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Re: FW: ARLB013 ARRL aiding effort to mitigaterepeaterinterference to military radars



Hi Ed et al...

The situation you propose is extremely relevant...if your signal is aimed
above the horizon, it should not interfere with celestial receivers...this
is a factor that any negotiations with the military to take into account.

At UHF frequencies, the spectrum is no longer defined by frequency but is
defined by interference which can be eliminated with some effort on both
ends of the chain. Directional transmission can solve many of these issues.

Roger
WA1KAT


----- Original Message ----- 
From: "Edward Cole" <kl7uw@acsalaska.net>
To: "Margaret Leber" <maggie@voicenet.com>
Cc: <amsat-bb@amsat.org>
Sent: Tuesday, April 24, 2007 11:12 PM
Subject: [amsat-bb] Re: FW: ARLB013 ARRL aiding effort to mitigate
repeaterinterference to military radars


> Yeah, I thought about that.  If your antenna has 20-dB gain, like my
> eme array has, it has a 3-dB beamwidth of 20-deg.  So at elev. 20 I
> could transmit 10w and only have 5w on the horizon.  Restricting my
> satellite operation above 20-deg. would be needed.  If you ran 25w,
> you would be restricted to above 40-deg.  But didn't someone say that
> most satellite passes are below 40-degrees?  How many folks use eme
> arrays for satellites?
>
> Now if you uplink on 5.7 GHz with a 3-foot dish then beamwidth is
> 4-deg. with 33-dB gain.  Your EIRP is 5w x 2000 = 10 kw  ...kind of
> shows the advantages of mw for space comm.
>
> I know I have definitely gone off topic...but it gives one something
> to think about.
>
> 73 Ed
>
> At 07:36 AM 4/24/2007, Margaret Leber wrote:
> >On 4/24/07, Edward Cole <kl7uw@acsalaska.net> wrote:
> >
> >>Build satellites that require no more than 5w EIRP from the ground
> >>station may be the only answer.
> >
> >Or transmit with a more directional antenna aimed skyward...which is
> >not a practical solution for terrestrial repeaters.
> >
> >--
> >73 de Maggie K3XS
> >Editor, Phil-Mont Mobile Radio Club Blurb - http://www.phil-mont.org
> >Elecraft K2 #1641 -- AOPA 925383 -- ARRL 39280
>
> 73,
> Ed - KL7UW
> ======================================
>   BP40IQ   50-MHz - 10-GHz   www.kl7uw.com
> 144-EME: FT-847, mgf-1801, 4x-xpol-20, 185w
> DUBUS Magazine USA Rep dubususa@hotmail.com
> ======================================
>
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