Vol 64, No 1 (2019)

Propagation of frequency-modulated signals in an anisotropic medium (Earth’s ionosphere) is numerically simulated with allowance for the effect of the electron collision frequency on deflecting absorption. Projections of ray paths onto different coordinate planes are considered. The influence of the divergence of the ray paths and absorption of radio waves on the attenuation of the radio signal for ordinary and extraordinary waves is studied. The calculations were performed for the daytime and nighttime models of the electron density and collision frequency of the high-latitude ionosphere.

Computer simulation and synthesis of waveguide selective devices based on circular waveguides with T-shaped metal ridges have been performed. A method for obtaining the initial approximation for further optimization of their characteristics has been described. As basic elements, cavity resonators consisting of sections of circular waveguides with two T-shaped metal ridges are used. The results of simulation of a band-pass filter have been presented.

Algorithms for correction of the aircraft navigation information by using a satellite navigation system and an inertial navigation system are studied. The satellite system signals contain abnormal measurements of various durations. Improvement of the accuracy of navigation determinations is performed by filtering noise, eliminating anomalous spikes from the data, and replacing them with predicted values. It has been proposed to use the theoretically predicted value of the updated sequence in the adaptive Kalman filter in the case of detection of an anomalous measurement. In the case of the appearance of a pack of anomalous measurements, they are replaced by the predicted values obtained by using the trend and the self-organization algorithm.

Nonlinear precession of the second-order magnetization in a normally magnetized plate with magnetoelastic properties is analyzed. Orientational transition of the magnetization vector that lies in a variation of the equilibrium position of the vector due to a variation in the magnetoelastic constant is studied. A system of equation for the equilibrium position of the magnetization vector relative to magnetization components and elastic displacement is derived and solved with the aid of the Cardano method. Parametric portraits are obtained for magnetization and elastic displacement, and the effect of magnetoelasticity on the geometrical properties is revealed using a model of potential. Models of effective fields and quadratic magnetoelastic coupling are proposed to interpret the dependence of the period of precession on the constant of magnetoelastic interaction.

The results of modeling of microwave and mechanical characteristics of an X-band switch based on the technology of high-frequency microelectromechanical structures are presented. A method for design of a device operating directly in the external environment and a device whose moving components are placed in a dielectric case. Characteristics of the optimized switches are determined. Estimated mechanical calculations confirming high stability of the developed high-frequency microelectromechanical structure switches in the temperature range specific of devices used in the space industry are also performed.

A solid-state pulse modulator for high-power microwave devices with grid control has been designed and tested. The output stage of this modulator uses a switching unit with two microsecond-band high-voltage switches toggled in antiphase. These switches were constructed on series-connected MOS transistors, have nanosecond switching times, and operate at voltages of as high as 10 kV. The modulator has demonstrated stable operation in tests performed to evaluate its potential to control high-power microwave devices.

The second approximation of the theory of narrow ribbon beams with a curvilinear axis and plane-symmetric flows is formulated. A complete hydrodynamic picture of the flow near the starting surface upon the emission in the \(\rho \)- and T-modes is constructed. The neighborhood of the singular points corresponding to the extrema of the potential at the base tube of current during its nonmonotonic change is studied.

Effects that may provide an increase in the stability of field emission and tunneling photoemission of a planar blade structure using an emitter that is covered with nanosized dielectric diamond-like carbon (DLC) film are analyzed. A model of specific features of the distributed zone of the field localization on the DLC surface in the structure (zone with a smooth peak of electric field) is constructed and the corresponding theoretical analysis is performed. It is shown that the DLC film with a thickness of 20 nm on a molybdenum blade (Mo blade) provides an increase in the area of the emission region by a factor of 15 in comparison with the area corresponding to the Mo blade without coating. The working time of the emission structure with the DLC film is increased by a factor of greater than 50 (to 8700 h) for the regime of long pulses (320 μs) with a relative interpulse period of 10 and the mean current density of the field emission of no less than 30 mA/cm². An increase in the sensitivity of the structure with the DLC film is demonstrated.

The realizability of an amplitude and balanced modulator on the basis of a resistor optron without nonlinear distortions in the spectrum of the modulating signal is shown. The developed device is used for direct multiplication of optical and electric signals. A prototype of the balanced modulator has been developed and mathematical simulation of the balanced modulator has been performed.