniques. This combination of breath and depth makes it impossible for any one individual to master all of the DSP technology that has been developed.
DSP education involves two tasks: learning general concepts that apply to the field as a whole, and learning specialized techniques for your particular area of interest.
(information provided by Andy Talbot,G4JNT)

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The low and medium frequency radio scrap book
Language:English
Author(s):K. Cornell (W2IMB) (SK)
Editor:
References:
Year:1992
Source(s):out of print
The purpose of this scrapbook (107 pages) is twofold. One is to offer circuits for simple transmitters, receivers and a new look at antennas.Also, many basic accessories for reception. The second is to introduce the reader to the low frequency radio spectrum that is ignored in most all of the popular radio handbooks.
The book is out of print, but it is worth to look for it at flea markets etc.
Contents : (information provided by Christer Andersson, SM6PXJ, and John Davis, KD4IDY)

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Loop Antenna Handbook
Language:English
Author(s):J. Carr (K4IPV)
Editor:Universal Radio, Inc.
References:
Year:1999
Source(s):Universal Radio, Inc.
Here is a comprehensive, but readable guide to understanding and building loops for longwave, medium wave, shortwave and VHF. Loop antennas can be very effective, even if you have limited space and a tight budget. Many diagrams and illustrations.
Chapters include: Loop Theory and Construction, Loop Projects, Quad Loop Beams, Small Loop Theory and Projects, Special Loops for Shortwave Bands, Loopstick Antennas, Radio Direction Finding, Small Loop Preamplifiers and Commercial Products.

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Articles

Performance of a Meandered Line as an Electrically Small Transmitting Antenna
Language:English
Author(s):T.J. Warnagiris, T.J. Minardo
Editor:IEEE Transactions on Antennas and Propagation
References:Vol. 46, No. 12, December 1998
Year:1998
Source(s):
For antennas to radiate at maximum efficiency, their dimensions must be on the same order as the radiated wavelength. At frequencies below 30MHz, antennas with efficient radiation are often too small for mobile and portable application. Smaller antennas can be made to radiate efficiently by use of matching networks. For installation convenience and ease of adjustment, these networks are usually placed between the transmitter and the antenna input; but it has been found that for best radiation efficiency, matching network elements should be placed at points on the antenna structure? Unfortunately, such matching networks must be tuned and, when mounted on the antenna, they cannoy easily be tuned. A meander antenna was found to present some electrical and mechanical properties allowing convenient placement of tuning elements when configured as an electrically small transmitting antenna. Some simplified design guides were derived from experimental data.
(information provided by Andr� Kesteloot, N4ICK)

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Low Height VLF Antenna System
Language:English
Author(s):H.R. Ray Jr
Editor:United States Patent
References:US Patent 3,984,839
Year:1976
Source(s):Delphion (intellectual property)
A low height, high efficiency antenna system in which a plurality of radiating elements are spaced to induce mutual radiation resistance in each other and the elements radiate using constant current which is obtained with a parallel folded element that receives the current prior to the radiating element and since the current is moving in opposite directions in the folded elements all but the constant current is cancelled. The edge of the supporting tower can be used as one or twe legs of the folded element.

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Short Low Loss AM Antenna
Language:English
Author(s):C.E. Smith
Editor:IEEE Transactions on Broadcasting
References:Vol. 35, No. 2, June 1989
Year:1989
Source(s):download here (GIF file)
The purpose of this paper is to explore ways to improve the performance of a relatively small transmitting or receiving AM antenna system. Short vertical towers can be top loaded to increase the radiation resistance and lower the base input capacitive-reactance. An insulated counterpoise is connected to the coupling unit so as to maximize the field strength radiated in the far field.
(information provided by Christer Andersson, SM6PXJ)

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Understanding electromagnetic fields and antenna radiation takes (almost) no math
Language:English
Author(s):R. Schmitt
Editor:EDN magazine
References:
Year:2000
Source(s):EDN magazine
Like most EEs, you probably wish you had a better understanding of electromagnetic fields and waves. Maybe the complex math keeps you from delving more deeply into this subject. This intuitive treatment goes light on math. In so doing, it brings life to a topic that many find dry and confusing.
(information provided by Andr� Kesteloot, N4ICK)

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Propagation of Long Radio Waves
Language:English
Author(s):J.A. Adcock (VK3ACA)
Editor:Wireless Institute of Australia
References:Amateur Radio, June to September 1991
Year:1991
Source(s):640X480 and 800X600 or higher resolution modes
The main purpose of this article is to present text book type information on the basics of propagation on frequencies between 100 Hz. and 200 kHz! Why should people be interested in such an unusual and restricted band of frequencies? Basically because some amateurs in several parts of the world have operated in this region and if an amateur band is ever allocated in the low frequency spectrum it is in this region that such a band would be allocated. Therefore, it is important that interested persons should understand operating conditions on these frequencies.

REMARK : a supplement to "Propagation of Long Radio Waves" (dated october 1999) can be found here.

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LF Propagation Abstract
Language:English
Author(s):G. Soegiono
Editor:
References:
Year:1998
Source(s):plain text or PDF file
This abstract intends to give an overview to the relevant mechanism of propagation of RF waves in the LF range, which according to ITU addresses frequencies from 30kHz to 300kHz. As usual a lot of simplifications are necessary to describe natural effects. This is called modelling. The following explanations are based on simplified, but scientifically accepted models to ease assumptions and predictions on propagation properties.

