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Largered



Member Since: 10 Jul 2016
Location: UK
Posts: 1978

.... 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.


.

Post #336109 28th Nov 2017 9:51 am
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dorsetfreelander



Member Since: 20 Jul 2013
Location: Dorset
Posts: 4336

United Kingdom 2014 Freelander 2 SD4 XS Auto Loire Blue

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

Post #336111 28th Nov 2017 9:56 am
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jubdad



Member Since: 12 Mar 2013
Location: Rugby
Posts: 103

2012 Freelander 2 SD4 HSE Auto Santorini Black

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.


.


Silver is the best electrical conductor followed by copper, then gold. If you really want the best then use a superconducting metal. It'd be a bit cold though.

Post #336121 28th Nov 2017 11:33 am
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dorsetfreelander



Member Since: 20 Jul 2013
Location: Dorset
Posts: 4336

United Kingdom 2014 Freelander 2 SD4 XS Auto Loire Blue

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 Shocked 3 x FL1 2 manual + 1 auto
5 x FL2 4 manual + 1 auto
Now Discovery Sport P250 MHEV SE

Post #336123 28th Nov 2017 11:43 am
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Yorky Bob



Member Since: 28 Apr 2015
Location: Yorkshire
Posts: 4561

United Kingdom 2013 Freelander 2 TD4 GS Manual Firenze Red

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


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

Post #336125 28th Nov 2017 12:08 pm
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dorsetfreelander



Member Since: 20 Jul 2013
Location: Dorset
Posts: 4336

United Kingdom 2014 Freelander 2 SD4 XS Auto Loire Blue

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

Post #336165 29th Nov 2017 2:37 pm
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dorsetfreelander



Member Since: 20 Jul 2013
Location: Dorset
Posts: 4336

United Kingdom 2014 Freelander 2 SD4 XS Auto Loire Blue

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

Post #336166 29th Nov 2017 2:38 pm
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dorsetfreelander



Member Since: 20 Jul 2013
Location: Dorset
Posts: 4336

United Kingdom 2014 Freelander 2 SD4 XS Auto Loire Blue

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

Post #336167 29th Nov 2017 2:38 pm
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Largered



Member Since: 10 Jul 2016
Location: UK
Posts: 1978

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

Post #336169 29th Nov 2017 3:02 pm
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dorsetfreelander



Member Since: 20 Jul 2013
Location: Dorset
Posts: 4336

United Kingdom 2014 Freelander 2 SD4 XS Auto Loire Blue

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

Post #336175 29th Nov 2017 3:48 pm
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Dan_NL



Member Since: 30 Jul 2016
Location: Dutch Highlands
Posts: 98

Netherlands 2010 Freelander 2 TD4 Sport Manual Santorini Black

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. Cool

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... Mr. Green

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... Embarassed

Oh : and all this before motion sensors spot them and put them in spotlights and record them over 14 CCTV cams... Rolling with laughter [ 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

Post #336178 29th Nov 2017 4:53 pm
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IanMetro



Member Since: 11 Sep 2017
Location: Somerset BS21
Posts: 2747

United Kingdom 2014 Freelander 2 SD4 Metropolis LE Auto Fuji White

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 - 74k+ miles) (MY2015)

Post #336207 29th Nov 2017 11:22 pm
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IanMetro



Member Since: 11 Sep 2017
Location: Somerset BS21
Posts: 2747

United Kingdom 2014 Freelander 2 SD4 Metropolis LE Auto Fuji White

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 - 74k+ miles) (MY2015)

Post #336220 30th Nov 2017 9:12 am
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RogB



Member Since: 16 Dec 2014
Location: Mansfield
Posts: 3867

England 2013 Freelander 2 SD4 HSE Lux Auto Santorini Black

Instead of Physics based solutions to this problem why not just use wood ?
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in the form of a baseball bat round the scrotes heads !!! Censored !!!

Post #336236 30th Nov 2017 11:35 am
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The Doctor



Member Since: 09 Jul 2010
Location: Gallifrey
Posts: 4612

United Kingdom 

Just ordered this:

RFID Signal Blocking Bag, Wisdompro&reg; 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

Post #337614 19th Dec 2017 9:06 pm
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