Selected problems in the theory of electromagnetic radiation

Electromagnetic interactions in space-time dependent media are investigated with applications to sinusoidal periodic dielectrics and plasmas and with the display of numerous radiation patterns. The coupled wave and Floquet approaches to periodic waveguides are compared and applied to distributed feedback lasers. Transient radiation problems are solved for a variety of systems - e.g. the cylindrical monopole by the Wiener-Hopf technique, infinitely long and finite cylindrical antennas, loop antennas by varied heuristic procedures; strong electromagnetic pulses at the boundary of a nonlinear plasma; and radiation of electromagnetic waves from oscillating sources in a suddenly created plasma. Models for transition radiation are investigated. New methods are developed for electromagnetic field calculations - the nonuniform lossless transmission line is treated by introducing a nonorthogonal warped coordinate system; a differential geometry scaling method is devised and applied to coaxial waveguide structures; and a shielding theory is constructed for metallic enclosures with apertures. The inverse scattering algorithm is derived and applied to calculating the electron density profile of the ionospheric plasma.