Focusing in the stationary phase approximation

Authors

  • L. J. Nickisch


Abstract

A method for calculating focusing in the stationary phase approximation is presented. By considering variations of Hamilton's equations a set of equations is obtained which, by integration along a single ray, provides information on the convergence or divergence of infinitesimally separated rays. The method applies to three-dimensional ionospheric structure and is shown to be much more accurate than conventional finite flux tube approaches.

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