Aluminum foil for a ground plane?

[WRTC928]

Since base antenna ground planes are just radials, I'm guessing a ground plane doesn't have to be very thick. Would a sheet of aluminum foil placed over a flat wooden surface work well? Or would a thicker aluminum sheet be better?

[SteveShannon]

12 minutes ago, WRTC928 said:

Since base antenna ground planes are just radials, I'm guessing a ground plane doesn't have to be very thick. Would a sheet of aluminum foil placed over a flat wooden surface work well? Or would a thicker aluminum sheet be better?

Either would work just fine. Some people use aluminum screen, some use “faraday cloth”.

[WRYZ926]

I know window screen and faraday clothe works as a fairly good ground plain on the HF bands. I don't see why either would work well for VHF and UHF. Enough aluminum foil on a flat surface or a thicker aluminum sheet will work too.

Mobile antennas work just fine on the Ford F series aluminum trucks when placed at the center of the cab roof.

[LeoG]

A cookie sheet works well for most mobile antennas.

[Northcutt114]

6 minutes ago, LeoG said:

A cookie sheet works well for most mobile antennas.

When I first got started in GMRS, I was using a mag mount Midland MTS25 Ghost on a cookie sheet on top of my Big Green Egg on my deck. It wasn't pretty, but it worked.

 

[WRYZ926]

A large cookie sheet or a large pizza pan definitely works.

I started out with a mobile 2m/70cm mobile antenna on a large cookie sheet attached to the side of my house when I first got my technician license. It was a bit directional being mounted to the wall but it got me on the air.

[WRTC928]

1 hour ago, LeoG said:

A cookie sheet works well for most mobile antennas.

I've used a cookie sheet, but it's quite a bit thicker than foil. I didn't think the thickness would matter much, but I figured there's no harm in asking what others think. I'm going to put an antenna under the roof on my back deck and figured it could benefit from a generous-sized ground plane like a sheet of plywood covered in aluminum foil.

[WRYZ926]

You can always splurge for the heavy duty aluminum foil as it is a little thicker than the cheap stuff.

We know that aluminum works as a ground plain as more vehicles are made out of aluminum and mobile antennas work fine on them.

[SteveShannon]

Thickness will not matter. UHF travels along the outer surface of conductors. It’s referred to as the “”skin effect.”

[WRYZ926]

7 hours ago, SteveShannon said:

Thickness will not matter. UHF travels along the outer surface of conductors. It’s referred to as the “”skin effect.”

I only mentioned using the heavy duty aluminum foil in that it will be more durable than the cheap stuff. The Dollar General foil is super thin and tears easy.

[BoxCar]

You can get small sheets of steel plate at most home improvement stores. I use a 2' x 2' sheet of steel under my magmount in my closet.

[WRYZ926]

Sheets of galvanized metal is pretty cheap at the big box stores but definitely not as cheap as even a roll of heavy duty aluminum foil. And there is nothing wrong with experimenting either. Especially if he has scrap wood sitting around. I would deffinetly use a piece of plywood at least 16 inches square myself.

A 12"x12" ground plain is enough for 70cm and GMRS since a quarter wave is about 6 inches.. But it never hurts to have a bigger ground plain. A 9x13 cookie sheet or 12" diameter pizza pan will work for 2m even though a quarter wave on 2m is actually around 19" which would mean you would want a 38"x38" piece of sheet metal.

More actual surface area will allow one to have a smaller ground plain. That is why a cookie sheet or pizza pan works for the 2m band.

I'll give a perfect example when it comes to ground mounted quarter wave HF vertical antennas. I have one that came with 4 33ft long ground radials. While it works pretty good, using 24 8.5 ft long ground radials makes an improvement as they provide more surface area.

[SteveShannon]

1 hour ago, WRYZ926 said:

I only mentioned using the heavy duty aluminum foil in that it will be more durable than the cheap stuff. The Dollar General foil is super thin and tears easy.

Very good point, and because the need is for a ground plane, and at least in the mathematical sense a plane is flat, I don’t know what the effect would be for the ground plane metal to deviate greatly from flatness.  Has anyone done experiments comparing corrugated metal or deeply curved “ground planes” versus more nearly flat ones? That might make an interesting research experiment, but I doubt the effects would be as deleterious as the lack of a ground plane.

[WRTC928]

1 hour ago, WRYZ926 said:

Sheets of galvanized metal is pretty cheap at the big box stores but definitely not as cheap as even a roll of heavy duty aluminum foil. And there is nothing wrong with experimenting either. Especially if he has scrap wood sitting around. I would deffinetly use a piece of plywood at least 16 inches square myself.

That's exactly the case. I have some 4' x 8' pieces of 1/4" plywood that came off an old shed I tore down. I was thinking of putting one of them up in the rafters and covering it with foil as a ground plane. It's sort of rotted and not good for much else, but it should work just fine for what I have in mind. I figured I'd glue on some heavy-duty foil which I already have and get a good ground plane for cheap. I have an antenna under the roof on my deck mounted 8' above ground level. I disconnect my "real" 10' antenna on a 36' mast and connect a cheap radio on a battery to the covered one when there are storms in the area so I can stay in touch with the local amateur radio weather net with less risk of attracting lightning. If the antenna and radio get fried, I won't care much, but I think I can benefit from a better ground plane than the 17" steel pizza plate I'm using currently.

[WRUE951]

Aluminium foil will work for a ground plane just as good as a 1/4 or thicker sheet of metal.  Whatever you use for a ground plane, make sure it is at least 1/4  in wavelength in radius for a 1/4 wave vertical antenna..  A larger ground plance is o.k. and even better.  The purpose of the ground plane is to act os the other half of the dipole antenna, reflecting the singal and providing a reliable impedence for effective radiation.   

[WRYZ926]

That's why a 38 inch square or round piece of metal would be best for a 2m antenna. the quarter wave length for 2m is 19 inches.

@SteveShannon I have not trying corrugated metal as a ground plane. I have no idea how well that would or would not work.

I do know that a large enough expanded metal cargo rack works well for a ground plain as that is what I use on my SxS.

I did a POTA activation this morning using a 1/4 wave vertical with 24 8.5 ft ground radials that definitely were not laying completely flat on the ground do to tall grass. The antenna worked just fine. 

[HHD1]

13 hours ago, SteveShannon said:

I don’t know what the effect would be for the ground plane metal to deviate greatly from flatness.  

The waviness of corrugated metal does increase surface area...  An interesting thought.

[73blazer]

On 10/3/2025 at 11:11 PM, WRYZ926 said:

You can always splurge for the heavy duty aluminum foil as it is a little thicker than the cheap stuff.

 

People who buy that cheap thin stuff should be brought in front of a tribunal and sentenced to 60 days of hard labor. 

[LeoG]

I don't care for the heavy duty for the most part.  Just that little bit of extra thickness makes a huge deal.  But if you need durability that's the way to go for foil.

[WRUE951]

13 hours ago, HHD1 said:

The waviness of corrugated metal does increase surface area...  An interesting thought.

probably would cause multi-path???? or signal splatter???   over a flat service.    I know as a kid growing up playing CB FOX hunts in the desert and being the Huntee, we would sometimes drive our antennas around large round water tanks to splatter our FOX signals..