Dogs love trucks but
HAMS LOVE ANTENNAS!!!!!
Wire Antennas
To me, antennas are the most interesting aspect of amateur radio. You don't have to go out and put up stacked arrays of monobanders on huge towers to work DX effectively as some would have you believe. I'm not saying they don't serve their purpose marvelously, it's just that most of the people I know don't have a few thousand dollars to spend on an aluminum forest. I've been asked by several of my friends that are studying to get their ticket, what kind of antenna(s) should they get to work HF. I always tell them to but 14 gauge stranded wire in bulk and we'll build some. They know wire antennas work as they've seen mine in action.
Everybody seems to be hung up these days on how much gain their shiny new antennas have. Talk about gain, try an 80 meter cage on 10 - 20 meters sometime then tell me about how much your antenna has. Depending upon the design and configuration, wire antennas can have considerable gain. Remember that gain works for reception as well. How many aluminum antennas can cover either 80 or 160 meters with a SWR of 1.5 to 1 or less? I haven't heard of any that can make that boast. My 80 cage uses 24" spreaders and doesn't that feat with ease. My 40 meter "fat" dipole using 1.5' spreaders has a 1:1 SWR across the whole band. Another plus is when you get any horizontal (or inverted V) up 1/2 wave above the ground, it WILL become directive simular to a bi-directional beam.
Regardless of what some amateurs will tell you, a transmatch is not a four letter word. What's the difference between having a matching network at the antenna or in the shack? I will admit there is some but I'm not worried about a little line loss. There are a lot of hams out there who say they wouldn't own a tuner. Ask these guys what kinds of antennas they use and I'll bet those antennas use a matching network. My turnstile uses a 1/4 wave 50 ohm matching section to give it circular polarization. You can't argue the point with these guys as they won't admit it even when they know your right. I do prefer though, to have these discussions face to face to see the looks I get. If you have not tried a "coxial" choke balun before, they work very well and are very simple to make. Simply take a piece of feedline and wrap it in a circle. I have the specs for HF in a text file if you need them.
So before you go out and spend a small fortune on an aluminum forest, pick up some books on wire antennas and try out a few designs. You'll end up with a good antenna system and something you can be more proud of it as you tell everybody yours is homebrew. Not to mention, the money you save can go for a new rig or something else for the shack. I'm not going to recommend any particular books as there are hundreds of good ones. I own several antenna books myself.
If you're looking for a directional antenna, don't rule out a wire beam. While there size on 40 through 160 meters would be difficult, they can be crafted for any band. Two dipoles spaced properly and cut to resonance make a beam. For other bands, get some PVC, fiberglass rods, or anything nonconductive to use as spreaders or housing. That right, I said housing. If you want a typical yagi design, just put your 1/2 wave dipole inside the pipe and there you go. Don't forget to make the director 5% shorter and the reflector 5% longer and use sturdy pipe for this one. While this is not the most broadbanded design, it's still a very good antenna and this one won't cost you an arm and a leg. This is also the way I constructed my turnstile.
I hope that you will try a few wire antenna designs and learn something new. I've been thinking about trying an underground antenna or maybe loading up the guttering on the house but I haven't tried it yet. If you have tried either, let me know how it turned out. Don't be afraid to try something new even if it means taking down one that's working fine. I've been known to take down a perfectly good dipole just to try out a new one. As a matter of fact, I currently have up more ropes and pulleys than I do antennas. I guess I need a bigger yard for the low band antennas.
A Heavy Duty Cage
I've tinkered with a few ways to broaden the bandwidth of wire antennas and found the best I've tried so far to be a Cage dipole. They are real easy to build and extremely broadbanded. I did something a little different than most for my spreaders that while heavy seem to do very well. What I used was PVC pipe with 45 deg elbows to make octagonal spreaders. I drilled holes in the center of each elbow and ran 14 gauge stranded wire through the holes. As I stated, this makes a very heavy antenna but one that will stand up to adverse weather. We had a localized blizzard this spring ('98) that dumped between 2 and 4 feet of wet snow. While the trees, pipe, and ropes broke that held the cages' ends up, the antenna survived. I did have the get the branches out of the wires, but I put the antennas back up and I'm still using them without having to rebuild anything. I do something else different you might find interesting at the ends of the cage. I DO NOT connect the wires. Instead I feed the wires through the holes and then terminate them by wrapping the wire around the spreader and then back around the wire. This prevents the wires from slipping and if the wires start stretching out and changing the resonance of the antenna, it will be easier to shorten it. This method has an interesting effect that shortens the length of the antenna. In other words instead of having a 125' dipole, my 80 meter cage is only abt 116'. I have had people explain to me why but it was over my head and I still don't understand why. If you wish to lighten the wieght of the cage you can always strip the insulation off the wire and use smaller diameter pvc. I use 4 spreaders on each leg of an 80 meter cage and only 2 on a 40 meter version. The 80 meter cage(s) I've built show less than 2:1 swr across the entire 75/80 meter band without a tuner and the 40 has about 1.2:1. Believe it or not, my antenna anylizer even shows the 80 meter cage resonant on the weak signal portion of 6 meters. I haven't used it in a band opening on 6 yet but I have worked some friends locally. I have built a couple of these and haven't had a bad one. I use my 40 meter cage exclusively when running 40 meter QRP and have worked California in the Novice band through the broadcast stations. I use the inboard tuner on my Kenwood 450 when on other bands only when necessary. Before anyone asks, I use a propane torch to solder those 8 14 gauge wires at the feedpoint . I simply haven't found anything else that works with that much wire.
Antenna Trimming Chart
Well if you've ever made a dipole and it wasn't resonant where it was supposed to be this should come in handy. I can't remember where I found this information but I have found it to be very close to accurate. The final adjustments will be up to you since everything surrounding your antenas come in to play anyway. Either lengthening (if high in resonance) or shortening (if low) the overall length of the antenna by the amount shown for the desired band will move the resonant frequency of the antenna by 100 kHz. For example, if you make a 40 meter dipole that is resonant at 7.0 MHz and you want it resonant at 7.2 MHz, you would shoerten the antenna by 20" (10" off each end). Always remember that it is easier to shorten wire than to lengthen it so instead of cutting all the excess wire off, I simply wrap some of it back around itself in case I over adjust.
80 meters 3', 4"
40 meters 10"
20 meters 3.25"
15 meters 1.25"
10 meters 5/8"
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