[NLRS] 10 ghz scatter!!???

[Jon Platt]

Pretty interesting stuff, especially given that Gene was 73 miles distant.
If you look at the current upper atmosphere plots from the NWS (called
Skew-T plots) from http://asp1.sbs.ohio-state.edu/skewt.html you can see
that there is a LOT of upper atmosphere "strucuture" with respect to
boundary layers comprised of sudden changes in temperature and sudden
changes in humidity with elevation (on the skew-t plots, the right hand line
is the temperature and the left hand line is the dew point).   Skew-t plots
are taken twice a day by the NWS stations and plot temperatue & humidity vs
altitude.  Does this "structure" provide for boundary layers for scattering
on 5.7 and 10 GHz ?   Got me, .... perhaps someone else would know this.
The evidence would tend to say so.   Try the same experiment in January when
the skew-t plots show very little upper atmospheric boundary structure and
see if you get the same results .... I would bet not.

The good news Mike is that you don't need that 0.2 degree accuracy on the
rotators any more.

73, Jon
W0ZQ


----- Original Message -----
From: "Mike King - KM0T" <scsueepe@mtcnet.net>
To: <nlrs@mailman.qth.net>
Sent: Saturday, August 03, 2002 12:33 AM
Subject: [NLRS] 10 ghz scatter!!???


> Hi all,
>
> Gene, N0DQS and I were testing all the bands tonight in preperation for
the
> UHF contest.  We spent a considerble amount of time ragchewing on 10 and
5.7
> ghz just to get a feel again for how it all was operating.
>
> Gene was in EN22GE, about 73 miles away.  Signals were 5x9+10 to 30 over
on
> 10 ghz and slightly lower on 5.7.  This was holding up very well over the
> course of an hour or so as we ran the other bands, so we kept going back
to
> 10 and 5.7 to see how conditions were changing.
>
> Anyway, I started to screw around with my elevation control and while we
> were on heading with each other, I started to point the dish at the
ground.
> We still copied each other well when my dish was pointed 45 degrees below
> horizon.  So after that, I decided to point the dish up.  I have the rotor
> setup so I can point straight up in the air so I can park the dishes
durning
> windy conditions.
>
> Well, we copied each other all the way up, even when my dish was pointed
> straight up.  Scratching our heads led me to say, "well, if the dish is
> pointed straight up, then I should be able to rotate any direction in
> Azmuith"
>
> I proceeded to rotate around the clock and copy was still managable all
the
> way, thus proving that the dish was straight up.  Not believing this
myself,
> I went outside to check the tower.  Yes indeed, the dish was pointed
> straight up.
>
> We tried 5.7 ghz and experienced the same thing!  Even with 250 milliwatts
> on that band.
>
> The next step was to rotate the antennas back down to the horizon and
start
> swinging my dishes around.  Well that led us to hearing each other almost
> all the way around the clock.  The strongest was when I was pointed
directly
> away from him (other than direct dish heading)  We also heard each other
on
> 5.7 ghz with the 180 degree dish heading away from him.
>
> The best I can figure is that there must have been an inversion up high
and
> that was scattering the signal.  It was 66 degrees here tonight when it
> happened (about 0400utc) from an 85 degree high.  Humidity was not that
high
> here today, pretty comfortable day, one of the nicest of the summer.
>
> Anyway, when I got pointed back on him directly and on horizon, the sigs
> jumped up to 30 over, so I know I was on the right IF and 10 ghz band!  So
> Gene then did the same thing on his side and sure enought, about the same
> was repeatable on his end, the band appeared to be fading abit by that
time.
> Direct heading sigs where then 5x9 on both bands.  Which may account for
not
> as good sigs when he was pointed straight up.  (he has az and el control
on
> his dishes as well.)
>
> One note, while I was pointed straight up with Gene coping me no problem,
he
> rotated off the beam heading and lost me right away, so it looks that at
> least one of us has to point at the other.
>
> So, from now on, I will just point my dish straight up and not worry about
> the dish heading.  I will let the rest of you worry about it :)
>
> Seriously, we will try it again tommorow, my guess is that it will not be
> repeatable when it warms up.
>
> So, any thoughts?  We sure had a good time giving the equipment a workout.
> As for drift, pretty much non-exisitant.  I think with the cooler wx
> ambient, that may be a factor.  The drifting we experienced weeks ago when
> we all worked, it was hotter than you know what!
>
> 73
> Mike - KM0T en13vc
>
>
>
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