卷 61, 编号 9 (2016)

Problems on reflection of a plane electromagnetic wave from various irregular interfaces between media are studied by the integral equation method in the cases of two- and three-dimensional incident electromagnetic field. The reflecting surfaces are meant as periodic transparent interfaces between two media and plane boundaries with locally inhomogeneous and transparent sections. The boundary value problems for the system of Maxwell’s equations in an infinite domain with an irregular boundary are reduced to Fredholm or singular integral equations, depending on the problem considered. Numerical algorithms for solving such integral equations are developed. Results of calculation of currents induced on inhomogeneities and characteristics of the electric field in the far zone are presented.Problems on reflection of a plane electromagnetic wave from various irregular interfaces between media are studied by the integral equation method in the cases of two- and three-dimensional incident electromagnetic field. The reflecting surfaces are meant as periodic transparent interfaces between two media and plane boundaries with locally inhomogeneous and transparent sections. The boundary value problems for the system of Maxwell’s equations in an infinite domain with an irregular boundary are reduced to Fredholm or singular integral equations, depending on the problem considered. Numerical algorithms for solving such integral equations are developed. Results of calculation of currents induced on inhomogeneities and characteristics of the electric field in the far zone are presented.

The interaction impedance of the of the output cavity of the klystron generally connected to N passive cavities forming a filter system is analyzed in the presence of parasitic oscillations.

The cross-section method is extended to the case of waveguides containing sharp metal edges. Such structures comprise strip lines, microstrip lines, and slot transmission lines. Relationships for eigenmode coupling coefficients in a section with parameters varying in the longitudinal direction are derived by passing to the limit: from a waveguide with smooth contour of the cross section to a waveguide with sharp edges. These relationships are applied to a single-mode strip line with conductor having variable width. It is shown that the obtained results agree with the results of the theory of microwave transmission lines.

The localization method, which makes it possible to find regions in the phase space that contain all attractors of the system is used to analyze a phase system. Systems of inequalities describing such sets have been obtained. Phase-lock systems of the fourth and third order, which allow existence of chaotic attractors of various types, have been investigated.

Algorithms for estimation of the number of signals with unknown amplitudes and several non-energy parameters are synthesized on the basis of the modified maximum likelihood method. Asymptotic values of the probabilities of the error in estimation of the signal number are determined. The effect of a reduced volume of the a priori domain of possible values and the dimensionality of the vector of unknown non-energy parameters on the quality of operation of the algorithms for estimation of the number of signals is investigated.

The results of 3D numerical modeling of a low-voltage compact K-band multibeam generator of monotron type with two different modes of electron beam bunching (bunching only in the first gap or successive bunching in the first and the second gaps) are presented. These results demonstrate that it is possible to achieve a microwave radiation power exceeding 1 kW at a frequency of 18.21 GHz with an accelerating voltage of 2.45 kV and an overall efficiency of approximately 44%.

Various opportunities to improve the quality with which an electron flow is formed by cathode arrays comprising multilayer planar structures with the vertical arrangement of autoemitters are investigated with the help of numerical simulation. It is demonstrated that field-emission cells with glassy carbon emitters shaped as smooth needles with aspect ratios of several hundreds and cathode arrays on their basis can be obtained using the efficient technology of microsized milling by laser radiation with nanosecond pulses. Field-emission cells with a vertically oriented ring blade-shaped emitter and emitters created by single spikes located on a circumference are comparatively analyzed.

The expressions describing the autodyne (AD) response are obtained with allowance for the internal noise of a frequency-stabilized microwave oscillator subjected to the action of its self-radiation reflected from an object. The results of analyzing the AD and noise characteristics of the stabilized oscillator built around the band-reflecting filter with resistive coupling are presented. The conditions leading to the appearance of the periodic non-stationarity of noise characteristics are established. It is demonstrated that frequency stabilization is ensured by a gain in dynamic range. The experimental data on unstabilized and stabilized hybrid-integral AD oscillators based on the two-mesa Gunn diode of 8-mm range are presented.

the possibility of using superconductor–insulator–superconductor (SIS) tunnel junctions in a cryogenic multiplexing system for setting an ac current through arrays of transition edge sensors and reading out the received signal, as well as for setting a dc current through arrays of superconducting quantum interferometers is studied. Operation of the SIS frequency converter at relatively low (below 10 GHz) working frequencies is experimentally investigated. Different operation regimes are implemented; the conversion loss in the quasiparticle mode is found to be 8 dB and the output saturation power is–58 dBm. The possibility of up-conversion of several input signal frequencies simultaneously is demonstrated. It is shown that the SIS junction can be used as a current source controlled by an external RF signal.