Ultrahigh-frequency Waves Research Articles

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.

Comparison of the Effects of Rosmarinic Acid and Electromagnetic Radiation-Induced Cardiotoxicity on Rats.

Electromagnetic radiation (EMR) causes stable aggregation of reactive oxygen species (ROS), producing oxidative stress. Rosmarinic acid (RA), a plant-origin antioxidant, has been proposed against the side effects of cell phone and ultrahigh-frequency waves. Forty-two male Wistar rats were randomly divided into 6 groups. Group 1 (controls) received 5 mL of normal saline with the gavage method, Group 2 received 915 MHz radiation, Group 3 received 2450 MHz radiation, Group 4 received RA plus 915 MHz radiation, Group 5 received RA plus 2450MHz radiation, and Group 6 received oral RA (5 mg/kg). Treatment and radiation (1 hour per day) continued for up to 30 days. EMR significantly reduced the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), the content of glutathione (GSH), and the level of total antioxidant capacity (TAC) and significantly increased oxidative stress indices, such as the levels of malondialdehyde (MDA) and nitric oxide (NO), and the content of protein carbonyl (PC). In contrast, RA significantly elevated TAC level (all groups), GSH content (the RA/cell phone radiation group), GPx activity (the RA/ultrahigh-frequency radiation group), SOD activity (all groups), and CAT activity (RA/ultrahigh-frequency radiation group) and conversely reduced MDA level (all groups), NO level (all groups), and PC content (all groups) in the RA/cell phone and RA/ultrahigh-frequency radiation groups compared with the NS/cell phone and NS/ultrahigh-frequency radiation groups, respectively. The administration of RA resulted in a significant reversal of cardiac markers in EMR-intoxicated rats. RA treatment showed a significant protective effect against EMR-induced cardiotoxicity.

Improved High-Order Cumulant TDE Parameter Accumulation Algorithm for Locating UHF Signals of Pulsed Electromagnetic Source

Ultra-high frequency (UHF) signal detection is one of the most effective methods for spatial orientation and partial discharge fault diagnosis. However, when the background noise, especially Gaussian white noise and narrow-band interference, is very high, or the detection region is remote, location accuracy may decrease. To improve this, a location system based on the improved higher-order cumulant time delay estimation (TDE) method combined with energy accumulation is proposed. In the system, the UHF waves are received by a four-antenna array. Improved fourth-order cumulants with a smoothed coherence transform (SCOT) window are used in the TDE, by which Gaussian white noise and narrow-band interference can be efficiently suppressed. The energy accumulation algorithm is applied to the cross-correlation results, by which the accuracy of TDE can be enhanced. The applicability of the proposed localization algorithm is evaluated by simulation and experiment. The simulation results show that the improved fourth-order cumulant TDE-parameter accumulation algorithm is superior in accuracy to traditional location methods. In the experimental measurements, two partial discharge measurement points located in a complex electromagnetic environment are tested. The results illustrate that the proposed method can effectively suppress Gaussian white and narrow-band noise, and the location results can satisfy accuracy requirements when the measurement point is within 70 m.

Theory of Optimizing the Tunneling Probability Through a Potential Barrier by Acoustically Augmented Phonons

In this research, the optimization of the tunneling probability through a potential barrier by superimposing ultra high frequency (UHF) acoustic wave over the source of the incoming particle wave function was examined theoretically and was shown to result in acoustically augmented phonons (AAP). The graph of the tunneling probability against the kinetic energy fraction [(E/V0)= x] of the particle shows a line of inflection at a non-dimensionalized critical height yc ≈ 3.12879, where yc is universal tunneling constant (UTC). As the barrier height (y) is increased further (y > yc), the reflection increases, and the tunneling probability sharply declines, in general. The lowest possible value of y is guided by the inherent particle kinetic energy, the superimposed wave number n and the material parameter β. The’ gradient of the increase in probability’ rises with a drop in the wave number n and is larger at higher values of y. A higher ratio (E/V0) coupled with a permissible-smaller wave number (n) of the applied UHF acoustic wave, leads to a higher tunneling probability. For increasing values of the UHF wave numbers and decreasing x-values, the potential barrier becomes increasingly opaque to tunneling. The higher the value of y is, the higher the tunneling opacity of the potential barrier becomes. The tunneling probability is highest (=0.98673) at y = 4, x = 0.9, when the orders of β and k are comparable.