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Field Strength Measurements of DGPS and FAA Beacons in the 285- to 325-kHz Band
Language:English
Author(s):J.R. Hoffman, J.J. Lemmon, R.L. Ketchum
Editor:Institute for Telecommunication Sciences (U.S. Department of Commerce)
References:NTIA Report 97-337
Year:1997
Source(s):HTML abstract and PDF documents
Signal strength measurements in the 285- to 325-kHz band were conducted on eight U.S. Coast Guard differential global positioning system beacons along the Gulf and West Coast, and on a Federal Aviation Administration beacon in Bennett, Colorado. Data were acquired continually en route between sites and tagged with geographical position. Field strength of each individual signal was plotted against distance from the transmitter. Cumulative distributions and histograms of deviation from the least squares fit were also plotted. Results of the measurements were used as model inputs and to compare results to model predictions.
(information provided by Christer Andersson, SM6PXJ)

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DGPS Signal Strength Measurements at a GWEN Site
Language:English
Author(s):J.R. Hoffman, J.J. Lemmon, R.L. Ketchum
Editor:Institute for Telecommunication Sciences (U.S. Department of Commerce)
References:NTIA Report 98-346
Year:1998
Source(s):HTML abstract and PDF documents
Field strength measurements of a 300-kHz Differential Global Positioning System signal transmitted at a Ground Wave Emergency Network site at Appleton, Washington were conducted. Data were acquired continually along five different routes and tagged with geographical position. Field strength along each individual route was plotted against distance from the transmitter and related to geological landmarks. Results were used as model inputs and to compare measured signal strengths with model predictions.
(information provided by Christer Andersson, SM6PXJ)

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Technique for Building and Calibrating VLF/LF Receive Loop Antennas
Language:English
Author(s):J.M. Birkett
Editor:Naval Command, Control and Ocean Surveillance Center (US Navy)
References:NRaD TR 1742
Year:1997
Source(s):PDF document
Prior to making measurements the VLF/LF receive loop must first be calibrated in a Helmholtz coil. Determining the magnetic field strength can then be accompished by taking readings with the VLF/LF receive loop while in the field of the transmit antenna. The voltage induced arround the receive loop is measured by a selective level meter (Hewleet Packard 3586C). Distance from the transmitting antenna to the VLF/LF receive antenna loop is provided using Global positioning System (GPS) instruments.
This document details the construction method for building the VLF/LF receive loop antenna as designed by Mr. Don Watt of Watt Enineering. The second portion of this report describes the Helmholtz loop calibration procedure.
(information provided by Christer Andersson, SM6PXJ)

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Dipole and Monopole Antenna Gain and Effective Area for Communication Formulas
Language:English
Author(s):J.C. Logan, J.W. Rockway
Editor:Naval Command, Control and Ocean Surveillance Center (US Navy)
References:NRaD TR 1756
Year:1997
Source(s):PDF document
A comparison involving antenna measurements and performance predictions has sometimes revealed a 6-dB discrepancy between ground-wave transmission measurements and the corresponding calculations. The source of this 6-dB discrepancy is attributable to an incorrect definition of the effective area of the receiving vertical monopole antenna. This erroneous definition is that the effective area of the vertical receiving monopole is one-half of the corresponding dipole. It is this value of effective area that resolves the 6-dB discrepancy between measurements and analysis. This definition has meaning in general forms of the transmission formula for communications and radar systems.
(information provided by Christer Andersson, SM6PXJ)

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Spiral Top Loading of a Short Vertical
Language:English
Author(s):R. Holland (VK1BRH)
Editor:Wireless Institute of Australia
References:Amateur Radio Volume 63 No 10, October 1995
Year:1995
Source(s):HTML document
Top-hat capacitance and inductive base-loading and centre-loading have traditionally been employed to bring short antennas to resonance; these methods are covered in detail in the literature. This article describes how the self-capacitance and inductance of a spiral coil can be employed as a top-loading element for a short vertical, with the obvious extension to end-loading of dipoles.
(information provided by Geri Kinzel, DK8KW)

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Short Vertical Antennas and Ground Systems
Language:English
Author(s):R. Holland (VK1BRH)
Editor:Wireless Institute of Australia
References:Amateur Radio Volume 63 No 10, October 1995
Year:1995, 1998
Source(s):HTML document
There have been a number of articles discussing the merits or otherwise of various types of ground systems. The analysis of such systems is complicated by the facts that practical ground system parameters are difficult to quantify, antennas are situated in less than ideal locations, and literature, that may provide insight into what is happening, often does not present the information in a practical or applicable form. Often the reader is left to extrapolate beyond the bounds of presented data and arrive at the incorrect conclusion. Some folk-lore has been generated as a result of these types of difficulty; one such lore is 'the higher the better', which is an over-generalisation if said without qualification.

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Field strength measurements on 136kHz
Language:English
Author(s):C. Andersson (SM6PXJ)
Editor:
References:
Year:2000
Source(s):HTML document
In February and March 2000 some measurements were made with a home-brewed field strength meter. The meter setup has been somewhat reconfigured during the test period. First I used an untuned loop as "sensing element". Later this was replaced with a tunable ferrite rod probe with a 11 dB FET preamp. The ferrite probe was calibrated and linearity checked between 0,5 mV/m and 10 mV/m with a pair of Helmholtz coils.

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Vertical antenna with inductive toploading
Language:English
Author(s):R. Strobbe (ON7YD)
Editor:
References:
Year:2000
Source(s):HTML document
In an environement with a lot of 'vertical objects' (trees etc.) close to the antenna inductive toploading can significantly increase the performance of a short vertical antenna.

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Horizontal Antennas above Real Ground
Language:English
Author(s):R. Holland (VK1BRH)
Editor:Wireless Institute of Australia
References:Amateur Radio Volume 64 No 10, October 1996
Year:1996
Source(s):HTML document
Antennas are influenced by the effect of the ground and by the type of conductors from which they are constructed. The feedpoint impedance is the summation of the radiator's self impedance, the mutual impedance of its image in the ground, and the loss resistance. Horizontal antennas are subjected to the influence of a broadsize image in the ground. The antenna and its image are in anti-phase, so radiation tends to be cancelled at low angles and the radiation resistance is lowered because the mutual impedance of the image is subtracted from the self-impedance of the driven element.

