Mobile Grounding?

[mjthomas59]

I saw something the other day that i hadn't ever seen before and was wondering if anyone had ever seen this also. A guy had a ground wire soldered onto an nmo mount on the back of his car. He had what looked like a dual-band antenna on it, maybe 30 inches tall. I asked the person who owned the car because at first i wasn't even sure what the wire was to begin with. He said it was to ensure a good ground, or ground plane, i'm not really sure exactly. Hopefully someone can shed a little light on this for me. Maybe i'm missing out on better reception because i don't have a ground wire soldered to my nmo mounts? Or maybe that other guy is just a moron. Either way thanks for the help!

 

[rpgbigman]

I use a NMO mount on my luggage Rack and had problems with it until I ran a Ground wire to it. So A good Ground dose Help. Ryan Kcownf

 

[52to12]

Where did you attach the other end of the ground?

 

[mjthomas59]

The guy i saw had it mounted on his trunk and had the ground run to a ground on the car inside the trunk. Can't remember exactly where the ground was located but it was a grounding point in the trunk for i think the trunk light or something. Not really sure.

 

[VernM]

Unless his is a fiberglass car, the sheet metal ought to do the job just fine. For High Frequency transmit, sometimes we find you have to augment ground routes to the frame, but not for this kind of application.

Methinks a lot of guys like to Over Engineer to impress the unwashed.

 

[kb2vxa]

Hi MJ and all,

Seems to me this guy doesn't know what ground is. Above 30MHz such a long wire tends to become resonant so it will not provide RF ground and as the man said the trunk lid provides the ground plane. In some cases bonding straps across the hinges may reduce electrical noise as they do elsewhere in the vehicle but still no real RF ground is provided.

 

[N_Jay]

Methinks a lot of guys like to Over Engineer to impress the unwashed.

Me thinks a lot of attempts at "over engineering" are actually mis engineering by the "unwashed"! :lol: :lol: :lol:

 

[toonman4]

OK, so here is a question about using an NMO mount on a Car that is not metal.

I've got a 99 Saturn (all body panels are plastic) If I installed an NMO antenna how lousy will the reception be and what could be done to improve the grounding? (receive only antenna)

 

[N_Jay]

Put metal foil or screen under the body surface or buy a no-ground-plane antenna (Typically a motorcycle or marine antenna)

 

[mjthomas59]

Maxrad and possibly Antenex both make a no groundplane antenna. Never tried one before though, but if anyone would benefit from it i'm sure you would.

 

[VernM]

It's receiving your'e working with. The coax shield will provide an adequate recieve ground.

 

[gcgrotz]

We used to scrape some paint away from the underside of the hole (assuming it is metal of course). That gives the little teeth something to bite in to, never seemed to have any problem with grounding.

I wonder what symptoms the guy had that led him to the conclusion it was his ground?

BTW, the real foil tape like you use on heating ducts works very well on plastic bodies. Make a big X on the underside.