Faraday Bag For Key?

[Old_Norm]

This is right, the car body really is a terrible faraday cage for the radio frequencies (wavelengths) used by key fobs. The window openings are much larger than the mesh size needed to shield transmission.

I haven't seen any post that claims the MME is a good faraday cage. The argument seems to be that it is not a Faraday cage. I've yet to find a reputable site that states that a metal automobile is not, or doesn't function as a, faraday cage.

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[Kamuelaflyer]

I crack up when people say that a metal container is a Faraday cage. There are so many gaps and openings in an item such as an automobile that the rate of attenuation is pretty bad. In some instances, a signal may be magnified. I say this as someone with many years of Electromagnetic Compatibily engineering experience. ??

Cars are as good at being a Faraday cage as a sieve is at carrying water.

 

[Old_Norm]

Cars are as good at being a Faraday cage as a sieve is at carrying water.

First you made yourself look silly claiming, "Airplanes are the furthest thing from a Faraday cage you can imagine." Now you are stating something that absolutely no one in this thread disagrees with. I'm promoting you from Captain Obvious to Colonel Obvious. Please don't reply. I've had enough of your BS to last a lifetime.

 

[Old_Norm]

One of the reasons I love Ford vehicles is the exterior keypad. I do a few outdoor sports where it is handy to leave the key in the vehicle and simply use the exterior keypad to get back in. But it seems like leaving the key in the Mach e would let anyone get into a take the car... not good.

Im wondering if anyone has tried to use a faraday case or bag for the key? Im hoping this would let me leave the key in the car but not communicating with the car.

Please disregard the "It's a faraday cage, it's not a faraday cage" one upmanship. Hopefully your question has been answered. I and others have used a faraday pouch successfully to store the key fob in the MME. Whether to do so or not is a personal decision, but it performs the function you are looking for. I cannot imagine how a faraday pouch could go bad unless it was handled so frequently as to wear a hole in it or open up a seam (or the faraday liquid leaked out ?). Hope that helps.

 

[InTheHills]

Hopefully your question has been answered.

I did get the answer I was looking for and I have ordered a Faraday Bog. I may also look for a small safe as one person suggested!

Thank you!

 

[Kamuelaflyer]

I did get the answer I was looking for and I have ordered a Faraday Bog. I may also look for a small safe as one person suggested!

Thank you!

The safes can be good for home storage as well. They can reduce the likelihood of thieves cloning the key.

As for the car, there’s no genuinely safe place to stash the key. Some hiding spots though are far easier to find than others. Some of the faraday bags are made with cheap shielding cloth. I had one that has lasted 3 years quite well while the other lasted less than a year. Both were in a dresser drawer.

 

[steve.panse]

I haven't seen any post that claims the MME is a good faraday cage. The argument seems to be that it is not a Faraday cage. I've yet to find a reputable site that states that a metal automobile is not, or doesn't function as a, faraday cage.

Posts 55, 58, and I think that you said so yourself in 85. In the post, it seems like you’re saying it’s not a Faraday cage, but you can’t find anything that says it’s not? I really don’t know what is your point.

The effectiveness of a Faraday cage depends on frequency of the signal, material of the cage, and physical construction, especially mesh/gap size. Cars aren’t a contiguous metal structure but an assembly of many parts with air gaps or insulating weather seals between them. The window openings and glass roof especially are too large of a mesh to shield the electromagnetic radiation.

When talking about leaving the key inside the car, it’s completely irrelevant how good of a Faraday cage the body of the car is. It might attenuate signals passing between the interior and exterior of the car, but if both the transmitter (key fob) and receiver (car antenna) are inside the cage there’s no attenuation. This is the purpose of the Faraday bag, to attenuate the signal between the key fob and car.

Instead of us arguing about it theoretically, test for what works. Mission Darkness bags work for me.

 

[Old_Norm]

Posts 55, 58, and I think that you said so yourself in 85. In the post, it seems like you’re saying it’s not a Faraday cage, but you can’t find anything that says it’s not? I really don’t know what is your point.

The effectiveness of a Faraday cage depends on frequency of the signal, material of the cage, and physical construction, especially mesh/gap size. Cars aren’t a contiguous metal structure but an assembly of many parts with air gaps or insulating weather seals between them. The window openings and glass roof especially are too large of a mesh to shield the electromagnetic radiation.