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A Modeling Perspective on "Ground" Planes
Language:English
Author(s):L.B. Cebik (W4RNL)
Editor:
References:
Year:1997
Source(s):HTML document
Most of what we have learned about ground planes beneath vertical antennas arose from LF and MF practice. There is another perspective from which we can approach the subject: modeling in programs like NEC and MININEC. Moreover, there is an alternative point of departure for investigations to the normal survey of landscape and subsoil properties. The alternative is free space. The combination of the two underlies the notes in this collection. My aim is not to replace classic vertical antenna theory. Instead, it is to see what antenna modeling might add to the array of considerations we give to vertical monopole antennas and their ground planes. To that end, I have let the modeling lead where it may. At most, the notes may guide some of our expectations, but they are not likely to alter our explanations.

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Radio Antennas (Crossed Field Antenna)
Language:English
Author(s):M.C. Hately, F.M. Kabbary
Editor:United States Patent
References:US Patent 5,155,495
Year:1989
Source(s):Delphion (intellectual property)
An antenna for a wide bandwidth electromagnetic field polarized in a predetermined direction at right angles to the field propagation direction includes plural metal elements that are not resonant in the bandwidth. The metal elements are excited to transduce an electric field in the polarization direction over the bandwidth range. The plural elements have an extent in the polarization no greater than an order of magnitude of the shortest wavelength in the bandwidth. A structure between the element, which may be either a coil or parallel electrodes which derive a displacement current, transduces a magnetic field having lines of flux at right angles to the polarization and propagation directions. The electric and magnetic fields are excited by power from the same source with phases so that in an interactive region of the field between a pair of metal elements there is ExH synchronism and a radiation Poynting vector having rotational E and H fields to transduce the electromagnetic field.

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High Efficiency Compact Antenna Assembly
Language:English
Author(s):G. Benf
Editor:United States Patent
References:US Patent 5,796,369
Year:1997
Source(s):Delphion (intellectual property)
A High Efficiency Compact Antenna Assembly for use as a vertical antenna, used for the radiation and reception of various band length signals. The antenna assembly includes an assembly such that operation of the antenna is as efficient as antennae of much greater height. The structure of the assembly preferably includes a large surface area housing atop a conductive mast anf in spaced apart electrical communication with a substancially circular collector. Spanning from the outside wall of the vertical cylinder to the mast is a minimal turn inducor so that the inductor does not create a field that would interfere with the field from the mast of the antenna. A transmitter/receiver is in connection with the antenna assembly at the mast and in the collector. The mast, minimal turn inductor, and vertical cylinder are in connection with each other, while the collector interacts electrically with each.

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The Crossed-Field-Antenna
Language:English
Author(s):M.C. Hately (GM3HAT)
Editor:AntenneX
References:
Year:2000
Source(s):HTML document
Please be aware this article introduces a completely new concept in antenna theory. In fact, this is considered the most important development relative to antennas in this century. It is so pervasive that a series of articles are required to cover the concept and its applications to the depth and extent it deserves. This is the first publication about the Crossed-Field Antenna (CFA) in the U.S.A. Even as you read this, there are continuing developments in the application of this concept. antenneX has more than a dozen articles about the CFA, including four construction articles (complimented by several more building experiments by readers from around the globe), plus a look at the actual CFA 1992 and 1995 versions of Tanta Station operated in Egypt. This is followed up by a tour of 10 of Dr. Kabbary's 17 more recent CFA broadcast stations in operation in Egypt and Australia. Further, of interest is that the Isle of Man, UK has chosen to install a CFA longwave broadcast station rather than a 845-foot (260m) tower.

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Loop antennas design and theory
Language:English
Author(s):D. Lankford, G.P. Nelson, J.V. Hagan, B. Foxworth, Ghoti, G. Thomas
Editor:NRC Publications, Box 164, Mannsville, NY 13661-0164 USA
References:ISBN 1-878994-13-1, Library of Congres 92-137758
Year:1991
Source(s):
A compilation of articles printed in DX News. The book is an interesting mixture of theory, practical experimentation and detailed designs.
Chapters as follows : (information provided by Peter Cleall, G8AFN)

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Optimal choice for number of strands in a litz-wire transformer winding
Language:English
Author(s):C.R. Sullivan
Editor:Thayer School of Engineering, Dartmouth College, Hanover, NH 03755-8000
References:Paper presented at IEEE Power Electronics Specialists Conference, June 1997
Year:1997
Source(s):HTML document
The number of strands to minimize loss in a litz-wire transformer winding is determined. With fine stranding, the ac resistance factor decreases, but dc resistance increases because insulation occupies more of the window area. A power law to model insulation thickness is combined with standard analysis of proximity-effect losses.
(information provided by Mick Reed)

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Sensitivity of Multi Turn Receiving Loops
Language:English
Author(s):W.E. Payne (N4YWK)
Editor:
References:
Year:1997
Source(s):HTML document or Word document
Multi turn wire loops are often used as low frequency receiving antennas. Applications such as geophysical research, oil exploration and survivable communications require maximum sensitivity of receiving loop antennas. The loop sensitivity decreases as frequency decreases, becoming a formidable problem below 1 Hz. Basic electromagnetic theory is developed here as it relates to electrically small multi-turn loops at low frequencies. Simple algebraic expressions are produced describing the sensitivity of loops in simple geometries. The concept of antenna factor (effective aperture) is introduced, which allows comparison of different loops, and conversion of observations to common magnetic units of measure. It is hoped this work will be a useful reference to geophysical researchers, and to anyone designing loops for low frequencies.

