Question

What is skip distance?

Answer 1

Hint : Skip distance is a term pertaining to sky waves (in contrast with ground waves) in radio frequency propagation. When a transmitter sends a radio frequency wave into the sky (always at an angle), it takes some time to reach the atmosphere and get reflected back to the receiver.

Complete step by step answer
For radio wave frequency signals (or waves propagation), there are two methods in which it can be done. One is to transmit it along the ground and another is to transmit it using an upper atmosphere called the ionosphere. The waves travelling along the ground are called ground waves, while the ones sent to the ionosphere are called sky waves.
Ground waves – when a local radio station for an example wants to transmit its message, mostly, it allows the transmitter to send a wave parallel to the ground to locate any receiver in its path. The waves are called ground waves. However, ground waves don’t go very far, they are absorbed by the environment, and generally reduce intensity as they move away from the source. The higher the frequency the faster the frequency drops.
Sky waves – when large distances are involved like say global transmission, sky waves are used. The transmitter transmits the wave to the sky at an angle to the vertical. These transmitted waves get to the ionosphere and get reflected back to the ground forming a path similar to a triangle. The distance between the transmitter and the point of reception, where the waves returned to the earth is called the skip distance.
The skip distance can be defined as the minimum distance between the point of transmission and the point of reception of a sky wave.

Note
For clarity, we say minimum because, when a sky wave is sent, not all the waves are reflected or refracted back at the same surface (some go farther than others before reflection). This allows some of the radio waves to have a shorter distance from transmission than others. But the skip distance is considered the minimum i.e. the distance of the reception from the transmission of the wave with the shortest path.