Jim,
They do, by virtue of the way the data is derived!
I make Open-Circuit and Short-Circuit S11 impedance measurements of the
line; from which Zo=SQRT(Zoc.Zsc).
Loss is determined from the input resistance at frequencies where the
line is multiples of a quarter-wave long.
Vf is determined by comparing the physical length with the
multiple-quarter-wave electrical lengths.
At that point the loss model is assumed to be of the form:
Total Loss = k1.SQRT(F) + k2.F
k1 is a coefficient representing the copper loss and k2 represents the
dielectric loss; the two coefficients are determined by best fit to the
measured total loss. As a check, k1 can be calculated directly from the
known RF resistance of the conductors.
Some of the underpinning maths here:
http://www.karinya.net/g3txq/wet_ll/tl_formulas.pdf
Hope that helps,
Steve G3TXQ
On 26/03/2014 12:31, Jim Lux wrote:
An interesting test would be to see if the copper losses go as the
square root of frequency (skin effect) and dielectric losses go
linearly with frequency.
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