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This paper describes an experiment designed to observe potential changes in electromagnetic propagation velocity. It has been widely demonstrated that if the frequency of an electromagnetic wave is fixed, then the associated wavelength is causally related to c. Furthermore, the logical conclusion related to this known association (of frequency, wavelength, and light speed) is that, if the generated frequency during an experiment remains the same, and there is a velocity change in c, there would be causally related expansion or reduction in the associated wavelength. With the use of a Lecher line and a standing electromagnetic wave, the experimenter can measure changes in wavelength by measuring electrical output at an assigned position on a Lecher line. Results of this experiment demonstrated an obvious and experimentally repeatable phase change associated with rotation of the Lecher line. This phase change was demonstrated by a change in electrical output measured at the assigned location on the Lecher line. This experiment was repeated using various frequencies and voltage inputs into the Lecher line with obvious results that demonstrated an anisotropic difference. Further experiments were completed attempting to find an alternative hypothesis for the phase change noted in the original experiment, but these experiments were unable to identify an alternative cause of the phase change and consequently support the hypothesis that the phase change was directly related to anisotropy secondary to a change in the measured wavelength of the electromagnetic wave. Based upon the logical conclusions associated with this experiment and the results obtained, this experiment appears to demonstrate variable speed light. Furthermore, this discovery brings into question the theory that electromagnetic propagation though space is at the constant of c. [ABSTRACT FROM AUTHOR]

Water utilities in Japan face a number of challenges, including declining water demand due to a shrinking population, shrinking workforce, and aging water supply facilities. Widespread use of smart water meters is crucial for solving these problems. The widespread use of smart water meters is expected to bring many benefits such as reduced labor by automating meter reading, early identification of leaks, and visualization of pipeline data to strengthen the infrastructure of water services, business continuity, and customer service, as detailed data can be obtained using wireless communication. Demonstration tests are actively conducted in Japan; however, many problems have been reported with cast iron meter boxes blocking radio waves. To address the issue, a low-cost slit structure for cast iron meter boxes is investigated in this study. The results confirm that the L-shaped tapered slit array structure with a cavity, which can be fabricated in a cast iron integral structure, satisfies the design loads required for road installation. The proposed slit structure achieved gain characteristics from −3.32 to more than 9.54 dBi in the 800 to 920 MHz band. The gain characteristics of conventional cast iron meter boxes range from −15 to −20 dBi, and the gain has been significantly improved. Antennas with a gain of −2.0 to +1.5 dB (0.8 to 2.5 GHz) were used for the transmitter antenna, which was found to have a higher gain than the transmit antenna in the 800 to 880 MHz frequency band. In the 1.5 to 2.0 GHz band, a high peak gain of 4.25 dBi was achieved at 1660 MHz, with no null and the lowest gain confirmed that this is an improvement of more than 10 dBi over conventional products. [ABSTRACT FROM AUTHOR]

Background. Turbulent fluctuations of the refractive index in the atmosphere lead to distortions during the passage of the radio signal. This can lead to distortion of the transmitted information due to the resulting fluctuations of the amplitude, phase and intensity of the electromagnetic wave that transmits the radio signal. Fluctuations in the intensity of the radio signal lead to flickering of the radio signal on the receiving antenna due to turbulent phenomena in the atmosphere, which are a complex multifunctional physical phenomenon. Aim. The problem of fluctuation of the intensity of the radio signal at the receiving antenna due to atmospheric turbulence is considered – the flicker of the radio signal. This problem is currently extremely actual, because there is a tendency of active, negative interference in the process of high-quality transmission of the radio signal on the background of naturally caused turbulent fluctuations. Methods. A theoretical analysis of the passage of a radio signal through a turbulent atmosphere is carried out. The spatial correlation function of fluctuations in the intensity of the received radio signal due to atmospheric turbulence is investigated. Results. The concept of the radio signal flicker characteristic is introduced as the average value of a random variable over the cross section of the receiving antenna – the dispersion of the logarithm of the radio signal power. A model of the occurrence of fluctuations in the case of two regions in the cross section of the receiving antenna with different levels of radio signal intensity is calculated. The correlation function for this model is found. Conclusion. Based on the Fourier-spectrum expansion of the two-point spatial correlation function of turbulent fluctuations of the refractive index, the dependence of the flicker characteristic of the radio signal on the wave number of turbulent fluctuations of the atmosphere is found. It is shown that the turbulence of the atmosphere has the greatest effect on the radio signal when the length of the electromagnetic wave is comparable to the scale of turbulent fluctuations.

