Alexey A. Vertiy

Cherenkov radiation based antenna with the funnel-shaped directional pattern

ABSTRACT An axially symmetric diffraction antenna of a new type is presented and studied in details in the paper. The antenna is based on the effect of Cherenkov-like radiation. In contrast to diffraction antennas presented earlier, the proposed antenna does not contain periodic structures, which are effortful in manufacturing for millimetre and shorter waves. The antenna consists of a dielectric-filled cylindrical waveguide which feeds a biconical dielectric prism. Simulation results show that the proposed antenna has high efficiency, low sidelobe level, and the radiation pattern with high directivity. The proposed antenna could be used in various communication and radar systems.

Inverse problems of electromagnetic sounding: Gradient medium and periodic boundary

The problems of the periodic interface profile reconstruction and the recognition of dielectric constant of the layered medium according to the values of the reflection coefficients for a finite set of probing frequencies are rather urgent in connection with the development of modern non-destructive testing methods. To solve them the original problems are reduced to the search for the optimal control (the profile of the dielectric constant) of the Cauchy problem for the Riccati equation. Construction of optimal control in the class of polynomial functions is based on the minimization of the corresponding functional. The criterion of selection of polynomial approximations for profile permittivity uses the separation of input data into Training and Testing sequences of probing frequency. An analysis of errors of the reconstruction of the imaginary part of permittivity of the layered medium was carried out.

Diffraction Radiation Phenomena: Physical Analysis and Applications

The chapter is devoted to the problems of analysis and applied usage of the diffraction radiation phenomena, which are exploited in antennas and generators for millimeter and submillimeter waves. The diffraction radiation occurs when surface waves of open waveguides or eigenfields of charged-particle beams are transformed by periodic gratings into radiated fields. Main properties of the diffraction radiation phenomena have been studied using the given-current approximation and rigorous methods taking into account actual size of devices exploiting the phenomena. The algorithm of experimental synthesis of planar diffraction antennas with record-breaking low side lobes level has been developed and applied to design a real-world device.

The Exact Absorbing Conditions Method in the Analysis of Open Electrodynamic Structures: Circular and Coaxial Waveguides

The exact absorbing conditions (EAC) have been constructed and used for truncating an unbounded domain of computation in open initial boundary value problems, which describe space-time transformations of electromagnetic waves in axially symmetrical waveguides. The equivalence theorem is proved that gives grounds for rigorous theoretical justification of the EAC-method.