I've been wanting a 1.2Ghz yagi so I could try to work the AO-51 satellite on 1.2 with my Alinco DJ-G7. After looking around at commercially available antennas, I decided to build one myself with some of the plans that are available online.
The design and specs are from WA5VJB. He says the measured gain is 13.5dbi. I followed his plans for the 1.2Ghz antenna almost precisely. The antenna elements are 1/8" steel rod and were measured using digital calipers. I wanted to use bronze or some other material that wouldn't rust, but Home Depot was out of the bronze rod on the day I happened to go there. The boom is a a 3/4" square wood piece, a little less than 4' long. I cut off a little of the excess. The elements are within a few 10,000's of an inch of the specs! I also carefully centered them on the boom from side to side and top to bottom so that they're all properly aligned
Here is the finished antenna:
The driven element is 12ga house copper ground wire. (WA5VJB used 10ga wire, but it shouldn't make any difference). I had some excess on the shelf in the garage, so I put it to use. I also had some RG8x that already had one PL-259 on it, so I just used that for the connection to the driven element. You can also see that all of the elements are epoxied into place.
You could move the driven element up on the boom and drill two holes, but it just happened to work out that the center of the square wood allowed for the driven element to be exactly 1/2" in diameter with the bottom of the element epoxied to the boom. I plan on covering the coax connection with RTV silicone, but I wanted to leave it bare for the picture.
And finally, here is the intended use for the 1.2Ghz yagi. The square wooden boom lays nicely on top of the 440Mhz Arrow boom and I just velcro'd them together. This is starting to get a bit heavy for handheld use, but I'll give it a try and see what happens.
I don't have an SWR meter for 1.2 Ghz yet, so I don't know what the bandwidth of the antenna is. A quick test however confirmed that the antenna indeed has some good gain! I was able to hit a repeater with my 1 watt
HT that is about 37 miles away that I could never hear or hit before
.
I've attached the design specs, which also includes plans for 2m, 220, 440, and 900 Mhz. If you plan on mounting this outside, you could easily attach a u-bolt. You would also want to weatherproof the boom and elements using some paint, marine varnish, or similar. Total cost for the antenna (not including coax & PL-259) was exactly $10.
Half of that cost was for the epoxy.
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