[SI-LIST] Re: Skin Effect question
- From: Robert Haller <rhaller@xxxxxxxxxxxxx>
- To: vachkumar@xxxxxxxxx, dbrooks7@xxxxxxxxxxxxxxx
- Date: Tue, 12 Jun 2012 08:56:30 -0400
I had the pleasure if working with Mike Tsuk (PHD) at DEC who did his
thesis on Skin effect and supported all our EM tools. When I left DEC his
parting gift to me was a very concise table comparing skin depth versus
frequency which I find invaluable (and published with his permission). You
can find this table in a paper I wrote comparing lossy versus lossless
T-line simulation results.
I keep his table on the wall of my cube to refresh my memory how dramatic
the skin effect is at high frequencies. Regards and hopefully you will
find this helpful.
At 1 MHz ~ skin depth is 2.5 mils
At 100 Mhz ~ skin depth is .26 mils
At 1 Ghz ~ skin depth is .08 mils
At 10G ~ skin depth is 26 uinches
http://www.iec.org/newsletter/aug06_2/design_eng_1.html
Regards
Bob
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Vachan
Sent: Monday, June 04, 2012 1:33 PM
To: dbrooks7@xxxxxxxxxxxxxxx
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Skin Effect question
I think that is the point of defining a skin depth - An exponential
current density is mathematically equivalent to an approximation where you
assume uniform current density just below the surface (up to 1 skin
depth), and then the current density suddenly drops to 0.
On Sun, Jun 3, 2012 at 7:44 PM, Doug Brooks
<dbrooks7@xxxxxxxxxxxxxxx>wrote:
> This question relates to skin effect.
> Consider a current density function with (surface density) Io=8 and
> skin depth = .125, unity radius.
>
> consider the current density function y=8*e^(-x/.125) integrate the
> area under this function between 0=<x=<1. The answer is
> .9997 (according to the tool I am using!)
>
> Consider the rectangle formed by the points 0,0, 0,8, .125,8, .125,0
> (Note that x=.125 [i.e. at the skin depth] is where the exponent of e
> in the current density function is -1.) the area under this rectangle
> is 1.0 (same as the area under the current density function.)
>
> Here is my question. Is this a fortunate coincidence or can this
> identity be proven mathematically?
>
>
> Doug has a new e-mail address dbrooks7@xxxxxxxxxxxxxxx check out the
> free resources at http://www.ultracad.com
>
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--
Vachan
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