Mikhail Popov

An explicit and efficient method for obtaining the radiation characteristics of wire antennas in metallic photonic bandgap structures

An explicit and efficient method for obtaining the radiation characteristics of wire antennas in metallic photonic bandgap structures

Identification of a transient electric dipole over a conducting half space using a simulated annealing algorithm

Identification of a transient electric dipole over a conducting half-space by measuring fields at two ground points is considered. A simulated annealing algorithm (a global optimization method which mimics the slow cooling behavior of an atomic system with many degrees of freedom) is used to reconstruct the location, the orientation, and the transient moment of the dipole in multiple steps. Numerical examples are studied for a dipole (tested at three different positions) over three typical conducting half-spaces, namely, seawater, dry earth, and fresh water. The identification results based on a ‘perfectly conducting half-space model’ search and a ‘finitely conducting half-space model’ search are compared.

The influence of the dielectric–air interface on the radiation pattern of an antenna in a metallic photonic bandgap structure in a dielectric host medium

The influence of the dielectric-air interface on the radiation pattern of an antenna in a metallic photonic bandgap structure in a dielectric host medium

Reconstruction of lightning currents and return stroke model parameters using remote electromagnetic fields

Reconstruction of lightning currents and return stroke model parameters using remote electromagnetic fields

Zero-order time domain scattering of electromagnetic plane waves by two quarter spaces

The zero-order term of the time domain scattered electric field of an electromagnetic plane wave normally incident upon the surface of two quarter spaces is determined. The general solution is a development from a previous exact and complete solution in the frequency domain. The zero-order term of the scattered electric field has been computed in the upper medium (z < 0). The incident wave in the frequency domain assumes the same function for three cases: (1) The conductivity vanishes everywhere; (2) only the conductivity of the upper medium is zero; and (3) the three media are conductors. Case 1 helps to understand cases 2 and 3. Case 2 is applicable to geophysical exploration. For cases 1 and 2 a causal time function decaying exponentially with time at every point above the fault (z < 0) describes the waveform of the incident plane wave. The zero-order term of the scattered field has been computed above the fault. At x = 0 it reduces to a closed expression for case 1 and to a single integral for the other two cases. In the three cases it contains an integral of a Hankel function for x ≠ 0. The computation of the high-frequency part of the inverse Fourier transform for x ≠ 0 employs asymptotic expressions for the Hankel function using analytical techniques of the geometrical theory of diffraction for cases 1 and 2. For case 3 the inverse Fourier transform may have two possible contributions: either from the residue at a single pole or from the integral along a branch cut in the ω plane. The wave front of the scattered field is well defined in shape, phase, and amplitude. Its amplitude is discontinuous at x = 0, and varies smoothly but presents a sharp jump for ∣ x ∣<<∣ z ∣. For ∣ x ∣ = O(z), there is a numerical noise that oscillates at 100 MHz.

Explicit full identification of a transient dipole source in the atmosphere from measurement of the electromagnetic fields at several points at ground level

Explicit full identification of a transient dipole source in the atmosphere from measurement of the electromagnetic fields at several points at ground level

An explicit method for the analysis of guided waves in a line-defect channel in a photonic crystal

An explicit method for the analysis of guided waves in a line-defect channel in a photonic crystal

Electromagnetic direct and inverse problems for a surface-breaking crack in a conductor at a high frequency

The electromagnetic direct and inverse problems for a surface-breaking crack in a conductor are considered at a high frequency. The direct problem, which is transferred to a two-dimensional potential problem in the unfolded configuration, is solved by a boundary integral equation method. The boundary integral equation (a well-posed Fredholm integral equation of the second kind) for the normal derivative of the potential on the interior boundary of the crack is derived. The potential distribution at the open mouth of the crack is used to determine the shape of the crack. The inverse problem is solved by a genetic algorithm combined with a conjugate gradient method.