On 12 Jun 2005 15:44:18 -0700, "Al" wrote:

Hm, why is that? How does an open stub prevent coupling from the antenna
to the feedline?

Roy Lewallen, W7EL

I was hoping we would not have to go through this AGAIN.

The typical J-Pole (Closed Stub) was designed to feed with open feed
line. Because Hams insist on feeding it with coax, a Band-Aid is
needed to choke off feed line radiation & common mode currents.
The Open Stub J-Pole was designed to feed with coax. So it don't need
the Band Aid.
The difference between the two is discussed in several antenna books.
Just ask anyone the owns one.
(http://www.eham.net/reviews/detail/1613)
Besides your (sic) the antenna expert, tell us why it would.


Careful Roy, you're goring a commercial ox.

Al, you have some really ingenious machinery and your products look to
be well made. But you should probably stick to machining and hire two
more folks: one to do antenna design and another to write copy and
manage your web site.

With just a cursory look I see that you sell "beems" instead of
"beams" and a claim that corner reflectors work better on packet than
do Yagis is pure snake oil.

Simply modeling your super J-pole and adding a third element to
represent the transmission line would show that the line radiates like
crazy and affects the feedpoint Z.