Aluminum Foil Ground Plane?

[back4more70]

I have a magnet-mount UT-72G antenna that requires a ground plane.  It works well on top of my car roof (steel).  I have used it with some success on a cookie sheet as well.  I'm wondering, would a sheet of aluminum foil function as a ground plane?  I'm not serious about doing this, but I wonder if it would be passable?

[Lscott]

7 minutes ago, kidphc said:

The foil is non ferrous so the magnetic nmo won't adhere thus no real capacitance.

There is definitely capacitive coupling. It's not magnetic so the mount won't hold, but electrical it will work just fine.

[SteveShannon]

21 minutes ago, back4more70 said:

I have a magnet-mount UT-72G antenna that requires a ground plane.  It works well on top of my car roof (steel).  I have used it with some success on a cookie sheet as well.  I'm wondering, would a sheet of aluminum foil function as a ground plane?  I'm not serious about doing this, but I wonder if it would be passable?

Yes

[kidphc]

Yes aluminum will work as a ground plane. Just not with a magnetic nmo.

The foil is non ferrous so the magnetic nmo won't adhere thus no real capacitance.

There are plenty of guys running around with drill through nmo mounts on aluminum surfaces.

Hell alot of antennas are actually made with aluminum. Most common being tv antennas.



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[OffRoaderX]

Aluminum will work, but your mag-mount wont stick to it as well as a cookie-sheet..  However the wife will probably complain less about using the foil vs the cookie-sheet.

I'm sure that "some people" will leave a more detailed, 10-paragraph explanation complete with the molecular differences between steel and aluminum and the RF calculations, all just to say "it will work" ....

[kidphc]

There is definitely capacitive coupling. It's not magnetic so the mount won't hold, but electrical it will work just fine.

Good to know

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[back4more70]

Thank you all, I guess the magnetic part was irrelevant, since it would be sitting on a desk or the ground.

[SteveShannon]

1 hour ago, back4more70 said:

Thank you all, I guess the magnetic part was irrelevant, since it would be sitting on a desk or the ground.

Hams going out into the field sometimes lay down aluminum screen and place a ground plane antenna on the screen. 
They also use a product sold as “Faraday cloth.”

[WRQC527]

55 minutes ago, OffRoaderX said:

 a more detailed, 10-paragraph explanation complete with the molecular differences

I couldn't resist. Full disclosure, I don't know the first thing about metallurgy, except that ain't no magnet gonna stick to no aluminium, and this is a shameless copy and paste that is coincidentally ten paragraphs.

 

Aluminum and steel are metallic substances. Aluminum is a commonly found metallic element in earth’s crust, while steel is essentially an alloy of carbon, iron, and other elements. These two materials have somewhat similar applications, but aluminum metal is comparatively softer than steel.

Aluminum is a chemical element having the atomic number 13 and the chemical symbol Al. Usually, this chemical element appears as a silvery-white, soft metal. Aluminum metal is nonmagnetic and highly ductile. It is abundant on earth (8% of earth’s crust). This metal is highly chemically reactive. Therefore, it is difficult to find native specimens of aluminum. This metal has a low density. It is lightweight and is able to resist corrosion via forming an oxide layer on its surface.

The electron configuration of the aluminum element is [Ne]3s13p1. It has a standard atomic weight of 26.98. Aluminum occurs in the solid state at room temperature and pressure conditions. Its melting point is 660.32 degrees Celsius, and its boiling point is 2470 degrees Celsius. The most common oxidation state of aluminum metal is +3.

There are different alloys of aluminum that are very helpful in different industries. Commonly used alloying chemical elements for aluminum include copper, magnesium, zinc, silicon, and tin. Aluminum alloys can come in two types as casting alloys and wrought alloys. Both these groups can be divided into two different categories as heat-treatable aluminum and non-heat-treatable aluminum alloys. The most commonly used form among them is the wrought alloy.