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Propagation prediction techniques and antenna modeling (150 to 1705kHz) for ITS broadcast applications
Language:English
Author(s):N. DeMinco
Editor:IEEE Transactions on Antennas and Propagation
References:Vol. 42, Issue 4, p. 9-34, August 2000, ISSN: 1045-9243
Year:2000
Source(s):
This paper discusses the basic aspects of radio-wave propagation and antenna modeling in the band of frequencies from 150 kHz to 1705 kHz. The paper contains descriptions of both sky-wave and ground-wave propagation-prediction models, in addition to the methodology used to analyze antennas that operate in this band. A method of calculating and normalizing antenna gain for systems computations is also discussed.
The sky-wave models described in this paper are valid from 150kHz to 1705kHz. The ground-wave models described in this paper are valid from 10kHz to 30MHz. The propagation of radio waves in the band of frequencies from 150 to 1705kHz includes both a ground wave and a sky wave, and is quite different from propagation at any other frequency. The methods used for antenna modeling and analysis in this band are also quite unlike those in other bands ...
(information provided by Bob Riese, K3DJC)

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On The Art of NDB DXing
Language:English
Author(s):S. Remington (KH6SR)
Editor:The LOWDOWN
References:
Year:1987-2000
Source(s): HTML document
This series is an exposition of strategies and techniques for DXing non-directional radiobeacons (NDB's), which operate in the longwave spectrum from 190 to about 535 kHz. This pursuit has recently begun to come of age and is at an exciting point in its evolution. It is hoped that this series will be a catalyst for NDB DXers, both newcomers and oldtimers, to maximize their individual and collective progress.
Most of the techniques have evolved slowly and painfully as each DXer tackled the challenges uncovered by earlier successes. Some were brought to NDB DX from other bands where weak-signal techniques were specially developed for the problems of those bands. In fact, the maturation of the NDB DX quest is due in large measure the influx of refugees from overcrowded bands, particularly the medium-wave broadcast band which has deteriorated substantially since the 1960's in its ability to produce weak-signal observations.
(information provided by Rick Warnett, P29KFS)

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A very brief summary of antennas and electromagnetic waves
Language:English
Author(s):J. Stanley
Editor:IEEE
References:IEEE Broadcast Technology Society 50th BT symposium (Sept 27-29,2000)
Year:2000
Source(s): HTML document or WORD document
A common way of presenting Electromagnetics is to develop "Maxwell's equations" using a great deal of vector calculus. This approach leaves behind a great number of persons who could benefit from an understanding of antennas, propagation, and other EM phenomena, but who have not had a sufficient mathematical background to follow the traditional presentation. It also, I believe, can, and sometimes does, obscure some important concepts as one gets so bogged down in the math that the physical picture of what is involved is lost. A simpler approach would be helpful, I believe, not only for those without command of advanced calculus, but also to keep those with such abilities from falling into some traps that may be out there when the basics are forgotten as one gets deeper into the forest of "Curls, Divs, and Grads".
(information provided by Johan Bodin, SM6LKM)

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Another Approach to Active Antennas
Language:English
Author(s):D. Rollema (PA�SE)
Editor:LWCA
References:
Year:2001
Source(s): HTML document
It has been mentioned several times that the input stage of an active receiving antenna is easily damaged by lightning in the vicinity due to the very high input impedance of the amplfier.
Several years ago Dr. (now professor) E.H. Nordholt of the Technical University Delft in The Netherlands developed an alternative design for an active antenna that does not suffer from this problem. Instead of making the input impedance very high it has been made very low by means of negative feedback.

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Some Thoughts on E-field Whistler Receiver Design
Language:English
Author(s):S. Fusare (N2BJW)
Editor:LWCA
References:
Year:2001
Source(s): HTML document or PDF file
A bit of research on E-field VLF/ELF receivers :
Per the literature an electrically short E-field antenna (in our case vanishingly short) may be modeled as a voltage source, as given by signal field strength times the equivalent height of the whip, in series with the reactance given by the isotropic capacitance of the whip, the radiation resistance and the loss resistance at the frequencies of interest. For our case I will consider the frequency range from 500 Hz to 20KHz and a 1-meter long vertical whip. Given these parameters, the radiation resistance is almost nil and the loss resistance so many orders of magnitude below the capacitive reactance that the antenna can be modeled as a capacitor in series with the signal source.

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Antenna ground system
Language:English
Author(s):W.W. Baker, D.R. Meyers
Editor:United States Patent
References:US Patent 5,495,261
Year:1994
Source(s): Delphion (intellectual property)
A shortened electrical grounding system for use with a vertical antenna, particularly AM limited range information stations. The grounding system has a plurality of fractional wavelength electrically conductive members joined together and connected to the electrical ground of the transmitter associated with the antenna. The fractional wavelength electrically conductive members can be made of wire or metal panels both of which can be fanned out about the base of the vertical antenna in a substantially circular pattern. The electrical grounding system can be buried in the ground or can be used above ground as a counterpoise. The electrical conductors making up the ground system can also be incorporated into a mat made of plastic or other suitable material which can be positioned at the base of the vertical antenna.

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Method and apparatus for separately controlling sky wave and ground wave radiation from a medium wave antenna
Language:English
Author(s):O.L. Presholdt
Editor:United States Patent
References:US Patent RE033276
Year:1990
Source(s): Delphion (intellectual property)
In one embodiment, a horizontal antenna mounted electrically separated from but near the top of a vertical antenna. For a given wattage and frequency and for two stations separated a known distance apart, the proscribed angle of elevation for ionospheric reflection for each station can be computed. The current and phase of the signal applied to the horizontal antenna can be adjusted to cancel the electromagnetic field waves emitted from the vertical antenna in the selected azimuth and angle of elevation. The cancellation effects waves of a certain angular orientation at the proscribed angle of elevation for ionospheric reflection.

