Advantages of graphene technologies in the design of antenna systems for the Internet of Things in the decimeter range of cellular operators (LTE, GSM, 5G)

The characteristics and resistance to external influences of flexible graphene antennas are considered. In particular, the analysis of the influence of single and cyclic bends at different cycle times is carried out. Resistance to water of such antennas is analysed. The results of characteristics comparison of the literature data with the results obtained by the authors are presented. The design of a flexible graphene eco-friendly two-layer antenna on a paper substrate operating in the LTE frequency range has been proposed. The technology discussed in this report will help fill the gap in the literature in eco-friendly double-sided graphene printing technologies. The literature review shows that the development of graphene inks for printing on flexible substrates has made a breakthrough in the development of flexible electronics due to their unique advantages. The influence of edge effects on the change in the graphene surface resistance at the edges of the manufactured sample is estimated.

The effect of electromagnetic radiation on indexes of antioxidant defense in rat erythrocytes and blood plasma

Цель исследования - изучение влияния электромагнитного излучения дециметрового диапазона на показатели антиоксидантной защиты в эритроцитах и плазме крови крыс. Методика. Эксперименты выполнены на крысах находившихся под влиянием электромагнитного поля дециметрового диапазона в течение 3-х мес. Проведен хемилюминесцентный анализ эритроцитов и плазмы крови животных. Интенсивность свободно радикального окисления в эритроцитах и плазме крови оценивали по показателям: максимальной интенсивности хемилюминесценции (Imax); светосуммы (S); светосуммы после максимального значения хемилюминесценции S(imax); коэффициентам Zlmax и Dec. Спектрофотометрически определяли содержание восстановленного глутатиона в эритроцитах. В плазме крови определяли содержание церулоплазмина, меди и железа. Анализ этих показателей был проведен в динамике исследования через 30, 60 и 90 сут. Результаты. Длительное (в течение 3 мес) нахождение животных в условиях действия электромагнитного поля приводит к изменениям показателей хемилюминесценции эритроцитов. Изменение показателей Imaх, S, Simax свидетельствует о нарушении процессов свободнорадикального окисления. В эритроцитах периферической крови крыс при этом установлено повышение содержания глутатиона. В плазме крови выявлено увеличение концентрации церулоплазмина и меди, снижение содержания железа. Заключение. Длительное нахождение животных в условиях действия электромагнитного поля приводит к нарушению равновесия в прооксидантно-антиоксидантной системе в эритроцитах. Антиоксиданты глутатион и церулоплазмин являются мишенью для действия электромагнитного излучения дециметрового диапазона. Установлено влияние длительного электромагнитного излучения на показатели минерального обмена: снижение содержания железа и увеличение содержания меди в плазме крови. The aim of the research was to study the effect of decimeter-range electromagnetic radiation on indexes of antioxidant defense in rat erythrocytes and blood plasma. Methods. Experiments were performed on rats exposed to decimeter-range electromagnetic field for three mos. Chemiluminescent analysis of erythrocytes and blood plasma was performed. Intensity of free-radical oxidation in erythrocytes and plasma was evaluated by parameters of maximum chemiluminescence intensity (Imax), light sum (S), the light sum after the maximum chemiluminescence value (imax), and ZImax and Dec coefficients. The content of reduced glutathione in peripheral blood erythrocytes and the plasma contents of ceruloplasmin, iron and copper were measured spectrophotometrically at 30, 60, and 90 days. Results. A long-term exposure of animals to the electromagnetic field for 3 mos. led to changes in chemiluminescent parameters of erythrocytes. The changes in Imax, S, and Simax indicated impairment of free-radical oxidation processes. The content of glutathione was increased in peripheral blood erythrocytes. The plasma contents of ceruloplasmin and copper were increased whereas the content of iron was decreased. Conclusion. The long-term exposure of animals to the electromagnetic field results in an imbalance of the erythrocyte pro-/antioxidant system. The antioxidants glutathione and ceruloplasmin are targets for the decimeter-range electromagnetic radiation. The study demonstrated the effect of long-term electromagnetic radiation on indexes of mineral metabolism evident as a decrease in the content of iron and an increase in the content of copper in the blood plasma.