The accurate prediction of a signal's attenuation is essential for the development of reliable, modern, mobile radio-communication networks. In this study, the accuracies of four propagation models in diverse terrains and environments were analyzed using field measurements along a comprehensive test route. We evaluated the ability of the models—Egli, Okumura, Hata–Davidson, and Longley–Rice—to predict signal propagation in the Very-High-Frequency (VHF) and Ultra-High-Frequency (UHF) bands. Based on a meticulous comparison, we present valuable insights into the strengths and limitations of these models, enhancing coverage-prediction methodologies for evolving mobile radio networks. The Egli model, despite its simplicity, introduces significant inaccuracies due to its assumptions and a lack of consideration for the terrain. The Okumura model, which is widely used in urban areas, requires careful correction selection, while the Hata–Davidson model improves upon the former's weaknesses. The Longley–Rice model excels in flexibility and accuracy, especially in the VHF bands, using topographical data, though it can overestimate the attenuation in shadowed areas. The study concluded that no single model was universally accurate, as each model has its strengths and limitations. It highlights the need for informed model selection based on the terrain's characteristics and specific requirements. The results will be useful to network planners, helping them to design efficient, mobile communication networks with reliable coverage and optimal spectrum utilization. The Longley–Rice model emerged as particularly powerful, offering detailed predictions across diverse environments. [ABSTRACT FROM AUTHOR]

Interaction of an electromagnetic wave, as the determined wave process spreading in an atmosphere and atmospheric turbulence, as stationary stochastic wave process is considered. The differential equation for eikonal fluctuations of an electromagnetic wave is received. On basis of this equation the occurrence of amplitude and a phase fluctuations of an electromagnetic wave at distribution of a radio signal into a turbulent atmosphere is investigated. In particular the differential equations for fluctuations of amplitude and a phase of the electromagnetic wave caused by turbulent pulsations of a parameter of an atmosphere refraction are received and solved. Fourier-spectra of two-point correlations of a parameter of an atmosphere refraction, amplitude and a phase of an electromagnetic wave are considered. Are received also by a method of introduction of Green’s function the differential equations for these correlations are solved. On basis of the analysis of various wave ranges of an atmospheric power spectrum of turbulence the dependences of amplitude and a phase Fourier-spectra of a radio signal on parameters of an electromagnetic wave and turbulence of an atmosphere are found.

Radical pair kinetics is determined by the coherent and incoherent spin dynamics of spin pair and spin-selective chemical reactions. In a previous paper, reaction control and nuclear spin state selection by designed radiofrequency (RF) magnetic resonance was proposed. Here, we present two novel types of reaction control calculated by the local optimization method. One is anisotropic reaction control and the other is coherent path control. In both cases, the weighting parameters for the target states play an important role in the optimizing of the RF field. In the anisotropic control of radical pairs, the weighting parameters play an important role in the selection of the sub-ensemble. In coherent control, one can set the parameters for the intermediate states, and it is possible to specify the path to reach a final state by adjusting the weighting parameters. The global optimization of the weighting parameters for coherent control has been studied. These manifest calculations show the possibility of controlling the chemical reactions of radical pair intermediates in different ways. [ABSTRACT FROM AUTHOR]

