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why high frequency signals cant be transmitted through normal wires

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rafalizou

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why high frequency signals cant be transmitted through normal wires
 

KJ6EAD

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Why can't high frequency signals be transmitted through ordinary wire?

Because radio frequency (RF) signals, as their name implies, tend to radiate out of the wire like from a radio antenna, significantly reducing the power of the signal transmitted through or along the wire to the receiving end.

See Transmission line - Wikipedia, the free encyclopedia.
 

rafalizou

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This is due to "Skin Effect". The Skin Effect is tendency of high frequency current to be highest at surface of conductor and decay exponentially towards centre.

http://www.ultracad.com/articles/skin effect.pdf
Skin effect - Wikipedia, the free encyclopedia


Then sir, pls tell what kind of wires can be used.

Also, I would like to know how do signal travel in wires/waveguides/cables..
ie. do they travel as EM waves or like beam of electrons [as in, a DC current flowing thru a copper wire].
 

lostinxlation

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Then sir, pls tell what kind of wires can be used.

Also, I would like to know how do signal travel in wires/waveguides/cables..
ie. do they travel as EM waves or like beam of electrons [as in, a DC current flowing thru a copper wire].
In the end, it's a flow of electron.
But when you are in the situation that has to deal with Maxwell equation, you might be able to see it like EM wave.

The waves that come and go on sea shore is nothing but water.
 
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yadavvlsi

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rafalizou

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Why are waveguides (or coaxial cables)
incapable of carrying low frequency (or dc) signals
 

KJ6EAD

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They're not. READ the links.
 

rafalizou

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They're not. READ the links.

I mean, waveguides are not suitable for propogating signals having wavelengths not comparable to their dimensions (higher)..
Why so..?
 

elgen

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The transmission lines are for carrying TEM waves and waveguides are for carrying other TE/TM modes. For transmission lines, you can calculate the characteristic impedance given their geometry and the materials. If the geometry is not comparable to the wavelength, you will find the characteristic impedance not matched to the common source impedance, i.e. 50 Ohm. This leads to ineffective transmission of power.

Similar argument applies to waveguides for TE/TM modes, thought you need to define the characteristic impedance for each mode.
 

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thannara123

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I think , increase in frequency the ,due to skin effect the there will loss in through the wire .(in practically increase in frequency makes the decrease in resistance in between the wires ) So there is loss in signal .the cable length,cross section also depend the frequency
You can use coaxial cable for high frequency
 

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