The use of HF surface wave radar as an effective method for inspecting the environment of the ocean in the beyond-the-horizon area has been developing in recent years. However, because the radiating beam of the transmitting antenna is of a certain width and its electromagnetic radiating power propagates not only along the sea surface but also to the upper space, as a result, after interacting with the ionosphere or a scattering object on its path, the backscattered signal then returns to the radar along the radiative path. Thus, if we analyze the echo signal received by the radar, we can obtain some information about the ionosphere. This paper presents a method of sensing the ionosphere using HF ground wave radar, which can give information about the altitude of the ionosphere, Doppler, meteor showers, etc.