Sources Of Electromagnetic Fields Research Articles

Electromagnetic Field Radiation Exposure Assessment from Mobile Phones Based on Call-Related Factors

For many years, there have been concerns about possible human health risks connected to the usage of mobile phones especially at close proximity. This is primarily due to the exposure to electromagnetic field (EMF) radiations that emanate from them. These concerns have in turn provoked a large bulk of research studies. However, the conflicting reports of previous research works on the effect of the exposure to EMF sources lead researchers to continue studying the issue. In this work, by means of the exposure evaluation technique, measurements of EMF radiations, in terms of power density, are conducted on different models of mobile phones in an indoor environment via the call-related factors: between the dial and reception of a call from different models of mobile phones, for a period of six months. The investigated brands of mobile phones were all placed to face the field strength meter sensor in active call modes at 0.05m measurement interval when taking reading on the tri-axis planes. The results obtained revealed that the EMF radiation intensity, in terms of measured power density from the mobile phone, varies and depends on the mobile phone model brand. It ranges from 1.25 to 800.5 mW/m2 with the highest from ITEL phone (Model-TI65800) with MTN Network along the Z-plane and the lowest from NOKIA phone (Model-105) with MTN Network along the Y-plane. The highest radiation intensity was recorded for calls made during the dial (before picking) from all the selected mobile phone models. In particular, from the results, it was observed that the amount of EMF radiations decreased about 20 to 30 % if the mobile phone handset is moved away from the EMF meter from 1cm to 5cm. Accordingly, for EMF exposure safety, it is recommended that the mobile phone is placed 5–10 cm away from the body during conversation.

Check measurements of magnetic flux density: Equipment design and the determination of the confidence interval for EFA 300 measuring devices

The stability of the measuring device is associated with its accuracy at repeated measurements provided under the same conditions. We designed equipment for checking of the measurement accuracy and stability of the device EFA 300 that we called Stability Control Stand (SCS). The reason for our interest in the development and realization of the SCS was based on the internal need for laboratory checks of device EFA 300. The magnetic flux density B at different distances from the probes to the electromagnetic field source in the anechoic chamber was measured. In the experiment, we used the method of repeated measurements. The distribution of magnetic field has been verified through mathematical simulations. The measured values of the magnetic flux density are almost identical to the values which are simulated using the mathematical model. With respect to the sensitivity and accuracy, we identified the optimal distance of 20cm from the source of magnetic field to the geometric center of the probe in which the probe indicates the most accurate values. The measured data were processed using a mathematical statistics and subsequently, the expanded measurement uncertainty and confidence interval was calculated. The processed results with the expanded measurement uncertainty represent the B like reliable values at the next measurements with SCS.

Ultrabroadband single-cycle terahertz pulses with peak fields of 300 kV cm−1 from a metallic spintronic emitter

We explore the capabilities of metallic spintronic thin-film stacks as a source of intense and broadband terahertz electromagnetic fields. For this purpose, we excite a W/CoFeB/Pt trilayer (thickness of 5.6 nm) on a large-area glass substrate (diameter of 7.5 cm) by a femtosecond laser pulse (energy 5.5 mJ, duration 40 fs, and wavelength 800 nm). After focusing, the emitted terahertz pulse is measured to have a duration of 230 fs, a peak field of 300 kV cm−1, and an energy of 5 nJ. In particular, the waveform exhibits a gapless spectrum extending from 1 to 10 THz at 10% of its amplitude maximum, thereby facilitating nonlinear control over matter in this difficult-to-reach frequency range on the sub-picosecond time scale.

