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Vol 70, No 6 (2025)
ELECTRODYNAMICS AND RADIO WAVE PROPAGATION
The Earth Atmosphere Influence on the Resolution Ability of Orbital Synthetic Aperture Radar
Abstract
Under the assumption of the cascade power law model of turbulence, the mutual influence of the Earth’s ionosphere and troposphere on the azimuth and range resolution is analyzed when the effect of the Earth’s magnetic field can be neglected. Results of the calculation for the typical troposphere and ionosphere turbulence parameters and their combined effect are presented. Simple approximate formulas for the range resolution and systematic shift error are derived for a linear frequency modulated impulse traversing the ionosphere regular layer.
Radiotehnika i èlektronika. 2025;70(6):535-546
535-546
Magneto-electro-optically controlled microwave interferogram of a meta-interferometer with a metastructure as a beam spliter
Abstract
In a modified interferometer based on a waveguide tee with a controlled beam splitter (a metastructure containing a ferrite plate + a butterfly dipole loaded with a varactor), a combined effect on the interferogram of ferromagnetic resonance (FMR) controlled by an external magnetostatic field H and electro-optically controlled dipole resonance (DR) was experimentally detected in the range of 3...6 GHz. The non-reciprocity of microwave transmission in the FMR, DR, and interference exclusion bands was found, characterized by a change in the transmission coefficient T during inversion of H, and magneto-electro-optical control using a remote laser pointer was demonstrated when using the photodiode mode in the varactor/photodiode scheme. The functional capabilities of a meta-interferometer in photovoltaic mode and direct fiber-optic control with a semiconductor-loaded metastructure based on linear resonant dipoles are shown.
Radiotehnika i èlektronika. 2025;70(6):547-555
547-555
Spatially spaced the meta-interferometer contains metastructures controlled independently by different methods: optical and electrical
Abstract
For controlled multichannel multiband microwave filtering and effective decoupling between signal and control channels and between control channels, a proposed and experimentally investigated meta-interferometer with spatially spaced M1 metastructures (as a beam splitter) and M2 (in a shorted h-arm as a Fabry-Perot resonator reflector) controlled by independently by different methods: M1 – fiber-optically and M2 – electrically. The functional capabilities of a meta-interferometer with M1, containing a grating of parallel resonant dipoles with an orthogonally asymmetrically arranged copper strip (a CdS semiconductor plate in a gap), and with different M2 are shown: a butterfly dipole loaded with varactors and a dipole ring, as well as a grating with copper strip (varactor in a gap). The possibility of independent control of individual interferogram exclusion bands in accordance with the effects of resonant M1 responses (amplitude band transformation) and M2 (frequency transformation).
Radiotehnika i èlektronika. 2025;70(6):556-563
556-563
THEORY AND METHODS OF SIGNAL PROCESSING
A Simulation Model for Signature Formation of Complex Low-Observable Targets
Abstract
A simulation model has been developed for generating radar signatures of complex targets, taking into account their spatial configuration, radar-absorbing materials and coatings, diffuse scattering and jet engine modulation of the reflected signal. The model enables investigation of capabilities and robust features for detection and recognition of such complex targets, including those with fractal structures. Estimates of radar cross-section, frequency components of jet engine modulation spectrum, and radar signatures of both elementary and complex targets – including employing Stealth technology – have been obtained. Additionally, radar data necessary for implementing signal processing algorithms based on inverse synthetic aperture synthesis have been generated.
Radiotehnika i èlektronika. 2025;70(6):564-582
564-582
Linear Frequency Modulated Signals in a Multipath Channel with Time and Frequency Offsets
Abstract
The algorithm for generating and processing signals with linear frequency modulation (LFM) called Reduced Set is considered. It is shown that signal processing in the Reduced Set algorithm can be improved. A modified Reduced Set algorithm is proposed, which enhances the probability of correct demodulation of symbols in the presence of multipath propagation, as well as timing and frequency offset. Under these conditions, the proposed algorithm demonstrates a reduction in the probability of a bit error by more than 3 orders of magnitude compared to the classical Reduced Set algorithm processing approach.
Radiotehnika i èlektronika. 2025;70(6):583-597
583-597
Comparative Analysis of Sparse Image Reconstruction Methods in Remote Sensing Problems
Abstract
A comparative analysis of sparse image reconstruction methods in remote sensing problems is presented. The efficiency of the methods is estimated by objective criteria of the quality of the reconstructed digital images. The following methods are used as tested: the interpolation method of the sequentially calculated Fourier spectrum, the projection method onto convex sets, the amplitude iteration method, and spline interpolation. The problem is the reconstruction of sparseness modeled according to a randomly uniform law (at least 90 percent of information is missing). The conducted study allows us to draw a conclusion about the fundamental possibility of using the proposed methods for reconstructing sparse images obtained during remote sensing.
Radiotehnika i èlektronika. 2025;70(6):598-606
598-606
PHYSICAL PROCESSES IN ELECTRONIC DEVICES
The effect on the dynamics of intrinsic stimulated picosecond emission of the AlxGa1–xAs–GaAs–AlxGa1–xAs heterostructure exerted by a dynamic photonic crystal induced by this emission
Abstract
It has been found that those interference of stimulated picosecond emission of the AlxGa1–xAs–GaAs–AlxGa1–xAs heterostructure, created by a dynamic photonic crystal induced by this emis-sion in a GaAs layer, significantly modifies the pulse envelopes of the spectral components of the emission. It has been established that discrete changes in the photonic crystal that change the interference occur under the influence of those part of the emission reflected from the end of the heterostructure.
Radiotehnika i èlektronika. 2025;70(6):607-615
607-615
NEW ELECTRONIC SYSTEMS AND ELEMENTS
Simulator for testing methods of generating data transmission of analog signals in the form of a sequence of command codes in communication channels
Abstract
The necessity of developing a simulator for testing the operation of control command code sequence generation units, monitoring in various switching systems and transmission of measured environmental parameters and their processing after transmission via an optical channel is substantiated. The simulator design is presented using an air-optical communication channel for transmitting information in the form of a command code sequence. The features of using a command code sequence when transmitting analog signals in an optical communication channel are established. The validity of using the proposed method for generating analog optical signals for transmitting them over long distances is confirmed.
Radiotehnika i èlektronika. 2025;70(6):616-624
616-624