The Effects of a Low-Altitude Nuclear Burst on Millimeter Wave Propagation
ROME AIR DEVELOPMENT CENTER GRIFFISS AFB NY
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The main objective of this paper is to examine the limitations imposed on millimeter wave propagation by the dust produced by a low altitude nuclear burst. The closer the burst is to the surface, the larger will be the dust loaded into the nuclear fireball, a extremely hot and high ionized spherical mass of air and geasous weapons residues. The fireball absorbs, scatters and refracts the propagated wave amy also produce scintallations. In this study, only losses due to absorption and scattering are calculated. Since there is great of uncertainty as to how representative the dust model is of the true nuclear environment, a sensitivity analysis of attenuation dependence on the pertinent dust parameters was first conducted. It was found tht the dust attenuation is very heavily dependent on the maximum particle radius, the number of large particles in the distribution and the real and imaginary components of the index of refraction over the range from dry sand to clay. The attenuation is also proportional to the fraction of the atmosphere filled with dust. The total attenuation produced by a 1 megation burst at the surface is then computed using the WESCOM code. The attenuation includes losses due to fireball ionization, dust and atmospheric oxygen and water vapor. Results are obtained as a function of time after burst, distance from burst, elevation angle and frequency up to 95 GHz. It is found that very high attenuations occur within about 20 seconds after the burst if the path intersects the fireball. At later times attenuations of the order of tens of dB are present. Oxygen and water vapor attenuations are typically less than one dB in the window regions.
- Radiofrequency Wave Propagation