Steel is an alloy of iron and carbon along with some other chemical elements. The carbon content in this alloy ranges up to 2% by weight. The most important properties of steel include high tensile strength and low cost. This is the most common material for building infrastructures. In addition, it is important for the production of tools for construction as well.

The crystal structure of pure iron has very little resistance to the iron atoms slipping past one another. Hence, pure iron is very ductile. But steel has carbon and some other components that can act as hardening agents. Thus, the ductility of steel is lower than that of pure iron. The crystal structure of pure iron has dislocations that can move, making the iron ductile, but in steel, components such as carbon can prevent the movement of these dislocations via entering into the crystal structure of iron.

We can find four types of steel; carbon steel, which contains iron and carbon, alloy steel, consisting of iron, carbon, and manganese, stainless steel, which contains iron, carbon, and chromium and tool steel, containing iron and trace amounts of tungsten and molybdenum.

Furthermore, steel can undergo corrosion upon exposure to air and moisture, except stainless steel. Stainless steel has chromium, which makes it corrosion resistant by forming a chromium oxide layer on the steel surface when it is exposed to normal air.

Aluminum and steel are important metallic compounds having a wide range of uses in different industries. Aluminum is a metallic element having the atomic number 13 and the chemical symbol Al. Steel is an alloy of iron and carbon along with some other chemical elements. The key difference between aluminum and steel is that aluminum is less hard than steel.

Aluminum and steel are metallic substances. The key difference between aluminum and steel is that aluminum is less hard than steel. This is mainly because the hardness of steel is enhanced by adding different chemical elements, and steel can be modified into different forms according to the purpose of its use.

[WRUE951]

i know folks with Ford Trucks are using this and apparently it works.  https://www.amazon.com/Buyers-Products-8895404-Magnetic-Mount/dp/B0781XXBCY?th=1

[WRXB215]

@WRQC527 I used to understand all that metallurgy but for some strange reason I'm not into it anymore. 

@WRUE951 I've seen some mag mount antennas that come with a small round version of that for use on fiberglass tops like Jeep tops. 

[Lscott]

1 hour ago, WRUE951 said:

i know folks with Ford Trucks are using this and apparently it works.  https://www.amazon.com/Buyers-Products-8895404-Magnetic-Mount/dp/B0781XXBCY?th=1

Interesting product. Didn't know anything like it existed.

[WRYZ926]

I actually use something similar to those square plates on my aluminum tool box. The magnet mount holds pretty good.

I've seen people use sections of aluminum window screen material as ground plane for vertical HF antennas and it works. And I agree, the wife would probably be let upset if you use aluminum foil versus a good cookie sheet.

[WRUW493]

On 3/14/2024 at 10:23 AM, back4more70 said:

I have a magnet-mount UT-72G antenna that requires a ground plane.  It works well on top of my car roof (steel).  I have used it with some success on a cookie sheet as well.  I'm wondering, would a sheet of aluminum foil function as a ground plane?  I'm not serious about doing this, but I wonder if it would be passable?

Same as above, plus: keep in mind that aluminum is non-ferrous, meaning that is actually repels magnetic fields. Sure it's thin, but there might be a risk of deteriorating the magnet if left on the aluminum long term. Consider a large steel washer below the magnet to "capture" the magnetic fields, then place that combo on the aluminum foil. 

[Lscott]

50 minutes ago, WRUW493 said:

Same as above, plus: keep in mind that aluminum is non-ferrous, meaning that is actually repels magnetic fields. Sure it's thin, but there might be a risk of deteriorating the magnet if left on the aluminum long term. Consider a large steel washer below the magnet to "capture" the magnetic fields, then place that combo on the aluminum foil. 

The aluminum foil won't hurt the magnet at all. Don't worry about it.

Sticking something magnetic on the back side of the foil the magnet can be attracted to is a good idea to hold the foil in place. The foil needs to be a rough square at lest 6 inches on a side or a circle about 12 inches in diameter. Put the magnet mount in the center. 

