"rickman" wrote in message
...
Looking at the chart of loss vs. frequency for Belden 1694A Coax I see
0.24 dB at 1 MHz, 3 dB at 270 MHz and 6 dB at 1000 MHz. I don't see
any factor for frequency in I^2R. I suppose this could be skin effect
increasing the conductor resistance.

How do you tell when the losses are mostly due to the dielectric?


It is the skin effect of the center conductor mostly up to around 1000 mhz.
Below that the dielectric has very little loss.

There are places that show how to calculat the various losses depending on
the material and frequencies, but the math gets involved.

There is a chart here that shows the relative effect.
https://www.google.com/url?sa=i&rct=...56256383257029