"Tom Horne" wrote in message
...
Can anyone direct me to the dimensions to build a six meter J-pole
that is patterned after the Arrow Antenna two meter design that had
the feed point at the bottom of one of the elements rather than at a
point part way up the height of the matching stub.

The reason that I would like to use that design is that I would like
to use Rigid Aluminum Conduit to build the antenna. There not being a
lot of simple inexpensive fittings for Conduit the way there is for
copper pipe a mechanically simpler design would be easier to build.

Replies are welcome on or off list. Let me say that I would rather
not be subjected to any tirades about the inferiority of the J-pole
approach or the superiority of some other antenna design. That does
not mean that I am not open to suggestions for a better approach as
long as it is civilly stated and I am spared the application of Rant
Mode.

--
Tom Horne, W3TDH

Certainly not a rant but a question about the question:

Is your reason for this approach mainly your access to beaucoup aluminum
conduit? I ask because I'm a j-pole fan and I've built dozens of them,
including three for 6m using copper pipe and one 6m from window line. The
feed is less than 7 inches from the bottom of the active portion of the 6m
version.

Using your conduit, you might employ the "standard" j-pole design and bolt
the segments together, placing wooden dowels inside your conduit ends to
resist crushing forces. Am I striking a chord, yet?

A brace near the top of the stub section would likely be required to prevent
rotation where the bottom of the "j" attaches to the main section. You
might be well-served to wrap the bottom of the "j" with a tight spiral of
mesh sleeve (like the braid-only of some unneeded coax) and clamp the ends.
This would help mitigate the electrical consequences of a bad joint or two.
Alternatively, bridge (jumper) the individual joints.

But see http://www.wagnercompanies.com/cast_aluminum.aspx , where a single
3/4 - inch tee or elbow is about $7.00. Do-able?

Note, my 6m copper j-poles are all 3/4 - inch material except the top three
feet of of the long section. I tried using all 1/2 - inch copper once but
that build was so wobbly that I immediately took it apart. (It's about 13
feet tall.)

Some of my j-poles have benefitted from having a capacitor from the feed
connector center pin over to the the long side, in lieu of a straight piece
of wire. I use one whenever the VSWR is mid-band but above 1:1. No science
to it; I just tried a few around 100pF and SHAZAM! I was inspired by the
capacitive feed in a gamma match.

Happy brewing.

"Sal"
(KD6VKW)