Vol 62, No 7 (2017)

Methods and systems of remote energy supply of unmanned aerial vehicles (UAVs) are reviewed. It is expedient to use microwave radiation for efficient energy supply of UAVs at distances of several hundred meters. It is shown that energy transfer with the use of microwave radiation is realizable for recharging of UAVs at distances of about 100 m with an efficiency of 50–80%. It is demonstrated that main difficulties in implementation the UAV remote energy supply systems is associated with the lack of Schottky-barrier microwave rectifying diodes, reduction of the mass and overall dimensions of the receiving antenna, hardware and software efficiency increase methods, and methods for ensuring the electromagnetic compatibility.

A ferromagnetic sphere rotating with constant angular velocity ω₁ is considered when the directions of magnetization vector M applied external magnetic field H and rotation frequency ω₁ do not coincide. The intensity of electromagnetic waves radiated by this sphere is found. It is shown that the radiation is strongly anisotropic and nonstationary.

An improved resonator method for determination of the complex permittivity of materials in a reflective resonator is presented. The method is specific in the following. In the obtained relationship, imaginary part ε₂ of the permittivity of an investigated material is determined using the variation of the resonance frequency and coupling coefficient of the resonator observed when a specimen is introduced, which increases the measurement accuracy. The method is approbated in the investigations of high-resistance silicon specimens.

New radiators for slot stripline leaky-wave circular-polarization antennas for high-accuracy GLONASS/GPS receivers have been developed. The main technical characteristics of antennas with new radiators have been theoretically and experimentally studied. It is shown that application of the new radiators improves the axial ratio, increases suppression of the cross polarization, increases the stability of the antenna phase center, and thus can increase the GLONASS/GPS positioning accuracy. The results of the analysis of the GLONASS/GPS positioning accuracy with the use of these antennas in an angle-measuring receiver and as elements of a few-element antenna array are presented.

Reconstruction of measured holograms is performed by the backward propagation method and by means of a preliminary measured instrument function (IF). It is shown that the results of the reconstruction can be improved by reducing the IF measuring error, e.g., by averaging over a ring. It is established that images of a part of subsurface radio holograms can be obtained not only if the known part of a hologram is an entire fragment but also if the measured points of the hologram are not nearest neighbors of each other.

A two-block model of an analog radio channel of a digital communication system is proposed. Problems of identification of the model of the data transmission channel and synthesis of a digital precorrector for adaptive linearization of nonlinear dynamic distortions are solved using the stochastic gradient method. The results of comparative analysis of two-block and one-block structures are presented.

Models of rectangular and axially symmetric resonator slow-wave structures, which are built using transmission matrix for determining the characteristics of the slow-wave structures in different operation modes, are investigated. Elements of the transmission matrix are determined from the results of 3D simulation with the use of the HFSS software. In the analysis of the dispersion characteristics, slow-wave structures with two microwave propagation channels are studied and simulated using a 4×4 transmission matrix.

One-way shape-memory effect (SME) controlled by temperature and magnetic field in rapidly melt-quenched (RMQ) Heusler-alloy (Ni₅₃Mn₂₄Ga₂₃) ribbons is experimentally studied. Two-way SME that results from training is demonstrated for submicron Ni₅₃Mn₂₄Ga₂₃ samples. Reversible thermally and magnetically controlled bending of no less than 1.5% and deflection of no less than 2 μm are reached for composite Ni₅₃Mn₂₄Ga₂₃/Pt microactuators with sizes of 25 × 2.3 × 1.7 μm³ in the presence of magnetic field of μ₀Н = 8 T at an initial temperature of 63°С.

A new scheme of the power modulator of laser beam is based on a corner-reflector unit with a relief diffraction grating that is placed on a plane of the unit and has a relief depth of several wavelengths of the laser radiation. It is shown that angular oscillations of the unit make it possible to implement modulation of the zero-order diffraction beam at a modulation depth of almost 100% and a relatively high linearity of the modulation characteristic that is reached at modulation depths of greater than 50%.