[Antennas] RE: J POLE QUESTION

2002年7月10日 22:09:06 -0400

de WB2CPN South Central Pennsylvania 2002年07月10日
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