This article is devoted to the theoretical and experimental study of diffraction radiation effects. Diffraction radiation is generated by the scattering of an eigenfield of density-modulated electron beam or a surface eigenwave of open dielectric waveguide on a nearby periodic structure. For the first time, these effects were studied using rigorous models exploiting exact absorbing conditions (EACs). This article also details the design and experimental testing of radiating elements for planar diffraction antennas with extremely low sidelobe levels, which exploit diffraction radiation effects.

We consider the problem of radiation from a vertical short (Hertzian) dipole above flat lossy ground, which represents the well-known “Sommerfeld radiation problem” in the literature. The problem is formulated in a novel spectral domain approach, and by inverse three-dimensional Fourier transformation the expressions for the received electric and magnetic (EM) field in the physical space are derived as one-dimensional integrals over the radial component of wavevector, in cylindrical coordinates. This formulation appears to have inherent advantages over the classical formulation by Sommerfeld, performed in the spatial domain, since it avoids the use of the so-called Hertz potential and its subsequent differentiation for the calculation of the received EM field. Subsequent use of the stationary phase method in the high frequency regime yields closed-form analytical solutions for the received EM field vectors, which coincide with the corresponding reflected EM field originating from the image point. In this way, we conclude that the so-called “space wave” in the literature represents the total solution of the Sommerfeld problem in the high frequency regime, in which case the surface wave can be ignored. Finally, numerical results are presented, in comparison with corresponding numerical results based on Norton’s solution of the problem.

A review of basic papers related to development and implementation of rather efficient mathematical methods aimed at formation of Green's functions for various types of anisotropic media: uniaxial and biaxial, generalized gyrotropic, layered etc. is provided. Advantages and drawbacks of the methods aimed at both the analytical results and the possibility of numeric or asymptotic estimates of the sought functions are highlighted. The outlook for using them while solving practical problems of current importance are determined.