Experimental Research on Relationship between UHF Partial Discharge Signals and Discharge Quantity in GIS

Apparent discharge quantity is usually recognized as judgement standard for severity of partial discharge in the field of electrical equipment insulation diagnosis. In recent years, the ultra-high-frequency (UHF) method has been widely used due to its unique advantages on on-line monitoring and positioning, but the relationship between UHF partial discharge signals and discharge quantity is still a difficult problem of UHF method. In order to research relationship between UHF partial discharge signals and discharge quantity in GIS, a large number of experiments, based on four kinds of typical insulation defects in the GIS, are carried out. Degree of correlation, between parameters including UHF energy, quadratic integral, peak voltage, peak-to-peak value, wave area and discharge quantity, the square of discharge quantity, is studied based on coefficient of determination. The experimental results show there is linear relation between UHF signal energy and the square of discharge quantity with high related degree.

Location of PDs inside transformer windings using UHF methods

Diffraction of Ultra-High-Frequency (UHF) electromagnetic waves generated by partial discharges (PDs) inside a transformer will decrease the amplitude when passing through the winding and delay the arrival time of initial wave at the UHF sensors installed on the internal wall of the tank. It may be difficult to locate PDs inside the winding based on detection of UHF signals. To study the feasibility of locating PDs inside the winding using UHF methods, the propagation of UHF wave through windings was simulated by the XFDTD software and the cause of arrival time delay was analyzed by a geometric model. Experiments were carried out on a 220 kV oil-immersed transformer to test the measurement sensitivity and the location accuracy of UHF method for PDs inside windings. The theoretical research results indicated that the UHF wave passed through windings along broken lines, and the propagation time from the PD source to UHF sensors was compared to the time of wave travelling along a straight line. It was found that the arrival time delay caused by diffraction was less than 1ns. The experimental results showed that PDs about 500 pC inside the windings could be detected and located. The amplitude of the UHF signal decreased by about 18 dB, the errors of time difference measurements were less than 0.5 ns, and the location errors were less than 0.1 m.

Study of cavity type antenna structure of large-area 915 MHz ultra-high frequency wave plasma device based on three-dimensional finite difference time-domain analysis

A large-area planar plasma source with a resonant cavity type launcher driven by a 915 MHz ultra-high frequency wave was developed. Theoretical analysis with the three-dimensional finite difference time-domain simulation was carried out to determine the optimized launcher structure by analyzing the resonant transverse magnetic mode in the resonant cavity. Numerical result expects that the resonant electric field distribution inside the cavity dominantly consists of the TM410 mode. The resonant cavity type launcher having 8 holes in an octagonal geometry was designed to fit the resonant transverse magnetic mode. Adjusting 8 hole positions of the launcher to the field pattern of the resonant TM410 mode, we found that the plasma density increased about 40%∼50% from 1.0∼1.1 × 1011 cm−3 to ∼1.5 × 1011 cm−3 at the same incident power of 2.5 kW, compared with the previous results with the launcher having 6 holes in the hexagonal geometry. It is also noted that the electron density changes almost linearly with the incident wave power without any mode jumps.

Experimental investigation of side wave formation in forest covers

Experiments on propagation of very-high-frequency and ultrahigh-frequency waves over short distances between antennas immersed in the forest environment with different structure and species composition are discussed. It is shown that the biometric parameters of the forest vegetation and the radiation frequency play a decisive role in the formation of side walls propagation along the top layer of the forest. It is found that the conventional approach to describing the attenuation property of the forest environment using the notion of the attenuation per unit length is incorrect in the presence of side walls.

Development of a large-area planar surface-wave plasma source with a cavity launcher driven by a 915 MHz UHF wave

A large-area planar surface-wave plasma (SWP) source driven by a 915 MHz ultrahigh frequency (UHF) wave was developed. To avoid using large, thick dielectric plates as vacuum windows, we propose a cavity launcher consisting of a cylindrical cavity with several small quartz discs at the bottom. Three types of launchers with quartz discs located at different positions were tested to compare their plasma production efficiencies and spatial distributions of electron density. With the optimum launcher, large-area plasma discharges with a radial uniformity within ±10% were obtained in a radius of about 25–30 cm in Ar gas at 8 Pa for incident power in the range 0.5–2.5 kW. The maximum electron density and temperature were approximately (0.95–1.1) × 1011 cm−3 and 1.9–2.0 eV, respectively, as measured by a Langmuir probe located 24 cm below the bottom of the cavity launcher. Using an Ar/NH3 SWP with the optimum launcher, we demonstrated large-area amino-group surface modification of polyurethane sheets. Experimental results indicated that a uniform amino-group modification was achieved over a radius of approximately 40 cm, which is slightly larger than the radial uniformity of the electron density distribution.

