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The Vertical Helical Antenna

By Don Moore


I found this in my's an e-mail exchange I had on May 2, 1995.

Could you please also give approx diameter of the PVC pipe and the length of the pipe on which the wire was wound?

I used a ten foot (3 meter) section of 3 inch outer-diameter PVC - say about 7.5 cm. The wire was wrapped around this with turns spaced about 3-5 cm apart. I didn't take any great care to keep the distances the same. This PVC was then mounted on another piece of PVC with an inner (the hole) diameter of 3 inches. I put two strong bolts through the second piece of PVC, putting one each about 3 feet from each end. The first piece then slipped into the second piece, giving me a 17 foot (about 5.25 meters) mast. I then attached a wood support to the highest point or peak of my garage roof with a well-supported 8 foot length of wood 2x2 board (a common board here that is 2 inches on each side square). The bottom half of the 2x2 was attached to the garage and the top half projected above the peak. I then stood on my garage roof and carefully stood the PVC mast upright, lifted it, and then slipped it over the 2x2, until the PVC rested on the second bolt. This was the hardest part and shouldn't be done on a windy day! Including the height of my garage, the bottom on the actual antenna coil is about 20 feet (6 meters) from the ground.

I connected the conductor of a 50 ohm coax to the bottom end of the antenna. I connected the shield of the coax to a ground wire which runs down the mast from the bottom of the actual antenna to a ground rod directly below the bottom of the antenna. The end of the antenna wire was wrapped in electrical tape to prevent water from getting in the insulation, but there is no connection at the top.

1995 Photo of this Antenna - I no longer live at this house or have this antenna.

In which situations/bands do you find the helical most beneficial?

It does not consistently beat out my other antennas on any particular band or for any particular area of the world. At least, I have not noted a pattern yet. However, sometimes it provides a better signal (or less noisy and more listenable signal) than any of my other three antennas. This is not often, but it is often enough for me to want to keep the antenna.

I first used a helical when I lived in Honduras in 1982-1984. I had one wrapped around a tall piece of bamboo which I then tied to the side of a palm tree for support. It worked well except every two to three months a palm frond would fall and break the lead-in.


This website is maintained by Don Moore,
Association of North American Radio Clubs
DXer of the Year for 1995

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