The majority of satellites are solar powered but not all of them.

Just like space probes, many have been equipped with radioisotope thermoelectric generators.

A good example is the u.s Nimbus satellite program.

Such RTG's either use the nuclear decay heat of Cobalt 60, Strontium 90 , Ruthenium 106 , Caesium 137, Cer 144, Promethium 147, Thulium 170, Polonium 210 (the stuff that killed that russian guy),
Plutonium 238, Curium 242 , Curium 244 or Americium 241 to produce electricty and usally work for decades.

Needless to say thats modern satellites rather rely on solar power. The Nimbus 1 satellite crashed into sea near the californian coast in 1968, its RTG was recovered and found to be intact. Nonetheless incidents like this led to a slow phase out of RTG's as energy source for earth orbiting satellites.

Its a bit the same as with the glorious idea to simply put all radioactive waste of this world into rockets and fire them into the sun to get rid of that stuff once and for all.
Nice idea but sadly rockets explode from time to time. What would happen if a rocket with several tons of highly radioactive waste explodes on its way ?

Nobody wants tons of highly toxic and radioactive material to fall on his house. People dont want to have pieces of nuclear powered satellites to fall on them either.
So solar power is the prefered energy source for satellites today. No new ones are being built but lots of very old RTG powered ones are orbiting our earth as dangerous space trash.

But space probes like the u.s Voyagers or the european Cassini-Huygens probes all utilize Plutonium RTG's for obvious reasons.

No, you don't understand how radios work, do you? Satellites aren't involved unless you're trying to beam a signal to the other side of the world.

Radios were in use long before man-made satellites were ever launched.

There were satellites left. The games didn't hint at the communications rigs surviving, but they would've been there. The earth-based equipment would've been EMP'd Goldeneye-style by 5-mile altitude nuclear airbursts to kill any civilian comms or power grids. Then again, if that were the case, you couldn't reach a satellite unless you had intact or rad-shielded equipment on Earth in the first place. Don't forget about Highwater Trousers or the Enclave mini-nuke orbital platforms. They're so fun to play with.