Ultra-high Frequency Research Articles

RFID Tags for On-Metal Applications: A Brief Survey

Radio-frequency identification technology finds extensive use in various industrial applications, including those involving metallic surfaces. The integration of radio-frequency identification systems with metal surfaces, such as those found in the automotive sector, presents distinct challenges that can notably affect system efficacy due to metal’s tendency to reflect electromagnetic waves, thus degrading the functionality of conventional radio-frequency identification tags. This highlights the importance of conducting research into academic publications and patents to grasp the current advancements and challenges in this field, aiming to improve the applications of radio-frequency identification tags technology on metal. Consequently, this research undertakes a concise review of both the literature and patents exploring radio-frequency identification technology’s use for on-metal tags, utilizing resources like Google Scholar and Google Patents. The research categorized crucial aspects such as tag flexibility, operating frequency, and geographic origins of the research. Findings highlight China’s prominent role in contributing to metal-focused radio-frequency identification tag research, with a considerable volume of articles and patents. In particular, flexible tags and the Ultra-High Frequency range are dominant in both scholarly and patent documents, reflecting their significance in radio-frequency identification technology applications. The research underscores a vibrant area of development within radio-frequency identification technology, with continued innovation driven by specific industrial needs. Despite the noted advances, the presence of a significant percentage of no longer valid patents suggests substantial opportunities for further research and innovation in radio-frequency identification technology for on-metal applications, especially considering the demand for flexible tags and for solutions in systems that offer specialized characteristics or are tailored for specific uses.

Enhancement of Cobalt Bismuth Nano-Ferrite via Heat Treatment to be Applied in High-Frequency and Antimicrobial Applications

Cobalt bismuth nano-ferrite (Co/Bi) with the chemical formula CoBi0.02Fe1.98O4 was produced using a simple flash auto-combustion method at three different temperatures: as-prepared, 600°C, and 800°C. A single-phase spinel structure was confirmed using X-ray diffraction, and the nano-scale morphology was examined using AFM (atomic force microscopy). Magnetic measurements demonstrated that increasing the annealing temperature increased the saturation magnetization Ms by 1.3 times. However, the coercivity Hc changed from semi-hard ferrite (as-prepared sample) to soft ferrite (Co/Bi nano-ferrite at 800°C) and reduced 10.7 times that of as-prepared nanoparticles. Therefore, the 800°C Co/Bi nano-ferrite with a low coercive field is recommended for transformers, recording heads, inductor cores, magnetic shielding, and microwave devices. The as-prepared sample and that at 600°C displayed super-high microwave frequency (SHF) in the X band in high-frequency applications calculated from magnetic measurement. The 800°C sample also has an extremely high microwave frequency in the Ku band, which is utilized in radar and satellite communications. Antimicrobial characterization showed that raising the annealing temperature increased the effectiveness of the samples against tested microorganisms. Thus, the samples under investigation are highly suggested for ultra-high microwave frequency applications and biological antibacterial nanomaterials.

Innovative Use of UHF-RFID Wireless Sensors for Monitoring Cultural Heritage Structures

This paper reports a novel investigation in applying commercial Ultra High-Frequency RFID tags (UHF-RFID tags), which are widely used in logistics as sensing elements in civil engineering structures, particularly for monitoring out-of-plane displacements of brick masonry walls. Both laboratory tests and in situ experimental tests assessed the feasibility of the proposed application. Laboratory tests showed a very satisfactory response while the in situ experiments showed a weaker response. Nevertheless, the potential reliability of the proposed technique can be stated. The authors traced back the causes of the performance decrease to environmental interference, mainly due to the extensive presence of a rigid steel frame surrounding the out-of-plane loaded panels. Measurements of displacements, in fact, are obtained indirectly from the phase of UHF-RFID signals that strongly suffer from multipath generated by metallic surfaces. Despite some limitations, the proposed measurement technique permits a reliable and sustainable approach to the monitoring of structures. The use of commercial UHF-RFID wireless tags, in fact, assures easy and fast installation operations and assures the possibility of placing a large number of sensors over the structure with very low maintenance costs with respect to the more traditional monitoring techniques. Moreover, using very thin and small commercial UHR-RFID tags on cultural heritage structures can represent an opportunity for sustainable long-time monitoring with reduced costs. Overall, the results of this study are sufficiently satisfactory to be considered as the opening of new possible scenarios in wireless structural monitoring in the civil engineering field. The authors propose as future work to use UHF-RFID tags for the real-time monitoring of an existing masonry facade that, not being characterized by the presence of a steel frame, can potentially assure an adequate response and properly transmit the electromagnetic signal.