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Vertical antenna with improved artificial ground system
Language:English
Author(s):A.C. Doty Jr.
Editor:United States Patent
References:US Patent 4,658,266
Year:1987
Source(s): Delphion (intellectual property)
The present invention relates to vertical antenna systems employing an improved artificial ground system. In a low frequency design, the artificial ground system provided is in the form of a counterpoise or ground screen that is provided with an efficient, economical and practical electrical radial wire design. A high frequency design is also provided in the form of an integral antenna structure. This high frequency integral design entails a vertical antenna, a counterpoise in the form of a metal plate, a ground plate, and wherein said metal plate forming the counterpoise is insulated from the ground plate. In either type of antenna system, the counterpoise functions to collect antenna return currents and direct them back to the feed point of the antenna in an efficient and effective manner.

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Multi-phase coupler with a noise reduction circuit
Language:English
Author(s):J.A. Scharfe Jr.
Editor:United States Patent
References:US Patent 6,078,299
Year:2000
Source(s): Delphion (intellectual property)
A multi-phase coupler including a noise reduction circuit which provides two output signals which are separately shifted in phase with respect to an input radio frequency (RF) signal. The input RF signal is capacitively phase-shifted to lead the phase of an input RF signal to provide one output signal and is inductively phase-shifted to lag the phase of an input RF signal to provide a second output signal. The two phase-shifted outputs are impedance matched to the dual input ports of a balanced radiating structure that acts as a point source when the input ports are driven in phase quadrature.

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Discussion of antennas and related topics from the LF reflector
Language:English
Author(s):P. Dodd (G3LDO)
Editor:
References:RSGB LF reflector
Year:2001
Source(s): HTML document
A discussion of active receiving antennas was held on the RSGB LF reflector. The article includes circuits of several pre-amps.

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Loading Coils for LF
Language:English
Author(s):P. Dodd (G3LDO)
Editor:
References:RSGB LF reflector
Year:2001
Source(s): HTML document
This is a discussion on where to put the loading coil and does it contribute to radiation; and in what circumstances should a loading coil be screened - and how.

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Characteristics of the CFA obtained by numerical and experimental modeling
Language:English
Author(s):J. S. Belrose
Editor:
References:IEEE BTS 50th Broadcast Symposium
Year:2000
Source(s): PDF document
An antenna is sometimes described as a coupling device, coupling electromagnetic energy into the propagation medium. Pursuing this line of thinking, amateurs and antenna specialists have wondered whether there were methods of achieving this process in more efficient ways than realized using conventional antennas. One proposal that has stimulated a considerable current interest, is that by Kabbary and colleagues, which describes a ground plane crossed field antenna, in which the E- and H-fields are said to have been generated separately, and so can have the required time phase and quadrature space relationships in the near field for real power, as given by an out-going Poynting vector P = ExH.

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Discussion on the Use of Maxwell's Fourth Equation in Describing the Crossed Field Antenna
Language:English
Author(s):T. B. Silliman
Editor:
References:IEEE BTS 50th Broadcast Symposium
Year:2000
Source(s): PDF document
When the crossed field antenna concept appeared in the headlines a couple of years ago, ERI received several calls concerning this 'new concept' of radiation. Customers and colleagues were interested in finding out whether or not the crossed field antenna worked as claimed. I was interested in the concept, and I spent many hours studying the idea. I am a manufacturing engineer, and I always try to keep an open mind when it comes to new ideas in the antenna field, but when I researched the crossed field antenna design, I had a problem with the "crossed field" concept. Reversing the equal sign in an equation isn't new and profound, yet this was the great discovery that the inventors had made.
As an explanation of the concept, the inventors used the fourth equation of Maxwell, reversed the equal sign, and said that the displacement current in a capacitor was responsible for generating a magnetic field that could, along with an electric field, generate a far field situation very close to an antenna. However, they ignored the currents that fed the antenna. This is the subject of my discussion.

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Magnetic fields from displacement current densities generated by the Crossed Field Antenna
Language:English
Author(s):J. B. Hatfield
Editor:
References:IEEE BTS 50th Broadcast Symposium
Year:2000
Source(s): PDF document
Based on Maxwell's equations the antenna currents and voltages are calculated as required to make the CFA antenna work as claimed by the inventors. Even if you do not want to go through all the maths it is worth reading the conclusion :
The final conclusion is that, for operation with 1 KW into the pipe section of the CFA, it would take 1.23 megavolts into the plate with a current of 1667 amperes to provide enough magnetic field from the plate to provide the plane wave synthesis claimed by the inventors of the CFA. The pipe section of the CFA also creates a magnetic field and is much more efficient at producing magnetic field than the plate. It would take 471,000 volts with a current of 636.7 amperes into the plate for the plate to produce a magnetic field of the same intensity as that resulting from 1 KW into the pipe.
The conduction current into the capacitor must equal the displacement current. Equal currents produce equal magnetic fields and a 0.6 meter wire that replaced the plate must, by the requirements of continuity, produce the same magnetic field as the plate. The pipe is much greater in length than the distance from the plate to ground and will produce correspondingly greater magnetic fields for equivalent currents flowing in both sections of the CFA. The contribution of the magnetic field from the plate to the total field, being so small, can safely be ignored compared to the magnetic field from the pipe. The question also arises of how the plate can be fed without the magnetic field in the feed wire canceling the magnetic field from the plate since the current in the feed wire runs in the opposite direction to the current in the plate.

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RF ground systems
Language:English
Author(s):J. E. Thompson (W4THU)
Editor:
References:RADIO WORKS' Reference Catalog
Year:1997
Source(s): HTML document
This article contains excerpts from a book that I am writing, entitled, "Antennas....from the Ground Up!�".
".... From the Ground Up!�" is a series of books I am preparing on various antenna topics.
From the telephone calls we receive, many of you are having problems with RF ground systems.
RF ground? Yes, most of us have ground systems that provide adequate DC grounding. Unfortunately, a good DC ground system may not be a good RF ground system. In fact, you may have an 'UN-GROUND'.
UN-GROUND? Absolutely. There are situations where your ground system may actually un-ground your station. The reason lies in the fundamental difference between DC and RF circuits.
(information provided by Dick Rollema, PA0SE)

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Radiation from an antenna
Language:English
Author(s):P. Dodd (G3LDO)
Editor:
References:
Year:2001
Source(s): HTML document
The purpose of this article is to explore the basic principles regarding how an antenna radiates.
Some explanations of electromagnetic phenomena have been around for many years but very little has found its way into amateur radio literature. It is hoped that the following will help to clear up the some of the mysteries of 'near' and 'far' fields and the differences between radiation resistance and ohmic resistance in an antenna.
The final part of the article describes how electromagnetic waves were discovered.

