Forget it!
See my response to your posting on the MARS forum. Alan and I are incomplete agreement.
FWIW, if the "amateur" antennas were any good, the land mobile and other commercial services would be using them. They don't. They use Larsen, and to a lesser extent Antennx. I have no experience with them but I have a lot of experience with the Larsens - none of it bad.
73,
Lon - W3LK
Baltimore, Maryland