Vol 64, No 9 (2019)

In this review, we present the main results on the creation of new information technologies based on textures, fractals, fractional operators, scaling effects, and nonlinear dynamics methods that were obtained from 1979 to the present at the Kotelnikov Institute of Radioengineering and Electronics, Russian Academy of Sciences (IRE, RAS). It is shown that new dimensional and topological (not energy!) signs or invariants that are combined under the generalized concept of “sampling topology” ~ “fractal signature” were proposed for the first time and then applied. Texture and fractal-scaling (topological) methods for detecting super-weak signals and fields in intense noise and interferences are proposed. A new type and a new method of modern radiolocation, namely, fractal-scaling or scale-invariant radiolocation was proposed, discovered, and developed. This entails fundamental changes in the structure of theoretical radiolocation, as well as in its mathematical apparatus.

The article investigates an electromagnetic crystal in the form of metal cylinders with capacitive gaps in the nodes of a rectangular two-dimensional periodic lattice between metal screens forming a flat waveguide. Using a standard electrodynamic modeling system, the authors studied the diffraction of a plane wave at the boundary of an infinite layer for one coordinate and a finite layer for another coordinate, and determined the band structure of the electromagnetic crystal. The behavior of the pass and stop bands was studied as a function of the crystal parameters. An additional passband was discovered, the occurrence of which is associated with excitation of a higher-type wave of a plane waveguide. The effect of series resonance in a capacitive cylinder on the damping of a wave in the stop band is considered. The possibility of an approximate description of an electromagnetic crystal in the stop band is investigated. A number of models are proposed, obtained via numerical solution of the problem of oblique incidence of a plane wave on the crystal boundary.

Artificial magnetic conductors (AMCs) based on band-stop and band-pass frequency-selective surfaces (FSSs) have been considered. Analytical expressions relating the AMC characteristics (position and operating bandwidth) and the FSS characteristics (resonance frequency and quality factor) have been obtained. Numerical calculations for specific FSS structures (with square and dumbbell-shaped slots) confirmed that the AMC characteristics can be estimated using analytical expressions. It has experimentally been proved that the AMC characteristics can be controlled by varying the FSS resonance frequency.

Ray-optic approximation is used to derive an analytical solution to the problem of synthesis of mirrors that form an axisymmetric three-mirror system with predetermined main mirror. Such a system provides transformation a spherical front of a source into an arbitrary front with the desired mapping law. The generatrix of an auxiliary mirror is represented as a polynomial in terms of even powers of angle. The solution can be used to exactly implement the output front and obtain the desired error of mapping law. The synthesis of a three-mirror telescope in which either parabolic or spherical mirror serves as the main mirror is considered.

A probabilistic–time model has been constructed for assessing the anti-interference ability of radio communication systems in electronic warfare conditions. Based on the model, a closed system of equations has been obtained, which makes it possible to estimate the anti-interference ability of radio communication channels, as well as the limiting capabilities of the reciprocal jamming station in the disruption of radio communication systems with pseudorandom operational frequency readjustment (PROFR). Numerical calculations of the dependence of the frequency switching rate of the signal with PROFR on the probability of error after countermeasures are given.

In this paper, we consider an algorithm for optimal symbol-by-symbol reception of signal constructions based on block error-correcting codes in non-binary fields. The basis of the developed symbol-by-symbol algorithm is shown to be the spectral transformation in the Walsh-Hadamard basis. The resulting complexity of the developed reception algorithm is shown to be determined by the dimension of the dual code, which determines the perspective of its application for block error-correcting codes with a high code rate. The simulation results of the developed reception algorithm for the purpose of studying the noise stability for signals based on parity check codes are presented.

The problem of illumination of objects and surfaces by artificial incoherent sources of microwave radiation (radio light lamps based on dynamic chaos generators) in order to observe them using special receiving equipment is considered. A scheme of a receiver is developed and an experimental model of such a receiver with a spatial resolution sufficient for the visualization of a part of the surrounding space in artificial radio light is implemented. Images of a room in radio light are obtained. The feasibility of detecting changes on these images, associated with the emergence of new objects, is shown.

Formulas are determined that describe the contribution from capacitive currents to the current measured in the external circuit when diagnosing heterogeneous anisotropic samples with slowly varying parameters.

A microwave radiation intensity indicator based on an antenna-coupled detector (rectenna), an amplifier, and a semiconductor light-emitting diode was constructed and tested. This device is a hybrid integrated circuit, where a microstrip log-periodic antenna on a dielectric substrate also serves as a mechanical carrier. The possibility of visual determination of the shape of the antenna radiation pattern and the shape of an object based on the reflected radiation intensity was demonstrated experimentally at 10 and 30 GHz.

Analytical and numerical calculations of limiting characteristics of electromagnetic radiation detectors based on Josephson junctions are carried out. Josephson junctions are described by a simple resistively shunted model and their Josephson energy is considered to be comparable to the energy of thermal fluctuations. The operation modes of such junctions as a classical detector using ac rectification on a static nonlinear current–voltage characteristic are established. The results of numerical and analytical calculations are compared, and it is shown that the classical detection mode can be analyzed and optimized using the derived analytical expressions for the main limiting characteristics. The study demonstrates the possibility of achieving a limiting sensitivity up to 2 × 10^–15 W/Hz^1/2, a dynamic power range of 10⁵–10⁶, and a spectral range up to 1.4 THz, in a temperature range 50–77 K using new Josephson thin-film junctions consisting of high-temperature YBa₂Cu₃O_7 – x superconductors with mutually tilted c axes.

The paper substantiates the necessity of expanding the dynamic range in a shortwave infrared (SWIR) photodetector (PD). The traditionally used methods have low efficiency, especially in large-format matrices with a step of not more than 15 µm. The greatest efficiency of expanding the dynamic range (up to 100 dB) is provided by accumulative cells with individually variable transfer characteristic depending on the brightness of the fragments of the observed scene. The paper proposes a simple, in topological implementation, and effective way of expanding the dynamic range based on the auto-tuning of accumulation time individually in each cell of the integrated reading circuit. At the same time, the high steepness and linearity of the transformation in the storage cells with moderate illumination (up to 50–70% of the maximum signal) remains, but the sensitivity in the cells close to saturation decreases. As a result, a linear-log transfer characteristic is formed, providing an extended dynamic range. The paper provides examples of images with an extended dynamic range obtained using the first domestic SWIR camera of format 640 × 512 elements.

UV visible-blind and solar-blind 320 × 256 photodiode arrays based on Al_xGa_{1 – x}N heteroepitaxial structures (AlGaN HES) and sensitive in the near-ultraviolet range of 0.2–0.4 μm have been created and studied. The AlGaN HES were grown by organometallic vapor deposition (MOCVD) and molecular beam epitaxy (MBE) on sapphire substrates. To reduce structural defects, the state of the surface and the surface layer of epipolished sapphire substrates was investigated, and a finishing technology was developed. UV FPAs in the AlGaN HES were produced by ion etching. The dark current components for AlGaN photodiodes were simulated. The main dark current components, such as generation–recombination, shunting leakage, hopping conductivity, and Poole–Frenkel components, are calculated. The possibility of achieving photoelectric parameters on the level of the best foreign counterparts is demonstrated.