antenna mount on aluminum truck cap

[K9CNJ]

I have a '22 F50 SuperCrew with an aluminum ARE contractor style bed cap.

I would like to mount a 2m/70cm antenna to the cap so that I don't have to drill a hole in an expensive truck. I don't think the cap is electrically grounded to the truck chassis, although I could probably run a pigtail to make that happen.

In this case, is the truck and cap a unified grounding plane, or just the cap? For best results, can I mount the antenna near the front edge of the cap, or should it be in the center of the cap's roof?

Thanks in advance.
Pete

 

[mmckenna]

The ground plane for the antenna does not need to be grounded to the truck body, but it won't hurt if it is. The antenna/RF is looking for a 1/4 wave of ground plane in all directions under the antenna, so as long as you have 19" in all directions under it, you'll be golden.

So, 19" in from any edge of the topper roof will be just fine. If you are installing a single antenna, dead center on the left/right plane and at least 19" back from the front edge of the cap will do what you want.

 

[K9CNJ]

Thanks mmckenna. I'm going to have to give your signature line some thought.
Pete

 

[mmckenna]

Thanks mmckenna. I'm going to have to give your signature line some thought.
Pete

I've popped holes in the cabs of many Ford pickups. Never had an issue, never regretted it. My work truck, a 2017 F350 regular cab, has 3 NMO mounts and a GPS/LTE/WiFi antenna blade on the roof.
My personal truck is a 2025 F-250 regular cab with a single NMO mount with a Sinclair multi-band antenna.

I've done several others. These full size American trucks are really easy to install in.

Make sure you check out the Ford Upfitter guides for these trucks. There's a 12 volt 5 amp circuit tucked in the behind the passenger footwell kick panel that is ignition switched. I've used those for the ignition switched circuits on the radios to turn them on/off automatically.

 

[madrabbitt]

if you really wanted, you could get copper tape or metallic mesh and make a roughly 19 inch circle or a asterisk centered on the NMO affixed to the underside of the shell.

We do that with ATV and jeep installs on plastic and aluminum roofs even with NGP antennas just for the sake of having a decent ground plane.

 

[Abies]

The ground plane for the antenna does not need to be grounded to the truck body, but it won't hurt if it is. The antenna/RF is looking for a 1/4 wave of ground plane in all directions under the antenna, so as long as you have 19" in all directions under it, you'll be golden.

So, 19" in from any edge of the topper roof will be just fine. If you are installing a single antenna, dead center on the left/right plane and at least 19" back from the front edge of the cap will do what you want.

That's reassuring. I'm in a similar situation. My new Ford Bronco will be getting an aftermarket aluminum top. It'll have removable panels in the front and middle, so the usable ground plane will be somewhat less than 38" front to back (unfortunately). Still, this is the best I can do on this vehicle with any available top.

My plan is to install both a 144/440 antenna and a GMRS antenna, with fold-down bases to reduce interaction between them. My plan is to have the ham antenna 19" from one side edge and the GMRS one 16" from the other edge. Does this sound like a good plan?

I will in fact have the installer drill the damn holes.

 

[mmckenna]

My plan is to have the ham antenna 19" from one side edge and the GMRS one 16" from the other edge. Does this sound like a good plan?

GMRS only needs 6" around the base, or 12" wide. If you don't mind the aesthetic look of them offset, you can put them towards the outer edges.

You do want to keep some separation between the antennas, but you might do well with a basic 1/4 wave for GMRS and an appropriate dual band antenna on the ham side.

I will in fact have the installer drill the damn holes.

Nothing wrong with that, as long as it gets done.

 

[Abies]

GMRS only needs 6" around the base, or 12" wide. If you don't mind the aesthetic look of them offset, you can put them towards the outer edges.

You do want to keep some separation between the antennas, but you might do well with a basic 1/4 wave for GMRS and an appropriate dual band antenna on the ham side.



Nothing wrong with that, as long as it gets done.

Thanks for the info!