since most of the loss in practical coax cables is due to I^2R loss
(compared to V^2G)

A quick question. If most of the the cable loss is due to I^2R, how can one
explain that the foam versions of common coaxial cables show a much lower loss
than versions having solid PE insulation?

For instance RG-213 is rated at 8.5dB loss for 100 meters at 144 MHz, while
RG-213 foam at only 4.5 dB. If G is relatively unimportant with regard to loss,
how can one explain that a change of insulation material yields such a
tremendous change in loss?

Thanks and 73

Tiony I0JX