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LF Aerials and Loading coils
Language:English
Author(s):A. Melia (G3NYK)
Editor:
References:
Year:2002
Source(s): HTML document
It is probably a truism to say that any piece of conducting material, no matter what size, will act as an aerial, but it is all down to a matter of efficiency. The efficiency determines how much power you radiate on transmit and how big a voltage you are able to 'collect' from a distant station's transmission. Most amateurs are most used to the MF and HF bands were it is quite feasible to erect aerials that are of the same size as the dimensions of the wavelength in use. Now, when you consider that 73 kHz is a wavelength of 4.1kms and the shortest efficient aerial is a quarter-wave at just over 1000metres long ( 3300 feet for the traditionalists ), the size of the problem becomes clear. The average amateur might be able to erect an aerial of about 100 feet in length. Then you consider that this would be equivalent to attempting to operate on 80 metres with a 1 metre long aerial, less that half the length of most mobile 80m aerials.

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Receiver System Sensitivity tests on LF and VLF
Language:English
Author(s):A. Melia (G3NYK)
Editor:
References:
Year:2002
Source(s): HTML document
Ever since I became interested in 73 kHz and 136 kHz I have been haunted by the question "Is my receive system as good as it should be". This was reinforced by the occasional sound of stations transmitting CQs over continental DX., which I could hear being close to the East Coast. I have a number of receivers that cover or at least claim to cover the frequencies of interest. My object was to determine the weakest signal I could reliably detect and then to attempt to relate this to a definitive measure of field strength. The ultimate aim was to estimate whether it would be possible to hear a signal from the AMRAD beacon stations WA2XTZ. My interest was further stimulated by the monitoring work of Dick Rollema PA0SE and Vaino Lehtoranta OH2LX , which was discussed on the RSGB LF Internet reflector.

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Aerial-to-Aerial Coupling
Language:English
Author(s):F. O'Connor (EI0CF), A. Melia (G3NYK)
Editor:
References:
Year:2002
Source(s): HTML document
There has often been talk on the RSGB LF Reflector of the problems of using two aerials on LF. The usual instance is of a 'T' or inverted 'L' being used to transmit and a loop to receive. The idea is to use the loop to null out nearby interference, and leave the wanted signal in the clear. The effect of running a loop close to a tuned 'T' is that there nulls on the loop become 'blurred' and a lot of noise is received on the loop. What seems to be happening is that the currents in the tuned 'T' aerial, due to received signals, are inducing currents into the loop. I suppose the 'T' could be regarded as a single turn loop with the effect of the ground. If this was the case one would expect the coupling to depend on the orientation of the loop. I have never actually been able to confirm this, nevertheless I make use of the effect by allowing the coupling to feed signals to two separate receivers at almost the same strength. It makes an almost lossless diplexer, for use at times when I dont need the directivity of the loop.

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Some Design Notes on MF /LF Antennas for Small City Lots
Language:English
Author(s):R. M. Hartwell II (W5JGV)
Editor:
References:
Year:2002
Source(s): HTML document
For those experimenters, myself included, who are faced with operating from restricted space lots, the choice of proper antenna design becomes critical to the success of operating on MF or LF frequencies. After gathering a lot of information about low frequency antennas, I set out to analyze the available options. I needed to take into consideration such things as antenna gain (actually antenna loss, since any reasonable sized antenna constructed under such circumstances will have a negative gain value) and mechanical construction difficulties. After all, if you can't physically construct it, or can't afford it, then it doesn't matter how good the antenna is; it's not the one for you !

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Computer Modeling of LowFER Transmitting Antennas
Language:English
Author(s):L. Koehler (K�LR)
Editor:
References:
Year:2002
Source(s): HTML document
For many of us, antennas are the most mysterious, and also the most interesting aspect of the radio hobby. It's not too hard to understand how RF signals can be generated, amplified, detected, etc. But when it comes to launching signals into a non-existent "ether" and capturing them someplace far away, that's still black magic. It is hard to visualize what is really happening in an antenna. However, with the help of a few basic concepts, you can get a general feel for why certain antennas behave the way they do.

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LF Propagation and some effects of Solar Disturbances
Language:English
Author(s):A. Melia (G3NYK)
Editor:
References:
Year:2002
Source(s): HTML document
It is generally believed that propagation in the LF bands is stable and almost boring. This is only loosly the case. Historically the LF bands have been used were a wide service area is required which is relatively immune from interference and ionospheric effects such as fading. A lot of the research that has been carried out has had as its objective a determination of the severity of interference from signals beyond normal service range. In the years after WWII this was more to determine the reliable range of long distance navigation systems such as Decca Navigator, Loran-C and Omega. The criterial factor being the reliability with which the phase or timing of the signal could be determined. I have tried to approach my study from the standpoint of the ordinary radio amateur who is little concerned with service reliability. The Radio Amateur is willing to wait for and utilise whatever transient phenomena is available to achieve his ambition of long distance communication.

