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I'm wondering about the best materials for making a ground plane. I've found some websites that claim that non-ferrous materials (i.e. aluminum) are generally poor ground planes (or at least not as good as the same size of a ferrous ground plane). Other sources claim this is a myth.

Does having a ferrous material for a ground plane matter? If so, why does it matter?

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  • \$\begingroup\$ If you've found some web site, please post the links. \$\endgroup\$ Aug 6, 2013 at 17:15
  • \$\begingroup\$ Added a couple links. It's pretty easy to search for more on each side. \$\endgroup\$ Aug 6, 2013 at 17:19
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    \$\begingroup\$ @Computerish, we ask for links to get more context to understand your question. For example, the links show you're asking about ground planes in relation to antennas, which wasn't at all clear until you provided the links. \$\endgroup\$
    – The Photon
    Aug 6, 2013 at 17:24
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    \$\begingroup\$ @Computerish, both the links you included refer to the ground plane beneath an antenna in a CB setup. This ground plane is responsible for providing a image current that affects the radiation pattern of the antenna. If you're not asking about a ground plane beneath an antenna, could you give more context to clarify what you are asking about? What kind of circuit, what frequencies are involved, how much power, etc. \$\endgroup\$
    – The Photon
    Aug 6, 2013 at 18:16
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    \$\begingroup\$ @Computerish, in that case it does not matter what the material is so longs as it is conductive. Indeed the earth (I mean our planet) could form one plate of your capactior. Capacitance exists in a dieletric (insulator) between any conductor, no matter how poor a conductor it is. Read up on capacitive touch sensors. \$\endgroup\$
    – Jay M
    Aug 6, 2013 at 20:50

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Both your provided links sound like they were written by someone with very little understanding of how antennas work. I would ignore them entirely.

A ground plane is a necessary part of a monopole antenna, often called a "vertical" since that's how they are usually mounted. These antennas are essentially half a dipole, with the other half being the electrical "mirror" of the antenna on the other side of the ground plane.

The only requirement for the ground plane is that it conducts. The more conductive it is, the better. The bigger it is, the better. Professional AM radio broadcast antennas use lengths of copper wires buried just under the ground, radiating out from the base of the antenna, to make the Earth more like an ideal ground plane. I'm sure if iron worked better, they'd use iron, as it's much cheaper than copper.

If I had to guess, the reason CB operators think ferrous metals make better ground planes are two-fold:

  1. they have no clue about how antennas work
  2. magnet-mount antennas, very popular for CB, won't stick to non-ferrous metals (though other than not sticking, they work fine)

If you don't actually have an antenna, then none of this applies. The lesson to be learned is this:

Don't use references written by CB operators as a source for learning about electrical engineering of any sort.

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  • \$\begingroup\$ Another potential reason people don't like aluminium planes is it can be difficult to make a very good electrical connection to aluminium. It's much easier to make a good ground connection to steel/iron, as it doesn't form an insulating oxide layer. \$\endgroup\$ Aug 7, 2013 at 7:30

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