Radiotehnika i èlektronika

The calculation of the influence of amplitude-phase errors, failure or the random number of radiant channels on the main characteristics of antenna arrays (AA). The paper presents an algorithm for simulating the failure of elements and modules of AA based on known functions of amplitude-phase distributions. Qualitative characteristics of the orientation of the AA in conditions of the established channels, modules and the availability of errors in amplitude-phase distributions are calculated.

А series-fed antenna containing two parallel linear arrays in a common aperture is proposed in this letter. Elements of the arrays are elementary resonant radiators. Proposed antenna can operate both in a dual-frequency mode and in a mode with one extended frequency range. Such an antenna in the dual-band mode provides a maximum gain in a given direction in two separate frequency ranges. The convergence of the frequency ranges forms one common extended frequency range. An approximate approach for synthesizing the antenna is proposed. Using the HFSS system, several variants of a bi-periodic slotted waveguide antenna array are investigated. Numerical modeling confirms the results of the approximate theory. It is shown that the proposed array can operate in both specified modes, which significantly expands the functionality of antennas of this type.

Magnetoelastic interactions in the region of ferromagnetic resonance (FMR) in a thin ferrite film on a relatively thick dielectric elastic substrate excited by a magnetic film with a variable magnetic field are investigated. Dependencies of the period of elastically coupled resonance lines on the amplitude-frequency spectrum of FMR are constructed as functions of elastic damping parameters, magnetoelastic coupling, modulus of elasticity, and material density in linear and nonlinear regimes. The presence of a strong threshold nonlinear dependence of the resonance line amplitude on the elastic damping parameter is revealed.

In this work, results of development of a W-band O-type traveling-wave tube with sheet electron beam are presented. The staggered double-grating slow-wave stricture with wideband input/output coupling structures was designed and optimized and its high-frequency electromagnetic parameters were calculated. The results of 3D particle-in-cell simulation of beam-wave interaction in the TWT are presented. Gain over 30 dB in the 25-GHz frequency band was obtained. A sample of an electron gun with an impregnated cathode, focusing electrode, and anode, providing the formation of a sheet electron beam with a high-aspect ratio and a current of 0.1 A, was designed and fabricated. The design of the vacuum window is presented, and the technology of its fabrication is discussed.

An algorithm has been developed for determining from experimental field dependences the high–frequency impedance of silicon structures with an ultrathin (less than 5 nm) SiO₂ layer of the insulating gap capacity and concentration of dopant directly at the Si-SiO₂ interface. Relations allowing to estimate marginal errors of the developed approach are obtained. The proposed method is applied to experimental characteristics of the metal–oxide–semiconductor structure with a thickness of SiO₂ 4.2 nm. It is shown that the developed algorithm has sufficiently high accuracy and accessibility for use in processing high-frequency measurement data.

The problems arising in experiments using liquid flows are considered. The advantages of using nuclear magnetic resonance-based devices for flow parameter control both in research and in industrial parameter measurements are noted. A new method for forming a nutation line contour with a given profile from a liquid flow with magnetization inversion has been developed, and the features of controlling the processes of this contour formation have been established. Experimental studies have been conducted and the possibility of applying the new method for measuring the liquid flow rate q with rapid changes in the flow velocity has been proven. New coefficients in the Bloch equations are proposed that describe the motion of three magnetization components (M_x’, M_y’ and M_z’) in the nutation coil in a liquid flow in a strong inhomogeneous field. The nutation line contour has been calculated for various parameters B₀ and q. The minimum value of the magnetic field inhomogeneity has been established taking into account q and the parameters of the current medium, which must be ensured in the nutation coil location sector when forming the line contour at the noise level to implement the “magnetic” mark mode when measuring q. A comparison of theoretical calculations with experimental data was carried out.

A system for collecting, processing and storing information for a multichannel Fourier spectrometer is considered. The functional diagram of the electronic part of the device, a block diagram, as well as a brief description of the software that allows measurements to be carried out in an automated mode and to be able to record and store the received data are given. An experiment was conducted and the results obtained were analyzed.

The design and principle of operation of hardware and software complex for highpower laser active element’s temperature monitoring based on ultrasonic probing possibility research are described because of highpower laser active element heating may lead to amplified optical beam distortion as well as elements damage itself. Possible probing schemes are discussed. Methods sensibility and accuracy are estimated.