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| Antenna Modeling |
From The Shack |
 This
is a regular and popular monthly column by L.B. Cebik, W4RNL Because
computerized antenna modeling has become widespread, and its popularity as a design tool
continues to increase, this series is devoted to helping readers get the most from the
design software used. The articles focus upon the use of NEC and MININEC, along with
useful adjunct software as well. |
 This column is primarily for "Guest
Editorials" to provide a podium for our readers to voice their opinions to the rest
of the world too. This is a chance for readers to get on their "soapbox" and
speak about antenna and radio-related subjects. Don't miss these interesting views about
anything and everything about radio and antenna systems! Now, what have YOU to say?? |
Ham WorkShop |
Stone's
Throw! |
|
Ham WorkShop, is also another
regular monthly column filled with a variety of "RADIO-STUFF" of value to
almost everyone in amateur radio from Novice to Extra and those just beginning to take up
this special hobby. This includes subjects, but not limited to: VHF, choosing the right
antenna, coax cable, small to mid-scale construction projects in a practical manner, use of test
equipment, etc. It is also meant to help readers become more familiar with the technical
jargon and the fun side of radio. |
 Stone' Throw! a
monthly column by antenneX publisher,
Jack L. Stone, among other things, is to keep
the readers informed about our progress, new developments, plans for the future, and to
introduce the authors and their subjects each month. Also, our main slogan around here is
"we aim to please", so this serves as a place for the readers to tell the
publisher what is wanted or at least make suggestions. Just remember, the publisher is
only a Stone's Throw away! Go in for a visit and read this month's column. |
Propagation |
 Propagation
another monthly column by Marcel H. De Canck, ON5AU of Belgium. Signal propagation
is a subject that is one of the most basic ingredients of radio and is something everyone
in radio should know about in order to maximize communications in the most effective way.
It’s not enough to have the best equipment and the best antenna if you are trying to
send out a signal against a brick wall. Conversely, one may possess a very crude rig,
running low power, but yet transmit/receive a signal to great distances with ease, simply
by making use of a thorough knowledge about how signal propagation works within the
environment. Follow this column and learn more about propagation! |
FEATURE ARTICLES THIS MONTH IN THE LIBRARY
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|
A Trap 2-Band 2-Element Beam for 17
and 12 Meters
By L. B. Cebik, W4RNL (SK) |
|
Over the last 2 decades, we have seen a crossroad between older and
newer multi-band beam designs. Older multi-band beams tended to make
heavy use of traps to achieve 2-band and 3-band performance from a
minimum number of elements. Newer beam designs gave up the trap and
let each element serve only one primary band, whether the element
was a driver or a parasitic element. Initial feed systems, pioneered
by Force12, used open-sleeve driver coupling, although later makers
have tended toward forms of direct driver coupling. In the market
place today, trap and non-trap beams are available both in short and
simple and in long and complex designs. |
|
Practical Antennas: Part 2.4
By
Marcel H. De Canck, ON5AU |
|
The ionosphere plays a tricky but an important
role to our radio communications, and there is very little we can do
about it. But there is plenty you can do about having a good and
efficient antenna system. Yes, antenna system, it’s not the antenna
itself but the whole part as transmission line, and matching
properly the transceiver and the antenna to the transmission line.
It is a breath-taking concept that a simple length of wire or rod or
tube can transform electrical energy into invisible radio
electro-magnetic waves that can cross the space at the speed of
light.
How does an antenna system works? Why does the antenna radiate
electro-magnetic waves? These questions I heard many times and the
answers are not given with few words. Never-the-less, many books and
some of great weight and complexity have been written about antennas
and many antenna types have been developed and build. Often it is
not comprehensive to the layman to fully understand the whys and
hows of the radiation capabilities of an antenna and these counts
even for the simplest ones like a dipole or a groundplane. Also I
often hear many times misconceptions about antenna properties and
characteristics. To start with, understanding why and how a simple
antenna effective radiates will be explained in a clear view. The
dipole is the best antenna to do that and once the secrets of the
dipole characteristics and properties are fully understood it will
be much easier to have a clear insight of the hows and whys of more
complicated antennas.
