Tom v Thor

INTRODUCTION

ust in case you missed Part 1 of Tom Cox’s (KT9OM) series about lightning protection, be sure to take a look in the Ham WorkShop where Tom is a regular contributor, a member of our writing team and active charter member of the International antenna group, the GARDS. Part 2 is also in the Ham WorkShop now for the May 2003 issue.

Tom is in the process of erecting a 120-foot tower in his backyard and also has a series going about the process, including his Herculean effort to first obtain approval from the local powers that be in his Muncie, Indiana, USA community. For those who have never gone through that process, Tom presents an excellent recipe for doing it in his January 2003 article “Winning the Zoning War” now in the antenneX Archive VI.

Of course you don’t have to have a tower to worry about whether your lightning protection is adequate. Any exposed metal object like an antenna of any height can be a target and fry your system, right on into your shack. If you want to know more about lightning protection, or if you haven’t thought about it, you need to know more about the power of “Thor” and what to do about it, which is well presented in this multipart series of articles by Tom.

VIDEOS
Here’s a little preview for you in a couple of short MPEG videos, one is a pan of the tower under construction and the other is a look at the massive, lightning-protection base demonstrating the exothermic welding process (using tools and materials that go by the trade name “Cadweld”) to connect a cable to the structural steel and to the ground rods.

COMING NEXT
In Part 3, Tom will discuss measures for the “near end” – at, or shortly before the feedline enters the radio. Several manufacturers sell “lightning protectors” that are the last opportunity to steer lightning currents to ground before they enter your equipment. The strategies these devices use differ in interesting ways, and every manufacturer makes arguments and claims for why his work best. As with this entire project, Tom did some very thorough research before making his choices.

WERNER’S TESLAVERT X3
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Readers may recall Werner's earlier antenneX article (January 2002) about a capacitive-type antenna that he dubbed the “TeslaVert,” in honor of Nikola Tesla, the early inventor. Of particular interest was one variation of the design, for 160M, that used a flat coil and a spherical radiator at the top. As Werner studied the design, he started to think about the role of spherical shapes in general Physics and noted that virtually all real shapes, and shape models found in the universe are spheres or derivatives! So, Werner concluded why not use spheres for experiments with capacitive radiators? And why not see what could be learned about the superposition of fields, by using these shapes?

For the past 3 to 4 years, Werner Hödlmayr, DL6NDJ has been very much involved through the GARDS (an International group sponsored by antenneX) in experimenting with small antennas, especially with those shortened by capacitive loading. These types of antennas are often referred to as Capacitive Radiators. One fascinating aspect of this class of antenna is that they all seem to establish a more or less “pure” electrical field, similar in symmetry to Magnetic loops, adds Werner.

Many members of the GARDS are working on various concepts in pursuit of shrinking the size of the antenna toward an ideal compact antenna. This month, Werner presents his latest evolution of the TeslaVert as the "X3" toward this goal and as we draw ever closer in our joint search for the "Holy Grail".

FEED SYSTEM RADIATION
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One of the projects our science writer, Joel C. Hungerford, KB1EGI has been conducting over the past several months is an investigation into the effects the feed system has on the signal. The “feed system” considered here means whatever encompasses not only the feedline, but also any other components connected to and in between the transmitter and the antenna. Typically, one hooks up to an antenna without too much thought as to any enhancement or hampering the feed system may be causing. Not enough attention has been paid to this part of the system. Most credit for a good signal is attributed entirely to the “antenna” and some new theory is offered to explain why the new device "works." This has especially been the case with the emerging compact antenna technology. By very close scrutiny, Joel has tested components one-by-one and moved things around to see what effect if any it may have on the signal—then reports on what he discovered in each month’s issue of antenneX.

Additionally, in this month’s issue, Vadim Demidov of Russia has a treatise on this very same subject in his article “Radiating Feeder: Applying a Theory”. For his investigations, Vadim chose two of the current compacts, but which employ different theories of operation—the MicroVert and the EH Antenna. Vadim likes to look at the theories and simulations, but also sees the importance of actual experiments to see and verify the real results. This is an excellent article and one our readers should find of great interest while trying to sort out the proliferation of new compact technology.