A Multilayer Perceptron Neural Network–Based Model for Predicting Subjective Health Symptoms in People Living in the Vicinity of Mobile Phone Base Stations

Advances in modern technologies such as telecommunication have widely expanded the applications of wireless systems. Therefore, humans are continuously exposed to electromagnetic fields (EMFs) produced by widely used devices such as mobile and cordless phones and Wi-Fi routers. According to the World Health Organization, electromagnetic hypersensitivity (EHS) is the medical term for a variety of nonspecific symptoms that afflicted subjects attribute to exposure to different sources of EMFs. About 25% of the general population reports different levels of environmental intolerance to factors such as EMFs, and studies performed in Europe show that about 75% of general practitioners had visited patients complaining of EHS. In this paper, multilayer perceptron neural network (MLPNN)–based models are proposed to predict the subjective health symptoms in inhabitants living in the vicinity of mobile phone base stations. The classifier uses several parameters such as demographic data, environmental exposure to a mobile phone station, and the health conditions of an individual as input to estimate subjective health symptoms. Out of 699 data sets recorded from 363 men and 336 women via questionnaire, 70% were used for training, 15% for validation, and the remaining 15% for testing the developed system. The performance of the developed system (sensitivity and specificity) in predicting the subjective health symptoms is as follows: headache (72%, 91%), fatigue (8%, 98%), sleep disturbance (97%, 93%), dizziness (65%, 85%), vertigo (65%, 84%). These promising results suggest that this system might be useful as a means for predicting the health symptoms in people living in the vicinity of mobile phone base stations, which ultimately enhances the quality of life of these individuals through providing appropriate medical care and introducing effective methods for reducing the effect of these exposures. Key Words: Mobile phone base stations—Electromagnetic hypersensitivity (EHS)—Artificial neural network—Radiofrequency.

Ticks and radio-frequency signals: behavioural response of ticks (Dermacentor reticulatus) in a 900 MHz electromagnetic field

The electromagnetic field (EMF) is present in the environment throughout the world and encompasses both natural and human-made sources of electromagnetic fields. It has been shown that EMF influences a variety of biological systems, including the behavioural responses of both vertebrates and invertebrates. As such, determining the effects of the EMF on the ecosystem in detail may be important for understanding the ecology and biology of organisms, particularly those, such as ticks, that are important in disease transmission. Our main goal was to determine if the tick, Dermacentor reticulatus, interacts with the EMF. An experimental behavioural test of tick sensitivity to radio frequency power radiation was performed under laboratory conditions. Tests were performed in an electromagnetic compatibility laboratory in a radio frequency electromagnetic field (RF-EMF) anechoic chamber. Ticks were irradiated using a Double-Ridged Waveguide Horn Antenna with 900 MHz RF-EMF. The applied radio-frequency power was tuned below the proposed limit for public exposure to mobile phone base stations. We found that exposure induces an immediate tick locomotor response manifested either in a previously unreported jerking movement of the whole body or in jerking of the first pair of legs. Overall, ticks exhibited significantly greater movement in the presence of the RF-EMF. Significant sex differences relative to RF-EMF exposure were observed in both response variables. In the presence of RF-EMF, body jerking by females was greater than in males and vice versa for leg jerks. This study represents the first experimental evidence of a behavioural response of D. reticulatus ticks to exposure to RF-EMF.

Assessment of thermal effects in a model of the human head implanted with a wireless active microvalve for the treatment of glaucoma creating a filtering bleb

A 3D anatomical computational model is developed to assess thermal effects due to exposure to the electromagnetic field required to power a new investigational active implantable microvalve for the treatment of glaucoma. Such a device, located in the temporal superior eye quadrant, produces a filtering bleb, which is included in the geometry of the model, together with the relevant ocular structures. The electromagnetic field source—a planar coil—as well as the microvalve antenna and casing are also included. Exposure to the electromagnetic field source of an implanted and a non-implanted subject are simulated by solving a magnetic potential formulation, using the finite element method. The maximum SAR10 is reached in the eyebrow and remains within the limits suggested by the IEEE and ICNIRP standards. The anterior chamber, filtering bleb, iris and ciliary body are the ocular structures where more absorption occurs. The temperature rise distribution is also obtained by solving the bioheat equation with the finite element method. The numerical results are compared with the in vivo measurements obtained from four rabbits implanted with the microvalve and exposed to the electromagnetic field source.

