[amsat-bb] Re: Comparison Quadrifiar verses TMP ll

Robert Bruninga bruninga at usna.edu
Mon Nov 20 12:57:00 PST 2006

> If you go with a larger beam, anything more than 
> 3 or 4 elements, you will likely need an elevation rotor 
> as well, but this is a configuration more suited to HEOs 
> than LEOs.  

To amplify on that, for LEO's you don't need an elevation
rotator for beams of several elements probablly up to 8 or more
elements because 67% of all the times the satellite is in view,
it is below 20 degrees anyway.  It is only above 45 degrees less
than 5% of the time.  It is only above 60 deg 2% of all possible
time, so just mount the beam up at about 10 degrees and you will
get maximum gain down on the horizon up to about 40 degrees
where you need it most when the satellite is far away (95% of
the time).  When it is above 45 degrees it is 10 dB closer to
you anyway, and you can afford to be offpointed a bit.

> 73,
> Jerry, M0GOE
> ----- Original Message -----
> From: "Norman W Osborne VE3CJE" <nwosborne at shaw.ca>
> To: <amsat-bb at amsat.org>
> Sent: Friday, November 17, 2006 5:09 PM
> Subject: [amsat-bb] Comparison Quadrifiar verses TMP ll
> > Just wondering, how the comparison of Texas Potato Mashers 
> ll verses the
> > Quadrifilar Helix
> > for Leo's. Both with the ability to switch RHCP and LHCP
> >
> > Norman.
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