Economical Methods for Calculating LF and VLF Ionospheric Attenuation Based on Wave Theory.
A companion Memorandum to RM-5249-PR, "LF and VLF Reflection Loss in the Lower Ionosphere: A Theorem on Absorption and Its Application," demonstrating the usefulness of its methods. An analysis is made of a National Bureau of Standards publication in which L. A. Berry compared different methods of calculating the transmission loss caused by nuclear detonation, including the 1964 Crain and Booker method (RM-4031). The cases used in Berry's comparison were recalculated by the improved Booker-Crain method of RM-5249, in which an empirical constant was refined, and an alternative procedure from the same Memorandum was used to check the results. For profiles usually encountered in a nuclear environment the methods are reliable and economical, but care should be taken in applying them to profiles that are not basically exponential in character. 25 pp. Refs.