tell us more, 'dual-z0 shortened stub' sounds like something interesting.

"Cecil Moore" wrote in message
. com...
Yuri Blanarovich wrote:
When W8JI had a presentation at Dayton's Antenna Forum and spoke about
his "famous - same current along the antenna loading coil", ...

It is unusual for W8JI to give up on an argument so abruptly. I
wish I had thought of the dual-Z0 shortened stub concept years ago.
--
73, Cecil http://www.qsl.net/w5dxp

Dave wrote:
tell us more, 'dual-z0 shortened stub' sounds like something interesting.

In my quest to explain the phase shift in a 75m bugcatcher
coil, I thought about a dual-Z0 stub. The shortest 450/50 one
I have come up with that causes the maximum phase shift is:

---19 deg of 450 ohm line---+---18 deg of 50 ohm line---open

Believe it or not, that is an electrical 1/4WL stub with a
whopping 53 degrees of *lossless* phase shift occurring at the
'+' impedance discontinuity point. Are there any applications
for a stub that is physically 0.1 WL long instead of 0.25WL?

It could be shortened even more by using 600 ohm line with
50 ohm line. On top of everything else, the current in the
50 ohm section seems to be much lower than the current in
the 600 ohm section thus reducing the losses in the stub.

From these experiments, I have concluded that the phase shift
in a 75m mobile loading coil may be in the ballpark of 20 degrees
while the phase shift in the stinger is in the ballpark of 20
degrees with the majority of phase shift coming from the
impedance discontinuity between the loading coil and the stinger.
So neither side of the years-long argument was right or wrong.
--
73, Cecil http://www.qsl.net/w5dxp