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Medium Wave Frequency Radio Propagation Theory Notes
Language:English
Author(s):T. Giella (KN4LF)
Editor:
References:
Year:2001
Source(s): HTML document
I will try to keep things in simple to understand layman terms, as long complicated technical explanations can be boring and make one's eyes glaze over. Unfortunately though sometimes while trying to keep things simple certain definitions, meanings and technical aspects can get watered down or even lost, which tends to open me up criticism from well meaning fellow scientists that just don't understand the keep it simple stupid (KISS) principle.
(OK, not really LF stuff ... but interesting reading)

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Experiments with a Tower supported Umbrella Aerial
Language:English
Author(s):A. Melia (G3NYK), F. O�Connor (EI0CF)
Editor:
References:
Year:2002
Source(s): HTML document
After the interesting results on the top-loaded Spiral Aerials, Finbar determined to experiment further with his main top loaded tower supported aerial. This is in the form of an umbrella with the top load wires sloping from the apex which is pulled away from the tower. Finbar has a loop aerial which he uses as a directional RX aerial. The apex of the triangular loop is supported part way up the tower, and being beneath the main aerial top load wires it becomes �part� of the main aerial system. As a side effect Finbar was able to measure the effects of the loop on the main aerial system and determine the best arrangement to reduce the interaction.

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Thinking about ideal loops
Language:English
Author(s):M. Bruno (IK1ODO)
Editor:
References:
Year:2001
Source(s): HTML document or PDF document
Loop antennae have been used from ELF to UHF since the beginning of radiocommunications. At low frequencies, the main problem for loop antennae is to have enough sensitivity; the antenna being very small respect to the wavelength the collected energy is also small. To increase the output level the loop may be made resonant, so loosing it�s intrinsic aperiodic characteristics.

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Going low in frequency with loop antennas
Language:English
Author(s):P. Schmalkoke
Editor:
References:
Year:2001
Source(s): HTML document
The first part of this article dicusses an improvement to the loop antenna which was introduced by Marco Bruno in his article Thinking about ideal loops . Please read that article first.
With my observations of sferics and environmenmtal magnetic fields I sometimes felt upset by the very loud sferics in contrast to the sounds of lower frequencies. You probably know that even very short but loud clicks can cause permanent damage to the ear, especially when using headphones. Then I realized that the induced voltage from an open loop antenna is proportional to frequency and since then I was convinced that some kind of integration on the signal would be necessary. So I felt confirmed when I read Marco Bruno's article. Although his idea seems promisingto me, I must admit I have not tried it until now. So this text simply exposes my own ideas on that topic.

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Station setup and receiving techniques
Language:English
Author(s):R. Romero (IK1QFK)
Editor:
References:
Year:1999
Source(s): HTML document
This article is focussed on VLF reception but the various receiving antennas and pre-amplifiers described here can easily be adapted for LF. Some very interesting alternative ways to install a receiving antenna are given.

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Experiments on Remote Receiving Loops
Language:English
Author(s):L. Koehler (K�LR)
Editor:
References:
Year:?
Source(s): HTML document
Loop antennas offer many advantages for LowFER reception. They're compact, don't need to be high and in the clear, and their directional characteristics can be used to null out local noise or strong interfering signals.
Unfortunately a loop doesn't offer a good impedance match to a coaxial transmission line or to the input of most modern receivers. Also, unless the loop is balanced and shielded, the so-called "antenna effect" makes the loop act like a combination of a loop and a short vertical whip. The directional pattern becomes asymmetrical and the nulls off the side may be only a few dB down from the peak of the radiation pattern. An unbalanced, unshielded loop can also pick up conducted interference from the feed line.
You might find a quiet location in the "back 40", put your loop out there, and then re-introduce the noise from the house when you connect the coax. Shielding adds distributed capacitance to the loop and reduces the Q, which in turn reduces the loop's sensitivity. This article gives some ideas on how to use a simple unbalanced loop with a home-brew transformer to achieve most of the benefits of a shielded, balanced loop.

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VLF-LF and the Loop Aerial
Language:English
Author(s):L. Butler (VK5BR)
Editor:Amateur Radio
References:
Year:1990
Source(s): HTML document
The article discusses the theory of loop aerials for receiving and how they reduce the level of local noise. A Loop Aerial is described suitable for use on the LF and VLF bands together with a circuit of an interface loop tuner and preamplifier. The discussion extends to the problems of amplifier noise and the advantages of tuning the loop.

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Small Loop Antennas
Language:English
Author(s):J. Carr (K4IPV)
Editor:Universal Radio Research
References:Joe Carr's Radio Tech-Notes
Year:?
Source(s): HTML document
Small loop antennas are defined as loops that have a total wire length of less than 0.15 wavelength. These antennas perform quite differently than large loop antennas such as the bisquare or quad loop. Small loops are used in radio direction finding, and in ordinary DXing for receiving weaker stations in the presence of strong interfering stations.
The performance of the small loop is less than that of other antennas (e.g. the half wavelength dipole), but its extremely sharp nulls and broad maxima frequently make it the antenna of choice on very crowded bands. In those cases you are swapping gain for signal to QRM ratio.

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Using the Small Loop Antenna
Language:English
Author(s):J. Carr (K4IPV)
Editor:Universal Radio Research
References:Joe Carr's Radio Tech-Notes
Year:?
Source(s): HTML document
Small loop antennas have an overall wire length < 0.15 wavelength. They exhibit deep nulls perpendicular to the plane of the loop, and broad maxima off the ends of the loop. The pattern of these small loop antennas is a variant of the classic "Figure-8" pattern. Although the loop has less gain than a dipole, the radiation pattern and small size make the antenna quite useful for certain situations.

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Dealing With AM Broadcast Band Interference to Your Receiver
Language:English
Author(s):J. Carr (K4IPV)
Editor:Universal Radio Research
References:Joe Carr's Radio Tech-Notes
Year:?
Source(s): HTML document
If you live anywhere near an AM broadcast band (BCB) station, then you might have serious reception problems, even with a high quality receiver. Although one of the things you get when you pay the premium price for a high quality receiver is superior overload protection, the signal from a local AM BCB station might overwhelm its defenses.

