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Discussion Starter · #1 ·
I am looking for a way to protect FOB signal efficiently (Kia Niro EV but can be any car with FOB). I tried wrapping the FOB inside aluminum foil but when I came close to the car, I could still open the car by hand.

I tried some FOB Faraday bags from Amazon (carbon fiber) but I still could open the door by hand. They might weaken the FOB RFID signal but if I can still open the window, I do not know how efficient they can eventually protect from sealing the FOB signal by potential thieves.

Please inform the way that FOB can get protected.
 

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It isn't necessary to completely isolate the fob. If it's wrapped in foil, the range will be reduced to the point that the car thieves that use their devices to probe it from outside won't be able to reach it. For security, you simply need to reduce the fob range enough that they can't connect to it when the fob is inside your home while the car is outside. If you have to be within a foot of the car for the fob to work, the thieves will never be able to use their device to open the car. I don't think any sort of Faraday cage or other shield will ever be 100% effective. Removing the battery from the fob would be the only fool-proof method.
 

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I am looking for a way to protect FOB signal efficiently (Kia Niro EV but can be any car with FOB). I tried wrapping the FOB inside aluminum foil but when I came close to the car, I could still open the car by hand.

I tried some FOB Faraday bags from Amazon (carbon fiber) but I still could open the door by hand. They might weaken the FOB RFID signal but if I can still open the window, I do not know how efficient they can eventually protect from sealing the FOB signal by potential thieves.

Please inform the way that FOB can get protected.
For theft protection the question isn't whether the FOB works when you are touching the car (spoiler alert: it will almost always work in this case regardless of how effective any shielding may be), rather the question is how much does the shielding reduce the effective range. In your case, can you open the doors when you are 5 feet away? 10? The whole point of RF protection is to weaken the signal not completely eliminate it. Suppose your FOB works at 50 feet normally and that the range is reduced to 5 feet in a shield. Congratulations, you've reduced the signal by 10dB (roughly). Is that enough? Probably.

Annnnd ninja'd by @atc98092
 

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Discussion Starter · #4 ·
I double checked again the fiber carbon cage case that I purchased from Amazon. If the FOB case lead gets closed completely, the RFID signal gets blocked completely, even if I stay a few inches away from the car.
 

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I double checked again the fiber carbon cage case that I purchased from Amazon. If the FOB case lead gets closed completely, the RFID signal gets blocked completely, even if I stay a few inches away from the car.
That's what I would expect. It doesn't take much of an opening for a bit of RF to leak in/out. But that's all it does take. You fob (and your car) will be completely safe with the fob in a cage like that.
 

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I place my fob in a clean soup can when in the house. I tested the performance of the can in its ability to shield the signal. I can stand next to the car and the car door will not open. Can must be steel to act as a RF signal.

Greg - 2020 kia niro lxs
 

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I am looking for a way to protect FOB signal efficiently (Kia Niro EV but can be any car with FOB). I tried wrapping the FOB inside aluminum foil but when I came close to the car, I could still open the car by hand.

I tried some FOB Faraday bags from Amazon (carbon fiber) but I still could open the door by hand. They might weaken the FOB RFID signal but if I can still open the window, I do not know how efficient they can eventually protect from sealing the FOB signal by potential thieves.

Please inform the way that FOB can get protected.
I have a friend who is a very good engineer (multiple patents and several Emmys) and he wraps his Smart Pass device in a clear plastic bag which is conductive, and he claims that it completely eliminates having the Smart Pass "read" when driving around on freeways. I realize that's different that what you're asking, but it's a pretty elegant solution. The bag is transparent with a slight greenish-yellow sheen to it.
 

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I have a friend who is a very good engineer (multiple patents and several Emmys) and he wraps his Smart Pass device in a clear plastic bag which is conductive, and he claims that it completely eliminates having the Smart Pass "read" when driving around on freeways. I realize that's different that what you're asking, but it's a pretty elegant solution. The bag is transparent with a slight greenish-yellow sheen to it.
The bag should similar as the protective bags as the brand new Hard Disk and motherboards have when you receive it from the store. Good Idea. Anyway you can try to see if using a bag made with copper mesh where the holes between wire and wire of the mesh will be too small.
 

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I've wrapped my spare fob in aluminum foil and stashed in my car in case I lose the other one (with a physical key stashed outside). The car cannot see it where I have stashed it, nor testing it outside the car while wrapped in aluminum foil. I have to wonder if the OP had his other fob near the car when testing aluminum foil.
 

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Discussion Starter · #10 ·
If wrapping or caging the FOB can be done perfectly, the RF signal should get blocked completely. Otherwise, in case of slight leakage, the car still can detect the FOB if you are very close to the car for testing. I tested this using a carbon fiber FOB case (purchased from Amazon).

Anyway, as another user mentioned, a perfect RF signal block might not be needed, because wrapping/caging can significantly attenuate the RF signal. You can try this at home.
 
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