Thanks Domenico for the reply. You are correct the physical temperature and the equivalent noise temperature are not related. Bob wb4apr suggested that a 1/4 wave antenna in LEO has a noise equivalent temperature of ~ 150 k . What is the consensus of the group ? We are trying to do an uplink budget and one of the variables is the system temperature.
nick -----Original Message----- From: i8cvs [mailto:domenico.i8...@tin.it] Sent: Monday, September 10, 2012 4:32 PM To: Nick Pugh; Amsat - BBs Subject: Re: [amsat-bb] Re: e: Satellite technical question Hi Nick , The equivalent noise temperature of an antenna do not depends by it's phisical temperature but only by the noise temperature emitted by the object that the main lobe of the antenna is looking. The equivalent noise temperature of the antenna radiation resistance do not depends by the phisical temperature of the antenna but only by the noise temperature emitted by the object that the main lobe of the antenna is looking. As an example, if you install a parabolic dish on the Nort Pool at very low temperature and a similar parabolic dish in the desert at the equator at high temperature and you point both the antennas toward the Sun than the received Sun Noise will be the same no matter the structural temperature of both dishes will be. Of coarse only the phisical temperature of the antenna preamplifiers and all the associated receivers phisical temperature must be the same. 73" de i8CVS Domenico ----- Original Message ----- From: "Nick Pugh" <quadp...@bellsouth.net> To: "'Nick Pugh'" <quadp...@bellsouth.net>; <amsat-bb@amsat.org> Sent: Sunday, September 09, 2012 8:15 PM Subject: [amsat-bb] Re: e: Satellite technical question I am sorry I did not mean the physical temperature What I wanted is the equivalent noise temperature. Thanks for those who replied nick -----Original Message----- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Nick Pugh Sent: Sunday, September 09, 2012 10:07 AM To: amsat-bb@amsat.org Subject: [amsat-bb] e: Satellite technical question e: Satellite technical question Assume a cubesat with a monopole ΒΌ wave antenna at 400 mhz. The satellite is in full sun with a 500km orbit. What is the antenna temperature in full sun and in eclipse? TNX in advance Nick CAPE Team _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
