
Accession Number : AD0678869
Title : EXACT SOLUTION FOR THE PROPAGATION OF ELECTROMAGNETIC PULSES OVER A HIGHLY CONDUCTING SPHERICAL EARTH,
Corporate Author : RAND CORP SANTA MONICA CALIF
Personal Author(s) : Sollfrey,W.
Report Date : OCT 1968
Pagination or Media Count : 55
Abstract : The report presents an analytic solution for the propagation of electromagnetic pulses by ground waves, a problem previously treated by the saddlepoint method or numerical integration. In this study, the various integrals are evaluated exactly. First the problem is formulated and the limitations of the saddlepoint method are discussed. Then the required integrals are evaluated exactly as products of Airy functions. Detailed results are worked out for a step and ramp source; the technique is also applied to a waveform of nuclear origin that had previously been investigated by numerical integration. The step and ramp function responses are shown to be well approximated by a single mode for early and intermediate times. The saddlepoint approximation is valid only for times before the peak, but is a good approximation out to 50 times that duration. At late times, the singlemode exact response goes through zero, reaches a broad negative maximum, and then returns slowly to zero, while the saddlepoint single mode and the mode sum responses remain positive; the ramp function displays corresponding behavior. For the nuclear waveform, the exact curves have the same general character and about the same peak values as the numerical integration results, but the exact curves consistently display a faster time scale, and the spectrum peaks at a higher frequency. (Author)
Descriptors : (*ELECTROMAGNETIC PULSES, PROPAGATION), (*NUCLEAR EXPLOSIONS, ELECTROMAGNETIC PULSES), RADIO WAVES, STEEPEST DESCENT METHOD, INTEGRALS, SPECIAL FUNCTIONS(MATHEMATICAL), CORRELATION TECHNIQUES, EARTH(PLANET)
Subject Categories : Nuclear Weapons
Distribution Statement : APPROVED FOR PUBLIC RELEASE