S. D. Prijmenko’s research while affiliated with Kharkiv Institute of Physics and Technology and other places

The induced charge and current distribution along the transverse orientation linear antenna, while its surface is intersected by the relativistic point charge, has been calculated. The wave packet of the current with a step and delta-shaped fronts extends along the antenna. A normal component of the transition-radiation electric field is calculated. The normal component of the electric field, having a maximum along the normal to the antenna axis, is distributed in the form of a diverging spherical wave with a delta-shaped front. The uncompensated normal component of the transitionradiation electric field strength in the wave zone is a wave packet of different-polarity delta-shaped pulses. The delta-shaped pulses are related to the relativistic charge radiation itself and to the relativistic charge radiation reflected from the target. The relativistic charge radiation reflected from the target is much higher than the radiation of the relativistic charge itself.

A charge-image model was applied to solve the problem concerning the space-time formation of an electromagnetic field when the boundary between the vacuum and the perfectly conducting half-space is crossed by the point charge particle with a final velocity and acceleration. The cases of normal and oblique incidence of a charge at the boundary are under consideration. In the case of oblique incidence, unlike the normal one, the magnetic dipole “annihilation” at the boundary is observed. The longitudinal electromagnetic wave is formed in the far-field region. This wave has strength component of the potential electric field being normal to the wave front.

The singularity part of the electrical Green's function for a circular cavity field is singled out in an explicit form as a Green's function for the infinite space. The problem of the Green's function construction for a field is solved as a problem of a diffraction of tensor divergent spherical and quasispherical waves on the circular cavity walls The analytical expressions for singular and regular parts of the tensor Green's function and the calculation results of one of its component are given.

Consideration is given to the possibility of realization of the transition radiation antenna. The radiation is formed by relativistic point charge scattering on a metal surface. A plane disk is proposed to be used as a reflector. For the spectrum of a point charge field 0 Hz les f les 1 THz the disk diameter should not exceed 1 m. The discrete character of radiation formation is marked. The antenna is a UWB antenna of a low-level power and can be used in the space-based systems.

The impedance cylindrical surface with a discrete change of the curvature radius is considered. It is shown, that the discrete curvature change leads to the discrete change of the charge surface density, normal component of an electric field intensity and phase velocity of a current wave. The boundary conditions for the surface current density, electric field intensity components and phase velocity in the place of discrete curvature change are formulated.

Singular part of the Green's function of unbounded space is singled out in explicit form and contains all singularities, including a delta-shaped singularity. The problem of construction of Green's function for a field is solved, as a problem for diffraction of potential and rotational components electric field intensity of a point current source on the circular waveguide walls. The singling out of the electric field intensity singularity in an explicit form about a source enables to develop an effective algorithm of Green's function calculation at any distance between the source point and observation point in a circular waveguide.

The electric Green function of a circular short-circuit waveguide with anisotropic plasma has been constructed for the electric-current point source with a singularity, which is singled out in an explicit form as the Green function of an infinite uniaxial anisotropic medium. The regular part of the electric Green function was obtained as a sum of continuous and discrete spectra. The problem of the Green function construction for the point electric current source was solved as a problem of diffraction of ordinary and extraordinary tensor divergent waves on the internal surface of a circular short-circuit waveguide.

A linear impedance antenna of transient radiation exited by the electron bunch scattered on its end face is considered. The radiation is analyzed at the stage of a bunch approach to the antenna. The radiation is an induced or diffraction one and has a nature of forced oscillations. The radiation spectrum has an extremum. The dispersion equation of an antenna is derived. The expressions for the components of the discrete spectrum of the current force and the strengths of electric and magnetic fields, radiated by the antenna, are constructed as a series in the antenna eigen functions. It is shown, that the antenna element is radiative if the strengths of extrinsic and intrinsic electric fields are in phase and in antiphase accordingly to the antenna current. In this case the extrinsic electric field strength accelerates the conductivity electrons and the intrinsic electric field strength brakes electrons, producing the radiation of latter ones

The boundary conditions in the closed form for the electric current density are obtained on the infinitely conducting wedge as distinct from the Mexner asymptotic conditions. The behaviour of a wave vector and radiation is analyzed. Symmetric, antisymmetric and asymmetric conditions of excitation are considered