Faraday Cage

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Matie has a posh boat built with exotic things like carbon fibre and kevlar, amongst other things.

On a nice day, he likes to sit in the cockpit with his laptop, connect to the local wifi and do whatever people do on the web. When it rains, he nips inside and that is when his humour fails (he is German, so it is a very serious failure) because the wifi no longer works.

Do I need to give Claus a briefing about the effects that Mr Faraday waffled on about or will a Faraday cage built of carbon fibre or kevlar be useless as a Faraday cage.

TIA and I look enlightening Claus about a thing or two, jaa.
 
stingo said:
Matie has a posh boat built with exotic things like carbon fibre and kevlar, amongst other things.

On a nice day, he likes to sit in the cockpit with his laptop, connect to the local wifi and do whatever people do on the web. When it rains, he nips inside and that is when his humour fails (he is German, so it is a very serious failure) because the wifi no longer works.

Do I need to give Claus a briefing about the effects that Mr Faraday waffled on about or will a Faraday cage built of carbon fibre or kevlar be useless as a Faraday cage.

TIA and I look enlightening Claus about a thing or two, jaa.
Click to expand...

An electromagnetic pedant writes ...

The Faraday Cage effect is the lack of static electric fields inside a closed conducting surface. It's only indirectly related to the electromagnetic shielding effect of a conducting enclosure.

For example, a glass sphere coated with a thin layer of gold makes a good Faraday cage but still allows EM radiation to penetrate.
 
What Uber said.

Carbon fibre behaves pretty much like a metal. My mast is carbon; when I was having it built I asked for a radar reflector to be built inside it. The designer laughed saying radar bounces off the surface so it would be totally ineffective but the mast itself would be a good reflector in its own right. He was correct. In fact on another similar boat with a mast chord of 1.3 metres we saw a large obstruction ahead while reaching along a coastline. It turned out to be a reflection of the radar signal from the shore that had bounced off the mast.

All the guy has to do is stick a wifi antenna outside.
 
snowleopard said:
All the guy has to do is stick a wifi antenna outside.
Click to expand...

It'll help if he connects it to his 'puter as well! Cutting slots the same length as the wifi wavelength in his coachroof might help but wouldn't do much for keeping the rain out
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Ubergeekian said:
An electromagnetic pedant writes ...

The Faraday Cage effect is the lack of static electric fields inside a closed conducting surface. It's only indirectly related to the electromagnetic shielding effect of a conducting enclosure.

For example, a glass sphere coated with a thin layer of gold makes a good Faraday cage but still allows EM radiation to penetrate.
Click to expand...
Yaa Boo! he asked a simple question, for the purpose of this question, Faraday Cage is a good enough description. Our radio repair man in Angola had a chicken wire looking contraption that he used to sit inside whilst he did black magic. He called it a Faraday Cage.
Stingo knew what he meant, we knew what he meant!
John, go and take the pee out of the Kraut, Snow Leopard put it very simply!
Stu
 
Carbon fibre is not much like metal, it is much lossier.
Some carbon fibre structures make very poor radar reflectors, the resistive carbon dissipates the radar wave rather than reflecting it. This does depend on the detail of the situation though.
Kevlar is not conductive, so does not contribute much loss.
A structure with plenty of carbon in it may block wifi quite effectively.
The layer of rain on the deck may not help either.
The dielectric of the resin will cause some reflection.
In practice it depends on how much spare signal strength there is, sometimes losing 90% of the energy won't be noticed.
Sometimes a small loss is enough to trash a marginal link.
This also applies to GPS aerials below deck.
 
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