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 ======================================
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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participants (2)
-
Edward Cole -
Roger Kolakowski