long waves can travel around the surface of the earth in a curve, this is
caused by a form of refraction
long waves require big arials otherwise they won't transmit, arial size is
proportional to wavelengh
small arials only transmit high frequencies, hence
very small arials only transmit microwaves and that makes them line of site
as microwaves travel in straight lines,
the power necessary to get a signal 2 meters away from a transmitter is four
times as much as for 1 meter.
you can imagine how much power would be required to send a signal to a
in a grain if rice???