On Fri, 1 Jul 2005 04:54:35 +0000 (UTC), "Reg Edwards"
wrote:


"Owen"
Any thoughts. Is there an inconsistency between the explanation that
G
is principally due to D of the dielectric material, or I have I
messed
the maths up?

Owen
===================================

From where did you obtain D 2e-3 for RG 58 ? That's the most likely
source of the discrepancy.

Also the highest grade polyethylene is unlikely to be used for the
manufacture of RG58.

The only way to investigate is to lay 100 feet on the ground, in the
form of a circle, and measure attenuation vs frequency between the
ends from 1 MHz to 1 GHz.

I took the figures published by Belden for their 8262 cable at
frequencies from 1MHx to 1Gz (9 points) and did a polynomial
regression to MLL=k1*f**0.5+k2*f, then substituted k2 into the
expression described in my original post.

I didn't measure the losses, and I recognise that Belden might have
smoothed their results by an intermediate regression, but I figure
that they are not going to exaggerate the effect of k2 unnecessarily.

Owen

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