[amsat-bb] Re: New Preamp

Edward Cole kl7uw at acsalaska.net
Wed Sep 19 23:14:49 PDT 2007

I'll need to revisit these as it has been awhile since I looked in my 
Microwave Exp. Handbook.

I will make one comment on the noise temperature formula that Bob 
Atkins shows in his article.  There several terms left out making the 
formula under-estimate noise temp. for cascaded stages 
of  receiver.  I puzzled over this long and hard back in late 1990's 
and finally modified the formula to include the missing terms.  You 
can see the corrected formula by downloading the spreadsheet:

This spreadsheet will calculate effective receiver noise temp for a 
cascade of three receiver stages, then estimate the total system 
noise temp.  With that one can enter antenna, transmitter, and 
feedline losses to arrive at eme link performance.  Note this program 
is limited accuracy to under 500-MHz.  For an expanded formula 
appropriate for mw frequencies see:
http://www.kl7uw.com/emeOVROcalc.htm  shows the derivation of the mw version

73 Ed - KL7UW

At 02:21 PM 9/19/2007, i8cvs wrote:
>----- Original Message -----
>From: <k0vty at juno.com>
>To: <kl7uw at acsalaska.net>; <domenico.i8cvs at tin.it>; <amsat-bb at amsat.org>
>Sent: Wednesday, September 19, 2007 6:53 PM
>Subject: Re: [amsat-bb] Re: New Preamp
> > Thanks to Dom and Ed.
> >
> > From you two gentlemen, a few words please on field proofing antenna
> > systems using sun noise and a EME signal should add nicely to this
> > discussion.
> >
> > Joe  K0VTY
> > Amsat #860
>Hi Joe, K0VTY
>About this matter the best I can suggest is to read the following
>"Noise Temperature,Antenna Temperature and Sun Noise "
>by Bob Atkins, KA1GT
>"Microwave Systems Calibration Using the Sun and Moon"
>by David B. Shaffer, W8MIF
>Both articles are published in the ARRL UHF/Microwave
>Experimenter's Manual ARRL Order No. 3126
>73" de
>i8CVS Domenico

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 at hotmail.com

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