[TowerTalk] SteppIR interaction with 40m beam

[john at kk9a.com]

I am really not a fan of mounting beams at 90 degrees but I concur that the
40m beam will work well with the short SteppIR boom. It will not work with
my 60ft boom homebrew Yagis. A standard tribander design with uninsulated
elements may also have a boom resonant near 40m. What Joe did not mention is
that when using the SteppIR on 17m, 15m or 12m, the 2el 40m beam's boom
(depending on the model) can interact when installed this way.

John KK9A  


To:	towertalk at contesting.com
Subject:	Re: [TowerTalk] SteppIR interaction with 40m beam
From:	"Joe Subich, W4TV" <lists at subich.com>

If you make them 90 degrees to one another, then the boom of the
Steppir could well interact with a 40 meter beam.

The boom of the SteppIR will *not* interact with a 40 meter antenna.
The SteppIR is only 1/4 wave on 40 meters and is *NOT* resonant.  In
order to couple to a yagi, an element needs to be close to 1/2 wave
long (+/- 20% or so - not - 50%)!

Take a little time to model a 1/4 wave element parallel to a 1/2 wave
element and look at the current in the 1//4 wave element - you will
find it to be zero or very close to it.

73,

   ... Joe, W4TV