Strain regulation of bond length in single Ru sites via curving support surface for enhanced hydrogen evolution reaction

The intrinsic activity of single-atom catalysts is influenced by the local electronic structures of metal centers, with existing modulation strategies limited to adjacent atomic coordination. However, the impacts of support surface geometry on local bonding environment, and thus electronic structures of single-atom centers have rarely been known. Here, we prepared highly curved B,N co-doped carbon-supported ruthenium catalyst with an ultra-low Ru loading of 0.4 wt%, which exhibited an ultrahigh turnover frequency (TOF) of 10 H2 s−1 (38 times that of Pt/C) and superior stability in alkaline hydrogen evolution reaction (HER). We found that curving support surface induced the strain, resulting in 1.5% compressed Ru-N and 4% stretched Ru-B bonds, leading to the accumulation of positive charge and quenching of spin polarization at Ru sites, thereby achieving the optimal binding of H* and enhanced performance for HER. This work highlights the significant support effects upon the structural design of active sites.

Thermocoagulation of resection surfaces of parenchymal organs using a new source of ultrahigh frequency energy (experimental study)

Relevance. Modern surgery is characterized by the use of various technical means to perform classical surgical techniques - separation and connection of tissues, hemostasis. The study of the applicability of new surgical devices and the search for technological techniques are an important task.The aim of the study: to evaluate the capabilities of the developed device based on microwave energy for hemostatic coagula­tion of resection surfaces of parenchymal organs.Materials and methods. The method is based on the principle of converting microwave energy into heat when it is absorbed in biological tissue. The choice of the microwave range is due to the higher efficiency of power supply to the heat­ing area. Based on the prototype of a medical microwave complex developed in 2011 for thermal effects on biological tissues (RF Patent 2481080. 2011), a prototype of a microwave coagulator for working with parenchymal organs was created. The device was tested on the paren­chymal organs of large laboratory animals under conditions of preserved and switched off blood flow in various energy supply modes. Tissue samples from coagulated lesions were studied histologically.Results. At the site of exposure of the applicator-coagulator to the parenchymal organ, a zone of coagulation changes appears. A clear dependence of the size of coagulation necrosis on the time and power of exposure was noted. When the blood flow is turned off, the necessary stable hemostasis is achieved by shorter exposure time of the coagulator antenna on the surface of the organ.Conclusions. The most effective and reliable hemostasis is achieved on the liver parenchyma. The use of temporary vascular isolation, especially on the kidneys and spleen, involves a single use of microwave energy to stop bleeding. By changing the power and duration of exposure, it is possible to dose the thermal load on biological tissue with great precision. This adjustment allows you to select the operating mode for each specific case. The obtained results of the experiment of the described system during surgery for the purpose of hemostasis in parenchymal bleeding.

A Concise State-of-the-Art Review of Crack Monitoring Enabled by RFID Technology

Cracking is an important factor affecting the performance and life of large structures. In order to maximize personal safety and reduce costs, it is highly necessary to carry out research on crack monitoring technology. Sensors based on Radio Frequency Identification (RFID) antennas have the advantages of wireless and low cost, which makes them highly competitive in the field of structure health monitoring (SHM). Thus, this study systematically summarizes the research progress of crack monitoring based on RFID technology in recent years. Firstly, this study introduces the causes of cracks and the traditional monitoring methods. Further, this study summarizes several main RFID-based crack monitoring and detection methods, including crack monitoring based on chipless RFID technology, passive RFID technology, and ultra-high-frequency (UHF) RFID technology, including the implementation methods, as well as the advantages and disadvantages of those technologies. In addition, for RFID-based crack monitoring applications, the two most commonly used materials are concrete materials and metal materials, which are also illustrated in detail. In general, this study can provide technical support and a theoretical basis for crack monitoring and detection to ensure the safety of engineering structures.

