It is technically true that the dielectric losses are a little bit
lower than for the same solid material; but dielectric losses aren't
important anyway, so using foam makes almost no difference to the
overall cable loss.


While I have no disagreement with everything else Ian stated, I do take
some exception to the above comment about foam. Just take a look at RG-8
for example. With all other aspects of it remaining the same, there
certainly is a significant difference in loss figures when the dielectric
is changed from solid to foam.


Ed K7AAT