In message <8ce362b4daae905-16b4-13...@webmail-d105.sysops.aol.com>, 
dated Wed, 31 Aug 2011, Derek Walton <lfresea...@aol.com> writes:

>A cable is only its characteristic impedance when fed and terminated in 
>matching impedance. That's why I said non-perfect impedance of the 
>cable

The characteristic impedance IS an intrinsic property of the cable; the 
full expression is:

  Z = sqrt((R+jwL)/G+jwC)), where R, L, G and C are per (the same) unit 
length.

At a sufficiently high frequency, wL>>R and with a sufficiently low-loss 
dielectric G<<wC, so that Z simplifies to sqrt(L/C).
-- 
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
When I point to a star, please look at the star, not my finger. The star will
be more interesting.

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