so ive been going back and forth on this for a few weeks now and figured id just ask here. i've got a full size pickup with a steel roof rack on it - the kind that sits up maybe 4 inches above the roof on standoffs - and im trying to decide if mounting a dual band antenna up there is actually worth the hassle vs just doing a standard NMO lip mount on the rain gutter like everyone else does.

the rack is grounded to the truck body through the mounting bolts so i dont think ground plane is going to be a huge issue but honestly i havent tested it, im kind of guessing. the height gain would be nice for VHF/UHF into the repeaters around here, some of them are line of sight limited and even a foot or two makes a difference in the hills. but running the coax down through the rack and into the cab without it getting chewed up is going to be annoying.

currently running a Diamond NR770HB on a lip mount and it works fine, just wondering if im leaving anything on the table. anyone actually done this or is it more trouble than its worth

did almost exactly this on my jeep with an aftermarket rack a couple years back. honestly the height is real, i was getting into a repeater about 35 miles out that i couldnt hit reliably before. but the coax routing was a pain, i ended up using a short run of LMR-400 down to a right angle connector at the rack base and then switched to a thinner run through a rubber grommet i made in the weatherstripping. took two weekends to do it right and not have it rattle or pull.

the ground plane thing though - i'd actually check that before you commit. with the rack standoffs and rubber isolation pads if it has them it might not be as solid a ground as you think. i'd throw a meter on it just to confirm continuity. if there's any resistance in that path your SWR is gonna do weird things especially up on 70cm.

lip mounts get a bad rap but for a NR770 or similar they really do work fine, ive never felt like i was missing much. that said if the rack is already there and grounded i'd probably use it just because why not, you're already up higher and the antenna is more centered on the vehicle which helps the pattern be a little more omnidirectional instead of biased toward one side like a lip mount tends to be.

coax routing is the real question, i hate seeing guys with coax just zip-tied along the door jam flopping around. use loom, route it properly or dont bother