GMRS Antenna grounding (not ground plane)

[WSEX658]

Hi all, newbie here. I am preparing to install a GMRS radio in my automobile. Said automobile does not have a steel roof, rather, a molded plastic composite, (2024 Bronco). The antenna mount will be mounted to a plastic accessory that is not naturally (DC) grounded. My question is: Should I, or do I have to attach a ground strap from the body/chassis to the antenna mounting bracket. The antenna uses an NMO mount and I see that there are raised "scallops" on the t-nut part of it that I assume are designed to penetrate paint and such in order to be grounded? If I do have to use a short ground strap, I have read on the interwebs that a ferrite bead should be used to "isolate" the antenna? any direction would be greatly appreciated!

[SteveShannon]

15 minutes ago, WSEX658 said:

Hi all, newbie here. I am preparing to install a GMRS radio in my automobile. Said automobile does not have a steel roof, rather, a molded plastic composite, (2024 Bronco). The antenna mount will be mounted to a plastic accessory that is not naturally (DC) grounded. My question is: Should I, or do I have to attach a ground strap from the body/chassis to the antenna mounting bracket. The antenna uses an NMO mount and I see that there are raised "scallops" on the t-nut part of it that I assume are designed to penetrate paint and such in order to be grounded? If I do have to use a short ground strap, I have read on the interwebs that a ferrite bead should be used to "isolate" the antenna? any direction would be greatly appreciated!

Welcome!

Grounding an antenna is not the same as providing a ground plane. In order to provide a ground plane you need a metal plate, such as a metal roof or hood. 
In your case I would suggest buying an antenna that doesn’t require a ground plane. 
I doubt that you need any kind of a ground strap. 

[Socalgmrs]

As already stated the antenna does not need a chassis ground. However it does need a ground plane or it will not work correctly.  Many manufacturers make non ground plane antennas.  Some people also affix a 12x12 steel or aluminum sheet to fiberglass or plastic.  

[Socalgmrs]

2 minutes ago, WSEX658 said:

Thanks Steve!  I do have an antenna that doesn't require a ground plane. I was just concerned about the DC grounding since I noticed the sharp points on the NMO mount and assumed it was for grounding purposes, and the coax shielding terminates on that.

The sharp bits act as a lock washer. They are not for grinding into paint.  

[SteveShannon]

3 minutes ago, WSEX658 said:

Thanks Steve!  I do have an antenna that doesn't require a ground plane. I was just concerned about the DC grounding since I noticed the sharp points on the NMO mount and assumed it was for grounding purposes, and the coax shielding terminates on that.

Not necessary. There’s no DC in your coax. In fact most people use a magnetic mount and the only “connection” to the metal roof is via capacitive coupling to allow the roof to be the ground plane. 
If you have a non-ground plane antenna you don’t need to worry about ground. 

[WSEX658]

2 minutes ago, SteveShannon said:

Welcome!

Grounding an antenna is not the same as providing a ground plane. In order to provide a ground plane you need a metal plate, such as a metal roof or hood. 
In your case I would suggest buying an antenna that doesn’t require a ground plane. 
I doubt that you need any kind of a ground strap. 

Thanks Steve!  I do have an antenna that doesn't require a ground plane. I was just concerned about the DC grounding since I noticed the sharp points on the NMO mount and assumed it was for grounding purposes, and the coax shielding terminates on that.

[WSEX658]

7 minutes ago, Socalgmrs said:

The sharp bits act as a lock washer. They are not for grinding into paint.  

Thanks Socalgmrs!  I will consider my concern addressed!  I do have an antenna that is published as "no ground plane required" and as this will be mounted on the front corner of my front fender, I cant put any metal under it, other than what ever the aluminum hood may provide, (although they are not "coupled").  

[WSEX658]

1 minute ago, SteveShannon said:

Not necessary. There’s no DC in your coax. In fact most people use a magnetic mount and the only “connection” to the metal roof is via capacitive coupling to allow the roof to be the ground plane. 
If you have a non-ground plane antenna you don’t need to worry about ground. 

That's good news for me!  Thank you so much!