Simpleton's Guide to:
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he first VHF antenna I ever built was this 2-meter quad. I was scanning the 2-meter band one night and heard a fellow amateur, his signal was weak but I gave him a call. He came back to me and we had a very interesting conversation. We got onto the discussion of antennas and he said I should build a quad antenna to improve my reception. He described it to me over the air and I wrote down all the figures and measurements.|
I went out to the local hardware store and bought some wood: a 4 foot length of 2"x2" for the boom and 8 pieces of 1"x1"x36" for the quad elements. I had some extra copper wire from my HF dipole creations to use on the four elements. If you follow my construction steps, you'll have a really great antenna and learn something too.
First I center notched the 1"x1" wood pieces. This would allow them to fit together in four crosses. I then measured and drilled holes in the ends of the cross arms to hold the wires in place. The holes must be spaced perfectly to hold the wire elements to the proper lengths. Refer to the table below for the proper hole spacing.
Cut four pieces of wire about 6 inches longer than the measurements shown. Feed each wire through the four holes in the cross elements. Twist together the ends and solder the joint.
The driven element will require special care. An additional hole will be needed for the coax. The shield of the coax is solder connected to one end of the element wire and the center conductor is soldered connected to the other end of the element.
When I first built this antenna I knew something was wrong. This would short the center conductor to the shield. After discussing it with fellow amateurs I was assured that the design was correct!! The length of element wire creates the proper impedance for the frequency.
Now that all the elements are constructed, it is time to attach them to the 4' boom. They must be spaced properly. The proper spacing creates the gain for the antenna. Use two screws to attach each elements to the boom.
Pick up the antenna and find the balance point. This is the position you should use to mount it to the vertical mast.
If you want vertical polarization, the coax should feed from the side of the quad, for horizontal polarization feed it from the bottom or top.
This quad worked great and I learned quite a bit. I'm sure you will also.
Thank you to that amateur who shared this antenna with me over the air.
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