In message , Owen Duffy
writes
ai8o wrote in news:1bcefed7-a087-4fda-976d-
:

I am thinking of making a 2 meter J-Pole from 3/4 or 5/8 copper pipe.

Most plans that I can find on the web call for a 58 inch main leg and
a 20 inch support below, making the antenna
78 inches or so in height.

I want to install it in my attic where I have 66 inches of clear
space.

Can I cut the lower support leg down to 8 inches without a major
impact on the performance of the antenna?

End fed antennas are an implementation risk.

What's an 'implementation risk'?

Have you considered a vertical dipole hung from the roof structure, and
taking the feedline away horizontally for a couple of wavelengths, then
down. You could make it a folded dipole (TV ribbon?) and use a half wave
coax balun.

Are you suggesting that a centre-fed dipole is better than a J-Pole?
There is absolutely no problem with the J-Pole / Slim Jim type of
antenna, or with feeding it.
--
Ian