The powerful radio waves can ignite explosive gases. Therefore, it is necessary to reasonably set the radio wave explosion-proof safety power and energy threshold emitted by the radio transmitter to limit the radio wave power and energy emitted by the radio transmitter. The radio wave explosion-proof safety power and energy thresholds specified in European Standard CLC/TR 50427:2004 Assessment of inadvertent ignition of flammable atmospheres by radio-frequency radiation-Guide are the ignition power and energy threshold. The national standard GB/T 3836.1-2021 Explosive atmospheres-Part 1: Equipment-General requirements and the international standard IEC 60079-0:2017 Explosive atmospheres-Part 0: Equipment-General requirements directly cite the radio wave explosion-proof safe power and energy threshold specified in the European standard CLC/TR 50427:2004. But the continuous radio wave explosion-proof safe ignition power threshold is incorrectly modified as the product of the effective output power of the transmitter and the antenna gain. This leads to the reduction of the continuous radio wave explosion-proof safe transmission power threshold. Under certain transmission attenuation and reception sensitivity conditions, the wireless transmission distance is reduced. This is not conducive to the promotion and application of mine wireless communication system and personnel positioning system. Therefore, the safe power threshold for continuous radio wave explosion-proof specified in national standard GB/T 3836.1-2021 and international standard IEC 60079-0:2017 should be the ignition power threshold, not the product of the effective output power of the transmitter and the antenna gain.

Water utilities in Japan face a number of challenges, including declining water demand due to a shrinking population, shrinking workforce, and aging water supply facilities. Widespread use of smart water meters is crucial for solving these problems. The widespread use of smart water meters is expected to bring many benefits such as reduced labor by automating meter reading, early identification of leaks, and visualization of pipeline data to strengthen the infrastructure of water services, business continuity, and customer service, as detailed data can be obtained using wireless communication. Demonstration tests are actively conducted in Japan; however, many problems have been reported with cast iron meter boxes blocking radio waves. To address the issue, a low-cost slit structure for cast iron meter boxes is investigated in this study. The results confirm that the L-shaped tapered slit array structure with a cavity, which can be fabricated in a cast iron integral structure, satisfies the design loads required for road installation. The proposed slit structure achieved gain characteristics from −3.32 to more than 9.54 dBi in the 800 to 920 MHz band. The gain characteristics of conventional cast iron meter boxes range from −15 to −20 dBi, and the gain has been significantly improved. Antennas with a gain of −2.0 to +1.5 dB (0.8 to 2.5 GHz) were used for the transmitter antenna, which was found to have a higher gain than the transmit antenna in the 800 to 880 MHz frequency band. In the 1.5 to 2.0 GHz band, a high peak gain of 4.25 dBi was achieved at 1660 MHz, with no null and the lowest gain confirmed that this is an improvement of more than 10 dBi over conventional products.

The analysis of the field strength variability using the meteorological parameters (temperature, pressure and relative humidity) retrieved from the archive of National Aeronautical and Space administration (NASA) was conducted for 61 locations between 2016 and 2020 to check for the spatial and seasonal variation. The result shows a seasonal variation with higher field strength variability during the dry season and lower field strength variability during the wet season. The spatial variation shows a significant difference between stations in the drier locations up north and those in the coastal areas. This could be attributed to the moisture contents of the atmosphere. Further analysis of the Inter-Tropical Discontinuity (ITD) position during the study period has confirmed this assertion where we discovered the northward movement of the ITD brings along with it more moisture and consequently a weak field strength. The variation in the high grounds is not manifesting because of the fact that pressure has little influence on the field strength variability. A careful study of the pressure contour explains that. The mean field strength is found to be between 2:8 dB and 17:9 dB. This implies that the output of the receiving antenna should be less than 2:8 dB and can be as high as 17:9 dB. [ABSTRACT FROM AUTHOR]

The analysis of the field strength variability using the meteorological parameters (temperature, pressure and relative humidity) retrieved from the archive of National Aeronautical and Space Administration (NASA) was conducted for 61 locations between 2016 and 2020 to check for the spatial and seasonal variation. The result shows a seasonal variation with higher field strength variability during the dry season and lower field strength variability during the wet season. The spatial variation shows a significant difference between stations in the drier locations up north and those in the coastal areas. This could be attributed to the moisture contents of the atmosphere. Further analysis of the Inter-Tropical Discontinuity (ITD) position during the study period has confirmed this assertion where we discovered the northward movement of the ITD brings along with it more moisture and consequently a weak field strength. The variation in the high grounds is not manifesting because of the fact that pressure has little influence on the field strength variability. A careful study of the pressure contour explains that. The mean field strength is found to be between 2.8 dB and 17.9 dB. This implies that the output of the receiving antenna should be less than 2.8 dB and can be as high as 17.9 dB.

