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Old October 4th 08, 04:18 PM posted to rec.radio.amateur.antenna
John Smith John Smith is offline
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First recorded activity by RadioBanter: Nov 2006
Posts: 2,915
Default Effective length of braid dipole leg?

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