Multiple Scattering by Two PEC Spheres Using Translation Addition Theorem

An analysis of multiple scattering by two Perfect Electric Conducting (PEC) spheres using translation Addition Theorem (AT) for spherical vector wave functions is presented. Specifically, the Cruzan formalism is used to represent the AT for spherical harmonics, which introduces the translation coefficients for transformation of spherical harmonics from one coordinate to another. The adoption of these coefficients with the use of two PEC spheres in a near zone region makes the calculation of multiple scattering electric fields very efficient. As an illustration, the mathematical formation using advanced computational approaches was inspected. Then, the generic truncation criteria in the scattered electric field by two PEC spheres was deeply investigated using translation AT. However, the numerical validation was obtained using Comsol simulation software. This approach will allow to evaluate the scattering from macro-structures composed of spherical particles, i.e., biological molecules, clouds of airborne particles, etc. An original and fully general solution to the problem using vector quantities is introduced, and the convergence of the solution in several numerical examples is also demonstrated. This approach takes into account the effect of multiple scattering by two PEC spheres for spherical vector function.

OPERATIONAL CHARACTERISTICS OF SMALL-SIZED ANTENNA DEVICES OF THE MEDIUM FREQUENCY RANGE IN MINES

Представлены результаты исследования трех малогабаритных антенн (электрического,магнитного и магнитоэлектрического типов)СВ-диапазона с целью определения особенностей их эксплуатации в рудниках и шахтах,т.е. в диспергирующих средах. Рассмотрены импедансные характеристики и изменение частотных зависимостей коэффициента стоячей волны в ближней зоне антенн, обусловленное непостоянством электрических характеристик горных пород при перемещении антенн вдоль горной выработки. Проведена оценка стабильности работы портативных радиостанций при подводимой к малогабаритной антенне мощности 1 Вт с учетом времени,характерного для сеансов связи. Даны рекомендации по эксплуатации антенн в условиях рудников и шахт. The article investigates three main types of small antennas (electric, magnetic and magnetoelectric) of the medium frequency range in order to determine the features of their operation in mines, i.e. in dispersing media. The impedance characteristics and the change in the frequency dependences of the standing wave ratio are considered when the situation in the near zone changes. An assessment of the stability of the operation of portable radio stations at an input power of 1 W has been carried out, taking into account the time characteristic of communication sessions. Recommendations for the operation of antennas in mines are given.

The investigation of the features optical vortices focusing by ring gratings with the variable height using high-performance computer systems

The diffraction of vortex laser beams with circular polarization by ring gratings with the variable height was investigated in this paper. Modelling of near zone diffraction is numerically investigated by the finite difference time domain (FDTD) method. The changes in the length size of the light needle and focal spot size are shown depending on the type of the ring grating.

Modal Analysis of Pseudo-Schell Model Sources

All pseudo-Schell model sources have been shown to possess the same continuous set of circularly symmetric modes, all of them presenting a conical wavefront. For keeping energy at a finite level, the mode amplitude along the radial coordinate is modulated by a decreasing exponential function. A peculiar property of such modes is that they exist in the Laplace transform’s realm. After a brief discussion of the near-zone, we pass to the far-zone, where the field can be evaluated in closed form. The corresponding features of the intensity distribution are discussed.

Characteristics of the electromagnetic environment created by radiations of user equipment of ...4G/5G/6G cellular (mobile) communications in buildings

The goal of the work is to substantiate the technique for assessing the intensity of electromagnetic background generated by the set of radiating user devices of mobile communications in multi-storey buildings. For known empirical models of radio wave propagation in buildings, expressions are obtained for the probability distribution density and expectation of the power flux density of electromagnetic fields generated inside building by these sources from various parts of the building's interior space: from the near zone with radio wave propagation conditions similar to free space; and from the far zone, for which, along with intense attenuation of radio waves due to internal obstacles, a «quasi-waveguide» propagation of radio waves along corridors and industrial premises is also possible in certain directions. Relationships are obtained for the average levels of individual components of the electromagnetic background, determined as scalar sums of power flux density values of the fields generated by the sets of radiating devices of both the near zone and the far zone as a whole or its individual parts, characterized by different conditions of radio wave propagation. A method is proposed for assessing the electromagnetic background inside buildings based on approximation of sections of the inner surface of the premises in which the observation point is located, and the outer surface of the building, in the inner space of which radiation sources are randomly distributed, by the corresponding sections of the inner and outer spherical surfaces that are the subtend areas of the corresponding solid angles, in space elements of which a different spatial densities and radiation powers of sources and different conditions of radio wave propagation are possible. The results can be used to analyze the electromagnetic ecology of habitat and the electromagnetic safety of population at the full-scale implementation of 4G/5G/6G mobile communications, as well as to analyze the electromagnetic compatibility of systems using frequency bands for mobile communications on a primary and secondary basis.

Strange radiation and LENR: what's the relation?

A review of studies showing the phenomenon of "strange radiation" is given. The issues of relation of this phenomenon with low energy nuclear reactions (LENR) are discussed. The results of our own experiments, revealing such a relation, are presented on the example of two LENR reactors. Based on the developed technique for assessing the intensity of tracks on sensitive materials, it is shown that tracks of strange radiation with high intensity appear only in the near zone of reactors (up to 20 cm). The aftereffect is described, when the tracks appear after the reactor is turned off. The large variability of the intensity of the tracks makes it difficult to use them as a marker of LENR. The paradoxical properties of strange radiation are discussed.