Association between electromagnetic field exposure and abortion in pregnant women living in Tehran

With great interest, we have read the article by Abad et al. entitled “Association between electromagnetic field exposure and abortion in pregnant women living in Tehran” that is published in International Journal of Reproductive BioMedicine Vol. 14. No. 5. pp: 347-354, May 2016. In this article, the authors evaluated the possible associations between electromagnetic waves exposure level and the rate of miscarriage in pregnant women. The electromagnetic radiation, in this study, had a significant association with the increased abortion in women who were exposed to these radiations. These findings were based on the measurements of electromagnetic waves within the residential locations of the 413 samples, very close to the entrance door of their home, according to the standard instructions of ICNIRP. Over the past several years, our laboratories at the Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC) have expanded their focus on studying the health effects of exposure to some common and/or occupational sources of electromagnetic fields (EMFs) such as cellular phones (1-9), mobile base stations (10), mobile phone jammers (11, 12), laptop computers (13), radars (2), dentistry cavitrons (14) and MRI (15, 16). Although the paper authored by Abad et al. is a well-structured article and addresses a very challenging issue, it has some major shortcomings. The first shortcoming of this paper comes from this cardinal point that the authors have simply ignored the role of exposure to extremely low frequency EMFs (e.g. exposure of the pregnant women living in houses close to power lines). It is worth noting that the NARDA SRM-3000 used in their study operates in the frequency range of 27MHz-3GHz and cannot measure extremely low frequency EMFs. It is also worth mentioning that previous studies conducted in Iran indicated that the exposure to extremely low frequency electromagnetic fields is probably related to early spontaneous abortions (17). Another shortcoming of this paper comes from ignoring the role of mobile phone/cordless phone use by pregnant women in evaluation of the risk of abortion. It should be noted that some studies conducted in Iran showed that the use of mobile phones can be linked to the early spontaneous abortions (18). We hope that our comments help better understanding of the effects of EMF on the pregnancy outcome.

Wireless LAN Electromagnetic Field Prediction for Indoor Environment Using Artificial Neural Network

Normal 0 21 MicrosoftInternetExplorer4 A simple neural model for electromagnetic field prediction in indoor environment was created based on field strength measurements at 2.4 GHz, conducted at University of Split , Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture (FESB Split). Vertical rod antenna (omnidirectional in the horizontal plane) was placed in a faculty hallway and used as the electromagnetic field source. Electromagnetic field distribution was defined by commonly used rectangular grid of uniformly distributed measurement points. However, instead of commonly used Cartesian coordinates for measurement points location description, we used polar coordinates of distance and azimuth angle measured from the field source. These coordinates are found to be more suitable for the organization of input data, as the physical distribution of the field strength around the antenna depends on the same variables. This resulted with predictive ability improvement of the neural model, as confirmed by simulation results. Three-Layer Perceptron, trained with Levenberg-Marquardt (LM) algorithm, produced the best results.

Уровни напряженностей магнитных полей от высших гармонических составляющих выпрямленного тока

The article presents the sources of electromagnetic fields which have harmful effects on the electrical engineering personnel servicing electric plants. The authours consider, depending on the rectification circuit (6, 12, 24 pulse) –the range of higher harmonic components of the rectified current, 12-pulse converters, in addition to the main harmonic with a frequency of 50 Hz of electrical alternating current rectifier, have higher harmonic components of the rectified current with frequencies starting from the eleventh (11; 13; 23; 25, etc.) in the primary curve of the rectified current, while 24-pulse converters, in addition to the main harmonic with 50 Hz frequency, have higher harmonic components of the rectified current with frequencies from the twenty-third (23; 25, etc.) in the primary curve of the rectified current.It is shown that the safest from the point of view of the magnetic field impact on the electrical staff of the traction power supply is a 24-pulse rectifier having a mi­nimum frequency range: 50 Hz, 1150 Hz, 1250 Hz. The calculation of the magnetic field of the rectified current on the work stations in the area of “+” and “–” bus of RU-3.3 kV with the superposition method without taking into account the influence of the earth. It is revealed that at traction substations, even in the presence of a smoothing filter unit, the personnel is influenced by a number of harmonic components of the magnetic field of the rectified current the maximum allowable levels of which are not currently standardized in Russia and their harmful effects on the electrical staff has not been considered until recently.

