On Friday, April 4, 2014 11:58:29 AM UTC-5, Wimpie wrote:

Other thing with the half wave end-fed can be absorption of the

plastic insulation. To make UV-resistant black they frequently use

carbon black. When the concentration is too high the dissipation

factor of the plastic increases signficantly. Recently I had really

weird results with a half wave monopole design. Everything went wrong.

It was the black UV-stabilized HMPE plastic containing around 2.5%

carbon black. When changing to green HMPE everything was according to

my calculations.

All my 1/2 waves have been made from aluminum tubing, and fed with
the gamma loop type matching scheme.
They worked very well, and my final version had a decoupling section
with a lower set of radials.
But all the variations of 5/8 antennas did even better on 10m local paths.