The study aimed to seek for the effect of meteorological parameters and conditions on wave transport for both radio wave band that used by mobile phone communication and microwave band that used in 'TV' satellites by showing which atmospheric variable and conditions have a positive or negative effect on signal strength. Data of study was recorded perfectly from one selected point by hand using the same devices for all recording to exclude the error caused by changing device types. The results showed that atmospheric conditions had a noticeable effect on microwave signal band that used by 'TV' satellite especially when there was a rainy case, and for atmospheric 'UV' index it had a direct positive effect on radio waveband used by mobile phone because there was an increase in signal strength corresponding with increasing of 'UV' index (from 1 to 5 of UV index range). For temperature, the result showed inverse proportion with radio waveband signal, but relative humidity didn't show up any relations with both study band's signals. Day time variation of signals was recorded for both wavebands, the result of radio waveband signal fluctuated in semi sine wave shape but with decreasing trend along day time, and for 'TV' satellite microwave band signal the result recorded increasing trend along day time, and this may because of solar radiation activity but in general, the satellite band signal was higher affected by weather condition as compared with mobile phone radio wave signal band.

The shielding of radio wave by steel-containing structures is desirable for electronics protection but undesirable for telecommunication signal reception. This work investigates the shielding behavior of steel structures consisting of members in various configurations, with the practical aim of determining how the configuration can be exploited to control the shielding. Differently oriented continuous steel reinforcement (stranded/unstranded wires in the unidirectional, crossply and planar coil configurations) are evaluated for electromagnetic interference (EMI) shielding at 600–2000 MHz, using unpolarized radiation. The absorption loss SEA dominates the reflection loss SER. The crossply configuration gives the highest SEA, SEA/thickness and SEA/SET (SET = total loss); the planar coil configuration gives the lowest values. The SEA, SEA/thickness and SEA/SET are moderately higher for the crossply configuration than the unidirectional configuration, because steel's electrical isotropy allows the 0° electric field to interact with the 90° wire. The SEA/SET is comparable for the stranded and unstranded wires. [ABSTRACT FROM AUTHOR]

Given the inherent need to have technological tools to reduce the number of incidents caused by the operation of heavy machinery, this document briefly describes the design of a prototype Accident Prevention System for industrial vehicles using Radio Frequency Identification Technology (RFID). ) that warns about the proximity of people to the area of operation of industrial equipment, the deployment of Open Source technology provides the necessary resources for a Raspberry Pi 3 B + control device to execute information processing through a control interface that will activate an alarm and through a management module the RFID components (TAGS and Readers) will be managed and the reports of the readings will be obtained. Finally, considering factors such as frequency, the operating environment, the type of modulation, the antenna height, the radiation pattern of the antenna, the antenna gain and the receiver gain influence the propagation of the waves radio will perform a predictive investigation in different scenarios by means of an estimation of the coverage based on the model of propagation of loss in free space to verify the reliability of the prototype that operates with Ultra Narrow Band technology and employs techniques of Spread Spectrum by Jump Frequency.

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Objective: Astronauts are exposed to a wide range of environmental stresses during spaceflights that reduce their immune responses and make them more susceptible to infections and malignancies. Exposure to a low dose of a certain stress induces an adaptive response, which leads to resistance to higher doses of the same or other types of stress. We designed this study to investigate the effect of radiofrequency electromagnetic field (RF-EMF)-induced adaptive response on immune system modulation in a mouse model of hindlimb unloading (HU) as a ground-based animal model of spaceflight conditions. Materials and Methods: In this experimental study, serum levels of T helper (Th)-mediated cytokines were determined by the multiplex cytometric bead assay in four groups of mice (n=10 per group): HU mice, RF-EMF-treated mice, HU mice pre-exposed to RF-EMF; and untreated controls. Mice were exposed to 2450 MHz RF-EMF with SAR 0.478 W/ kg for 12 hours/day for three successive days. Results: Tumor necrosis factor-alpha (TNF-α), interleukin-9 (IL-9) and IL-22 were significantly decreased in HU mice. Comparison between HU mice and RF-EMF-treated mice showed an opposite change in IL-6, while IL-9, IL-22, IFN-γ and TNF-α decreased in both groups. However, just interferon gamma (IFN-γ) was significantly decreased in HU mice that were pre-exposed to RF-EMF compared to the control group. Conclusion: The effect of RF-EMF in elevating IL-6 and reducing IL-9 in opposite directions in HU mice suggest a modulating effect of RF-EMF on HU-induced changes in these cytokines, as Th2 and Th9 eventually returned to normal levels and balances in cytokine ratios were also restored in HU mice pre-exposed to RF-EMF. [ABSTRACT FROM AUTHOR]