Utilization of the boundary exposure assessment for the broadband low-frequency EMF monitoring

Abstract Exposure to low-frequency electromagnetic fields (EMF) has become an issue considering a number of high-power low-frequency EMF sources installed in residential environment. Therefore, the EMF monitoring and appropriate exposure assessment are highly important regarding the safety, since residents can spend considerable time in the vicinity of such high-power objects. This short paper brings the case study related to the broadband continuous monitoring of the low-frequency magnetic field in the vicinity of the outdoor power substation, as a particularly important and interesting EMF source. Moreover, the exposure assessment of the general population, performed by a newly proposed adaptive boundary exposure approach, is presented. This approach assesses the upper and lower daily exposure boundaries, offering the range where real exposure is positioned. The reduction of difference between boundaries can be attained by frequency spectrum analysis, while in this case study the initial boundary difference was reduced from 99.6% to 33.3%.

The SEMONT’s database support for quad-band monitoring of EMF exposure

The expected technological development, mostly found in the communication domain, will accordingly increase the number of artificial electromagnetic field (EMF) sources, as well as corresponding EMF exposure in the environment. Thus, EMF monitoring has been required worldwide and some innovative monitoring systems are being developed. Some of them are intended to simultaneously perform long-term monitoring and exposure assessment, as well as to timely inform the public on present EMF levels. The Serbian Electromagnetic Field Monitoring Network – SEMONT is one of such systems which has been activated recently. Considering the diversity of the existing EMF sources, as well as the opinion of the public that base stations generally contribute to the increased EMF level, the SEMONT system was designed to perform monitoring of the high-frequency electric field strength in four bands. First, in a wideband, from 100 kHz to 3 GHz, it observes the field strength from all local sources, and then in three sub-ranges of GSM 900, GSM 1800 and UMTS 2100, using the modern quad-band Narda AMB 8057/03 sensor station. In this paper, the SEMONT’s database support for the quad-band sensor utilization, as well as the results of initial in situ monitoring, have been presented. Regarding the test location, the acquired field strength results in all bands appear to be far below the Serbian prescribed reference levels.

Development of a source-exposure matrix for occupational exposure assessment of electromagnetic fields in the INTEROCC study.

To estimate occupational exposures to electromagnetic fields (EMF) for the INTEROCC study, a database of source-based measurements extracted from published and unpublished literature resources had been previously constructed. The aim of the current work was to summarize these measurements into a source-exposure matrix (SEM), accounting for their quality and relevance. A novel methodology for combining available measurements was developed, based on order statistics and log-normal distribution characteristics. Arithmetic and geometric means, and estimates of variability and maximum exposure were calculated by EMF source, frequency band and dosimetry type. The mean estimates were weighted by our confidence in the pooled measurements. The SEM contains confidence-weighted mean and maximum estimates for 312 EMF exposure sources (from 0 Hz to 300 GHz). Operator position geometric mean electric field levels for radiofrequency (RF) sources ranged between 0.8 V/m (plasma etcher) and 320 V/m (RF sealer), while magnetic fields ranged from 0.02 A/m (speed radar) to 0.6 A/m (microwave heating). For extremely low frequency sources, electric fields ranged between 0.2 V/m (electric forklift) and 11,700 V/m (high-voltage transmission line-hotsticks), whereas magnetic fields ranged between 0.14 μT (visual display terminals) and 17 μT (tungsten inert gas welding). The methodology developed allowed the construction of the first EMF-SEM and may be used to summarize similar exposure data for other physical or chemical agents.

Self-reported mobile phone use and semen parameters among men from a fertility clinic

There is increasing concern that use of mobile phones, a source of low-level radio-frequency electromagnetic fields, may be associated with poor semen quality, but the epidemiologic evidence is limited and conflicting. The relationship between mobile phone use patterns and markers of semen quality was explored in a longitudinal cohort study of 153 men that attended an academic fertility clinic in Boston, Massachusetts. Information on mobile phone use duration, headset or earpiece use, and the body location in which the mobile phone was carried was ascertained via nurse-administered questionnaire. Semen samples (n=350) were collected and analyzed onsite. To account for multiple semen samples per man, linear mixed models with random intercepts were used to investigate the association between mobile phone use and semen parameters. Overall, there was no evidence for a relationship between mobile phone use and semen quality.

