To Ground or not Ground

[mikebennett]

I am about to upgrade vehicles and will be mounting my scanner antenna in a slightly different location.

Currently I have an "L" mount attached to the roof rail on my car. It's attached to a bolt and is grounded. The new vehicle has the same type plastic roof rail but I want to mount the "L" directly to the plastic. Is there any electrical/reception benefit to running a ground wire to the "L" bracket? I can accomplish this on the underside of the rail so it won't show.

The base of the current antenna configuration is about three inches above the roof but I get excellent reception.

Any engineering types care to weigh in?

 

[mmckenna]

Antennas work best when mounted on the ground plane. Hovering it a few inches above it isn't going to help as much.
A ground wire to the body might provide a DC ground, but that is different than an RF ground plane.

Give it a try and see if performance changes.

 

[trentbob]

Best results will be grounded to the body of the car. More centered, the best. Your best results will be achieved by drilling a hole.

 

[mikebennett]

My first option was to center mount on the roof however I carry a kayak up there and it would interfere. I've now pretty much switched to an inflatable which can be stored inside and only use the roof kayak two or three times a year. I'm thinking about going ahead and mounting the antenna there and on the few occasions I have to haul the boat I'll just use a mag mount. Thanks for the input.

 

[riverradio68]

I have something similar to that set-up with a CB antenna. I have the NMO L-bracket drilled into the inside of the luggage rack rails. It seems to be working okay. Those roof rack rails are generally attached to the roll bars which are tacked to the frame. Also, if that is just attached to a scanner at the cabin end, you should be fine as the cable grounds to the radio. Not much different than using a mag-mount for a scanner.