Effects of propagation on the high-frequency electromagnetic radiation from low-altitude nuclear explosions

The high-frequency electromagnetic pulse radiation from nuclear explosions presents a possible detection mechanism. This paper first considers the selective attenuation of the higher-frequency components of the pulse when it travels via ground wave, and shows how the waveform is modified with distance. Effects of the height of the source are included. Propagation via sky wave is investigated, and it is demonstrated that ionospheric dispersion considerably stretches the pulse for reasonable propagation distances. The receiver bandwidth should be selected to match the ionospheric dispersion at the receiver frequency.