Eli5: how does voyager send a message 15 billion miles with ~200watts of power and we struggle with cellphones and satellites signals right here on earth?

Question

Eli5: how does voyager send a message 15 billion miles with ~200watts of power and we struggle with cellphones and satellites signals right here on earth?

In: Engineering

Answer 1

We have dedicated radio telescopes that point directly at Voyager. The parabolic shape of the telescopes causes the meager radio waves produced by the probe to become concentrated on a receiver which is then able to pick up the signal. The Voyager probes themselves also have a parabolic transmitter which allows them to send a parallel radio signal to Earth instead of having it radiate in all directions.

Cell phones don’t have enormous parabolic receivers, since that would be very impractical to carry around (the Voyager probes are the size of a bus). Likewise, we can’t put those parabolas on cell towers because they have to process hundreds of signals at once, which would require just as many receivers that need to be pointed at every device. Again, very impractical. Same again with satellites that communicate with satellite phones.