State primary standard of the unit of wave resistance in coaxial waveguides GET 75-2023

The issues of measuring the wave resistance and complex reflection and transmission coefficients of devices operating at ultrahigh frequencies in coaxial waveguides are considered. Measurements of these parameters are important in the development and production of communication and information transmission systems, radar and radio navigation systems. In order to ensure the uniformity of measurements, reproduction and transmission of wave resistance units and complex reflection and transmission coefficients to measuring instruments with coaxial connectors of type 1 mm in the frequency range 0.01–67 GHz, the state primary standard of the unit resistance in coaxial waveguides GET 75-2023 has been approved. It includes means of reproducing the unit of wave resistance, complex reflection coefficients, a comparator and comparison standards in a coaxial path with a cross section of 1.0/0.434 mm with a connector of type 1 mm. The expressions for calculating the parameters of coaxial waveguides with bimetallic conductors are refined. The technical characteristics and results of metrological studies of GET 75-2023 are presented. The results of the research confirmed the high accuracy of GET 75-2023, which has comparable metrological characteristics with the standards of national metrological institutes of other countries.

Anisotropic attenuation of GHz-frequency acoustic phonons and the Grüneisen tensor in MgO crystal

We report on measurements of the anisotropy of velocities and attenuation of GHz-frequency acoustic phonons in a cubic MgO crystal at room temperature. They are used to quantify the strong anisotropy of the Grüneisen parameter and calculate the attenuation anisotropy for Rayleigh surface acoustic waves. These observations constitute important building blocks for better understanding of ultrafast laser-based magneto-acoustic and nonlinear acoustic experiments at ultrahigh frequencies.

RETRACTED: Contactless human activity and sport action identification based on UHF RFID tag wall and AI

The existing approaches to activity assisted living(AAL) are complex, expensive, and intrusive, which reduce theirpracticality and end-user acceptance. However, advancements inconcomitant technology, such as artificial intelligence and wirelesscommunications, can be leveraged to improvise advanced AALsystems that can reduce healthcare costs and hospitalisations. Such systems can identify, monitor, and localize hazardousactivities to respond swiftly to unforeseen events. To addressthese issues, we present a Transparent RFID Tag Wall (TRTWall) that utilizes a passive ultra-high frequency (UHF) arrayof radio frequency identification (RFID) tags and deep learningbasedpredictive analytics for contactless human physical activitymonitoring. Specifically, we consider five different activities thatinclude sitting, standing, walking (in both directions), and noactivity. Our experimental results demonstrate that TRT-Wallcan accurately differentiate among five distinct activities withan average accuracy is 95.6%. This suggests that our proposedcontactless AAL system possesses the significant potential toenhance elderly patient-assisted living.

Rosmarinic Acid Protects the Testes of Rats against Cell Phone and Ultra-high Frequency Waves Induced Toxicity.

Cell phone and Ultra-High Frequency (UHF) waves produce oxidative stress and cause testicular toxicity. This investigation was directed to evaluate the effectiveness of Rosmarinic Acid (RA) against oxidative stress caused by UHF radiation in rats. Forty-two male Wistar rats were divided into six groups. The control received 5 mL normal saline (0.9% NaCl) by gavage, the cell phone group received 915 MHz, the UHF waves group just received 2450 MHz, the RA/cell phone group received RA plus 915 MHz, RA/UHF waves group received RA plus 2450 MHz, and RA just received RA (20 mg/kg). After 30 days of consecutive radiation, the biochemical and histopathological parameters of their testes were measured. Statistical comparison was made using one-way ANOVA followed by Tukey's post hoc test. Cell phone and UHF wave radiation significantly diminished the activity of antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase, and glutathione content (P<0.001). On the opposite, UHF significantly increased oxidative stress indices including malondialdehyde level, nitric oxide level, and protein carbonyl content (P<0.001). UHF also significantly reduced the number of Sertoli cells, spermatogonia, primary spermatocyte, epithelial height, and seminiferous tubular and luminal diameters (P<0.001). RA, as an effective antioxidant, reverses the above-mentioned harms and moderates the adverse effects of UHF on the testes of rats by significantly diminishing the oxidative stress indices and antioxidant enzyme rise and improving the histological parameters (P<0.001). RA can protect the testes of rats from UHF-induced toxicity by reducing oxidative stress. RA as a food supplement might be useful for protecting humans exposed to UHF environmental contamination.

