A J-Pole is a 1/2 wave vertical antenna, that sits on TOP of a U
shaped 1/4 wave matching section.
During construction, the 1/2 wave vertical element AND ONE of the 1/4
wave legs of the Transformer are constructed of the same piece of
tubing. Thus the J appearance and name.

RF is invisible to whatever lies below the Horizontal Member, so
whether the mast is grounded or not would have no impact on the
J-Poles performance. However, the shield MUST be grounded for obvious
reasons.

It is Normal and Proper to RUN the COAX up the center of the mast,
INSIDE the Antenna and EXIT the vertical element at the Horizontal
Member.
If you don't, THEN you will need to stop stray RF that runs along the
coax and/or use a Balun.

When you connect your COAX to the J-Pole:
If it is a MonoBand J-Pole, run the center conductor to the STUB,
leaving the sheild jacket intact up to within about 1/2 inch of the
stub. Then run a wire from the shield horizontal to the horizontal
member and affix this to the vertical.
If it is a Multi-Band J-Pole, the center conductor should be connected
to the Vertical Element and a wire from the shield runs horizontal
over to the stub.

Although a J-Pole will work with the coax connected either way. On
MonoBand J-Poles, having the center conductor going to the Stub
reduces the noise level slightly. It can make a difference when you
are trying to pull in QRP stations.

Using 3 or 4 1/8th wave wires, like a capacity hat, protruding outward
on the top of the vertical element will give the same noise reducing
effect.

TTUL
Gary







verbositized:

I have been reading alot on different designs and have read
contradictory information on this. Does nayone here have an opinion?

Also, when building a j-pole, could I run the wire inside the tube.
(Regular jacketed copper wire) to the bottom of the tube to a pl
connector? Or would this mess up the impedance?