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Some Simple Geometry applied to propagation and some thoughts on possible mechanisms for some of the phenomena
Language:English
Author(s):A. Melia (G3NYK)
Editor:
References:
Year:2002
Source(s): HTML document
First a warning......the geometry I am going to explain is used only to give a feeling for the scale of the propagation problem. It should not be thought that it actually happens this like this. Ionospheric propagation is very complicated, but I believe we can get a grasp of the problem by using some simple calculations. I will use the term "reflection" (and reflection height) but it will normally be in single quotes to indicate that this is not physical (mirror-like) reflection, but rather a gradual bending (refraction).

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Amateur use of novel signalling methods at low frequencies
Language:English
Author(s):A. Talbot (G4JNT)
Editor:IEEE
References:IEEE Conference, London, 24/25 October 2002
Year:2002
Source(s): PDF document
In 1996 Radio Amateurs in the UK gained a new frequency band at 73kHz for experimentation and research into antennas and signalling methods at Low Frequencies. It soon became apparent that some novel techniques would have to be employed to make use of the 1 Watt Effective Radiated Power power limitation and the high losses associated with realistic �back garden� antennas. Initial tests with aurally received Morse code indicated that distances of a few tens of kilometres were achievable with 100 watts of RF power when employing antennas of around 8m tall � typical of an amateur installation. With this set-up, ERPs in the range of 0.1 to 2mW were usually possible depending on antenna system efficiency. To achieve greater distance would need either a lot more RF power or a considerable reduction in bandwidth.

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Getting The Most Out Of LowFER Transmitting Antennas
Language:English
Author(s):L. Koehler (K0LR)
Editor:The LOWDOWN
References:
Year:1993
Source(s): HTML document
Designing an efficient antenna for the 1750-meter band presents a real challenge because of the FCC's 15-meter length restriction. 15 meters doesn't sound so short until you think of it in terms of wavelength. If I scaled my LowFER antenna for operation on the 20-meter amateur band, it would be less than 6 inches high, and would look like a wire representation of a Bonsai tree.

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A Newcomer's Guide to LF Weak Signal Receiving Techniques
Language:English
Author(s):J. K. Andrews (W1TAG)
Editor:
References:
Year:2002
Source(s): HTML document
The very weak received signal levels found in U.S. "Lowfer" (160-190 kHz) and European amateur (136 kHz) operation require special transmitting and receiving techniques if large distances are involved. This article focuses on U.S. Lowfer issues, but applies equally to amateur operation, though higher transmit power is permitted.

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AM Loop Antennas
Language:English
Author(s):B. Carter
Editor:
References:
Year:2003
Source(s): HTML document
An AM loop antenna is one of the true marvels of electronics. Requiring no power, it takes advantage of the resonant properties of an inductor and a capacitor connected in parallel to receive weak AM stations. The "loop" part of the antenna is the inductor, and the tuning capacitor makes it resonate at a desired frequency. As a boy in Abilene in 1967, I discovered the basic principle of the loop antenna. By removing a relatively small planar loop in my five tube table radio, and substituting a much larger loop salvaged from an older radio, I could receive my favorite station - KLIF from Dallas better. I hid the loop in a cardboard holder featuring the logo of a favorite rock band, and enjoyed many hours of good listening. Lacking the mathematical background to understand antenna theory - I could not take the concept to the next phase: designing my own loop. Nevertheless, the planar loop - combined with the antenna section of the radio's tuning capacitor - formed a very good loop antenna. I understood quite well that the bigger the loop, the more stations I could receive.

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Forecasting LF DX windows
Language:English
Author(s):A. Melia (G3NYK)
Editor:
References:
Year:2003
Source(s): HTML document
This is probably an ambitious title, but I have tried, based on experience of watching long distance propagation over the last 3 years, to analyse the geomagnetic conditions over the last solar cycle. The intention was to determine what the possibilities would be for good DX conditions at distances greater than 3000 kms during the solar minimum. Experience with practical amateur aerials has shown that contacts over distances of 2000 to 3000 kms are obtainable in daytime, for well equiped stations. The longer Trans-Atlantic contacts, and contacts (from Europe) with Asia and South America will most probably be limited to night-time paths.

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  • Aerial Measurements with Selective Level Measuring Sets (5 May 2003)

    Aerial Measurements with Selective Level Measuring Sets
    Language:English
    Author(s):A. Melia (G3NYK)
    Editor:
    References:
    Year:2003
    Source(s): HTML document
    Using the Wandel and Goltermann SPM-12, the PS-12, and the RFZ-12. The RFZ-12 is an accessory for the SPM-12 and PS-12 combo. The SPM-12 is a selective measuring set with a range from 200Hz to 6MHz , measuring levels down to -120dBm. The PS-12 is a matching source which can be locked to the synchronised local oscillator in the SPM-12, and provides an output of up to 0dBm into 75ohms. I was lucky enough to acquire an RFZ-12 with my units as well. This is titled as a "Reflexion Measuring Attachment", and is in effect a return loss bridge covering 200Hz to 6MHz. It has switched accurate loads inside for all the common line impedances but it also has the facility to attach an external load via the standard 3 in-line 4mm connectors. The attachment is driven from the PS-12 and the meter in the SPM-12 is used to measure the return loss directly in dBm.

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    Magazines

    The LOWDOWN
    Language:English
    Author(s):
    Editor:Longwave Club of America
    References:
    Year:
    Source(s):LWCA
    The LOWDOWN contains information on 1750 meter band operations, help with ID's, loggings, letters, want ads, and technical articles. The text in The LOWDOWN is supplied mainly by members and in some cases may be covered by a copyright and printed with specific permission of the copyright holder. Reproduction of any of the text or articles that appear in The LOWDOWN should not be made without written permission of the LWCA publisher or the author or copyright holder thereof.

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