Simple eqn to remember ( 2 skin depth = sqrt ( -------------- ) ( w * u * sigma
w is radians per sec; or 2 pi f, with f in Hz u is permeability . or . u rel * u free space u free space is 4 pi 10-7 sigma is conductivity in S/m all MKS units so skin depth in meters One important point to remember is that this formula calculates skin depth, like attenuation versus depth, for a *PLANAR WAVE* If the impinging wave has curvature, like from a close by radiator; that wave really "punches" through and there is not as much attenuation. How much? Depends on curvature, but for close sources the effective thickness can be reduced to less than half. Conclusion:. Use thicker material than you think you need. - Robert - Robert A. Macy, PE .. m...@california.com 408 286 3985 . . . .. . . fx 408 297 9121 AJM International Electronics Consultants 101 E San Fernando, Suite 402 San Jose, CA 95112 On Fri, 8 Aug 2003 13:33:24 EDT garymcintu...@aol.com wrote: > My anal-retentive self is having some trouble > with an occasional > example in the text and I need either a confirmation or a > slap in the forehead. > I was just fiddling around with the text and > reviewing some of the > examples and in section 6.4 he presents a table of skin > depth for copper, but > then in question 6.2 he asks for the skin depth of steel > - and the numbers for > the skin depth are the same. My calculations say > otherwise and makes sense to me > since the permeability is different between the > materials. copper = 1 and > steel is 1000, that and the conductivity is different > between the two. > If you have the text and little or nothing else to > do could you give > me the number you come up with? ( in mm's or mils) > When I'm trying to learn or relearn stuff and I'm > at odds with the > various references it just drives me wild and I don't > have anyone else to confer > with up here. One is torn between the I'm right response > and the author's > obvious authority on the subject. > Thanks > Befuddled (Gary) > This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc