Any antenna that is this short is bound to have problems on VHF lo (and that would include 6 meters as well). Loss figures notwithstanding, I have been very pleased with mine on VHF lo, even tho I didn't expect to have it work as well as it does.
A little background - I had this antenna on a Diamond NMO trunk lip mount on my 2001 Camry (since got rid of the car), and used this antenna with a Uniden BCD396T and 245 (yes the venerable analog Uniden trunker...). Our local Md. State Police runs mostly on 39 Mhz (where I cut the top whip). I made certain I had a decent connection between the base of the mount and chassis by scraping a little paint and testing with a VOM (the other end of the VOM was on a mounting bolt for one of the seats).
Admittedly not particularly scientific, but it worked.
The terrain here is hilly and urban - but I still managed to hear the Glen Burnie barracks from my parking lot in Bowie (scratchy, but it was there)- a good 1/2 hour or more drive. I've had similar success hearing the Golden Ring barracks from Howard County (similar distance, roughly). I've even heard mobiles - not just the barracks base (it's primarily a simplex, not a repeater, system)
So don't let the loss fool you. It's not going to replace a 6 foot or so whip (and I wouldn't be so silly as to claim that it would), but it does work surprisingly well on VHF lo. There are practically no 6 meter repeaters here to speak of, so I can't comment on how it works there.
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