The results of development and research of a 2-mm band detector based on a series pair of the Schottky barrier diodes (SBDs) are presented. The realised waveguide-microstrip design of the detector and the principle of operation are described. The linear calculation of the detector characteristics and the model of the nonlinear element based on the equivalent parameters of the SBDs in the operating mode are considered. The technique of measuring the characteristics of the 2-mm detector is specified. Experimental results of voltage sensitivity, current sensitivity, return loss of the detector input are given. The dependence of the voltage drop on the series pair of SBDs on the power of the EHF signal is investigated. The dependence of the voltage sensitivity and VSWR of the detector input on the bias current is also investigated. The influence of the equivalent parameters of the nonlinear element on the voltage sensitivity and VSWR of the detector input is considered.

The description of a passive W-band multiplier and its calculation, development process and methodology for measuring its characteristics are given. A parametric multiplier based on nonlinear resistance is implemented, which uses a pair of Schottky barrier diodes with Pt/Ir contacts. The operating principle of the proposed frequency multiplier is described. The electromagnetic modeling data and the experimental results on the efficiency and the conversion and return losses are presented.

The paper presents theoretical calculations and experimental data on the permittivity of conductive porous acrylonitrile butadiene styrene. It is found that spectrum regions with differential absorption are caused by the volume resonance of electromagnetic waves inside pores and in the matrix material between them. Resonant frequencies with increased differential absorption can be controlled by changing the pore space, dimension, and matrix permittivity.

Methods of reconstructing holographic images of objects made of the composite based on carbon fibermodified acrylonitrile-butadiene styrene and a thin electrically conductive film are presented. Holograms are obtained in the axial scheme when the collimating lens is placed on the source axis. Results of comparison of the calculated frequency response of the model transmission coefficient with measurements on an experimental setup are presented.

In this paper, the results of the research of electromagnetic characteristics of millimeter-wave notch filters based on metasurfaces are presented. The samples of metamaterials were three-layer planar structures based on split-ring resonators made on metallized textolite FR4 using photolithography technology. Topological parameters elementary cells of researched metamaterials are shown. In the CST Studio software package by frequency solver comprehensive modeling of transmission, reflection and absorption coefficients were carried out. Experimental research of metamaterial samples was carried out on two measuring setups (continuous wave and time-domain spectroscopy) in frequency range from 34 GHz to 1 THz. The considered metastructures have a wide band-stop frequency region of the order of 40–50 GHz, which can be shifted in frequency by changing the unit cell parameters of the periodic metasurface. The use of such materials will make it possible to create band-stop filters for various frequency ranges or microwave sensors for electromagnetic parameters of the medium.

In this paper, the problem of creating homogeneous composites with on carbon nanotubes is described. To control the quality of the manufactured composites, a system of terahertz visualization of material inhomogeneity using a continuous radiation source is used. An increase in the homogeneity of the composite based on multi-walled carbon nanotubes with an increase in the time of ultrasonic processing during polymerization is noted. The advantages of THz imaging in comparison with optical microscopy are shown.

In this study, a new method is proposed for producing polymer composites via the adsorption of multiwalled carbon nanotubes (MWCNTs) on the surface of polystyrene spheres (PS) to provide a cellular distribution of MWCNTs in the composite. The method makes it possible to control the cell size down to the submicron level and the conductivity of the composite in a wide range. The effect of the MWCNT concentration on the surface of PS on the structure of the resulting composites and their electrophysical properties are studied in the frequency range of 115 GHz–1.4 THz. The percolation nature of the composite conductivity was established. It was shown that the obtained composite is a regularly chaotic medium, and its regularity scale corresponds to the sizes of the PS. MWCNTs on the PS surface form two subsystems: the first is a pseudo-regular subsystem on the edges of cuboid-like PS, while the second subsystem consists of chaotically scattered MWCNTs with unclosed ends on the faces of PS. The first subsystem belongs to the regular part of the structure and mainly determines the properties of the medium at frequencies above 500 GHz. The second subsystem of nanotubes is characterized by a small electrodynamic scale comparable with the size of one PS cell and determines the effective properties of the composites at frequencies below 500 GHz.

The effect of the addition of magnetite in the form of pyrite stubs on the physico-mechanical and radio-absorbing properties of the synthesized glass composite by the method of “cold” foaming is considered. Replacing glass powder with magnetite in the initial liquid-glass composition reduces the foaming coefficient from 80 to 20 %, which is due to a decrease in the viscosity of the composition due to the particle size of the additive (160 ?m), their high density (5100 kg/m3) and porous structure. It has been established that the optimal content of magnetite for obtaining a material with radio-absorbing properties is no more than 10 %. A porous glass composite with an average pore size of 2, containing 10 % magnetite, has an absorption coefficient of electromagnetic radiation in the high-frequency range (120 – 250 GHz) on average 10 % more than a composite without an additive.

The effect of silicon carbide (10 – 40 wt.%) on the physicomechanical and electrophysical characteristics of composites was considered. The effect of an additive on the radio absorption capacity of the material was determined by measuring the coefficients of absorption, transmission, and reflection of electromagnetic radiation as well as the dielectric constant of the material. It was found that introducing 30 wt.% silicon carbide into the composition increases the strength in compression to 2.4 MPa due to the reinforcing role of silicon carbide needle crystals. The additional dielectric losses and the average pore size of the composite on introduction of 30% silicon carbide afford an absorption coefficient of electromagnetic radiation from 95 to 98% in the frequency range 120 – 250 GHz. The results of this work expand the areas of application of porous glass composites as well as the raw material base for obtaining the material.