When talking about leaving the key inside the car, it’s completely irrelevant how good of a Faraday cage the body of the car is. It might attenuate signals passing between the interior and exterior of the car, but if both the transmitter (key fob) and receiver (car antenna) are inside the cage there’s no attenuation. This is the purpose of the Faraday bag, to attenuate the signal between the key fob and car.

Instead of us arguing about it theoretically, test for what works. Mission Darkness bags work for me.

Post 55 says nothing about the efficiency of the MME as faraday cage. Post 58 is simply the poster not understanding that the failure of being able to open the car with the key fob inside has nothing to do with a faraday cage. Again, no mention of the effectiveness of the MME as a faraday cage. In post 85 I said, " There is no physical cage per se. The entire car is a Faraday cage because it is made of metal. How on earth did you conclude that I said it’s not a Faraday cage?

You have completely lost the thread here. There are basically two conversations going on. One, buying and using a faraday pouch and two, whether an automobile can be a faraday cage. At no point did I say or suggest an MME could act as efficiently as a faraday pouch. My first post was to advise the OP that I use the pouch and it is 100% effective. If you disregard Shutterbug's misinformed ravings, the subsequent posts about Faraday cages had nothing to do with pouches vs MME cage effectiveness.

Apparently you failed to read or ignore my several postings on automobiles as faraday cages. Not one of them suggested that an automobile was an effective faraday cage. So let's get you back on course:
1. Faraday pouches work for the the intended purpose the OP inquired about.
2. Metal automobiles are faraday cages but not effective ones.
That is all, as you were.

 

[Jynxy in Texas]

Maybe I got a dud, but my cheap faraday bag that looks like the ones referenced in this thread do not work. I can walk up to the car with the key in the faraday bag and push the button - sometimes it takes four or five times, but eventually, it will open. I learned this when I let someone use my car, and left the key in the car. Told them to call me when they got to the car and I would unlock it and tell them where the key was in the car. They got in and were driving it, when they called me.

 

[Kamuelaflyer]

Maybe I got a dud, but my cheap faraday bag that looks like the ones referenced in this thread do not work. I can walk up to the car with the key in the faraday bag and push the button - sometimes it takes four or five times, but eventually, it will open. I learned this when I let someone use my car, and left the key in the car. Told them to call me when they got to the car and I would unlock it and tell them where the key was in the car. They got in and were driving it, when they called me.

The cheap bags use an impregnated cloth material for the shielding. I think some of those degrade over time. I know one of mine did. I took the bag out of the dresser after a year and walked to the car with fob still in the bag and had no issues opening and starting the car. I live in a very rural area with a detached garage. The car is a considerable distance from the house where my phone was.

After that experience I bought a metal Faraday case designed for a single fob back when I kept the fob in the car. As @steve.panse mentioned above, Mission Darkness bags are good.

 

[Old_Norm]

Maybe I got a dud, but my cheap faraday bag that looks like the ones referenced in this thread do not work. I can walk up to the car with the key in the faraday bag and push the button - sometimes it takes four or five times, but eventually, it will open. I learned this when I let someone use my car, and left the key in the car. Told them to call me when they got to the car and I would unlock it and tell them where the key was in the car. They got in and were driving it, when they called me.

How did they get in the car?

 

[Jynxy in Texas]

How did they get in the car?

They just hit the button a few times, and it opened. They didnt even have to locate the key

 

[Old_Norm]

They just hit the button a few times, and it opened. They didnt even have to locate the key

Something is weird here. You can't open the car with the key fob inside just by pushing the door button. It doesn't matter if the key fob is in a pouch or not. If that happened as you describe it, you have problems other than a faraday pouch.

 

[Jynxy in Texas]

I leave the key in the car all the time. It is in the garage. I walk up and just open it every day. ??

 

[Old_Norm]

I leave the key in the car all the time. It is in the garage. I walk up and just open it every day. ??

Sorry to keep bugging you. Do you leave the car unlocked? Supposedly the car can't be unlocked with the button if the key fob is inside. I'll try it when the wife gets home.

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