This paper describes the design and performance of the search coil magnetometers (SCM), which are part of the Plasma Wave Investigation (PWI) instrument onboard the BepiColombo/Mio spacecraft (Mercury Magnetospheric Orbiter), which will measure the electric field, plasma waves and radio waves for the first time in Mercury's plasma environment. The SCM consists of two low-frequency orthogonal search coil sensors (LF-SC) measuring two components of the magnetic field (0.1 Hz – 20 kHz) in the spacecraft spin plane, and a dual-band search coil sensor (DB-SC) picking up the third component along the spin axis at both low-frequencies (LF: 0.1 Hz – 20 kHz) and high-frequencies (HF: 10 kHz – 640 kHz). The DB-SC and the two LF-SC sensors form a tri-axial configuration at the tip of a 4.6-m coilable mast (MAST-SC) extending from the spacecraft body, to minimize artificial magnetic field contamination emitted by the spacecraft electronics. After the successful launch of the spacecraft on 20 October 2018, an initial function check for the SCM was conducted. The nominal function and performance of the sensors and preamplifiers were confirmed, even with the MAST-SC being retracted and stowed in the spacecraft body, resulting in the detection of large interference signals likely from spacecraft electronics. The MAST-SC is scheduled for deployment after the Mercury orbit insertion of Mio in 2025, allowing the SCM to make the first higher frequency measurements of magnetic fluctuations in the Hermean magnetosphere and exosphere, and the local solar wind. These measurements will contribute to the investigation of fundamental problems in the Hermean plasma environment, including turbulence, magnetic reconnection, wave-particle interactions and particle acceleration. [ABSTRACT FROM AUTHOR]

The Plasma Wave Investigation (PWI) aboard the BepiColombo Mio (Mercury Magnetospheric Orbiter, MMO) will enable the first observations of electric fields, plasma waves, and radio waves in and around the Hermean magnetosphere and exosphere. The PWI has two sets of receivers (EWO with AM2P, SORBET) connected to two electric field sensors (MEFISTO and WPT) and two magnetic field sensors (SCM: LF-SC and DB-SC). After the launch on October 20, 2018, we began initial operations, confirmed that all receivers were functioning properly, and released the launch locks on the sensors. Those sensors are not deployed during the cruising phase, but the PWI is still capable performing magnetic field observations. After full deployment of all sensors following insertion into Mercury orbit, the PWI will start its measurements of the electric field from DC to 10 MHz using two dipole antennae with a 32-m tip-to-tip length in the spin plane and the magnetic field from 0.3 Hz to 20 kHz using a three-axis sensor and from 2.5 kHz to 640 kHz using a single-axis sensor at the tip of a 4.5-m solid boom extended from the spacecraft's side panel. Those receivers and sensors will provide (1) in-situ measurements of electron density and temperature that can be used to determine the structure and dynamics of the Hermean plasma environment; (2) in-situ measurements of the electron and ion scale waves that characterize the energetic processes governed by wave–particle interactions and non-MHD interactions; (3) information on radio waves, which can be used to remotely probe solar activity in the heliocentric sector facing Mercury, to study electromagnetic-energy transport to and from Mercury, and to obtain crustal information from reflected electromagnetic waves; and (4) information concerning dust impacts on the spacecraft body detected via potential disturbances. This paper summarizes the characteristics of the overall PWI, including its significance, its objectives, its expected performance specifications, and onboard and ground data processing. This paper also presents the detailed design of the receiver components installed in a unified chassis. The PWI in the cruise phase will observe magnetic-field turbulence during multiple flybys of Earth, Venus, and Mercury. After the Mercury-orbit insertion planned at the end of 2025, we will deploy all sensors and commence full operation while coordinating with all payloads onboard the Mio and MPO spacecraft. [ABSTRACT FROM AUTHOR]