Asimov wrote:

Thanks for the info. I had read that submarines communicated in a
band of a few 10's of Hz because of the problems with water. As for
the polar molecules aligning themselves, this implies it takes some
time to achieve. Thus there is a resonnant point in this and if there
is resonnance then there might be anti-resonnance too. Might you know
where this natural molecular resonnance is? Might this be the standard
microwave oven frequency?

Sorry, I don't know. If any of the readers of this newsgroup do, I'd
really appreciate your enlightening us.

Roy Lewallen, W7EL