On the nature of sources of audio-frequency electromagnetic interferences

It has been shown that metal elements of electronic equipment executing mechanical vibrations under exposure to the dc or low-frequency magnetic field could be sources of low-frequency electromagnetic interferences. The general solution of a boundary problem of electrodynamics was obtained that dealt with the electromagnetic field emission by a rod with circular cross-section made of metal of the non-ferromagnetic group under harmonic elastic oscillations in the dc magnetic field. A model example was considered for the situation where a source of low-frequency electromagnetic field was the rod with circular cross-section that executed longitudinal harmonic oscillations of compression–tension at the transverse dc magnetic field. An estimation of numerical values of the intensity of low-frequency magnetic field and the induced voltage of interference were also provided.

A new approach to control for confounding and reverse causality in radiofrequency electromagnetic field research on health related quality of life

Introduction The most relevant sources of radiofrequency electromagnetic fields (RF-EMF) are related to lifestyle such as mobile phone or WLAN use. As a consequence, confounding by unmeasurable psychological factors and reverse causality is a concern, in particular when addressing health related quality of life (HrQoL). To better disentangle the psychological effects of media use from the RF-EMF exposure a new approach is proposed where different usage types are separately considered. Methods We applied latent class analysis to define qualitatively distinct patterns of media usage varying on 11 different use variables in a Swiss sample of 850 adolescents investigated in the years 2012 – 2015. Multivariable regression models were fitted to assess the relationships between the extracted classes and HrQol as measured by the KIDSCREEN questionnaire. Results Five distinct media use profiles could be identified: Gamers, Low users, Medium users, Callers, and High social network users. Group affiliation was dependent on gender and the time of investigation. Affectivity, Self-Perception, parent and school relationship and peer contact scores differed significantly between the five user groups. For instance, high social network users had a lower score on negative affectivity (coefficient: -6.00; 95% CI: (-8.72, -3.29)) and Self-Perception (-3.81; (-6.03, -1.59)) and higher score for peer contact (5.37; (3.05, 7.69)) compared to Low users. Conclusion We found different health profiles in the five user groups which may be due to unmeasured psychological variables and reverse causality. To conduct exposure-response association with RF-EMF within each group separately may be an efficient way to control for such bias and to evaluate potential associations between RF-EMF and HrQol in a robust manner.

The adaptive boundary approach for exposure assessment in a broadband EMF monitoring

Abstract The boundary approach for the assessment of daily exposure to electromagnetic fields (EMF) has been recently proposed for the continuous and broadband EMF monitoring of the Serbian Electromagnetic Field Monitoring Network – SEMONT. This approach is based on the determination of the daily upper and lower exposure boundaries, combining data of the continuous in situ EMF monitoring in a broadband frequency range and the minimal and maximal prescribed reference levels. The real exposure is positioned between these boundaries. In this paper, the enhancement of the boundary approach is presented. By adjusting the existing boundaries and reducing the difference between them, the precision of the daily exposure assessment in the SEMONT system has been improved. The frequency selective measurement has been used to determine the frequencies on which EMF sources radiate over a particular area and in situ location. Consequently, the new minimal and maximal reference levels can be selected; these are suitable for a particular in situ location and should be used for the calculation of exposure boundaries on that location. A simple in situ test measurement of the high-frequency electric field strength was performed, in order to verify the proposed adaptive boundary approach. The analysis shows that this approach attained reduction in boundaries difference of 36.25%, regarding the Serbian legislation, resulting with the increased precision of the daily exposure assessment for the broadband EMF monitoring.