Model of radar station functioning in energy potential instability conditions

The energy potential of the radar is evaluated at the stage of testing when accompanied by reference spacecraft-calibration spheres. At the same time, special attention is paid to the readiness and serviceability of the radar equipment for conducting measurements and providing tests with high-precision data on the position in space and the effective scattering area (ESA) of the reference spacecraft. However, during the normal operation of the radar, it is often not possible to provide such conditions – the state of the radar equipment during measurements is constantly changing, and the limited number of calibration spheres in orbit does not allow measurements to be carried out with sufficient frequency. At the same time, in the radar field of view, there are constantly associated spacecraft for various purposes, measurements of the trajectory parameters of which can be used to assess the energy potential of the radar in real time. When making such measurements, it is necessary to take into account the actual state of the radar equipment and the fluctuations of the signal reflected from the spacecraft of complex shape. The presented model describes the factors that affect the instability of the energy potential during the operation of the radar in real operating conditions when accompanied by associated spacecraft, and allows us to identify the most significant of them. Currently, there are radar models that take into account the features of tracking space objects when changing the conditions for the propagation of electromagnetic waves in space, maneuvering targets, when observing targets against the background of interference, and others. At the same time, the combination of changes in the energy parameters of the radar and the reflected signal in these models was not fully considered. The need to create a model for the operation of a radar station in conditions of instability of the energy potential is also due to the development of technologies for creating small-sized spacecraft, the main distinguishing feature of which is the low radar visibility for stations in the decimeter range. As the ESA decreases, the power of the signal received by the antenna decreases, which increases the relative measurement error and increases the probability of a false target miss. Small-sized spacecraft are understood to be spacecraft with linear dimensions of the order of 0,1x0,1x0,1 m. The ESA of such objects varies in the range from a few hundredths to units of square meter σэф = (0,01…4) m2.

INFLUENCE OF ELECTROMAGNETIC RADIATION ON THE PERMEABILITY OF ERYTHROCYTE MEMBRANES

The purpose of the survey is to experimentally study the influence of electromagnetic radiation from the decimeter range on the permeability of erythrocyte membranes. The object of the study was the blood of 80 white rats, 60 of them for three months were under the influence of electromagnetic radiation of the decimeter range. 20 animals of the control group were not exposed to electromagnetic fields. The intensity of free radical oxidation was evaluated using chemiluminescent analysis of red blood cells and blood plasma. The permeability of erythrocyte membranes and the content of reduced glutathione in blood erythrocytes were determined spectrophotometrically. A prolonged stay of animals under the influence of an electromagnetic field leads to pronounced changes in chemiluminescence indices in erythrocytes: a decrease in the maximum intensity of chemiluminescence (Imax), light sum (S), and light sum after the maximum value of chemiluminescence (Simax). Despite the increase in the content of glutathione and the chemiluminescent analysis index tg2 reflecting the antioxidant potential, there is an increase in the permeability of erythrocyte membranes under the influence of electromagnetic radiation

ANALOG PHASE SHIFTERS OF THE DECIMETER RANGE FOR INCREASED POWER LEVEL

The results of designing a phase control device in the decimeter wavelength range in the form of a tunable bandpass filter are presented. Tuning such a filter by 1/2 of the relative bandwidth, not exceeding 40 - 50%, provides a frequency-independent controlled phase shift. The minimization of parasitic amplitude modulation, along with an increase in the high-frequency power transmitted by the phase shifter, is achieved by optimizing the switching factor of the varicap into the quasi-polynomial bandpass filter circuit.

Evaluation of the microwave power of a buncher in a repeated magnetic field

The article considers the klystron method of grouping in a repeated magnetic field. In the long-wavelength range, in addition to gyrocon and magnicon, microwave tetrodes and multi-cavity klystrons are used. Conventional klystrons in the decimeter range have significant dimensions, and their application becomes problematic, and microwave tetrodes have a significant power level, but low efficiency and gain ratio.

The Problems of Passive Remote Sensing of the Earth’s Surface in the Range of 1.2–1.6 GHz

The main problems of remote sensing of the Earth’s surface within the frequency range 1.2–1.6 GHz are discussed. They are related to the resonant quantum properties of the radio wave propagation medium in the lower ionosphere. It is shown that, for the passive remote sensing, the main source is incoherent microwave radiation of the D and E ionospheric layers in the decimeter range. For the first time, a theoretically grounded principally new scheme of measurements is suggested. The scheme assumes that the radiation source exists below the satellite orbit and accounts for the fact that two types of radiation (direct and reflected) reach the satellite sensor. The separation of the respective fluxes is a serious problem that should be solved for the correct interpretation of the measurements. The question is raised regarding the correct calibration of measuring equipment, depending on the current state of the ionosphere.

CHANGES IN THE PARAMETERS OF IRON METABOLISM IN RATS’ BLOOD UNDER DECIMETRIC ELECTROMAGNETIC RADIATION

Introduction. The intensive development of radio and electrical communications, as well as various electronic devices, leads to the electromagnetic pollution of the environment.Aim. In this work, the authors set out to study the serum iron parameters of rats exposed to chronic electromagnetic radiation (EMR) of the decimeter range.Materials and methods. The research was carried out on rats that were divided into experimental and control groups. The experimental group was further divided into 4 subgroups of 10 animals each, which were subsequently exposed to electromagnetic radiation at a frequency of 460 MHz (Volna-2 apparatus) for 1, 2, 3 and 4 weeks. The control group (10 rats) was exposed to pretend irradiation, with the device being turned off. The following parameters were estimated: serum iron (SI), total iron-binding capacity (TIBC) and unsaturated iron-binding capacity (UIBC) of serum, transferrin saturation (TS), as well as serum concentrations of transferrin, haptoglobin, malondialdehyde and lipid hydroperoxides.Results. Differences in the SI concentration were found in the subgroups of animals exposed to radiation for 3 and 4 weeks (44.1 ± 3.1 μmol/l and 56.8 ± 4.4 μmol/l, respectively), as compared to the control group (30.5 ± 3.3 μmol/l). In experimental animals, TIBC increased by 41 % (p <0.05) — relative to the control group (110.8 ± 10.1 μmol/l) — only following 3 weeks of irradiation (156.2 ± 18.2 μmol/l), with a decrease in TIBC to 123.6 ± 16.4 μmol/l being noted during the 4th week. The concentration of transferrin increased from 45.6 ± 8.0 μmol/l (control) to 81.0 ± 11.5 μmol/l during the 3rd week of radiation exposure, with a decrease to 55.9 ± 6.7 μmol/l being observed during the 4th week. TS increased from 27.5 % (control) to 45.9 % only following 4 weeks of irradiation. The content of lipid hydroperoxides and malondialdehyde in the blood of irradiated rats was higher, as compared to the control animals. The serum concentration of haptoglobin amounted to 26.7 % in the control group, reaching 53.8 mg % and 47.8 mg % following 3 and 4 weeks of exposure, respectively.Conclusion. The total chronic exposure to decimetric EMR produces an oxidising effect on organisms.

METHOD FOR CONSTRUCTING MULTIFUNCTIONAL L BAND ACTIVE PHASED ARRAY ANTENNAS FOR RADAR SYSTEMS

The article poses the urgent task of increasing the efficiency of functioning of active phased antenna arrays (APAA) radar stations. Particular attention is paid to the development of modern multifunctional phased L-band arrays. Contradictions in the main criteria for ship antennas are revealed, and ways to eliminate them are proposed. Based on the study of radar and classification systems for ship-based targets and on the analysis of the results, a new method for constructing L-band multifunctional APAA for these systems has been proposed. It is proposed to use a dipole-type emitter in antenna arrays, which operates in the decimeter range and the lower part of the centimeter range. It has high mechanical and electrical strength. The article presents a scheme for constructing an APAA classification system, simulation results and an example of the practical implementation of the proposed method.