The purpose of this Note is to outline and numerically illustrate the essential details of a fully three-dimensional method of calculating the radiated electromagnetic signal from magnetic deflections of a distribution of Compton electrons produced in the upper atmosphere by prompt gamma radiation from a high-altitude nuclear detonation. The three-dimensional method evaluates the radiation fields (at a given time) from individual electrons. It uses Lienard-Wiechert potentials and sums the fields from all the spatially distributed electrons which contribute to the observer field at a given time. Section II gives details of the principal steps of the electron field summation methods of EMP calculation. For simplicity in presenting the method, vertical geometry and a magnetic field perpendicular to the burst/observer path are used, and numerical values are illustrated for all steps in the development of the method.
Crain, Cullen M., Calculation of Radiated Signals from High-Altitude Nuclear Detonations by Use of a Three-Dimensional Distribution of Compton Electrons. Santa Monica, CA: RAND Corporation, 1982. https://www.rand.org/pubs/notes/N1845.html.
Crain, Cullen M., Calculation of Radiated Signals from High-Altitude Nuclear Detonations by Use of a Three-Dimensional Distribution of Compton Electrons, Santa Monica, Calif.: RAND Corporation, N-1845-ARPA, 1982. As of January 13, 2022: https://www.rand.org/pubs/notes/N1845.html