From all the responses, I got a lot to think about. Thanks.
I got the impression that resistance in the wires is the main cause for loss
in a transmission line.
NOTE: I recall some line having much higher losses at higher frequencies.
(so substitute x for R ??)
Another note - I noticed some coax has different capacitance rating per ft.
depending on the type and brand, etc.
(I thought about using a length of coax for a capacitor in a trap at one
time).
Question: could some of this loss be caused by the capacitance in the line ?