3 Oct 2008
The ARRL Propagation report (link on my website) today reports some interesting findings about very high altitude noctilucent clouds reflecting radar signals, raising the possibility that extreme, INTERCONTINENTAL, UHF/SHF DX might be possible using reflections from such clouds. See
"...the clouds contain ice coated with sodium and iron from micro-meteors and sit at about 53 miles (85 km) altitude, mostly between 50-70 degrees latitude, and sometimes as far south (or north, in the southern hemisphere) as 40 degrees latitude or less.
The clouds are highly reflective of radar signals, and instead of diffraction as we see in ionospheric propagation, ripples in the clouds seem to reflect in unison, reinforcing each other.
Noctilucent clouds are sometimes visible at night, because their altitude is so high that they reflect sunlight into areas of darkness. They are also known as polar mesospheric clouds, and appear most often at twilight during the summer."
Imagine working many thousands of miles on 10GHz QRP by a mesospheric
reflection mode. Now that would be something REALLY different!