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 Previous: Field Day 2007 Offers a Learning Opportunity for HF Newcomers |  Next: Games Astronauts Play in Space Among ISS Ham Radio Contact Topics |
By Gary Hoffman, KB0H
Contributing Editor
March 13, 2007
It's always about the antenna -- or, as Antenna Whiz Dean Straw, N6BV, likes to say: "RF gotta go somewhere."
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 the ceiling.
The "experiment" 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.
It's always 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.
Antennas started 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 work?
But truthfully, 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.
During my 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. Since other 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.
I will 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.
The easiest 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 looked 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.
Eventually I 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 tremendously.
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.
Imagine that?
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 Web page. Readers are invited to contact the author via e-mail.
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