2-way radio antenna grounding

[openwheeler37]

I've lived with less than ideal radio reception for a while now, and I've finally decided to look into it. My antenna - https://racingelectronics.com/collec...cts/etrab4500n - is mounted to my fiberglass body using a grounding plate - https://racingelectronics.com/collec.../products/k332 - but the ground plate is not grounded to anything else. Shouldn't it be tethered to the chassis or battery negative? If so, can I get away with just running a wire from the plate the the chassis or battery negative connection?

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[DaveW]

My ground plane plate is not grounded through anything except the antenna cord. It's mounted to the dash and not to the chassis. It works perfectly like that. Photo below.

I had reception issues on and off with my analog radio setup. With the digitals I have now it's very good. The ground plane and antenna are/were the same for both.

[openwheeler37]

My ground plane plate is not grounded through anything except the antenna cord. It's mounted to the dash and not to the chassis. It works perfectly like that. Photo below.

I had reception issues on and off with my analog radio setup. With the digitals I have now it's very good. The ground plane and antenna are/were the same for both.

It looks like your ground plate is bolted to the chassis, though, right? And I assume your chassis is grounded. My ground plate is just sandwiched between the antenna mount and fiberglass of the body.

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[DaveW]

My ground plane plate is not grounded through anything except the antenna cord. It's mounted to the dash and not to the chassis. It works perfectly like that...

It looks like your ground plate is bolted to the chassis, though, right? And I assume your chassis is grounded. My ground plate is just sandwiched between the antenna mount and fiberglass of the body...

As I said - see my above quote...not grounded to anything except the antenna cable.

[openwheeler37]

As I said - see my above quote...not grounded to anything except the antenna cable.

Okay, thanks. I just wanted to make sure. It looked like the plate was secured to the frame, so I just wanted to make sure I understood.

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[Steve Davis]

FWIW - the SIZE of the ground plane and the FREQUENCY of your radio is what matters. If you are at UHF (as I assume Dave is) it doesn't take much. If, OTOH, you are using VHF, it will take a measurably larger ground plane ... like 3 or 4 times larger .. depending on the exact frequencies. The DC ground aspect is not really that important .. as Dave says.. it gets that DC aspect through the antenna cable. At VHF frequencies (~150 MHz) you'll need about a 20" radius plate (thickness is NOT important - can be thin sheet AL). At VHF (300 - 500 MHz), you only need about 6 or 7 inches. (it needs to be longer than 1/4 wavelength at the freq of interest from the antenna base to the edge of the plate.)

In MOST cases, all this is only relevant for TRANSMITTING from your car. If you only LISTEN, then the size of the ground plate becomes WAY less important.. but bigger is better either way.
Steve, FV80

[Hardingfv32]

Self adhesive sheet copper attached to the underside of the body is the hot setup for large planes. I believe the radius of the plane should match the height of the antenna.

Brian