The first episodes will handle completely about antenna fundamentals
mostly with the half wavelength dipole as study example. The dipole
is also often a part element of more complicated antennas such as a
Yagi and others. In particular for the low frequency bands, the
dipole is used by many radio amateurs as transmitting or receiving
antenna and its many practical installations and shapes will be
fully studied and explained in a chapter later on. In fact many
other antenna types will become subject to explanation as the
antenna story develops. |
|
NewcomerNotes: Radio Propagation for
Beginners
By Robert Gulley, AK3Q |
Tuning up and down the dial
willy-nilly will always bring in radio signals of some sort simply
because there are so many signals out there. Serendipity certainly
has its place and its own rewards, but if one wants to get serious
about the radio hobby there comes a time when the study of
propagation (or how signals get to where they’re going) is a must.
Not only will understanding some basics about propagation make
listening opportunities more productive (read “fun”), but it will
also allow you to take advantage of special situations where
opportunities pop up only for a few minutes or a few hours at best.
Catching elusive signals, or even better transmitting under special
conditions is a thrill all its own. I'm a newbie at most aspects of
this fascinating hobby, so come on and learn along with me! |
|
A
No Counterpoise Antenna:
2-Element Vertical Phased Array
By Martin Steyer, DK7ZB |
|
It has been found
that the “no counterpoise” antenna presents an easy to match
impedance across a very broad range of frequencies with the
resistive and reactive components never rising above a few hundred
Ohms. Therefore, if feeding these with a twin feed line, then the
line losses resulting from high SWR will remain very small,
especially when the line length is short as in a typical /p type
operation. I therefore decided to see how a pair of vertical “no
counterpoise” antennas would cut it when used in a phased array. |
|
More Multi-Band L-pole Vertical Antennas
14 to 29.7MHz Broad-banded and 2-6-10-Meter Multi-band Antennas
By Edward J. Shortridge, W4JOQ |
|
Two
previous articles gave a detailed introduction to the "L"
broad-banding method, so if you are in doubt about the method,
please refer to the previous articles. The last article primarily
covered vertical antennas that use dual radiators to simulate a
larger diameter single radiator or uses a triangular tower, which
actually is a larger diameter radiator. This new article presents
6-10-meter dual-band antennas using a smaller diameter radiator.
Additionally, a 2-meter coupled-resonator was added to the
6-10-meter antenna in order to form a tri-band antenna covering the
2-, 6- and 10-meter bands. |
|
Yagi Antenna Insulated Elements Boom
Correction
By Dragoslav Dobričić, YU1AW (Serbia) |
The boom of Yagi
antenna is an inevitable part of its construction. Theoretically and
practically, a Yagi antenna can work fine without a boom. A
conducting boom is not an intended radiating part of antenna but
only an inevitable part of its support construction.
As we know the Yagi antenna can be built in a few ways. It can be
built so that elements are insulated and separated by some safe
distance from any conducting boom or so that elements pass through
boom. The latter method can be done with elements electrically
bonded to the boom and elements electrically insulated from the
boom. All of these element mounting methods have their mechanical
and electrical advantages and disadvantages plus different boom
influences to antenna elements.
So far, in several previous articles, we have investigated how the
boom dimension, its cross section shape and its distance from
antenna elements influence performance of six different 2 m Yagi
antennas which are very similar in all characteristics except in Q
factor values. In other articles, we have shown how a boom presence
influences Yagi antenna performances when elements are insulated and
separated by various distances from a conducting boom and finally
how the boom influences Yagi antenna performances when elements pass
through a metal boom and they are electrically bonded to it. This
article investigates the results of correcting yet another
unintended consequence of construction as the title implies. |
|
|
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December 31, 2009
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