[NLRS] 10 GHz Rain Scatter Question

[Dr. Gerald N. Johnson]

On Mon, 2007-04-23 at 01:13 -0500, Bruce Richardson wrote:
> 
> Hi Scott:
> 
> Thanks for the Blue Angels link.  Sad.
> 
> I was initially going to just send this to you, but I really would like
> to hear W0ZQ's, WA2VOI's, and others thoughts.
> 
> Well, I don't think we ever tried 10mw on Rainscatter because we thought
> it wouldn't be possible. You know, volume of space illuminated, distance
> traveled, attenuation, etc. If you take 10mw and distribute it over a
> rain shaft 20-70 miles away, you're probably illuminating on both sides
> of the shaft. Plus, if you're illuminating from 10,000' to 30,000 feet,
> the actual energy being picked up by the droplets is pretty small for
> re-radiation.
> 
> BUT......... Sigs sure have been strong coming back, at times, now that
> we are playing with 2 watts.
> 
> Let me pause and do some db math comparing 10mw to 2 watts......10 20 40
> 80 160 320 640 1280....2000
> 
> That's 10dBm to 33dBm -- a difference of 23db-- so you could understand
> that they might not hear you if you hear their 2 watts.  That's just 4 S
> units on some scales.
> 
> 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 must tell you that I did my first rainscatter when I had 400mw. (still
> need to finish those qualcomm amp boards :-) )
> 
> Pending other responses, I hope you end up trying and are successful. It
> would prove 10mw IS possible when a bigger station probes and illuminates
> the best shafts.
> 
> 73
> Bruce (in Seattle at the moment)
> W9FZ

Its possible a larger dish will make up for some of the lower power if
it doesn't narrow the scattering volume too much and it should help
receiving too. It does tend to get clumsy for roving going past 6'

73, Jerry, K0CQ