NEW ANTENNA DISCUSSION MAIL LIST LAUNCHED
In my column last month, I mentioned our intention to launch a new Majordomo-type mail list for the purpose of the general discussion of antennas and antenna-related subjects. At the time of the writing, we had not yet come up with a name for the list. After some thought and review of various suggestions, the name became obvious—Antenna Discussion. What could be more simple and apropos? Thus during the month of April 2003, two new lists were launched: 1) a regular list to accommodate separate postings and threads and 2) a daily digest containing a collection of the postings for those who do not want to receive the individual emails from the regular list.

We chose the Majordomo system, as it is a very stable and proven mail list management program able to efficiently handle very large memberships. I’m aware of some as large as 50,000, but there may be others that are even larger. With 60,000+ readers, the system will easily handle the potential growth of this new mail list, and then some. If you want the pleasure and fun of exchanging ideas or questions with folks from 183 countries, this makes it easy to do. Plus, the prospect of making new friends from all around the globe.

This is not a moderated list—it for the members to discuss issues between themselves, and as the list grows, I doubt if a question can be asked that could not find an answer from such a list with the level and variety of talent among our readers.

If you haven’t already joined, you are invited and encouraged to do so. Just click here and follow the instructions on how to join and have fun with the rest of us. If you don't participate—an opportunity lost!

TWO MORE COUNTRIES JOINED LAST MONTH!
Countries number 182 and 183 just joined the listing of "Where in the World is antenneX?" As is our custom, we welcome the latest newcomers and try to tell a little about the countries, some of the history and any other things our research discovers that might be of interest. The US CIA's World Factbook is most helpful in this research. A warm welcome to these latest newcomers!

WELCOME SAINT HELENA, COUNTRY #182
Saint Helena is located in the South Atlantic Ocean, about midway between South America and Africa. The terrain is rugged, volcanic with small scattered plateaus and plains. The highest point is at 2,060 m is Queen Mary's Peak on Tristan da Cunha. The volcanos are still active.

Now with a population of some 7,300, it was uninhabited when first discovered by the Portuguese in 1502, Saint Helena was garrisoned by the British during the 17th century. It acquired fame as the place of Napoleon BONAPARTE's exile, from 1815 until his death in 1821, but its importance as a port of call declined after the opening of the Suez Canal in 1869. Ascension Island is the site of a US Air Force auxiliary airfield; Gough Island has a meteorological station.

Life expectancy is good at an average of 77 years - female 80+ and male 74+.

The economy depends largely on financial assistance from the UK, which amounted to about $5 million in 1997 or almost one-half of annual budgetary revenues. The local population earns income from fishing, the raising of livestock, and sales of handicrafts. Because there are few jobs, 25% of the work force has left to seek employment on Ascension Island, on the Falklands, and in the UK.

COMMUNICATIONS:
Telephones: 2,000
Telephones - mobile cellular: none
Radio Broadcast Stations: AM 1, FM 0, shortwave 0
Radios: 3,000
TV Broadcast Stations: None - broadcasts are received via satellite and distributed by cable
Televisions: 2,000
Internet Service Providers (ISP): 1 with country code of ".sh"
Internet Users: N/A

WELCOME BENIN, COUNTRY #183
Benin is located in Western Africa, bordering the North Atlantic Ocean, between Nigeria and Togo. The name was changed from Dahomey to Benin in 1975. It gained its independence from France in 1960. From 1974 to 1989 the country was a socialist state; free elections were reestablished in 1991.

The climate is tropical; hot, humid in south; semiarid in north. The terrain is mostly flat to undulating plain; some hills and low mountains with the highest point of 658 m at Mont Sokbaro.

Current environmental issues are inadequate supplies of potable water; poaching threatens wildlife populations; deforestation; and desertification.

The country has a population of some 6,787,625. Estimates for this country explicitly take into account the effects of excess mortality due to AIDS; this can result in lower life expectancy, higher infant mortality and death rates, lower population and growth rates, and changes in the distribution of population by age and sex than would otherwise be expected. It is estimated that 160,000 people are living with HIV/AIDS. Thus, life expectancy is an average of about 49 years with not much difference between male and female.

The economy of Benin remains underdeveloped and dependent on subsistence agriculture, cotton production, and regional trade. Growth in real output averaged a stable 5% in the past five years, but rapid population rise offset much of this increase.

