The ability to communicate with Voyager is a function of the transmission and reception system. We have to send an incredibly focused transmission to Voyager fo

The ability to communicate with Voyager is a function of the transmission and reception system. We have to send an incredibly focused transmission to Voyager for it to pick up our signal and listen with very sensitive instruments on a long temporal baseline to detect Voyager's signals. The inverse square law tells you that the flux of a signal decreases at a square of the distance. A receiver 2 miles away from a transmitter will receive a signal at a quarter of the strength of a receiver only a mile away. Our broadband omnidirectional broadcasts don't actually reach very far out into the solar system let alone the galaxy. Only very powerful narrowband signals reach very far and those are very directional.