3 Element wire yagi

Another antenna that I've built and works well, giving good DX results throughout the 11 metre band. Because the antenna is based in the attic, It's best used as a fixed antenna system as turning an antenna of this size is quite difficult in a small attic.

For this, I used a length of 20S.W.G. (1.0mm) single core wire (but anything will do) and cut to the sizes in the table below. However some trial & error is needed as this calculation varies for a number of reasons ie. height above groung, wire size used and even influenced by nearby objects.

NOTE:- At this point may I suggest cutting the wire length longer than is needed as it's alot easier to shorten the element length than add bits on.

The feed to the antenna is easy as the feed impeadance of the yagi is around 40-80 Ohms, thus a good match for 50 Ohm (RG-58) coaxial cable. As with the Inverted Vee antenna I used a 15 Amp terminal strip for the feed connections but a number of choices are available. See below Fig.2

Once the connection to the antenna is made then I used drawing pins to support the wire elements during testing. On a low power setting, check the S.W.R. throughout the band (say 27.555 Mhz is the target). Remember If the S.W.R. is lower on the lower frequencies then the antenna element will need shortening and visa versa. Below (Fig.3) I've shown the results of testing I carried out when Installing the antenna.

Once all the trimming is done then the elements can be secured to the rafters using what ever method you prefer. However to be honest I left it with the drawing pin supports. Later I added a 1:1 balun at the feed point which made the antenna work over a wider band ie. gave the antenna a larger bandwidth. For More Information about the balun I made click here or on the menu toolbar.