"Chuck Olson" wrote in message
. ..

"Steve N." wrote in message
...

[...snip...]

Then I'd like clarification on your comment:
"... If you analyze the operation of the very successful "Open Stub
J-Pole" that Arrow makes, you will find they use the 0.95 FV for both
the
radiator and the stub,..."

Can you be more specific about this. What is the electrical length of
the
stub for said analysis? I like that design, though there is controversy
about it.

I'm old fashioned, so I use an HP17BII calculator which has a "solve"
function, and with the formula, LIN = 11811 / F(MHZ) / 4 x VF, given any
two
of LIN, FMHZ, and FV, I can obtain the third for a 1/4 wave stub.

We find on the Arrow site http://www.arrowantennas.com/j-pole.html the
longest element for operation at 146 MHz is 57.5", and the shorter
element
that makes the 1/4-wave stub is 19.25". With FMHZ = 146 and LIN = 19.25"
we
solve for VF of that shorter element and get 0.95 (which refers to the
free
space 1/4-wave as 1.00). Subtracting the 19.25 from 57.5 we get the
radiator
length of 38.25". Since that is a 1/2-wave length, we divide by 2 so we
can
use the 1/4-wave formula, and solving for VF we again get 0.95. I hope
this
helps.



OK, then I believe you are assuming the short section is exactly 1/4 wave?
That's what I was after. I'm not convinced this is the case, but it is a
complex arrangement...matching 50 to an end fed half-wave.

73, Steve, K9DCI