You've got to be careful with cause and effect. There's not a direct
correspondence between loss and characteristic reactance.

A transmission line can be very lossy, yet have a completely real
characteristic impedance. Such a line doesn't have any reactance term in
its characteristic impedance to "account for" its loss. To learn more
about these, look up "distortionless line" in the index of your favorite
transmission line text.

The converse, however, isn't true. Any line which has a reactive Z0 does
have loss. You can find the equations needed to calculate Z0 and loss
coefficient alpha from R, G, L, and C in _Reference Data for Radio
Engineers_. Deriving from them an equation directly relating alpha and
Z0 should give you something to do for a number of long winter evenings.
Maybe even give you a break from thinking about waves of average power
bouncing about.

Roy Lewallen, W7EL

Cecil Moore wrote:
David Robbins wrote:

"Cecil Moore" wrote:

Does (R+jXL)/(G+jXC) really equal 2500 for RG-174 on 12m? The specs
say the Z0 of RG-174 is a nominal 50 ohms.


of course its not exactly 2500, otherwise there would be no loss. but
its
close, maybe 2500+j10 or something like that. and even the resistive
part
may not be exact, the nominal 50 ohms could be 45 to 55 depending on the
tolerances of the manufacturer.


Comparing the 6dB loss of RG-174 to the 0.14 dB loss for hardline -
is all that extra loss accounted for in the +j10 term?