On Fri, 3 Mar 2006 02:28:54 -0800, "Harbin"
wrote:

Howdy Dan:
Thanks for the info on "Mobile Vhf Ant.pdf", very interesting stuff.
I was checking out the rest of your site, and found an interesting pdf on the "Skeleton Sleeve Antenna",
and it's similarity of the J-pole, and you state that the distance from the 1/4 wave elements, and the 1/2 wave
element is not that critical. I have heard this before about the elements on the J-pole too, but what I don't understand
is why this dimension is not critical, it is an electrical path that should be subtracted from both elements, right?
Is it correct to shorten both elements by 1/2 of the dimension between the elements?

Harbin,

By "critical" I meant that the dimension shown can vary somewhat with
no loss of performance. For example, if you do the math you'll see
that the distance (shown in Figure 5) between the center 3/4-wave
element and the shorter 1/4-wave elements is 3.889 inches. If that
figure varied say between 3.5 and 4-inches there would be no
noticeable effect on operation. The important thing is (as I stated in
the article) is to maintain equal spacing the between the center
element and each of the outer 1/4-wave elements. The equal spacing is
the critical thing. What little change there might result in the
resonate frequency can easily be adjusted as stated in the article.

73,

Danny, K6MHE