The Generation of Ultrahigh Repetition-Rate OAM Frequency Combs in Dual-Concentric Germania-Doped Ring-Core Fiber

The Generation of Ultrahigh Repetition-Rate OAM Frequency Combs in Dual-Concentric Germania-Doped Ring-Core Fiber

Improving technology for disinfecting grain from pests of bread stock using ultra-high radiation frequencies

The article is devoted to the study of baking properties of flour made from microwave disinfected grain. The article also discusses methods that can assess the quality and safety of grain products. Measures taken for disinfestation of grain storage facilities are complex, expensive and require a complete shutdown of production, so it is relevant to search for new approaches to disinfestation of grain storage facilities without complete suspension of the work process. In this regard, methods of grain disinfestation using microwave radiation, electric fields and other physical methods that do not require stopping production are of considerable interest. The results of studies have shown that the use of microwave irradiation with high-frequency electromagnetic fields significantly increases the efficiency of destruction of pests in grain. The analysis of the effect of microwave irradiation on moisture, gluten content and temperature of grain indicates that the use of electromagnetic fields with a power of 180 W for 120-160 seconds does not affect the physical and chemical characteristics of grain. According to organoleptic evaluations, at optimal treatment parameters (180 W/m2 for 120-160 seconds) the color, aroma and taste of grain remain unchanged.

CALOTRITON: a convective boundary layer height estimation algorithm from ultra-high-frequency (UHF) wind profiler data

Abstract. Long time series of observations of atmospheric dynamics and composition are collected at the French Pyrenean Platform for Observation of the Atmosphere (P2OA). Planetary boundary layer depth is a key variable of the climate system, but it remains difficult to estimate and analyse statistically. In order to obtain reliable estimates of the convective boundary layer height (Zi) and to allow long-term series analyses, a new restitution algorithm, named CALOTRITON, has been developed. It is based on the observations of an ultra-high-frequency (UHF) radar wind profiler (RWP) from P2OA with the help of other instruments for evaluation. Estimates of Zi are based on the principle that the top of the convective boundary layer is associated with both a marked inversion and a decrease in turbulence. Those two criteria are respectively manifested by larger RWP reflectivity and smaller vertical-velocity Doppler spectral width. With this in mind, we introduce a new UHF-deduced dimensionless parameter which weighs the air refractive index structure coefficient with the inverse of vertical velocity standard deviation to the power of x. We then search for the most appropriate local maxima of this parameter for Zi estimates with defined criteria and constraints such as temporal continuity. Given that Zi should correspond to fair-weather cloud base height, we use ceilometer data to optimize our choice of the power x and find that x=3 provides the best comparisons. The estimates of Zi by CALOTRITON are evaluated using different Zi estimates deduced from radiosounding according to different definitions. The comparison shows excellent results with a regression coefficient of up to 0.96 and a root-mean-square error of 71 m, which is close to the vertical resolution of the UHF RWP of 75 m, when conditions are optimal. In more complex situations, that is when the atmospheric vertical structure is itself particularly ambiguous, secondary retrievals allow us to identify potential thermal internal boundary layers or residual layers and help to qualify the Zi estimations. Frequent estimate errors are observed nevertheless; for example, when Zi is below the UHF RWP first reliable gate or when the boundary layer begins its transition to a stable nocturnal boundary layer.

