DIY Microwave Antenna Horn Applications with Food or Coffee Can

Looking for a highly effective microwave horn antenna? Look no farther than your pantry! Food cans (empty, of course) can be just the right size to give you lots of gain-just watch out how much YOU gain by emptying the cans! 

You can turn a coffee can into a quick and simple horn antenna with 8.5 dBi gain for 1296 MHz. Its bandwidth is very broad and this horn can be used as is from 1100 MHz to 1500 MHz. It works great in SSB, CW, FM, ATV, satellite, and even SET1 (Search for Extra-Terrestrial , Intelligence) applications. Take an empty 3-pound coffee can and drill a hole for the coax connection along the solder seam 4 l/2 inches from the bot- tom (see Figure 1 for other dimensions). Now mount a Type "N," BNC, or SMA connector in your hole. Inside, solder the probe to the coax connector (the probe is the actual antenna element, generally cut to l/4-wavelength at your proposed operating frequency). You want the probe to be sort of thick; #16 copper wire, I/~-inch copper or brass tubing, and ll4-inch-wide strips of .032-inch sheet brass have all been used and have all worked well. 

One is good, so two is better, right? Yep, in this case. The probe is pretty close to the opening of the 3-pound coffee can, 

adding a second 3 pound coffee can will improve the gain from 8.5 to 10.5 dBi (see Figure 2). Just cut the bottom out of the can (I'll assume the top has already been removed and the contents have already been consumed), so you just have a steel tube. Attach the second can to the first and extend the horn. You don't have to com- pletely solder the gap between the cans. I've found 

that a couple of spot solder points work fine. I've also used that alu- minum wallboard tape with good results, and have even used duct tape once or twice. 

The super glues I tried didn't work well at all. Now, I know exactly what you're thinking (I tried it over 15 years ago). If one can is good, and two are better, 

let's go for three! Without going into wave- guide theory, I can tell you that it won't work. When I tried using three cans, overall gain dropped to only 7 dBi. 

I have taped these to poles and stuck them up in the air for "rover" contacts. I nailed one to a rafter in my roof, pointed it at a local 1200-MHz repeater and 

used it for several years. And a dozen years ago, WSDBY in Ft. Worth, Texas, worked a station near Miami, Florida, on 1296-MHz SSB. For many years, 

this 1,100-mile QSO was the U.S. 1296-MHz tropo record. And yes, WSDBY was using a 3-pound coffee can duct taped to his tribander for this record QSO.