Unlike XM, Sirius does not use GEO satellites. Instead, its three
SS/L-1300 satellites form an inclined elliptical satellite
constellation. Sirius says the elliptical path of its satellite
constellation ensures that each satellite spends about 16 hours a day
over the continental United States, with at least one satellite over the
country at all times. Sirius completed its three-satellite constellation
on November 30, 2000. A fourth satellite will remain on the ground,
ready to be launched if any of the three active satellites encounter
transmission problems.
http://search.netscape.com/ns/boomfr...ite-radio3.htm
Larry W4CSC wrote:

krj wrote in
:


Using an antenna on a dish would work for XM if you put the feed at the
correct focal point for C band (DirectTV and Dish are Ku band), but
would be a problem for Sirius because their three satellites are not
GEO. They are LEO in an eliptical orbit so you would need the latest
Keplers and a tracking antenna. Also they are at 2.3 Ghz.
krj



If Sirius' birds were LEO and they only had 3 of them, you'd only have
service in three 8 minute periods per 90 minute orbits, but only if those
changing orbits caused by the earth's rotation were to happen to have you
in their footprint. No, Sirius is Geosynchronous, too.

You are right about the 2.3G on the C-band dish, but there would be some
reflection. I'd bet the excellent TV hackers across the Caribbean at fixed
locations have some big dishes pointed to XM or Sirius birds to get enough
signal for a lock on exotic islands.