I've seen several simpler J-pole coaxial antenna plans, but this one ain't
bad KD0FGX

http://www.w7dk.org/10%20meter%20vertical%20project.pdf

Rollie wrote:
I've seen several simpler J-pole coaxial antenna plans, but this one ain't
bad KD0FGX

http://www.w7dk.org/10%20meter%20vertical%20project.pdf

I would argue that the gamma match on a 1/2 wave radiator is so close to
the efficiency (or better than) than the 1/4 matching section of the
j-pole, that this 1/4 matching section only becomes an encumbrance and
should be avoided (if you don't mind the length, consider lengthening
the 1/2 wave section to 5/8 wave.)

However, it (the gamma match) is absolutely more efficient than the
coil/cap circuit in this design mentioned above.

A homemade coaxial cap. (a few refer to is as trombone cap) is easily
constructed for the match--meaning parts can all be found around the
home or from the nearest junk pile!

And, don't forget the UnUn ...

Regards,
JS

"Rollie" wrote in message
...
I've seen several simpler J-pole coaxial antenna plans, but this one ain't
bad KD0FGX

http://www.w7dk.org/10%20meter%20vertical%20project.pdf


Interesting. Near the bottom of Page 1, right column, the author states he
doesn't want to try to support a full 23-foot vertical structure on his
garage roof. Yeah -- me neither.

Would it still work if the "J" had an obtuse angle between the u-shaped stub
and the half-wave radiating element? I'm thinking the stub section could
lay on the garage roof and the radiating element could be elevated, being
somewhat easier to support at 16.5 feet of height.

I have a nice 6m Field Day J-pole I made from 450-ohm ladder line and feed
with 50-ohm coax. I will use it to test the concept and report back. I
think 6 and 10 are close enough for this.

Sal M. Onella wrote:

...
Interesting. Near the bottom of Page 1, right column, the author states he
doesn't want to try to support a full 23-foot vertical structure on his
garage roof. Yeah -- me neither.

Would it still work if the "J" had an obtuse angle between the u-shaped stub
and the half-wave radiating element? I'm thinking the stub section could
lay on the garage roof and the radiating element could be elevated, being
somewhat easier to support at 16.5 feet of height.

I have a nice 6m Field Day J-pole I made from 450-ohm ladder line and feed
with 50-ohm coax. I will use it to test the concept and report back. I
think 6 and 10 are close enough for this.

Yeah, exactly, why not keep those undefined feet of loss enabling
network whether we need it or not ... I always consider that first ... ;-)

Regards,
JS