In paper results of research of metamaterial surface based on split-ring resonators obtained by photolithography are presented. Numerical simulation of electromagnetic response of the created structure are shown. Experimental researches of the transmission coefficient using quasi-optical methods of continuous and time-domain spectroscopy in the frequency range from 34 to 200 GHz were carried out. Area of broadband screening in the EHF range has been found.

The results of studies of the electromagnetic response from composite structures made of a carbon-containing polymer with the inclusion of spherical pores in the bulk of the material and with pyramidal corrugation on the surface of the material are presented. The results of modeling the frequency dependences of the transmission, reflection and absorption coefficients in the EHF range are shown. Samples of composite carbon-containing structures with technological inhomogeneities have been fabricated by 3D printing. Measurements of the electromagnetic response from experimental samples were carried out in the frequency range from 100 to 1000 GHz. At frequencies up to 250 GHz, the inclusion of air pores in the polymer volume reduces the transmission coefficient, practically does not affect the reflection, and increases the absorption. Pyramid corrugated material absorbs more than 99% of radiation in the frequency range from 200 to 635 GHz.

The paper presents the results of studying electromagnetic response from polymer composite materials in the frequency range from 0.1 THz to 1.6 THz obtained using a BWO-based spectrometer and a time-domain spectrometer. The composites used were epoxy resin with the addition of barium titanate (BaTiO3) with a mass concentration of 40% to 80%. Based on these data, the values of the complex permittivity of composite samples are calculated and analyzed, and the electromagnetic response from the samples is modeled. An assessment of the applicability of this material in the elements of the THz range technology is carried out.

Terahertz imaging system based on backward wave oscillator for the defectoscopy of composites in the industry is presented. At a frequency of 874 GHz images of multiwall carbon nanotube agglomerates in a composite are obtained. The possibility of detecting inhomogeneities using level filtering is shown.

The spectra of complex permittivity of the composites consisting of rubber silicone compound and electroconductive fine-dispersed silver-coated copper powder were investigated. To enhance the effectiveness of the composite interaction with microwaves and reduction of its weight and dimensions characteristics two and three-layer constructions were produced. Matching layers were made of foam glass material with addition SiC and Fe3O4.

The article discusses monitoring water bodies pH level automated system implementation using an unmanned aerial vehicle (UAV). Floating structure prototype for supporting UAV on water surface is described, taking into account creating a rotor thrust theory. Water hydrogen ions monitoring activity concept using a UAV is presented. Testing results water monitoring system in Lake Boyarskoye (Tomsk, Russia) are presented.

The paper presents the modeling of the reflectance in the terahertz range from the plane-parallel aerogel layers formed by multi-walled carbon nanotubes (MWCNTs), which were synthesized via the original one-step technique using a preformed Fe–Co/CaO catalyst at 650–700°C in C2H4/Ar feedstock. With an increase in frequency from 100 GHz to 1.5 THz, the reflectance decreases by more than a factor of two. Based on the experimental data and the well-known wire medium model formed by a three-dimensional lattice of intersecting conductors, a model of a regular wire medium is constructed using MWCNTs with effective electrophysical characteristics equivalent to those of an irregular aerogel medium. This model reveals that a significant drop in the reflectance in the terahertz frequency range occurs because the plasma frequency of the equivalent medium is located here. The model allows estimating the properties of the aerogel environment in the frequency range extending up to 5 THz and with variations in the packing density of MWCNTs in aerogel. Estimates of the reflection, transmission, and absorption are presented for the case of normal EMI incidence on thin (submillimeter) layers of such a medium.

The spectral sensitivity and morphological characteristics of a pyroelectric photosensor based on tetraaminodiphenyl thin films were investigated. It was found that the pyroelectric sensor sensitivity weakly depends on the radiation frequency in a wide spectral range from visible to millimeter waves and is 2...8 times higher than the sensitivity of known pyrodetectors and the Goley cell. The tetraaminodiphenyl surface morphopology has a significant roughness of up to few μm with a 1 μm film thickness. The role of the abnormal skin effect is discussed.

Porous materials are promising for use in the terahertz range, when they have valuable properties: low weight, chemical inertia, thermal stability, and relatively low cost. These materials are required for effective shielding of electromagnetic radiation, attenuators, filters. Electromagnetic characteristics in the frequency range of 0.15 – 0.5 THz are considered. Samples are porous composite materials filled with carbonyl iron, waste from semiconductor production, and carbon nanostructures. Foamed polyurethane and foam glass material is used as a dielectric binder. The combination of high electromagnetic efficiency and the "green" origin of the constituent composites opens the way for successful practical use.

Results of research of lateral scattering of electromagnetic radiation by aerogel of MWCNTs are presented. Frequency dependences of lateral scattering of THz radiation of spherical MWCNTs aerogels with diameter of 4.5 and 6 mm at frequency range 43-970 GHz are given.