Andy,
This is pure speculation so take it that way. I've noticed that
any antenna with 'sharp points' associated with it has typically been
noisier than antennas without those sharp points (capacity hats in
this case). That's certainly not 'definitive' in any way, so...
speculation. Also, considering where those cap-hats are mounted,
using a very smooth huge ball instead of those 'sharp-points' is sort
of dumb. So they did the best they could, right?
- 'Doc


(Completely beside the point. Once used a very large metal ball as a
capacitive hat on a mobile antenna. Worked fine sitting still. Not
very broad banded, but certainly shorter than the usual whip.
Absolute catastrophe when trying to drive! Didn't last long at all.)