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