ИЗЛУЧАТЕЛИ ДЛЯ СВЕРХВЫСОКОЧАСТОТНЫХ КОНВЕКТИВНЫХ УСТАНОВОК. РЕЗУЛЬТАТЫ МОДЕЛИРОВАНИЯ

The studies were carried out to simulate the distribution of the electromagnetic field to assess the efficiency of three types of emitters according to the following parameters: standing wave coefficient, which makes it possible to compare the consistency of emitters; radiation efficiency, showing the amount of energy transferred to the grain layer; microwave field radiation pattern, which allows one to evaluate the uniformity of the field distribution in the grain layer. For evaluation and comparison, three types of waveguides were considered: horn, rectangular with slot emitters; semicircular with slot emitters. The distribution of the electromagnetic field was modeled using the CST Microwave Studio program. The use of horn waveguides in ultra-high-frequency convective installations makes it possible to produce fairly simple devices for grain processing. The standing wave coefficient for the operating frequency in this case is 1.3, with a radiation efficiency of 78 dB. However, they do not ensure uniform distribution of the ultrahigh frequency field at the exit from the waveguide, which affects the efficiency of grain processing. The use of rectangular waveguides 55 mm × 110 mm with slot emitters ensures more uniform radiation of the electromagnetic field across the entire spectrum of wave types. The standing wave ratio is 1.0 and the radiation efficiency is 94.43 dB. However, their use requires additional design developments to ensure the supply of coolant to the processing zone. Semicircular waveguides with slot emitters provide a standing wave ratio of 1.0 over the entire frequency range from 2 to 3 GHz. Radiation efficiency is 94.28 dB. The uniformity of the electromagnetic field distribution along a semicircular waveguide is better than along a rectangular one.

Discoveries and timing of pulsars in M62

ABSTRACT Using MeerKAT, we have discovered three new millisecond pulsars (MSPs) in the bulge globular cluster M62: M62H, M62I, and M62J. All three are in binary systems, which means all ten known pulsars in the cluster are in binaries. M62H has a planetary-mass companion with a median mass Mc, med ∼ 3 MJ and a mean density of ρ ∼ 11 g cm−3. M62I has an orbital period of 0.51 d and a Mc, med ∼ 0.15 M⊙. Neither of these low-mass systems exhibit eclipses. M62J has only been detected in the two Ultra High Frequency band (816 MHz) observations with a flux density S816 = 0.08 mJy. The non-detection in the L-band (1284 MHz) indicates it has a relatively steep spectrum (β &amp;lt; −3.1). We also present 23-yr-long timing solutions obtained using data from the Parkes ‘Murriyang’, Effelsberg, and MeerKAT telescopes for the six previously known pulsars. For all these pulsars, we measured the second spin-period derivatives and the rate of change of orbital period caused by the gravitational field of the cluster, and their proper motions. From these measurements, we conclude that the pulsars’ maximum accelerations are consistent with the maximum cluster acceleration assuming a core-collapsed mass distribution. Studies of the eclipses of the redback M62B and the black widow M62E at four and two different frequency bands, respectively, reveal a frequency dependence with longer and asymmetric eclipses at lower frequencies. The presence of only binary MSPs in this cluster challenges models which suggest that the MSP population of core-collapsed clusters should be dominated by isolated MSPs.

Enhancing frequency stability and mode control in a Brillouin random fiber laser with a strongly scattering disordered grating

Random fiber lasers (RFLs) with disordered scattering feedback media provide a range of functionalities and properties. The primary drawback with weak Rayleigh scattering (RS)-based RFLs is their large frequency drift and mode hopping, which are caused by the random walk of photons at different round trips. Here, we present a technique to control the mode propagation of RFLs by using a narrow gain bandwidth from stimulated Brillouin scattering and photon localization from a strongly scattering disordered grating. Multiple scattering of light within the disordered grating leads to photon localization and narrow reflection peaks, which suppresses frequency drift and reduces the number of modes. The compact Brillouin random fiber laser (BRFL) with a 200 m strongly scattering disordered grating enables single-mode lasing with an ultra-narrow linewidth of ∼650 Hz. The results of the real-time spectral evolution obtained by the heterodyne method demonstrate long-term stability of the lasing frequency, confirming the capability of the strongly scattering disordered grating to control mode propagation of the BRFL. The BRFL exhibits an ultra-high frequency stability of 0.48 MHz and mode-hop-free operation up to 120 s. This work provides a perspective on the development of RFLs with high coherence and stability.

Bayesian semi-parametric estimation of compound inhomogeneous Poisson processes for ultra-high frequency financial transaction data

Marked point processes provide a flexible framework for studying ultra-high frequency financial data that records the time and price for each transaction. This paper estimates compound, inhomogeneous Poisson processes (CIPP) where trades arrive according to an inhomogeneous Poisson process, and returns are drawn from a distribution after arrival. The intensity functions have Gaussian process priors to model time-of-day (diurnal) effects, which have bursts of activity at the open and close and a midday lull, and lagged returns from the previous trade, which are idiosyncratic and depend on the stock. The nonparametric density estimator for returns imposes a shape constraint to obtain a unimodal distribution that is asymmetric and leptokurtic. A mixture model separates trades into time sensitive and time insensitive trades with different intensity functions. The latter group tends to have larger orders and higher returns. The proposed model is compared to B-splines and geometric Brownian motion.

