Anyone here experienced with GNSS geodesy equipment?

[John Ackermann N8UR]

I have inherited several older Trimble, Ashtech, etc. dual-frequency GPS
antennas intended for survey/geodetic use. They have quite varying
physical designs (conical choke ring, flying saucer, etc.) and I haven't
been able find any info on their comparative performance.

If there's anyone here familiar with such things, I'd appreciate any
info (probably off-line to avoid boring everyone else with minutiae).

Thanks!
John
jra at febo dot com