Energy losses of dipoles traveling relative to a moving medium

We consider the radiation from nonoscillating dipoles traveling with constant velocity directed parallel or antiparallel to the velocity of a homogeneous transparent moving medium. It is assumed that the medium in its rest frame is isotropic and has no spatial dispersion. We obtain expressions for the radiative energy losses and estimate the polarization energy losses of electric and magnetic dipoles of different orientations. In particular, it is shown that the energy loss of a source is negative if it moves in the direction of the medium motion and the source velocity is less than the medium velocity. Estimates for the energy losses of dipoles in the cases of an electron beam and a flow of a weakly dispersive medium are given. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 6, pp. 502–512, June 2006.     

Electromagnetic-wave diffraction by slot in faster-than-light flow of nondispersive medium

Plane-wave diffraction by a slot in an ideally conducting shield in a moving nondispersive medium is examined. The main diffraction characteristics are determined for the case of faster-than-light motion of the medium. The particular cases of narrow and wide slots are analyzed.St. Petersburg State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, No. 8, pp. 678–687, August, 1992.     

Diffraction of electromagnetic waves by a half-plane located in a moving cold plasma

Diffraction of plane electromagnetic waves by a conductive half-plane located in a parallel flow of cold plasma is studied. The velocity of the plasma motion and the propagation direction of the incident wave are normal to the half-plane edge. A general solution of the problem is obtained using the Wiener-Hopf-Fok method. The behavior of the field is analyzed far from the half-plane edge and in its vicinity. State University, Saint Petersburg, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 4, pp. 475–494, April, 1998.     

Energy characteristics of radiation of oscillating dipoles moving in a nondispersive medium and a cold plasma

We consider radiation of moving oscillating electric and magnetic dipoles, whose moments are oriented along their velocity. We have derived general expressions for field components and radiation power, which are valid for isotropic homogeneous nonabsorbing media. Special cases of a nondispersive medium and a cold plasma are considered. In these cases, the dependences of energy spectral distributions and radiation powers are analyzed as a function of the velocity of the sources and the parameters of media.     

Radiated power of oscillators traveling in a moving medium

We consider the radiation from oscillating electric and magnetic dipoles moving with constant velocity directed parallel or antiparallel to the velocity of the surrounding medium. It is assumed that the medium in its rest frame is isotropic and has no spatial dispersion. We obtain expressions for the spectral density of the radiated power. In the case of a nondispersive medium, algebraic expressions for the total radiated power in the regime of “subluminal relative motion” are also obtained. In particular, it is shown that the energy loss of a source is negative if it moves in the direction of the superluminal motion of the medium and the source velocity is somewhat smaller than the medium velocity. It is noted that this phenomenon takes place for a smaller difference between the velocities of the source and the medium compared with a similar phenomenon for nonoscillating sources. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 4, pp. 316–328, May 2007.     

Features of Radiation Fields of Some Sources in a Subluminal Flow of a Nondispersive Medium

We study radiation fields of various dipole sources as well as of a source of bisphere type moving in a nondispersive medium with velocity less than the speed of light in this medium. In particular, it is shown that in certain cases, there is a displacement of the angular pattern of a source in the direction opposite to the medium flow. Expressions for energy losses of the considered sources are obtained. It is pointed out that the radiation power of both a bisphere and a toroidal dipole increases with increasing velocity of motion of the medium more rapidly compared with the ordinary dipoles.     

Energy characteristics of radiation from an oscillating dipole moving in a dielectric medium with resonant dispersion

Radiation produced by oscillations of an electric dipole moving along its dipole moment through an insulator with the resonance-type dispersion is considered. The total power of radiation and the power density spectrum are studied both analytically and numerically. It is shown that the radiation spectrum consists of either two separate frequency ranges or a single frequency range depending on the parameters of the problem. The dependences of the radiation power on the velocity of the source are revealed for various values of the resonant and Langmuir frequencies.     

Diffraction of electromagnetic waves by a half-plane which is permeable to a stream of cold plasma

Diffraction of plane electromagnetic waves by a conducting half-plane located in an orthogonal stream of cold plasma is studied. It is assumed that the half-plane has almost no mechanical effect on the particles of the medium. (For example, the half-plane can be a model of a metal grid with fairly small cells.) The general solution of the problem has been obtained by the Wiener-Hopf-Fock technique. The scattering field containing waves of two types is studied analytically and numerically. The behavior of these waves away from the half-plane edge is analyzed. It is shown that the electric field at the edge is finite, and the shadow area is absent under certain conditions. Radiophysical Research Institute of the State University of St. Petersburg., Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40. No. 4, pp. 399–419, April, 1997.