Ultra-high Frequency Research Articles

Low profile cavity-embedded ultra-wideband UHF array antenna with end-fire beams

A low profile, vertically polarized, ultra-wideband array antenna with end-fire beams operating in an ultra-high frequency (UHF) band is developed in this paper. The array antenna consists of 1×16 log-periodic top-hat loaded monopole antenna arrays and is feasible to embed into a shallow cavity to further reduce the array height. Capacitance is introduced in the proposed antenna element to reduce profile height and the rectangular top hats are carefully designed to minimize the transverse dimension. Simulated results show that when the antenna array operates in a frequency range of 300 MHz–900 ​MHz, the end-fire radiation pattern achieves ±45° scanning range in the horizontal plane. Then prototypes of the proposed end-fire antenna element and a uniformly spaced linear array (1×2) are fabricated and validated. The end-fire antenna array should be suitable for airborne applications where low profile and conformal scanning phased antenna arrays with end-fire radiations are required. This design is attractive for airborne platform applications that are used to search, discover, identify, and scout the aerial target with vertically polarized beams.

The preparation and performances of Co-Zn 18H hexagonal ferrite with an ultra-high magnetic resonance frequency and low-loss characteristics

Modern 5G communication technologies require evolution of antennas towards high frequency and miniaturization. The search for magneto-dielectric materials with simultaneous high permeability, matched dielectric constant, and low loss properties for sub-6 GHz band applications has received considerable attention from both academic and industrial circles. Due to the low magnetic resonance frequency and high magnetic loss, traditional spinel and hexagonal ferrites hardly meet these requirements. In this study, polycrystalline Co-Zn 18H ferrites (Ba5Co2-xZnxTi3Fe12O31) were synthesized by co-precipitation method with only one-step sintering process. The polycrystalline Co-Zn 18H hexagonal ferrite possesses an ultra-high natural resonance frequency (14.5 GHz) and low magnetic loss (tanδμ≤0⊡10), which provides a better performance factor (PF= 68.6 GHz) at a higher operating frequency (4.97 GHz) compared to traditional microwave ferrites. The miniaturization rate of the planar inverted F antenna (PIFA) with Co-Zn 18H ferrite working at 4.0 GHz reaches 13.3 %. These results demonstrate the high potential of Co-Zn 18H ferrites for high frequency and low loss applications.

Optimization Design of Variable Reluctance Resolver Based on Three-phase Symmetrical Winding

Optimization Design of Variable Reluctance Resolver Based on Three-phase Symmetrical Winding

Ultra high frequency ultrasound enables real-time visualization of blood supply from chorioallantoic membrane to human autosomal dominant polycystic kidney tissue

Ultra high frequency (UHF) ultrasound enables the visualization of very small structures that cannot be detected by conventional ultrasound. The utilization of UHF imaging as a new imaging technique for the 3D-in-vivo chorioallantoic membrane (CAM) model can facilitate new insights into tissue perfusion and survival. Therefore, human renal cystic tissue was grafted onto the CAM and examined using UHF ultrasound imaging. Due to the unprecedented resolution of UHF ultrasound, it was possible to visualize microvessels, their development, and the formation of anastomoses. This enabled the observation of anastomoses between human and chicken vessels only 12 h after transplantation. These observations were validated by 3D reconstructions from a light sheet microscopy image stack, indocyanine green angiography, and histological analysis. Contrary to the assumption that the nutrient supply of the human cystic tissue and the gas exchange happens through diffusion from CAM vessels, this study shows that the vasculature of the human cystic tissue is directly connected to the blood vessels of the CAM and perfusion is established within a short period. Therefore, this in-vivo model combined with UHF imaging appears to be the ideal platform for studying the effects of intravenously applied therapeutics to inhibit renal cyst growth.

Analysis of the correlation between GIS partial discharge current waveform and charge quantity with UHF signals

The Ultra-High Frequency (UHF) method, as a crucial technology for online GIS monitoring, struggles with the issue of being unable to accurately reflect the number of partial discharges, which poses a significant challenge for this technique. To examine the relationship between partial discharge waveforms, charge quantity, and UHF signals, a physical field model of partial discharge is developed using finite element simulation software, allowing a comparison of the peak-to-peak values of UHF signals with the parameters of the partial discharge current. Research demonstrates a roughly linear relationship between the peak-to-peak values of UHF signals and the magnitude of the partial discharge current but no definitive connection with the discharge quantity. These significant findings guide the quantitative detection of partial discharges in electrical equipment using the UHF method.

HTS Penta-Band Bandpass Filter for Radio Astronomy Broadband Receiver in the UHF Band

HTS Penta-Band Bandpass Filter for Radio Astronomy Broadband Receiver in the UHF Band

A novel approach of tongue cancer diagnostic imaging: a literature review

Objectives: This review article is aimed to provide a scientific information about novel approach of tongue cancer diagnostic imaging based on evidence-based reputed published studies. Review: The databases used in this literature review are Google Scholar, PubMed and Elsevier. The research results were selected by title and abstract according to their relevance to the review topic, then the results were selected again based on the inclusion and exclusion criteria. A total of 13 literatures were reviewed. This review shows the diagnostic imaging is a useful tool for staging and management planning in tongue cancers. In this era of technological development, a novel diagnostic imaging technologies that can be used for the diagnosis of tongue cancers such us Ultra High-Frequency Ultrasound (UHFUS), Diffusion-Weighted Imaging MRI (DWI-MRI), Dynamic Contrast-Enhanced MRI (DCE-MRI), Optical Coherence Tomography (OCT), Positron Emission Tomography (PET), Endoscopic images, and the other noninvasive imaging methods like vital staining, autofluorescence, Narrow-Band Imaging (NBI), and in vivo confocal microscopy. Besides that, imaging of tongue cancer requires a multimodality imaging approach to obtain accurate information about pathological condition such as PET/MRI, FDG PET/CT, and SPECT-CT. Conclusion: Each diagnostic imaging has limitations in imaging the patient's condition, so it can be used alone or in combination with one another to obtain accurate information about pathological conditions. FGD PET-CT and UHFUS reportedly provide a high level of sensitivity and specificity to diagnose and staging of tongue cancer.

Received signal evaluation for Ultra High Frequency (UHF)terrestrial television; Case of Ekiti State, Nigeria

This paper presents the evaluation of the received signal for UHF channel 41, (transmitting frequency of 631.25 MHz) and Star-times (transmitting frequency of 618 MHz). Using a Digital Field Strength Meter, the signal strength from the two UHF Transmitting Stations was measured throughout the state along two routes. The elevation, geographic coordinates, and line of sight of the various data points from the base stations were determined using a global positioning system (GPS) receiver. Regression analysis and correlation were used in the signal assessment process. Analysis of the data collected from the field measurements indicated that as line of sight increases signal strength reduces along all the routes for Ekiti Television (EKTV) and Star-times except along Route B for Star-times. Line of Sight and Elevation have a strong negative connection in almost all routes except along route A for star-times. Elevation and Signal strength correlation indicated negatively very high except for that along route B for EKTV and route A for Star-times. Regression analysis revealed that variance in Line of Sight and Elevation accounted for high significant changes in signal strength for EKTV and consistently very high changes for Star-times. Generally, it was observed that distance from the base station, topography/elevation, power of the transmitter, nature of signal (Digital/Analog) as shown for regression analysis and other factors affected the quality of service of the propagated signal. Terrestrial Television stations should ensure they transmit with the standard parameters. To improve service quality, the transition from analog to digital should be accelerated in Nigeria such that most stations transmit via the standard Digital method of transmission.

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.

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.