Outdoor and indoor sources of residential radiofrequency electromagnetic fields, personal cell phone and cordless phone use, and cognitive function in 5–6 years old children

BackgroundLittle is known about the exposure of young children to radiofrequency electromagnetic fields (RF-EMF) and potentially associated health effects. We assessed the relationship between residential RF-EMF exposure from mobile phone base stations, residential presence of indoor sources, personal cell phone and cordless phone use, and children's cognitive function at 5–6 years of age. MethodsCross-sectional study on children aged 5–6 years from the Amsterdam Born Children and their Development (ABCD) study, the Netherlands (n=2354). Residential RF-EMF exposure from mobile phone base stations was estimated with a 3D geospatial radio wave propagation model. Residential presence of indoor sources (cordless phone base stations and Wi-Fi) and children's cell phone and cordless phone use was reported by the mother. Speed of information processing, inhibitory control, cognitive flexibility, and visuomotor coordination was assessed using the Amsterdam Neuropsychological Tasks. ResultsResidential presence of RF-EMF indoor sources was associated with an improved speed of information processing. Higher residential RF-EMF exposure from mobile phone base stations and presence of indoor sources was associated with an improved inhibitory control and cognitive flexibility whereas we observed a reduced inhibitory control and cognitive flexibility with higher personal cordless phone use. Higher residential RF-EMF exposure from mobile phone base stations was associated with a reduced visuomotor coordination whereas we observed an improved visuomotor coordination with residential presence of RF-EMF indoor sources and higher personal cell phone use. ConclusionsWe found inconsistent associations between different sources of RF-EMF exposure and cognitive function in children aged 5–6 years.

Decomposition of Electric Motor Torque According to Electromagnetic Field Sources

This paper proposes a systematic approach to isolate and quantify electromagnetic forces and torques between any two distinct parts of an electric motor. The approach is based on a decomposition of the magnetic field into components that are generated by different magnetized or current-carrying motor parts. Forces and torques exerted by the field components can be computed using the conventional force and torque formulas. The proposed decomposition is applied to a squirrel-cage induction motor and to a permanent magnet synchronous motor. In these examples, the magnetic fields are decomposed according to current-carrying conductors, magnetized iron, and permanent magnets. Thereafter, the torques exerted by these fields are specified. The results predict which part-pairs of the motor produce the desired and undesired behavior, for example, torque and torque ripple, respectively.

Computational challenges in magnetic-confinement fusion physics

Magnetic-fusion plasmas are complex self-organized systems with an extremely wide range of spatial and temporal scales, from the electron-orbit scales (∼10−11 s, ∼ 10−5 m) to the diffusion time of electrical current through the plasma (∼102 s) and the distance along the magnetic field between two solid surfaces in the region that determines the plasma–wall interactions (∼100 m). The description of the individual phenomena and of the nonlinear coupling between them involves a hierarchy of models, which, when applied to realistic configurations, require the most advanced numerical techniques and algorithms and the use of state-of-the-art high-performance computers. The common thread of such models resides in the fact that the plasma components are at the same time sources of electromagnetic fields, via the charge and current densities that they generate, and subject to the action of electromagnetic fields. This leads to a wide variety of plasma modes of oscillations that resonate with the particle or fluid motion and makes the plasma dynamics much richer than that of conventional, neutral fluids. Simulating magnetically confined fusion plasmas is crucial to understand and control them. Here, the state of the art and the multi-physics involved are discussed: electromagnetism and hydrodynamics combined over vast spatiotemporal ranges.

Experimental study of energy harvesting in UHF band

A huge progress of down-sizing technology together with trend of decreasing power consumption and, on the other hand, increasing efficiency of electronics give the opportunity to design and to implement the energy harvesters as main power sources. This paper refers to the energy that can be harvested from electromagnetic field in the unlicensed frequency bands. The paper contains description of the most popular techniques and transducers that can be applied in energy harvesting domain. The overview of current research and commercial solutions was performed for bands in ultra-high frequency range, which are unlicensed and where transmission is not limited by administrative arrangements. During the experiments with Powercast’s receiver, the same bands as sources of electromagnetic field were taken into account. This power source is used for conducting radio-communication process and excess energy could be used for powering the extra electronic circuits. The paper presents elaborated prototype of energy harvesting system and the measurements of power harvested in ultra-high frequency range. The evaluation of RF energy harvesters for powering ultra-low power (ULP) electronic devices was performed based on survey and results of the experiments.