Numerical modeling of thermoelastic generation of ultrasound by laser irradiation in the coupled thermoelasticity

Laser-generation of ultrasound is investigated in the coupled dynamical thermoelasticity in the presented paper. The coupled heat conduction and wave equations are solved using finite differences. It is shown that the application of staggered grids in combination with explicit integration of the wave equation facilitates the decoupling of the solution and enables the application of a combination of implicit and explicit numerical integration techniques. The presented solution is applied to model the generation of ultrasound by a laser source in isotropic and transversely isotropic materials. The influence of the coupling of the generalized thermoelasticity is investigated and it will be shown, that for ultra high frequency waves (i.e. 100GHz) generated by laser pulses with duration in the picosecond range, the thermal feedback becomes considerable leading to a strong attenuation of the longitudinal bulk wave. Moreover, the coupling leads to dispersion influencing the wave velocities at low frequencies. The numerical simulations are compared to theoretical results available in the literature. Wave fields generated by a line focused laser source are presented by the numerical model for isotropic and for transversely isotropic materials.

Range Estimation Technique Using Received Signal Strength Indication on Low Frequency Waves

Recently, with the downsizing of computers and the development of wireless communication advances, sensor networks are being widely studied. However, it is necessary to know the location of each node, in order to apply sensor data. Many researchers have tried to find a good approach to position estimation in indoor environment. In our study, we focus on position estimation by using Received Signal Strength Indication (RSSI). It has the advantage of implementation with limited resources in the sensor network. However, since RSSI value is affected by multipath and obstacles, position estimation may yield considerable errors. In our research, we propose a range estimation technique with RSSI on Low Frequency (LF) waves. Since RSSI value on LF waves is less affected by multipath and obstacles compared with RSSI on Ultra High Frequency (UHF) waves used for a communication, position estimation with high accuracy can be calculated using this method. We show an RSSI measurement sensor which measures the RSSI on LF waves and a transmitter which sends radio waves on the 125 kHz band. Results of experiments using our developed modules and a ZigBee module demonstrated the robustness of RSSI on LF waves against multipath and obstacles compared with UHF waves. In this paper, a range estimation experiment was performed by applying the proposed modules and range estimation accuracy was evaluated through experiments.

Propagation model for mobile digital TV coverage under viaduct

[1] Viaducts over roads are common in many cities. In this paper, a three-dimensional multiray tracing model for in-vehicle mobile digital TV was used to explore the propagation properties of ultrahigh frequency waves under viaducts, subject to the transmitting antenna being higher than viaduct deck. The model is based on geometrical optics, physical optics, geometrical theories of diffraction, and especially the uniform theory of diffraction. The model takes into account direct propagation, ground reflection, transmission, as well as wedge diffraction to reveal the law of signal path gain under viaducts. Validation results show good agreement between calculated and measured data. The prediction for linearly, especially vertically polarized wave propagation provided by a six-ray model may be more helpful than that provided by a four-ray model.

Propagation mechanisms for UHF wave transmission through walls and windows

In this paper, both simulations and measurements are used to explore the propagation properties of ultrahigh-frequency (UHF) waves traveling through building structures and, in particular, windows. The propagation influence of several features of a typical window structure is examined, including the electrical properties of the surrounding wall, the homogeneity and roughness of this wall, and the incidence angle of the UHF wave. In these studies, ray tracing is benchmarked against both narrow-band measurements and the results of a full-wave moment method technique. Some of the inherent limitations of ray tracing are assessed and corrective methods are proposed in order to improve its accuracy.

Profile control of the large area ribbon beam ion source using 500 MHz ultrahigh frequency discharge

This article is concerned with the method of controlling the large area ribbon beam profile produced by the same extraction electrode size ion source. We used a bucket type large area ion source with 500 MHz ultrahigh frequency (UHF) discharge for the plasma production. The size of the ion source is comparable to one wavelength of 500 MHz rf. As the UHF wave propagates in the plasma, electrons are accelerated by the rf fields along the multicusp magnetic field produced by the peripheral permanent magnets set on the outer surface of the plasma chamber. We used several entrances of the UHF wave around the plasma chamber. We can control the ion beam profile by adjusting the size of the entrance hole. With this control, less than 2% of uniformity of the large area ion beam of 120 mm×220 mm is achieved for the source gases such as diborane, phosphine, and arsine.

