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RC Car + Copper

Hello, I bought a 2.4GHz controlled RC car from a Chinese vendor. Under the car chassis, there is a 30mm x 20mm copper plane attached.

Surprisingly, the customer's service team replied that "it's antenna. 2.4GHz antenna amplification device."

I couldn't believe what I heard. So I'm posting this question.

Can that copper plane act as a 2.4GHz antenna? Also, can this plane "really" amplify something?

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  • \$\begingroup\$ you need to add a description of the red wire/cable that is connected to it. \$\endgroup\$ – jsotola Dec 7 '17 at 6:55
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Can that copper plane act as a 2.4GHz antenna?

You bet. It's called a patch antenna.

Also, can this plane "really" amplify something?

Technically, no, but in common usage yes. It's more accurate to say that a properly-designed antenna will be more efficient, and produce a higher output signal, than a poorly-designed one.

If you start out with an antenna which is just a random length of wire, the odds are very good that this will make a crappy antenna. Put a properly-designed patch on the end of the wire, and its output will increase. Did the patch "really" amplify the signal? If you don't understand how the antenna works, the answer will seem to be yes, but if you have more knowledge you'll say no, it's just a better antenna.

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Yes a 1/4 wave antenna needs a ground plane to simulate a 1/2 wave dipole. A small one suffers some loss. None is even worse.

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The patch will affect the way the antenna behaves.

Whether the wire plus copper patch or wire without copper patch radiates more power depends on the length of the wire, so how each configuration is tuned.

The patch does allow the antenna to be brought into tune with a shorter physical length of wire, which may be important in a small model.

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That big piece of foil acts as a top-hat capacitively loaded antenna.

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There's two things that foil is likely doing.
1) Increasing the directionality of the signal so that you're not sending as much energy into the ground.
2) Increasing the efficiency of the antenna so that more of the energy gets converted to radio waves rather than heat.

Patch Antenna Radiation Pattern
Patch Antenna Radiation Pattern

Dipole Antenna Radiation Pattern
Dipole Antenna Radiation Pattern

If the dipole/wire isn't facing the correct direction, there could be very little signal between the controller and the car. If the patch is designed to limit the amount of directionality introduced, it may provide a pretty ideal radiation pattern for the application described given that the controller will most likely be somewhere above the car's horizontal plane.

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