The 2 Meter Coffee Can Antenna
The 2 meter coffee can antenna is easy to make and you'll have loads of fun making contacts with it! The coffee can antenna is actually a sleeve dipole antenna made using a large coffee can, or other similar size tin can, in place of using radials like that of a ground plane antenna or the other half of a dipole element.
This project was the first of several experiments using a vertical antenna element and some sort of metal ground plane surface or counterpoise. I knew beforehand that quite frequently home-brew ground plane antennas tend to be a little taller than the 1/4 wave that they start out to be. After trying antennas for different bands I found that each time the antenna was high in frequency and that the vertical element needed to be made longer. This seemed to be a typical characteristic for a vertical antenna using a smaller than normal counterpoise.
After mounting the antenna outdoors atop a 10' section of PVC pipe, the antenna then worked higher in frequency than as tested indoors. The final length of the vertical element came out to be 25-1/4" (64.1 cm). By the way, when using the number 1005 to calculate wavelength the vertical element works out to be about one half of 5/8 wave.
For a more rigid vertical element you may use a piece of copper or aluminum welding rod instead of the 12 gauge house wire. If a wire coat hanger is long enough you can also try that. Soldering the steel coat hanger wire to the SO-239 might not be as easy as soldering copper wire but an uninsulated butt end connecter can be added between the UHF connector and the wire element and filled with solder.
You can also sand, prime and paint the outside of the can if desired to help prevent rust and improve the look of the antenna.
A few tips from viewers: If using house wire a small wire nut can be added to the tip of the wire element for safety. Also, to help eliminate burrs when drilling holes in the top of the coffee can place the can over a board or piece of timber, so that the inside top of the can rests flat on the wood, then press down and drill.
Tuning is by either lengthening or shortening the vertical element. When I found that my original vertical length needed to be longer I used an uninsulated butt end connecter to splice another small section of wire on the end of the element. Making a new vertical element was not necessary but of course one solid piece of wire looks best and it only takes a few minutes to make.
Video Instructions Watch the video below to see how I build the coffee can antenna. Make the vertical element 25-1/4" (64.1 cm) instead of the 22" shown in the video.
The SWR reading, with the antenna mounted on 10' of PVC pipe, is 1.5:1 on each end of the band and about 1.3:1 in the center. One thing that I did not try with the 12 gauge house wire that might lower the SWRs is to form a loop at the top end of the vertical element (like the tuning stub on the 40/80/160m inverted V antenna). To try this you would make the vertical element longer and form a one inch loop at the top of the element, keeping the element the proper length measuring from end to end. Another idea for a vertical element is to use the stainless steel top section of an old CB antenna. The little ball at the tip of the element may also prove to be beneficial.
To mount the antenna outdoors run the coaxial cable down through the inside of a metal mast or a section of PVC pipe then secure the cable at the base of the mast. You can also make a mounting bracket using a small angle bracket mounted inside the top of the can which fastens to the outside of the mast with a hose clamp.
Large coffee can or other tin can, 6" (15.5 cm) dia. x 6-1/4" (16 cm) tall.
12 gauge housewire, or copper or aluminum welding rod, 25-1/4" (64.1 cm) long.
Safety First! Please use caution and keep common sense safety rules in mind when installing an antenna. Never install antennas near power lines or in any location that would place people or pets within the near field radiation pattern of an antenna. All users understand and agree that the owner of this web site is not responsible for accidents or other mishaps that may have been caused directly or indirectly as a result of the information published on this web site and/or in any of the video presentations.