so ive been running a Diamond NR770HNMO on my F-150 for about a year now and recently started messing around with where i actually put the mag mount. originally had it on the roof toward the rear and was pretty happy with it but moved it forward closer to the center of the cab just to try it and the difference is kinda noticeable on receive, at least subjectively. cant tell if its placebo or if the ground plane situation actually changes that much depending on position.

the truck has a full metal roof so i wouldnt think it matters that much but maybe the slope of the rear glass is doing something weird behind it. anyway now im curious if anyone has actually done real testing on this kind of thing or if its just one of those forum myths that placement on a car roof matters beyond like basic common sense stuff. i know center of roof is theoretically ideal but the practicality of getting the coax inside from there is annoying

yeah placement absolutely matters more than people think, especially on trucks where the roof geometry is all over the place. the ground plane on a pickup isnt the same as a nice flat sedan roof and the angle of the glass panels and stuff does affect the radiation pattern. forward vs rear can shift where the pattern is strongest by a meaningful amount. i had an Icom 2730 in a Tacoma a while back and spent a whole afternoon with a buddy driving laps around the neighborhood just keying up and comparing signal reports. center of roof was consistently better but the difference wasnt huge, like a few dB tops in most directions.

the coax routing thing is real though. i ended up running mine through the door seal and people say it damages the coax over time but honestly ive been doing it for three years and havent had an issue yet, just use good quality coax and dont let it kink at the bend

on my SUV i just drilled a hole through the roof and called it a day, no more mag mount debates lol. but seriously if youre noticing a difference its probably real, our brains are pretty good at picking up on consistent signal quality changes even if we cant always quantify it. the NR770 is a decent antenna tho so im guessing the variation is subtle either way