Hello,

Hope you are doing well.

As per your question:-

1) Ground wave propagation:-it is a type of radio propagation which is also known as a surface wave. These waves propagate over the earth’s surface in low and medium frequencies. These are mainly used for transmission between the surface of the earth and the ionosphere. These are made up of the number of constituent waves.

2) sky wave propagation :-it is also known as the skip is a type of radio wave propagation. It is either the reflected or refracted back waves to the earth from the ionosphere which is an electrically charged layer of the upper atmosphere.Medium and shortwave frequencies can be refracted back to earth which is beyond the horizon which makes them useful in the transcontinental transmission of the waves.

3) space wave propagation:-space waves are the radio waves of very high frequency ( between 30 MHz to 300 MHz or more). The space waves can travel through atmosphere from transmitter antenna to receiver antenna either directly or after reflection from ground in the earth's stratosphere region.

hope this information helps you and clear your concept regarding these all terms.

Thank you.