[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

RE: Primestar dishes



Since the Primestar system used a domestic Ku band satellite in the FSS 
service, the dish as it stands has a feed built for linear polarization and 
a minimum bandwidth of 11.7 Ghz to 12.2 Ghz.  My guess is that it will 
probably work pretty good down to high end of 10 Ghz. Unfortunately, the 
LNB and feed are probably integrated to form an LNBF, meaning that you just 
cant remove the LNB. It may be possible to modify the LNBF for amature 
frequencies.

There is no reason the Primestar antennas will not work on S band, provided 
an appropriate feed can be worked out. Two things are going to make that a 
little difficult. The first is that the antenna is elliptical, so the feed 
needs to have an asymetric illumination pattern. The second is that the 
antenna is an offset parabaloid, not a conventional parabola. This makes 
finding the focal point a little tough. If you can get the S band feed in 
about the same location and geometry as the original Ku feed, it should 
work OK.  With all the talk on this reflector concerning polarization 
effects, it should be noted that the asymetrical shape of the antenna will 
also cause it to have asymetrical gain. Even if the feed was circular, the 
gain would have an elliptical pattern, resulting in selective polarization 
fading. If you have enough gain to cover the fade, no big deal.


Howie
AB2S

----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home