Why are uplink dishes so big?

[Gav]

I remember seeing something about a dish on braniac, up linking to 28.2 east, seems fair enough, but the dish seemed huge - especially when you consider you only need a 43cm dish to pick up sky.

Any ideas why this is

[BGonaSTICK]

That's a good question.

Maybe it's required to provide the huge bandwidth that's needed?

Smaller dishes can be used to uplink though, as in two-way satellite broadband systems. It would be nice to hear from someone with some specialist knowledge.

[$ly]

How do you know they are uplinking I wonder?. It would make better sense to have the uplink antenna smaller than the other way round, as we have less power limitations down here.

Any particular sites in mind, we can look'em up if you like




L.

[bigtee]

From Wiki

Uplink satellite dishes are very large, as much as 9 to 12 meters (30 to 40 feet) in diameter. The increased diameter results in more accurate aiming and increased signal strength at the satellite. The uplink dish is pointed toward a specific satellite and the uplinked signals are transmitted within a specific frequency range, so as to be received by one of the transponders tuned to that frequency range aboard that satellite.

_http://en.wikipedia.org/wiki/Satellite_television

[BGonaSTICK]

Nice find

One uplink dish per uplink transponder? Then a frequency change before downlink... You learn something new every day...

Maybe that's not the whole story, but it goes some way to explaining things I guess.

[$ly]

Uplink frequencies are normally a couple of gigs higher than the downlinks we see.


L.

[Analoguesat]

Originally Posted by Lancelot

Uplink frequencies are normally a couple of gigs higher than the downlinks we see.


L.

Yup - for example Astra 1A uplink details were 14.25-14.5 GHz

[BGonaSTICK]

And is it really one dish for each uplink transponder? That would be a stupid number of dishes for the big providers if there were as many uplink transponders as downlink... :?