ve2pid wrote:
In other words, will both of these type of lines have about the same
loss to natural environment objects or is one more sensible than the
other?

If no common-mode currents exist on the coax, it will
be impervious to environmental losses. Under ideal
conditions, 100% of the energy fields are confined
inside the coax. That is not true for ladder-line whose
fields around the wires should be kept some distance
from environmental objects.
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73, Cecil http://www.w5dxp.com