Cellulose-water vapour interaction investigated by spectrometric and ultra-high-frequency methods

The cellulose-water vapour interaction has been investigated by near-infra-red spectrometric and ultra-high-frequency (UHF) methods. Spectra revealed 1.363 and 1.423 m bands of cellulose surface hydroxyls and transformation of these bands under the influence of adsorbed water molecules. The relation of the surface coverage to the sample's water content, the specific surface area of cellulose of about 90 and surface hydroxyl density of 2.5 OH were obtained using the simple model of hydroxyl arrangement on the inner surface of a cellulose fibre. Results of spectral and UHF measurements indicate that the saturation of hydrogen bonds of surface OH occurs at . During the monolayer formation stage the UHF wave absorption by molecules of adsorbed water is more than two times smaller than that for the phases of water on top of the monolayer. Surface parameters of cellulose are compared with those of divided silica.

Tunneling interference of counterpropagating waves in the region of negative magnetic permeability

The interference of two coherent ultrahigh-frequency waves incident normally on opposite faces of a transversely magnetized ferrite layer with negligibly small losses is investigated in the region of negative effective magnetic permeability. It is shown that a coordinate-independent energy flux is formed inside the layer as a result of tunneling interference. The ferrite layer can be made antireflective for appropriate values of the external field and the phases and amplitudes of the incident waves.

Assessment of the efficacy of treatment of hemangiomas

Assessment of the aftereffects of cryoexposure and ultrahigh-frequency cryoexposure on hemangioma tissue of various types, cavernous and squamous, showed a higher cryogenic effect in hemangiomatous tissue preexposed to ultrahigh-frequency waves. A quantitative criterion is proposed for assessing the efficacy of the studied methods of exposure.

Evaluation of wood characteristics: Internal scanning of the material by microwaves

Internal scanning of wood by microwaves presents many advantages for the automatic detection of defects and the evaluation of the characteristics of wood in the dry wood processing industries. Advantages are: access to more than one variable, efficient coupling in the air, easy automation and reasonable cost. Microwaves are electromagnetic waves the speed and attenuation of which depend of the medium in which they are propagated, especially its electric permittivity which depends on its moisture content and its density. Since wood is anisotropic, this dielectric constant also varies with the direction of fibers. An experimental apparatus was set up that allows to test the feasibility of automatic detection of wood characteristics and defects. It automatically measures the attenuation and dephasing of an ultra high frequency wave sent through a board and moving through two rotating antennas. The graphs and results obtained gave significant information of physical characteristics of wood (density, moisture content, slope of grain) and the detection of defects (knots, metallic objects, sapwood).

Ferromagnetic resonance in films with a plane anisotropy of electrical resistivity

High conductivity of metallic films leads to attenuation of an ultrahigh frequency field at the depth of the skin layer and, consequently, to a nonuniform distribution of the high-frequency magnetization component over the film thickness. This feature leads to a shift in the frequency and to widening of the ferromagnetic resonance line in a metallic film. In the present work, we study the effect of the plane anisotropy of electrical resistivity on the resonance behavior of polycrystalline magnetic films (Ni, Co, permalloy). Appearance of this anisotropy is related to the presence in the film of extended structural defects such as microgaps oriented along the chosen direction of the substrate texture (Lavsan, mica). In the geometry of the perpendicular magnetization and the normal incident angle of the ultrahigh frequency wave with respect to the film there are two resonance frequencies corresponding to the two orthogonal polarizations of the high-frequency field.

A Cathode-Ray Method of Wave Analysis

Complex periodic functions, when transformed into a corresponding voltage wave, may be analyzed with the use of a cathode ray oscillograph. The complex wave is represented upon the fluorescent screen of the cathode ray tube by a vertical displacement at the same time that a sinusoidal horizontal oscillation exists. If the frequency of the sinusoidal oscillation bears an integral relation to the fundamental frequency of the complex wave, a Lissajous figure is viewed on the screen. The areas of these Lissajous figures are directly related to the coefficients of the Fourier series of the complex wave. The area is determined by measuring a photograph of the figure using a polar planimeter. The method is based on the theory developed by Mr. L. W. Chubb in connection with the Chubb Polar Analyzer.4 Advantages of the method are that it is quick and convenient, only standard laboratory equipment is necessary, and with special equipment, it promises to make possible the analysis of ultrahigh frequency waves.