On Sat, 13 Jan 2007 08:14:05 -0500, "Robert11"
wrote:

Hello:

I understand that fm signals in the 150 MHz and higher range propagate
pretty much as line of sight.

But, is this also true for AM signals in this frequency range ?

Thanks,
Bob

Actually the MUF (maxiumum usable frequency) is the highest frequency
that propogates beyond line of sight, and the MUF is rarely beyond
about 30Mhz. On very rare occaisons it can get as high as about
60Mhz, but I don't think there is any record of it ever getting beyond
60 Mhz.

In general anything above 30Mhz is line of sight, regardless of the
modulation scheme (and mathematically, narrow band FM and AM are the
same creature). The Modulation scheme has nothing to do with how well
the signal bounces off the ionosphere.