The Amateur Amateur: Dances With Aerials
By Gary Hoffman, KB0H
about the antenna -- or, as Antenna Whiz Dean Straw, N6BV, likes to
say: "RF gotta go somewhere."
March 13, 2007
I climbed down from the attic, already knowing that the experiment
was a failure.
Diagram of typical radiation from a center-fed dipole, from Elements of
Radio, by Charles I. Hellman (1943).
To work properly, antennas -- like this multiband, center-fed dipole --
must have two "halves."
I climbed down out of the attic, already knowing that the experiment was not
going to work. My wife Nancy gave a sigh of relief as I closed the
attic access door and folded up the ladder. She doesn't like me
crawling around up there, and I can't say that I blame her. There's a
very real possibility that one day I will come crashing down through
was an effort to solve an antenna problem. When using my makeshift HF
antenna, I beam much more radio energy into our house than I do into
the ether. There are a number of possible solutions, none of which is
appealing. So I keep looking for a fix
rather than a solution,
something that will allow me to use my current antenna configuration
as opposed to putting up a completely different antenna.
And why am I so
reluctant to change antennas? Because this
one actually works.
Even though most of the signal ends up resetting my digital clocks,
the little bit
of RF that gets into the air serves me well.
antennas, isn't it?
When I first
became an Amateur Radio operator, I didn't think about antennas very
much. I was much more fascinated with all of the cool transceivers
with their multitude of neat features. To me, antennas were just a
necessary nuisance, something I intended to give as little attention
as possible. As far as I was concerned, the only people interested in
antennas were mathematicians or hams who wanted to do specialty
stuff, like talk to the outer planets.
Now, of course, I
know better. Antennas refuse
to be ignored. By and large, the
antenna system is the most important part of any ham radio setup. In
extreme circumstances you might
be able to send out a signal
even if you don't have a radio. But you won't
be able to send
out a signal without an antenna of some sort.
catching my attention pretty quickly. It wasn't because I found them
sexy, though; it was because the ones I had didn't work. That was
hard to accept at first. Antennas are just chunks of metal or pieces
of wire. How could they not
some of them don't. And it's not always a design or manufacturing
problem. Sometimes it's how or where you install them or how you feed
(connect) them. You can't even assume that just because an antenna is
pointing in the right direction that it's going to work.
earliest days in the hobby it seemed like none of my equipment worked
very well. My handheld transceiver didn't receive much or send very
far. My mobile radio wasn't much better. And the first HF antenna
that I mounted on my house picked up static and little else.
Virtually no one responded when I transmitted from any of my rigs.
hams were faring much better, even with handheld
radios, I knew that the problems were on my end -- or, more likely,
with the way I was using my equipment.
give myself credit for not falling into the trap of believing that I
could solve all my problems by buying an amplifier and boosting my
output power. No. I figured out fairly quickly that it had something
to do with antennas.
problem to fix was the one with my handheld transceiver. The first
piece of advice virtually every new licensee hears is, "Get
something better than the rubber duck antenna that came with your
radio." I did, and it worked.
The problem with
my mobile setup was harder to diagnose, but it, too, turned out to be
the antenna. Simply put, it was junk.
I had installed
extremely cheap glass-mount antennas on both my car and Nancy's car.
Our mobile-to-mobile radio contacts were somewhat disappointing. We
had to be practically within shouting distance before we could hear
each other on the radio. I couldn't figure out why. The antennas
as though they should work.
I'll concede that
I was mystified by how the RF energy got through the glass, but I
figured that since it worked for cell phones it should probably work
for my ham rig as well.
figured out how glass-mount antennas work. It has to do with
capacitance. But it wasn't until I started doing a little independent
research on antennas that I was able to determine why ours
weren't working very well. Basically, the cheap little antenna on my
car was only half
an antenna. Something else, such as the body
of my car, was needed to serve as the other half. Once I understood
how the two "halves" of an antenna interact, it was easy to
see that what I had on my car was never going to work very well. I
switched to a simple mag-mount antenna, and the performance of my
mobile radio improved dramatically.
Maybe I kept
missing the clues, but it seemed to me the information on just how
antennas work -- the really elemental theory -- was nowhere to be
found. It wasn't until I stumbled across a couple really old books
that I got the basic idea of what happens in an antenna and how radio
frequency energy emanates from it. Just seeing a diagram helped
I didn't become
an overnight antenna guru. Perish the thought! A lot of antenna
configurations still baffle the heck out of me. But just having a
smidgeon of understanding -- being able to look at a really simple
antenna and being able to visualize how the energy radiates from it
-- has been an invaluable asset.
That's why I
knew, even before turning on my radio, that my experiment in the
attic wasn't going to work. I could see the antenna radiation pattern
in my head. Or at least I could sort
of see it. It was that
little bit of doubt that gave me hope that it would work.
It didn't. But I
no longer begrudge the time I have to spend fiddling with antennas,
going up on the roof and doing dances with aerials. It's an integral
part of the hobby, for sure, and it's definitely a learning
experience. But, truth be told, these days I actually enjoy it.
Editor's note: ARRL member Gary Hoffman, KB0H, lives in Florissant,
Missouri. He's been a ham since 1995. Hoffman says his column's name
-- "The Amateur Amateur" -- suggests the explorations of a
rank amateur, not those of an experienced or knowledgeable ham. His
wife, Nancy, is N0NJ. Hoffman has a ham-related
Readers are invited to contact the author via e-mail,
© 2007 American Radio Relay League