Ultra-broadband and ultra-high conversion efficiency difference frequency generation in a dual-layer thin-film LiNbO3 waveguide with reversed ferroelectric domain orientations

Although there is a great breakthrough in second harmonic generation based on the birefringence and quasi phase matching (QPM) concepts, the development of an efficient difference frequency generation (DFG) based on modal phase matching (MPM) is still in its infancy at present. In this paper, we propose an ultra-broadband and ultra-high conversion efficiency mid-infrared DFG on the basis of MPM in a dual-layer waveguide consisting of two reversed poled LiNbO3 thin-films on sapphire. The ultra-high conversion efficiency is ascribed to significantly enhanced nonlinear interaction realized by making use of spatial profile of optical nonlinearity of LN crystal produced by two reversed ferroelectric domain orientations in the dual-layer waveguide. The proposed DFG device has been modeled on the basis of a 0.98 μm pump wave and a 1.34–1.44 μm signal wave, the frequency difference of which generates a mid-infrared idler wave centered at 3.32 μm wavelength. The results show that the device exhibits excellent DFG performance, including an ultra-high nonlinear conversion efficiency 434.6 % W−1 cm−2 and an ultra-broad tuning band 340 nm meanwhile, which far exceed the performance of conventional MPM devices, even the QPM ones.

OPTIMIZATION OF CONDITIONS FOR OBTAINING URTICA DIOICA L. EXTRACT AND THE STUDY OF ITS ANTIOXIDANT PROPERTIES

The purpose of the presented study was to select optimal conditions and develop a technology for obtaining nettle extract, which in the future can be used in food technologies. Nettles were harvested in May before the appearance of inflorescences. The place where the plant is collected is a forest near the village of Lvovka in the Shigonsky district of the Samara region. Mathematical optimization of the conditions for obtaining water-alcohol extract of nettle dioecious was carried out. Nettle extraction was carried out in the traditional way, with ultrasound treatment and ultrahigh frequency currents. To obtain an extract with the highest yield of extractives, it is recommended to use 75% ethyl alcohol as an extractant at a hydromodule of 1 : 10, a temperature in the range from 45 to 55 °C, and an extraction time of 2 hours. In addition, it is possible to use ultrasonic radiation or microwave processing to obtain the extract, which also contribute to an increase in the yield of dry substances. Nettle extract, prepared with the help of ultrahigh frequency currents, showed the greatest antioxidant activity. This extract contains 1309.9 mg of gallic acid and 322.9 mg of catechin per 100 g of feedstock, and its antioxidant activity is 2.5 mg/ml. At the same time, with the help of a microwave field, the extract can be obtained in a minimum time.

Health and environmental effects to wildlife from radio telemetry and tracking devices-state of the science and best management practices.

This paper discusses the potential health risks and benefits to tagged wildlife from the use of radio tracking, radio telemetry, and related microchip and data-logger technologies used to study, monitor and track mostly wildlife in their native habitats. Domestic pets, especially canids, are briefly discussed as radio-tagging devices are also used on/in them. Radio tracking uses very high frequency (VHF), ultra-high frequency (UHF), and global positioning system (GPS) technologies, including via satellites where platform terminal transmitters (PTTs) are used, as well as geo-locating capabilities using satellites, radio-frequency identification (RFID) chips, and passive integrated responder (PIT) tags, among others. Such tracking technologies have resulted in cutting-edge findings worldwide that have served to protect and better understand the behaviors of myriad wildlife species. As a result, scientists, field researchers, technicians, fish and wildlife biologists and managers, plus wildlife and other veterinarian specialists, frequently opt for its use without fully understanding the ramifications to target species and their behaviors. These include negative physiological effects from electromagnetic fields (EMF) to which many nonhuman species are exquisitely sensitive, as well as direct placement/use-attachment impacts from radio collars, transmitters, and implants themselves. This paper provides pertinent studies, suggests best management practices, and compares technologies currently available to those considering and/or using such technologies. The primary focus is on the health and environmental risk/benefit decisions that should come into play, including ethical considerations, along with recommendations for more caution in the wildlife and veterinarian communities before such technologies are used in the first place.