[iyaaays01]

Hey group!,

I am looking at building a simple Parrot repeater and and needed some opinion on this.. 
My idea was to add a few strips of aluminum tape to cover the blue area you see and then gluing the red part creating a pressure fitting lid.

My question is will this be enough for a ground plane? and also should I add anything to make the connection better?
the plan is to run a sma extension cable and then use a whip antenna  on the top of the lid.. the lid is roughly 3"x6".

Looking for a more scientific mind than mine to help with this.

Thanks in advance!

[SteveShannon]

13 minutes ago, iyaaays01 said:

Hey group!,

I am looking at building a simple Parrot repeater and and needed some opinion on this.. 
My idea was to add a few strips of aluminum tape to cover the blue area you see and then gluing the red part creating a pressure fitting lid.

My question is will this be enough for a ground plane? and also should I add anything to make the connection better?
the plan is to run a sma extension cable and then use a whip antenna  on the top of the lid.. the lid is roughly 3"x6".

Looking for a more scientific mind than mine to help with this.

Thanks in advance!

That’s a little too small for a ground plane but it’s better than nothing (see the sizes mentioned in the post by @Lscott immediately above your post). Also, how are you connecting to the ground plane, electrically or capacitively coupling? How thick is the red layer and what is it?

[iyaaays01]

@SteveShannon So my idea was to use a couple of washers above and below the foil so that the SMA connector on the antenna and the extension cable( https://www.amazon.com/dp/B083D5QWNT?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_56&th=1 )made contact with the plane. Not sure what type of connection that is. The 2 parts of the lid were going to be made from PTEG.

[WRUE951]

this guy posted this here awhile back.. 

 

[SteveShannon]

23 minutes ago, iyaaays01 said:

@SteveShannon So my idea was to use a couple of washers above and below the foil so that the SMA connector on the antenna and the extension cable( https://www.amazon.com/dp/B083D5QWNT?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_56&th=1 )made contact with the plane. Not sure what type of connection that is. The 2 parts of the lid were going to be made from PTEG.

All I can say is try it.  

[WRUE951]

Just now, SteveShannon said:

All I can say is try it.  

yup, that's what makes everything fun..   

[iyaaays01]

With the limited amount of space I have.. do y'all have any other Ideas I might try..

[SteveShannon]

17 minutes ago, iyaaays01 said:

With the limited amount of space I have.. do y'all have any other Ideas I might try..

Really, try it as is. If it doesn’t work like you want either change to an antenna that doesn’t require a ground plane or add a roll up ground plane made from aluminum screen or faraday cloth. 

[Lscott]

2 hours ago, iyaaays01 said:

With the limited amount of space I have.. do y'all have any other Ideas I might try..

Yeah, you can try using one of those orange fiberglass marker poles sold at the hardware store stuck in a hole in the case. Then zip tie a simple ladder line J-Pole antenna to it. No ground plane required. If the area has trees you can simply hang the antenna from it for better range.

https://n9taxlabs.com/shop/ols/products/dual-band-murs-gmrs-slim-jim-with-10-or-16-foot-cable

https://vfcomms.com/shop/antenna/fara-j/fara-j-antenna-for-gmrs/?v=0b3b97fa6688

 

Edited December 16, 2025 by Lscott
Added link for a another roll up antenna type.

[iyaaays01]

Thank you.. will give these all a try and report back once i get to test!

[HHD1]

On 3/14/2024 at 11:23 AM, back4more70 said:

I'm wondering, would a sheet of aluminum foil function as a ground plane? 

Yes, and quite well.  But probably not so much with a mag mount, as others have mentioned.  My use, as pictured, is a layer of foil on a 2' x 4' sheet of 3/8" particle board. With a hole in the middle to slide a so239 barrel through. A large washer sandwiched with nuts couples the barrel to the foil. And a pl259 to bnc adapter allows an antenna of choice to be used.