[Antennas] RE: J POLE QUESTION

Wed, 10 Jul 2002 21:39:23 -0700

 From all the literature I read, the J-pole was just a method of matching 
so that a ground plane would not be needed on the 1/4 wl antenna.  That is 
why I built a co-linear.  It has a hair-pin match withcoax balun on the 
hairpin, coax attaches there.  The end of the hairpin has a mounting 
'stick' as the end is neutral.  However, I cannot mount it that way 
anymore.  I have seen but donot remember where a J-pole match for the 
colinear.  This would allow a construction similat to what Cletus 
mentions.  The coax comming up from the bottom rather than the side.

Anyone know where there is a diagram etc?

Chris opr VE7HCB

At 10:09 PM 2002-07-10 -0400, Cletus W Whitaker wrote:
>de WB2CPN South Central Pennsylvania   2002.07.10
>
>GoJolly, you make this old ham happy.  For once somebody
>agrees with what I've been saying about "J-Poles" for years.
>My design has a "tee" connector at the bottom of the 1/4 wave
>section.  There's a small hole drilled into the top side of
>the "tee".  My coax is routed up through the support pipe, up
>through the "tee" where the braid stops.  It's soldered to the
>top of the "tee" where it comes out of the hole.  The center
>conductor, now uncovered, continues up the middle between the
>two sides of the 1/4 wave section, makes a hard 90 degree turn
>to one of the two sides of the 1/4 wave section, and is soldered
>there. How far up the center conductor goes is something you
>can learn by adjusting the SWR, but it's about 4 or 6 inches.
>Note that the center conductor has to be made rigid so that it
>will stay exactly where it is supposed to be.  If you want to
>operate two of these antennas in an array the center conductor
>on one can be connected to a different side of the 1/4 wave
>section and have a 180 degree phase difference.  They make a
>nice end-fire 2-meter antenna.  Gain of one antenna is about
>the same as a vertical 1/2 wave.  I've found the bandwidth to
>be unusually wide, why I don't know.         73   Clete
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