Owen Duffy wrote in
:

....
If you use my calculator (link in earlier posting), it gives you the
coefficients of two terms of the loss model, one is due to I^2R and
the other V^2G. You can evaluate them at any given frequency and
determine the contribution that conductor and dielectric losses make
at that frequency for that cable type.

Lest someone confuses this with an incorrect calculation or estimate:

From TLLC, the matched line loss in dB of LMR400 (a foam coax of similar
OD to RG213) is 3.941e-6*f^0.5+1.031e-11*f. The first term is due to R
and the second due to G.

At 144MHz, the percentage of power lost per meter due to R is (1-10^-
(3.941e-6*f^0.5)/10)*100 is 1.08%. If you do similar for G, the loss is
0.034%, so loss in R is more than 30 times loss in G.

The numbers lead to a better understanding.

Does this make sense? Did I get it correct?

Owen

(BTW for RG213 at 144MHz, the percentage of power lost per meter due to R
is more than 6 times loss in G. Most of the loss advantage of LMR400
comes from reduction of the R loss component per metre from 1.6% to 1.1%
due to the larger diameter inner conductor.)


Owen