On Fri, 07 Oct 2005 15:09:25 -0700, Jim Kelley
wrote:


But think about it. The surge impedance (Zo) is basically just the
ratio of the capacitance per unit length to the inductance per unit
length. Those quantities might vary a little bit from one place to
another, but probably not by much. And there are undoubtedly end
effects which locally pull the capacitance and inductance values away
from the ideal. So the length really need only be long enough for the
variations to average out and for the total values to become large
enough to swamp the end effects.

I don't doubt there is a discontinuity that disturbs the fields and
V/I ratio.

What I am asking about is the basis for the 2% of wavelength factor.

If I use RG58C/U on 160m, I read that Cecil is suggesting that the V/I
ratio is significiantly different to Zo for 2% * 160m or 3.2m
(125")from the end of the cable, which seems large when the physical
distance between the inner and outer conductor is 0.001m (0.04").

I am looking for quantitative support for Cecil's 2%.

Owen
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