[NLRS] 10 GHz Rain Scatter Question

[Dr. Gerald N. Johnson]

On Mon, 2007-04-23 at 11:41 -0400, Glen Overby wrote:
> 
> 
> Bruce in Seattle wrote:
> > Now I think I remember why we didn't try it when we all were 10mw--it
> > would have been like looking through pin-hole lenses in a cave.
> > (Someone, help me with another analogy here :-) )  But I think players
> > SHOULD try with 10mw when the other stations have 2w or more. Sure, they
> > may not hear you.  But they might. And you will hear them and peak up on
> > the brightest specular highlight on the rain you are commonly
> > illuminating.
> 
> I believe I had the opposite experience this winter.  I worked W9FZ on snow
> scatter from home.  Bruce reported that my signal (8W) was loud, while his
> (2W) wasn't moving my S meter, but was quite copyable on CW.  Then I tried
> working K0SHF (2W) who also heard me at S9+, but who I maybe heard one blip.
> It sure seemed like my 8W was making the difference.
> 
> Glen
> 
Radar echoes from snow are generally considerably weaker than from rain
and rain is far weaker than from hail. So I'd expect scattering to be
the same. Low power should work the best on a super cell containing
hail. These show up on weather radar with the most intense echoes and
sometimes showing a bright spot beyond the cell from the radar where the
hail reflects the incident beam to the ground and that echo back to the
radar. Yes hail gives a strong refraction and echo. The right hail high
in a super cell may give sporadic E style scattering on 10 GHz.

In radar sensitivity, snow runs from -30 to +10 dBz, rain from +10 to
+80 dBz, hail +80 and up. And changes in density give stronger echoes (0
to 15 dBz) than snow which makes it really hard to automatically show
only precip on a radar display.
-- 
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer