Microwave Telecommunication Research Articles

Facile and scalable preparation of Ni/NiO/SiO2@porous carbon network with strong and wide bandwidth microwave absorption

Researchers are exploring high-performance electromagnetic wave absorbing materials to mitigate electromagnetic interference, focusing on minimizing surface reflection and enhancing attenuation capability. However, one single component and structure struggle to meet the aforementioned requirements. Here, a Ni/NiO/SiO2@porous carbon network (Ni/NiO/SiO2@PCN) with porous structures is synthesized via a pyrolysis process. The magnetic Ni/NiO and dielectric SiO2 nanoparticles are uniformly dispersed within the PCN matrix. The absorption capability of the material can be controlled by adjusting the SiO2 content in Ni/NiO/SiO2@PCN. Particularly, when the SiO2 loading is 0.5 wt%, the resulting Ni/NiO/SiO2@PCN-0.05 demonstrates outstanding EMW absorption properties, exhibiting strong broadband absorption attributed to its 3D porous architectures, the hybrid composition of Ni/C, NiO/C, and SiO2/C, and good impedance matching. At a filler loading of 20 wt%, the Ni/NiO/SiO2@PCN-0.05 achieves remarkable EMW absorption performance, with a minimal reflection loss reaching −71.42 dB at 2.6 mm and 11.18 GHz, and an effective absorption band extending over 6.24 GHz within the frequency range of 11.52 to 18.0 GHz at a thickness of 2.25 mm, effectively covering the entire Ku band. This study introduces a cost-effective and efficient fabrication approach for producing high-performance microwave absorbers, thereby offering promising prospects for applications in the field of microwave telecommunications.

Microwave and Telecommunication Technology are the Basis of Technological Independence (review of the 33rd International Conference “Microwave and Telecommunication Technology”)

The review analyses 50 scientific articles related to the development of the electronic and radioelectronic industry, which were discussed at the 33rd International Conference «Microwave Technology and Telecommunication Technologies». The conference was held in September 2023 in Sevastopol. The review includes reports on the scientific directions of the journal presented by scientists from universities, research institutes and enterprises of three countries: Belarus, Vietnam and Russia. The article analyses researches related to ensuring a technological breakthrough in the radioelectronic industry, the development of modern information and communication technologies in the civil, military and space industries.

Facile and scalable preparation of ultralight cobalt@graphene aerogel microspheres with strong and wide bandwidth microwave absorption

Cobalt@graphene aerogel microspheres (GCoAMs) with tunable porous structures are fabricated by using a unique spraying and crosslinking coagulation method. The graphene oxide (GO) and sodium alginate (SA) mixture aqueous dispersions were used for spraying. The cross-linking reaction occurs quickly between the carboxylic group of SA in the sprayed microdroplets and metal Co2+ in the collector bath, which fixes the microsphere shape and in-situ immobilizes the metal ion. After freeze-drying and the subsequent high-temperature thermal reduction, the ultralight GCoAMs are obtained. The pore structures of GCoAMs can be controlled by varying the GO/SA ratio. The GCoAMs exhibit strong and wide broadband microwave absorption due to its hierarchical porous structures and graphene/metal Co hybrid composition. At a GCoAMs loading content of 1.5 wt%, the minimal reflection loss reaches as high as −70.4 dB with a thin specimen thickness of 2.2 mm at 13.18 GHz and its effective absorption band achieves 5.65 GHz with a specimen thickness of 1.98 mm. At 2 wt% GCoAMs, the effective absorption band achieves 6.09 GHz with a specimen thickness of 2 mm, covering the whole Ku band. This work provides a novel, low-cost and easily scale-up method for preparing the lightweight and efficient microwave absorbers, which could be used in microwave telecommunication fields.

Improved Electrical Properties of Strontium Hexaferrite Nanoparticles by Co2+ Substitutions.

In this work, the sol-gel route was employed to synthesize a series of Co2+-substituted strontium hexaferrite nanoparticles (Sr1-x Co x Fe12O19, x = 0.0-0.50) to study the effect of cobalt ions doping on the magnetic, electrical, and structural properties of the nanoparticles. The structural analysis of the synthesized nanoparticles, performed by X-ray diffraction, showed the formation of a hexagonal structure having no secondary phases. The morphological analysis, performed through scanning electron microscopy, revealed spherical shaped nanoparticles with uniform distribution. Fourier transform infrared spectra demonstrated two consistent absorption bands indicating the intrinsic stretching vibrations around 600 and 400 cm-1 for tetrahedral and octahedral sites, respectively. It was observed through VSM that with cobalt addition, the saturation magnetization increased and the coercivity decreased. Also, a typical decreasing trend of DC electrical resistivity with increasing temperature measured by a two-probe method confirmed the semiconducting behavior of the synthesized samples. An impedance analyzer was used for the dielectric measurements at room temperature against the alternating frequency range of 250 Hz to 5 MHz, and it was found that the dielectric constant decreased with the increase in cobalt content, suggesting that the doped nanomaterials can be used for microwave absorption, electronics, telecommunication, and other high-frequency applications.

CHARACTERIZATION OF (Mg0.5ZN0.5)TiO3 CERAMICS AS MATERIAL CANDIDATES FOR DIELECTRIC RESONATOR AT MICROWAVE FREQUENCY

MgTiO3 ceramic is one of the dielectric materials used as a signal generator (dielectric resonator) in microwave telecommunication devices. This research is intended to explore the possibility of a new composition of MgTiO3-based ceramic, i.e. (Mg0.5Zn0.5)TiO3 (abbreviated MZT05) as a dielectric resonator material. The aim was to characterize the resonant frequency of the ceramics on the microwaves (measured using spectrum analyzer), and the results were correlated to structure (X-Ray Diffraction, XRD), microstructure (Scanning Electron Microscope, SEM), and bulk density data (Archimedes method) of the ceramics. The work was begun by compacting the MZT05 crystalline powder in a cylindrical shape with a diameter of 5 mm using a uniaxial die press to produce tablets. The tablets were sintered at 1300 ºC with variations holding times of 6, 8, and 10 h to produce ceramics. The structural data revealed that the MgTiO3 phase was identified as the main ceramics, i.e. (96.32-98.70) %molar. The bulk density increased with increasing sinter holding time, from 2.75 g/cm3 (6 h), 2.84 g/cm3 (8 h) to 2.99 g/cm3 (10 h) due to the increase in grain size diameter from 919.75 nm (6 h), 1090.62 nm (8 h) to 1180.72 nm (10 h) accompanied by a decrease in the size of the pore diameter from 924.14 nm (6 h), 917.05 nm (8 h) to 800.22 nm (10 h). The ceramics produced resonant frequencies of 5.07–5.08 GHz, which implies that the ceramics are proven to be potential candidates for dielectric resonator materials at microwave frequencies, especially at 5.07-5.08 GHz. The varying sinter holding time seems not to influence the resonant frequency of the ceramics because the variation holding times produce similar resonant frequencies.

High Q Dielectric Titanium Tellurite Thick Films on Alumina Substrates for High Frequency Telecommunications

The vital role of high-quality-factor (Q) high-frequency (f) dielectric resonators in the growing microwave telecommunication, satellite broadcasting and intelligent transport systems has long motivated the search for new, small size, and lightweight integrated components and packages, prepared by low cost and sustainable processes. One approach is replacing the currently used bulk ceramic dielectrics by thick films of low-sintering-temperature dielectrics fabricated by affordable processes. Here we demonstrate the fabrication of high-Q TiTe3O8 thick films directly on low loss Al2O3 substrates by electrophoretic deposition using sacrificial carbon layer. Nineteen-micrometre-thick TiTe3O8 films on Al2O3 sintered at 700 °C are found to have a relative permittivity εr of 32 and Q × f > 21,000 GHz. Being thus able to measure and provide for the first time the microwave dielectric properties of these films, our results suggest that TiTe3O8 films on Al2O3 substrates are suitable for microlayer microstrip array applications.

Microwave and Telecommunication Technology: Future Outlook (review of the 32rd International Conference “Microwave & Telecommunication Technology”)

The article deals with topical issues of technologies of the production of modern electronic products and research in the field of advanced information and communication technologies, which were the subject of discussion at the 32-nd International Conference «Microwave Technology and Telecommunication Technologies». The conference was held in September 2022 in the city of Sevastopol. The article analyzes 62 reports from 215 participants of the conference, to which the greatest interest of the scientific community was demonstrated. The review includes reports from 26 universities, research institutes and enterprises of three countries – Belarus, Russia and China. The problems related to new opportunities and technologies, the latest means of communication, the use of modern information and infocommunication technologies in civil and space industries are analysed.

XRD and EDX Analyses on the Formation of MgTiO3 Phase in (Mg0.6Zn0.4)(Ti0.99Sn0.01)O3 Powders Due to Calcination Temperature Variations

MgTiO3-based dielectric ceramics have been recognized as functional materials in the microwave telecommunications industry. Research and development on MgTiO3 dielectric ceramics has therefore developed rapidly. This paper reports x-ray diffraction (XRD) and energy dispersive x-ray (EDX) analyses on the formation of MgTiO3 phase in (Mg0.6Zn0.4)(Ti0.99Sn0.01)O3 powder due to variations in calcination temperature from 550 to 700°C for 2 h. The powder was synthesized via the dissolved metal mixing course using magnesium, zinc, titanium and tin metal powders (Merck) as starting materials. The Rietveld refinement on the XRD patterns of the samples revealed that increasing the calcination temperature reduces the molar% content of MgTiO3 phase of from (97.91±1.51) at 550°C to (87.81±1.29) at 700 °C and causes a decrease in the diffraction peak intensity. The remaining % belongs to TiO2 rutile. The calcination temperature also enlarged the size of MgTiO3 unit cell volume. The EDX data on the atomic% ratio of the elements confirmed the presence of the phases. Discussion of these results is presented in detail in this paper.

Investigation of Dielectric Resonator Oscillator Using High-Electron Mobility Transistor at 26GHz for Space Applications

An oscillator is a vital component as the energy source in microwave telecommunication system. Microwave oscillators designed using Gunn diode have poor DC to RF efficiency. IMPact Ionization Avalanche Transit-Time diode (IMPATT) oscillators have the drawback of poor noise performance. The transistorized oscillators have a limitation to the maximum oscillation frequency which means that they cannot be used for oscillators designed for high frequencies. To design negative series feedback Dielectric Resonator Oscillator (DRO), the resonant unit uses a dielectric resonator (DR) since it is small in size, light in weight, has high-Quality ([Formula: see text]) factor, better stability and also it is inexpensive. It has the benefits of low-phase noise, low cost, miniaturization, high stability, applicable for devices designed at high frequencies and had already been widely applied, so the research on microwave dielectric oscillator has also been one of the focus of today’s microwave integrated circuits. DRO is widely used in electronic warfare, missile, radar and communication systems. The DRO incorporates High-Electron Mobility Transistor (HEMT) as an active device since it offers higher power-added efficiency combined with excellent low-noise figures and performance. The entire circuit of DRO using HEMT at 26[Formula: see text]GHz is designed using Agilent Advanced Design System (ADS) software. In this, DRO different measurements of parameters are done such as output power which is typically [Formula: see text][Formula: see text]dBm for 26[Formula: see text]GHz DRO, phase noise at 10[Formula: see text]kHz offset for 26[Formula: see text]GHz DRO it is 80[Formula: see text]dBc/Hz. The frequency pushing and frequency pulling for 26[Formula: see text]GHz DRO its typical values are 30[Formula: see text]kHz/V and 1[Formula: see text]MHz, respectively.

An EnKF-based method to produce rainfall maps from simulated satellite-to-ground MW-link signal attenuation.

Measuring rainfall is complex, due to the high temporal and spatial variability of precipitation, especially in a changing climate, but it is of great importance for all the scientific and operational disciplines dealing with rainfall effects on the environment, human activities, and economy. Microwave (MW) telecommunication links carry information on rainfall rates along their path, through signal attenuation caused by raindrops, and can become measurements of opportunity, offering inexpensive chances to augment information without deploying additional infrastructures, at the cost of some smart processing. Processing satellite telecom signals bring some specific complexities related to the effects of rainfall boundaries, melting layer, and non-weather attenuations, but with the potential to provide worldwide precipitation data with high temporal and spatial samplings. These measurements have to be processed according to the probabilistic nature of the information they carry. An EnKF-based (Ensemble Kalman Filter) method has been developed to dynamically retrieve rainfall fields in gridded domains, which manages such probabilistic information and exploits the high sampling rate of measurements. The paper presents the EnKF method with some representative tests from synthetic 3D experiments. Ancillary data are assumed as from worldwide-available operational meteorological satellites and models, for advection, initial and boundary conditions, rain height. The method reproduces rainfall structures and quantities in a correct way, and also manages possible link outages. It results computationally viable also for operational implementation and applicable to different link observation geometries and characteristics.

Comprehensive study on structural, electrical, magnetic and photocatalytic degradation properties of Al3+ ions substituted nickel ferrites nanoparticles

A series of Al3+ substituted NiAlxFe2-xO4 (0.0 = x ≤ 0.5) nanoparticles was synthesized using the chemical co-precipitation route. The effect of Al3+ ions doping was investigated in terms of structural, degradation, magnetic and electrical properties of the nanoparticles (NPs). The XRD patterns confirmed the formation of the spinel cubic phase. FT-IR spectra revealedtwo consistent absorption bands indicating the intrinsic stretching vibrations of O2- Fe3+ around 591-615 cm−1 and 416-428 cm−1 bond lengths for tetrahedral and octahedral sites respectively. The magnetic properties decrease as the concentration of Al3+ increases. The decrease of magnetic parameters can be explained by the difference between magnetic moments of Al3+ and Fe3+ cations. Maxwell-Wagner model of space charge polarization was utilized to explain the dielectric properties with frequency. The increasing dielectric losses indicated the suitability of synthesized NPs for microwave absorption, telecommunication, electronics and other high frequency applications. The dependence of dielectric properties on grains and grain boundaries was further investigated via impedance spectroscopy and complex electric modulus. The study of photo-degradation efficiency of NPs was performed using organic methylene blue dye. The results showed satisfactory degradation with maximum degradation efficiency of 84.45% for NPs with composition NiAl0·5Fe1·5O4.

Influence of Lithium Substitution for Zinc on Crystal Structure and Microwave Dielectric Properties of Willemite Li2xZn2−xGeO4

Willemite ceramics have recently received considerable attention for microwave or millimeter-wave telecommunication because of their extremely high quality factor. Unfortunately, it suffers from difficulty in the formation of pure phase Zn2GeO4. Reducing ZnO content is favorable for its phase purification. In this work, an alternative method, introducing 2 Li to substitute Zn, was proposed to reduce the Zn content. Some Li2xZn2−xGeO4 ceramics were designed and fabricated. Limited solid solutions were revealed and single phase willemite-based ceramics were obtained when x ≤ 0.04, beyond which a Li-rich phase Li2ZnGeO4 appeared. Li substitution was also found not only reducing the densification temperature but also improving the relative permittivity and quality factor of Zn2GeO4 ceramics. The densification temperature of Zn2GeO4 ceramics was further reduced to 950 °C after 5wt.% B2O3 additives, rendering their potential applications in low-temperature devices.

Dual-Band High Q-Factor Complementary Split-Ring Resonators Using Substrate Integrated Waveguide Method and Their Applications

In modern microwave telecommunication systems, especially in low phase noise oscillators, there is a need for resonators with low insertion losses and high Q-factor. More specifically, it is of high interest to design resonators with high group delay. In this paper, three novel dual-band complementary split-ring resonators (CSRRs) featuring high group delay etched on the waveguide surface by using substrate integrated waveguides are investigated and proposed. They are designed for a frequency range of 4.5–5.5 GHz. Group delay rates for the first, second, and third resonators were approximated as much as 23 ns, 293 ns, and 90 ns, respectively. We also proposed a new practical method to develop a wide tuning range SIW CSRR cavity resonator with a small tuning voltage in the second resonator, which leads to about 19% and 1% of tuning frequency band in the first and second bands, respectively. Finally, some of their applications in the design of filter, diplexer, and low phase noise oscillator will be investigated.

Chromosome damage in human cells induced by UMTS mobile telephony radiation.

Environmental exposure to modern microwave telecommunication electromagnetic fields (EMFs) has increased to unprecedented levels with consequent health complaints and concerns. Many studies have already reported genotoxic effects on a variety of organisms and cell/tissue types. Human peripheral blood lymphocytes from six healthy donors were stimulated for mitosis and exposed to microwave EMF of Universal Mobile Telecommunications System (UMTS) or third generation (3G) mobile telephony (MT) EMF/radiation emitted by a commercially available mobile phone handset. Lymphocytes exposed during the G2 phase of the cell division cycle and observed at metaphase, exhibited chromatid-type aberrations (gaps and breaks) at highly significant percentages - up to 275% - compared to the control (sham-exposed) samples. Each subject exhibited a different sensitivity to the microwave exposure. Moreover, the percentages of aberrations in the control samples among subjects were different due to genetic and environmental factors. The MT EMF exposure induced mainly achromatic lesions (gaps), and secondarily terminal deletions (breaks) in a smaller degree. In conclusion, the present study shows that microwave 3G MT EMF/radiation - within the current exposure limits - has significant genotoxic action on human cells, and human exposure to this EMF/radiation should be kept at levels as low as possible.

Internal electrical and strain fields influence on the electrical tunability of epitaxial Ba0.7Sr0.3TiO3 thin films

Perpetual demand for higher transfer speed and ever increasing miniaturization of radio and microwave telecommunication devices demands new materials with high electrical tunability. We have investigated built in electrical and strain fields' influence on the electrical tunability in Ba0.7Sr0.3TiO3 thin film hetero-system grown by pulsed laser deposition technique. We observed the built in electrical field by local piezo-force microscopy (as deflected hysteresis loops) and macroscopic impedance analysis (as asymmetric tunability curves), with the calculated 88 kV/cm built in field at room temperature. Negative −1.4% misfit strain (due to clamping by the substrate) enhanced ferroelectric phase transition temperature in Ba0.7Sr0.3TiO3 thin film by more than 300 K. Built in fields do not deteriorate functional film properties—dielectric permittivity and tunability are comparable to the best to date values observed in Ba1−xSrxTiO3 thin films.

Comparison of heterogeneous network rain fade simulation tools: global integrated network SIMulator and MultiEXCELL

Two heterogeneous network simulation tools are compared and tested against measured data from terrestrial and Earth-space microwave links. Both global integrated network SIMulator (GINSIM) and MultiEXCELL are able to produce joint distributions of rain fade time-series for arbitrary networks of microwave telecommunications links. The tools are fundamentally different in that GINSIM has, as its input, time-series of composite rain rate maps produced by networks of meteorological radars and can produce time-series of joint rain fade. MultiEXCELL uses the rain rate distribution as an input to constrain distributions of parameters of simulated rain cells. This study tests the simulators by comparing a range of annual fade statistics produced by simulation with data measured on experimental links. Link fade data were measured on two, Ka band, Earth-space links and a convergent 38 GHz terrestrial link near Chilbolton in southern England; and a further Earth-space link located in Dundee, Scotland. Both GINSIM and MultiEXCELL are shown to be able to predict joint fade distributions and diversity gain, for the satellite and terrestrial links, to useful accuracy. Differences in performance are analysed, leading to suggested development routes for both systems.

Thin Film Multiferroic Nanocomposites by Ion Implantation

Thin film multiferroic nanocomposites might enable a range of potentially disruptive integrated magnetoelectric devices for information storage, spintronics, microwave telecommunications, and magnetic sensing. With this aim, we have investigated ion implantation of magnetic species into ferroelectric single crystal targets as a radically novel approach to prepare film nanoparticulate magnetic-metal ferroelectric-oxide composites. These materials are an alternative to multiferroic oxide epitaxial columnar nanostructures that are under intensive research, but whose magnetoelectric response is far from expectations. Here, we unambiguously demonstrate the preparation of such a thin film multiferroic nanocomposite of Co and BaTiO3 by ion implantation of a high dose of the magnetic species, followed by rapid thermal processing under tailored conditions. Results thus constitute a proof of concept for the feasibility of obtaining the materials by this alternative approach. Ion implantation is a standard technique for the microelectronic industry in combination with well-established patterning procedures.

Radio Frequency Numerical Simulation Techniques Based on Multirate Runge‐Kutta Schemes

Electronic circuit simulation, especially for radio frequency (RF) and microwave telecommunications, is being challenged by increasingly complex applications presenting signals of very different nature and evolving on widely separated time scales. In this paper, we will briefly review some recently developed ways to address these challenges, by describing some advanced numerical simulation techniques based on multirate Runge‐Kutta schemes, which operate in the one‐dimensional time and also within multidimensional frameworks.

Development of a heterogeneous microwave network fade simulation tool applicable to networks that span Europe

[1] Several research groups in Europe are developing joint channel simulators for arbitrarily complex networks of terrestrial and slant path, microwave telecommunications links. Currently, the Hull Rain Fade Network Simulator (HRFNS) developed at University of Hull can simulate rain fade on arbitrary terrestrial networks in the southern United Kingdom, producing joint rain fade time series with a 10 s integration time. This paper reports on work to broaden the function of the existing HRFNS to include slant paths such as Earth-space links and communications to high altitude platforms and unmanned airborne systems. The area of application of the new simulation tool is being extended to the whole of Europe, and other fade mechanisms are being included. Nimrod/OPERA has been chosen as the input meteorological data sets for the new system to simulate rain fade. Zero-degree isotherm heights taken from NCEP/NCAR Reanalysis Data are used in conjunction with the Eden-Bacon sleet (wet snow) model to introduce melting layer effects. Other fading mechanisms, including cloud fade, scintillation and absorption losses by atmospheric gasses, can be added to the simulator. The simulator is tested against ITU-R models for rain fade distribution experienced by terrestrial and Earth-space links in the southern United Kingdom. Statistics of fade dynamics, i.e., fade slope and fade duration, for a simulated Earth-space link are compared to International Telecommunication Union models.

Features of active stand-alone repeaters for synchronous DVB - T broadcasting networks

The work describes the results of analysis and approaches to creating a national network of digital terrestrial television broadcasting standard DVB-T stand-alone repeater with an output power 25 watts, which can provide highquality TV signal in populated areas of an uncertain reception or in areas of radioshadow. Using the new circuit solutions in the field of microwave electronics and telecommunications, as well as solar energy can be achieved by maintenance of individual settlements with minimal performance and energy consumption. These active transponders will create conditions to cover the entire territory of Ukraine by multichannel television services of acceptable