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Forum index » Science and Technology » Physics » Electromagnetics
Skin Depth in metals
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prateek
science forum beginner


Joined: 24 Jun 2006
Posts: 1

PostPosted: Sat Jun 24, 2006 7:03 pm    Post subject: Skin Depth in metals Reply with quote

As i understand, EM waves do not penetrate the metals. Only a small
portion of the energy is absorbed depending on the skin depth and rest
is all reflected.So how do the antennas, which are all metallic, absorb
the wave power?

prateek
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Dave
science forum Guru Wannabe


Joined: 23 Apr 2005
Posts: 191

PostPosted: Sun Jun 25, 2006 1:35 am    Post subject: Re: Skin Depth in metals Reply with quote

they don't absorb it, the fields cause the electrons in the metal to move
which induces currents in the metal.

"prateek" <prateekprashar2003@yahoo.co.in> wrote in message
news:1151175832.699731.121450@i40g2000cwc.googlegroups.com...
Quote:
As i understand, EM waves do not penetrate the metals. Only a small
portion of the energy is absorbed depending on the skin depth and rest
is all reflected.So how do the antennas, which are all metallic, absorb
the wave power?

prateek
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noshellswill
science forum beginner


Joined: 15 Apr 2006
Posts: 12

PostPosted: Mon Jun 26, 2006 5:46 am    Post subject: Re: Skin Depth in metals Reply with quote

On Sat, 24 Jun 2006 12:03:52 -0700, prateek wrote:

Quote:
As i understand, EM waves do not penetrate the metals. Only a small
portion of the energy is absorbed depending on the skin depth and rest
is all reflected.So how do the antennas, which are all metallic, absorb
the wave power?

prateek


BigP:

At the receiver-antenna surface, the tangential-component of H-field is
discontinuous , and proportional to an induced surface current_density ...
say J = J0*cos< w*t > ..... etcetc.

nss
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Timo Nieminen
science forum Guru Wannabe


Joined: 12 May 2005
Posts: 244

PostPosted: Mon Jun 26, 2006 11:39 am    Post subject: Re: Skin Depth in metals Reply with quote

On Sun, 24 Jun 2006, prateek wrote:

Quote:
As i understand, EM waves do not penetrate the metals. Only a small
portion of the energy is absorbed depending on the skin depth and rest
is all reflected.So how do the antennas, which are all metallic, absorb
the wave power?

As others have written, antennas don't work by absorption. Also, you might
want to compare the skin depth with the typical thickness of antennas.

The antenna doesn't absorb (or at least, that isn't why it works), the
circuit attached to the antenna absorbs. The antenna converts radiation in
free space into guided waves going into the rest of the circuit.

--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
E-prints: http://eprint.uq.edu.au/view/person/Nieminen,_Timo_A..html
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html
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