A consideration of the attenuation of the high-frequency electromagnetic pulse radiation from nuclear explosions when it travels via ground wave. Effects of the height of the source are included. The author finds that selective attenuation of the pulse does occur, with the higher frequency components suffering most. Ionospheric waves suffer relatively little attenuation, but are strongly dispersed, leading to limitation on the pulse length that can be resolved. The receiver bandwidth should be selected to match the ionospheric dispersion at the receiver frequency. It is found that propagation effects will strongly modify the pulse shape and pulse amplitude relative to free space.