Author Topic: 440 Cubical Quad antenna  (Read 3580 times)

Offline pkveazey

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440 Cubical Quad antenna
« on: November 22, 2016, 07:41:47 PM »
A while back, I built a Cubical Quad beam antenna. I already had a 440 quarter wave ground plane at 40 feet. Since 440 can be really unreliable due it's relatively short range, I built the quad to make sure I could hit the 440 machines to my North. I mounted it about 30 feet up the tower. I used PVC pipe for the whole project so there wouldn't be any interaction of the antenna and the spreaders and boom. Well, you can't bend the plastic pipe so I attached the beam to the tower as best I could to point northward. Just my luck, It was pointed exactly between two metropolitan areas, and it made the antenna almost useless. I got fed up with it so today I climbed the tower and me and my blowtorch took care of that bad direction. It's now pointed right across three 440 repeaters. Now I can bring up the 440 machine that's about 40 miles out when the ground plane antenna that's mounted at 40 feet can't make the trip. When we have the next band opening on 440, I'll be ready. I chose to build the Cubical Quad because it's quick and easy, has more gain than a three element Yagi, and is waaaay more broadbanded than a Yagi. It also doesn't require a Gama match or Tee match. However, you can add a matching stub if you want to. I've done it with and without. This one is without and has a VSWR of about 1.3 : 1. Why make more work for myself? OK, for those who want to know why I didn't put a rotator on it, it's because I've fought that battle in the past and always lose because the rotators know more ways to break than I know ways to fix them. Basically, where I live there are only two directions towards a metropolitan area. That would be East toward Norfolk or North toward Petersburg and Richmond. If you are not familiar with Cubical Quads, you should do some research. Where you attach the coax is supposed to determine its polarity. No matter where you attach it, you're still going to get some of both polarities. It's one of those, you can't go wrong things.

Offline JohnyMac

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Re: 440 Cubical Quad antenna
« Reply #1 on: November 22, 2016, 08:12:48 PM »
I have a cubical quad antenna design for 6 meter. You use "step on" fence posts put through 3" PVC pipe at right angles to support wire of the antenna.

I bought the fence posts and PVC but have yet to put it together as 6 meter propagation has been poor. I will try to find it and post it on the topic you started pkveazey.

Thx for starting the topic.  :bravo:
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Offline pkveazey

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Re: 440 Cubical Quad antenna
« Reply #2 on: November 23, 2016, 10:38:56 PM »
On all the Cubical Quads that I've built, I make an X and use either 1/4 inch fiberglass rods or small PVC pipe. By using something flexible, I can pull the wire nice and tight and cause the spreaders to bow slight!y. Then when the temperature changes, the spreaders can relax in hot weather and tighten in cold weather because of the wire reacting to the temperatures. The 440 band opened up a little bit, earlier tonight, and I heard a repeater station that I've never heard before. If you've never seen a Spider Quad, that is a really cool design. It allows you to put as many loops as you want and cover a half a dozen bands on one set of antenna spreaders. I love Quads.