Hams are mostly interested in the space wave radiated by an antenna system. The NEC4.2 plots below show how the space wave and ground wave fields launched by a vertical monopole are related to each other, over a range of r-f loss in the buried radial systems used with that monopole. Loss in that r-f ground connection directly affects the fields a vertical monopole radiates at all elevation angles below the zenith, including the horizontal plane. Space wave fields decay at a 1/r rate. Ground wave fields decay at greater than a 1/r rate due to the added propagation loss where the radiated field encounters a lossy ground plane (the Earth). The plots below show the fields close to the radiator, where propagation loss for the ground wave is very nearly the same as for the space wave. For long propagation paths, high frequencies and less than perfect Earth conductivity, the magnitude of the ground wave field is so low as to have no practical use. This is the condition shown by NEC and other MoM software when plotting the far-field (only) patterns of a vertical monopole over real earth, for infinitely long paths over a flat ground plane. This relationship between the space wave and ground wave fields is the reason that such ground wave field analyses are (or should be) valuable to hams. Also note that the greatest field actually launched by each of the systems in the graphic below always occurs in the horizontal plane -- not at some "takeoff angle" above it.