.... its true to say the better the conductive metal ...... the better the solid screen.

So make it of GOLD !!!

which in some cases would make the 'tin' for screening your contactless key be worth more than your vehicle.


.

There is also something called the "skin effect" where at higher frequencies the current penetrates less and less of the metal and travels on the outside. (this even shows up at 50Hz which is why long high voltage lines on pylons use multiple thinner cables rather than one thick one) The skin effect should make Faraday cages more efficient at higher frequencies.

Incidentally a microwave oven is in effect a resonating cavity which behaves like a reverse Faraday cage to stop radiation leaking out so this might be a good place to leave your keys as long as you don't forget they are in there next time you use it.

PS best conductor is silver but I remember as a student in a quantum mechanics lecture that no one could explain why. 3 x FL1 2 manual + 1 auto
5 x FL2 4 manual + 1 auto
Now Discovery Sport P250 MHEV SE

Largered wrote:

.... its true to say the better the conductive metal ...... the better the solid screen.

So make it of GOLD !!!

which in some cases would make the 'tin' for screening your contactless key be worth more than your vehicle.


.

Many years ago as a student I was working in a lab and in the evening I was building a radio at home. One of the technicians said that if I found odd transistors, resistors etc lying around I could take them. So one day there was a small bundle of insulated wire on one of the benches which looked just right for what I was building, i took it home and noticed that it soldered really easily. The next day the boss was wandering around at the lab asking if anyone had seen the expensive hi-grade silver wire that they had bought for a project. gulp  3 x FL1 2 manual + 1 auto
5 x FL2 4 manual + 1 auto
Now Discovery Sport P250 MHEV SE

LR NUT wrote:

A bit slow today bobby boy
http://www.freel2.com/forum/topic30572.html?highlight=mercedes

Computer was slow - I have the Merc  FL2 MY10 TD4 GS traded in at 2 years
FL2 MY13 TD4 GS Current

Whilst on the subject of Faraday cages, apparently it works with metallised crisp packets.....

http://www.telegraph.co.uk/news/2017/11/27...ereabouts/ 3 x FL1 2 manual + 1 auto
5 x FL2 4 manual + 1 auto
Now Discovery Sport P250 MHEV SE

Whilst on the subject of Faraday cages, apparently it works with metallised crisp packets.....

http://www.telegraph.co.uk/news/2017/11/27...ereabouts/ 3 x FL1 2 manual + 1 auto
5 x FL2 4 manual + 1 auto
Now Discovery Sport P250 MHEV SE

Whilst on the subject of Faraday cages, apparently it works with metallised crisp packets.....

http://www.telegraph.co.uk/news/2017/11/27...ereabouts/ 3 x FL1 2 manual + 1 auto
5 x FL2 4 manual + 1 auto
Now Discovery Sport P250 MHEV SE

so was I right with GOLD ...... GOLDen Wonder

Whilst on the subject of Faraday cages, apparently it works with metallised crisp packets.....

http://www.telegraph.co.uk/news/2017/11/27...ereabouts/ 3 x FL1 2 manual + 1 auto
5 x FL2 4 manual + 1 auto
Now Discovery Sport P250 MHEV SE

Its even easier then that. I had a home build of precast concrete elements, linked together at the rebar. This is the inner shell.
The outer shell is normal brick and wood. Now the effect is such that I have NO reception on my mobile and I can not open or close my cars from inside the house.

I have to walk up to the window and hold the remote of any car [ no : not a bad handset or flat battery ] almost to the window, to operate the locks at 5m distance.
As all internal walls are fabricated in the same way, they must have a map of my house, know where I keep my keys and then relay the signal through several points...

I didn't design the house like that, it turned out after it was build it shielded 90% of EM radiation off. Ofcourse its a handicap for my WiFi ; it just about get to the next room...

Oh : and all this before motion sensors spot them and put them in spotlights and record them over 14 CCTV cams...  [ Freelander 2 TD4e MY10 Sport manual. SVR badge engineered ] SOLD
& D3 MY06 HSE , many ,many extra's...
& 2011 MiTo 1.4T 135hp Centenario Blue Monte Carlo

As I remember it from my (ancient) waveguide and transmission theory, preventing any signal from being picked up is very hard.
As for a Faraday Cage, using mesh is very frequency dependant, and if it is solid (and well grounded) any small gap or slit will act as a aerial (again dependent on frequency).
To make matters worse household pipes and wiring are very good at picking up and relaying onwards any stray signals.
You have to hope that car thieves equipment isn't very sensitive or sophisticated. (YET)

Remote key theft is just another case of unintended consequences of our need for speed and convenience.

How about inventing a mechanical lock that only works when you turn it with your own unique bent bit of metal.
You know, like a key. FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 77k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

Following my experiences of my FL2s shutting down systems whilst parked for a few weeks at the airport, I have wondered if it could be arranged that an external 'normal' key could be fitted that shut the car down except for the perimeter alarm.
This would save the battery by not having to keep awake looking for the remote key, and also checking the interior alarm.

Now I see that it could be handy to have the means of disabling the remote locking overnight. FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 77k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

Instead of Physics based solutions to this problem why not just use wood ?
.
.
.
.
.
.
.
.
.
.
.
.


in the form of a baseball bat round the scrotes heads !!! !!!

Just ordered this:

RFID Signal Blocking Bag, Wisdompro® RFID Signal Shielding Pouch Wallet Case for Cell Phone Privacy Protection and Car Key FOB(Black) https://www.amazon.co.uk/dp/B01HETGX00/ref...oAbJCRJGZ3

Thought it was worth it for extra peace of mind. LL.B (Hons) - University of Derby
LOT (Lord of Time) - University of Gallifrey