[sdiy] skin effect

[John L Marshall]

According to The ARRL Handbook:

Skin effect in any non ferrous wire will begin to show where:

f = 124/d squared
f = frequency in MHz
d = diameter in mills

resistance increases 10x for each two decades in frequency or
3.2x per decade.

These are approximations.

Take care,
John
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Pacific Northwest Synthesizer Meeting
August 9, 2003
www.sound-photo.com
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----- Original Message ----- 
From: "Czech Martin" <Martin.Czech at Micronas.com>
To: "Sdiy (E-mail)" <synth-diy at dropmix.xs4all.nl>
Sent: Wednesday, May 14, 2003 3:54 AM
Subject: [sdiy] skin effect


> I have a question related to the following effect:
> 
> We can assign some inductance and resistance to a piece
> of wire. Also some capacitance (related to other wires
> or planes).
> 
> As we reach higher frequencies, the eddy currents in the wire
> will force the current out of the middle into the outer regions,
> this is called "skin effect". This is the reason why RF wires sometimes
> are silver plated.
> 
> If I remember well this will increase the resistance and increase the
> inductance of the wire. 
> 
> A simple spice model of the wire does not inlcude this effect.
> Therefore all simulations show too much ringing, or too less damping.
> 
> I therefore propose that the inductance/resistance is modeled
> as some parallel circuit of RL elements. The largest inductance
> and some resistance will model the DC case up to some frequency.
> Then a parallel branch will take over with less inductance
> and more resistance. And so on.
> 
> Will this be a good approximation for the skin effect, or
> is there some misconception in it?
> 
> m.c.
>  
>