Easy to build Antenna

[pkveazey]

I'm attaching a really poor picture of an antenna that I thought I had invented until one day when I saw a commercially built  one exactly like it on a Cargo Ship. I've built them for 10 meters, 2 meters, 1.25 meters, and 70 centimeters. They work a lot better than a basic 1/4 wave ground plane. I call it the "Basketball" antenna because the bottom looks like a basketball. The first one I built, I put four 1/4 wave radials on it and then bent them down in a half circle. Then soldered all 4 crossing points together. Well that was dumb. Then I built one with two 1/2 wave loops and soldered them at the point where they crossed each other. I could get all technical and try to explain the reason I built it with the insane radials but I'll just leave it at averaged impedance. I've compared it to a 1/4 wave ground plane with straight radials and a 1/4 wave ground plane with 45 degree drooping radials. It beat them all. There's no real gain involved but it must be a really low angle of radiation. The drawing is how to make one as an emergency antenna by just using an SO239 jack. If you are out in the woods and don't have a long pole or don't want to climb a tall tree, then just tie a string around it and throw the string over a high branch and haul it up temporarily.

[FeedingFreedom]

Thanks, I'll have to build one and hook it up to the analyzer and see what it does. Seems like it would be a lot sturdier than a normal 1/4-wave, they usually break where the radials join with the SO-239.

[pkveazey]

Thanks, I'll have to build one and hook it up to the analyzer and see what it does. Seems like it would be a lot sturdier than a normal 1/4-wave, they usually break where the radials join with the SO-239.

Your brain is right where mine was when I designed it. I needed a wind resistant antenna for 10 meters. I guess that's why I saw one later on a cargo ship. It should handle a hurricane. Now, as to what I was thinking when I shaped the radials. Straight out is a 32 to 37 Ohm antenna, a dipole is a 70 to 75 Ohm antenna, and 45 degree drooping radials is supposed to be somewhere about halfway between the two. I figured that if I started out straight and then curved the radials into a half circle then I'd probably get the same impedance match as with a 45 degree droop. Then I noticed that all the radials touched at the bottom so I soldered them all together. That's when I also realized that a complete loop[ would be easier to build and be stronger. When I started doing TX/RX comparisons I saw better results with the Basketball. My VSWR meter said all was right with the world. I bought one of those NANO meters and have come to trust it about as much as my VSWR meter. Its pretty good but I wouldn't bet the farm on it. One of the coolest features is the SMITH CHART because it will show what the impedance is of the circuit. If I can get anywhere near the 50 Ohm circle, then I'm happy.