Butrym O. Mode expansions in wideband problems of electromagnetics

The thesis is devoted to issues united by the concept of electromagnetic field expansion into superposition of spatial configurations - "modes". The consideration is performed in the time domain that allows studying ultrawideband processes (pulse signals) in natural and efficient way. A new scientific field of research was developed for studying wave guiding systems with transverse inhomogeneous filling in different configurations by building methods for mode expansions in time domain based on a more general technique of partial variables separation in Maxwell equations. The new method was applied to build analytic-numerical schemes for solving a row of problems in cylindrical and conical arrangements and for open waveguide structures. A new numerical-analytical method based on mode matching in time domain is proposed for modeling processes of pulse signal diffraction on waveguide junctions. Several new physical effects were revealed and analyzed: a pulse surface wave, that propagates along a dielectric waveguide with a speed of light in free space keeping its spatial skeleton unchanged; oscillations of surface and volumetric charges that occur under incidence of pulse E-wave on interface of conducting medium in a waveguide; anomalous absorption in thin conducting filaments. Several new methods for spatial and time-frequency filtering signals that are met in problems of magnetocardiog-raphy are proposed.