COMMUNICATIONS:
Telephones: 2,000
Telephones - mobile cellular: 55,500
Radio Broadcast Stations: AM 2, FM 9, shortwave 4
Radios: 660,000
TV Broadcast Stations: 1
Televisions: 66,000
Internet Service Providers (ISP): 4 with country code of ".bj"
Internet Users: 25,000

The Elusive Moxon Nest
By: L.B. Cebik, W4RNL

For the last decade or so, since the Moxon Rectangle emerged as a compact full-size 2-element array of considerable utility, folks have searched for a means of nesting Moxons for more than one band. Despite G6XN's reported successful use of wave traps to isolate elements within a multi-band array, there has been little success in nesting rectangles that have been optimized for maximum gain, maximum front-to-back ratio, and a direct-feed 50-Ohm impedance. This report will examine some of the reasons why nesting Moxons is difficult. It will also describe a successful design that combines 17 and 12 meter Moxons in a nested pair with a common feedpoint.

LAB NOTES: Loading the Dipole Center
By Joel C. Hungerford, KB1EGI

During the April 2003 experiments, Joel found that converting an antenna from a monopole with a loading coil to a dipole with two loading coils in the same configuration changed the resonant frequency depending on the coil position. This month Joel investigates more closely loading the center region of the dipole, a place that offers both an opportunity and a limitation for the antenna designer.

The LDE Phenomenon
By Igor Grigorov, RK3ZK

Igor draws the reader’s attention to a surprising phenomenon called “long delay-echo," (LDE) an echo with a radio signal delay of more than several seconds. The first time the LDE or long-delay echo phenomenon was described publically was in reference by the efforts of a Norwegian radio engineer, Jorgen Hals. At the end of summer in 1927, near Eindhoven, Danmark, he observed LDE from a short-wave broadcast radio PCJJ. This station worked on a wavelength of 31 meters. Jorgen Hals received echo returns of this radio with a delay of about 10 seconds. His receiving station was in Bygolo, near Oslo. LDE are still observed by radio operators. Do LDEs really exist?

TESLAVERT X3
By Werner Hödlmayr DL6NDJ

Readers may recall Werner's earlier antenneX article about a capacitive-type antenna that he dubbed the “TeslaVert,” in honor of Nikola Tesla, the early inventor. Of particular interest was one variation of the design, for 160M, that used a flat coil and a spherical radiator at the top. As Werner studied the design, he started to think about the role of spherical shapes in general Physics and noted that virtually all real shapes, and shape models found in the universe are spheres or derivatives! So, Werner concluded why not use spheres for experiments with capacitive radiators? And why not see what could be learned about the superposition of fields, by using these shapes? Thus, the "X3" evolved.

Radiating Feeder: Applying a Theory
by Vadim Demidov

Vadim Demidov of Russia joins us for the first time this month and his article deals with a feeder radiation phenomenon. Vadim says this phenomenon is well known, but Hams usually think of it as a small fraction of the total antenna radiation and mitigate it only when it distorts a radiation pattern of an antenna, or causes TVI. All the above is true for big good antennas. For small ones, like the Isotron, the DL7PE-microvert, and the EH antenna, the feeder radiation can exceed the radiation of the antenna itself by two orders of magnitude (20 dB). This leads to claims about a new method of the electromagnetic waves radiation, since the classic theory can't explain that. This leads to some new "theories" and revisions of the classic theory. Here we shall try to look at the radiating feeder phenomenon from the classic theory position; we shall try to model it using a well established software package; and we shall compare our figures against existing experimental data.

Theory and Testing of Duplexers - A Presentation
By Jacques Audet, VE2AZX

As the phrase goes, "a picture is worth a thousand words". If that is true then this one, with 60 pages is worth some 60,000 words! Being in "presentation" form, this article departs from our normal heavy-textual articles with a few supporting illustrations. This presentation is so well-done, it intrigued me enough to want to share it with our readers. It is sufficiently balanced with text along with approximately 60 illustrations in the form of pictures and schematics that our readers should find this one as much a joy to read and view as I did—and learn much about Duplexers in the process—Jack L. Stone

Well, there you have it, folks—thanks for listening and remember, the reading lamp is always on for you in the reading rooms. If I can be of further help, I'm just a Stone's Throw! away. May 2003 antenneX Online Issue #73
reGARDS, Jack L. Stone, Publisher jack@antennex.com