There is a beamwidth associated with a parabolic antenna's size and operating frequency. The attitude of a spacecraft is periodically corrected to keep earth wi

There is a beamwidth associated with a parabolic antenna's size and operating frequency. The attitude of a spacecraft is periodically corrected to keep earth within the beam's central lobe. It's approximate so corrections aren't required too frequently and become less of an issue as Voyager gets further away from earth's orbit around the sun. Once it's out of propellant it won't be able to correct for torque from the solar wind etc and the high gain antenna's central lobe will drift until its no longer pointing close enough to maintain an acceptable signal to noise ratio. Unless they can maintain contact through the omnidirectional antenna, Voyager will be effectively lost.