After an interesting weekend working DX on 17 meters using a homebrew 5 band vertical antenna, I had a thought....... how much better would it be to have a 2 or 3 element yagi on 17 and maybe 12 as well.

So here is the plan, either open sleeve feed the 17 and 12 meter driven elements by close coupling it to the trapped driven element of my old Wilson SY 2 tribander that is at 50 feet above the ground. Or build a open sleeve fed 17/12 meter 2 el yagi and position it on the same boom as the tribander and run a separate feeder to the 17 meter driven element thus allowing greater separation of the new elements from the original tribander elements.

I have looked around for generic trapped tribander models (MMANT-GAL) but have found nothing. I am new to antenna modeling, but have read that trapped triband yagis are difficult to model.

Is there any experience on the forum with this type of modification of an existing tribander and if so what were the results like.

I have a fair stock of aluminium to make the new elements from, so the project will cost me not much than the time I invest in it.

I am not interested in buying an all singing 5 band optibeam or StepIr antenna, I would like to increase my performance on 17 and possibly 12 meters without degrading my performance on 20, 15 and 10 too much. I also suffer from short arms and deep pocket syndrome.

Your thoughts (and sensible responses) are appreciated.

Mike VK3XL