[net.space] "shadowing" of satellites in GEO ...

henry@utzoo.UUCP (Henry Spencer) (01/02/86)

> Earth  station  operators  (like the plant I work at) already have to put up
> with  such  interference.  A few  (predictable)  times  a year,  the  SUN is
> directly behind the satellite we use for video conferencing.  The sun, being
> a prodigious radio source, wipes out the signal for about ten minutes.

Point of curiosity:  given that your receiver (okay, picky picky, your LNA)
is at the focus of a roughly parabolic antenna, how do you avoid having the
Sun fry the receiver?  I assume that you aren't moving the antenna to dodge
the sun, since antennas for geosynch satellites generally aren't fitted with
that flexible a mount.  Does it suffice to be careful about the infrared
reflectivity of the dish surface?
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry

bp@nyit.UUCP (Bruce Perens) (01/06/86)

> how do you avoid having the
> Sun fry the receiver?
> 				Henry Spencer @ U of Toronto Zoology

Infrared, having a shorter wavelength than microwave radio, is
DIFFUSED by the finish on most dishes. If you polished an unpainted
aluminum dish, this would become a problem. I would think the usual coat
of white paint is enough to eliminate the possibility of having your
radio dish act as a solar power plant.

				Bruce Perens
				decvax!philabs!nyit!bp