Do my mobile radio antennas need a grounding plane now?

[OFC Ranger]

Part of reconfiguring my rack, I created a weatherproof box for my various aneteeners instead of a messing glob of sealant on a standard bracket. Looks much nicer, but it dawned on me I recall reading that usually the antennas with a metal base (generally NMO type) use that as a grounding plane when installed (generally) on a metal bracket or fastener. Well, I don't have that now, just plastic.

I can create or buy a grounding plane easily enough, but wanted to make sure if it was required.

@Msfitoy @Glocker @DukeCanBuildit @D Fresh

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[Colo_Ranger]

A ground plane acts like a dish to project the signal and receive the signal. Do you need it? No. Will you get better performance if you have one? Most likely.

 

[LoneRNGR]

but wanted to make sure if it was required.

It depends on what wavelength your antenna is. 1/2 wave dipole antenna does not require a ground plane. Do you happen to know the specifications of your antenna?

 

[LoneRNGR]

A ground plane acts like a dish to project the signal and receive the signal. Do you need it? No. Will you get better performance if you have one? Most likely.

Wha ??

 

[Colo_Ranger]

Wha ??

Apologies, it’s only when transmitting. I worked for directv for a long time and the dish is used for receiving. I just got my technicians license, so I’m still learning about amateur radio.

 

[LoneRNGR]

I worked for directv for a long time and the dish is used for receiving.

The word "dish" threw me off.

 

[SigOris]

Part of reconfiguring my rack, I created a weatherproof box for my various aneteeners instead of a messing glob of sealant on a standard bracket. Looks much nicer, but it dawned on me I recall reading that usually the antennas with a metal base (generally NMO type) use that as a grounding plane when installed (generally) on a metal bracket or fastener. Well, I don't have that now, just plastic.

I can create or buy a grounding plane easily enough, but wanted to make sure if it was required.

@Msfitoy @Glocker @DukeCanBuildit @D Fresh

How does your SWR look?

 

[Colo_Ranger]

The word "dish" threw me off.

I was attempting to create a visual…

 

[canyonslicker]

There are base loaded antennas that don’t require a ground plane. What is the antenna gain, it’s expressed as dBi, the higher the number the better, SWR the lower the number the better.

 

[JesseS]

For a 1/4 wave or 1/2 wave dipole the vehicle body is the ground plane, be they loaded or not. I mounted my antenna in the fixed front section of my bed cover, because it is aluminum I used a 9" square sheet metal backing plate on the NMO mount, this acts as the ground plane. I have two antennas, a short 1/4 wave for the garage or around town, and a 32" center loaded 1/2 wave, which works well off road. I can get 30 LOS miles range from the Ranger back to the roof mounted 1/2 wave ground plane on the RV.

 

[GTGallop]

I'd like to see the inside of the plastic box. I'd suspect at some point that antenna is more bonded to the chassis / rack than you realize.

 

[Frenchy]

Can't really say if its needed or not. On my Pathfinder I did use the clamp braket for the antenna and mounted it to the spare tire carrier. Of course it's all steel so it probably wont matter. That said it works well. With what you have it should work just fine since you are giving it a nice area to cast its signal.

 

[9zero1790]

Part of reconfiguring my rack, I created a weatherproof box for my various aneteeners instead of a messing glob of sealant on a standard bracket. Looks much nicer, but it dawned on me I recall reading that usually the antennas with a metal base (generally NMO type) use that as a grounding plane when installed (generally) on a metal bracket or fastener. Well, I don't have that now, just plastic.

I can create or buy a grounding plane easily enough, but wanted to make sure if it was required.

@Msfitoy @Glocker @DukeCanBuildit @D Fresh

so im old and rusty have not been "into" radios in a long time. but, i dont think your antenna will "see" the plastic. as long as it is grounded to metal where it needs to be. if you have checked the s.w.r. and the numbers good I would give a roll and see how it goes. if it is not doing the walk get a piece of thin steel to slap on top of the plastic where the antenna will be happy or one of those lil radial kit mounts. also guessing the antenna may be using the rack as its ground plane and electrical ground. transmissions may be going more forward and slightly left lol.

 

[VegasRanger]

You can specifically buy an antenna that doesn’t require a ground plane. What’s the SWR on this setup currently?

 

[OFC Ranger]

No idea at the moment, still getting everything back together.

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