What is the primary communication method utilized in low frequencies?

The primary communication method utilized in low frequencies is ground wave propagation. This occurs when radio waves travel along the surface of the Earth. Ground waves are particularly effective at low frequencies, as they can diffract around obstacles and continue to propagate over the horizon, making them suitable for long-distance communication in this frequency range.

In contrast, sky wave propagation, while also effective for radio communication, typically pertains to higher frequencies that can be reflected off the ionosphere. Multipath wave refers to signals that arrive at a receiver via multiple paths due to reflections off various surfaces, which can apply to various frequency ranges but is not a specific method like ground wave is. Lastly, line of sight wave propagation primarily pertains to higher frequencies, where the waves travel in a straight path from transmitter to receiver without obstruction. Therefore, ground wave propagation is uniquely suited to leveraging the characteristics of low frequencies for effective communication.