Radio Frequency Electromagnetic Waves Research Articles

Large-scale numerical simulation of ionospheric Langmuir turbulence excited by a radio frequency electromagnetic wave

A numerical simulation is presented concerning an L/O mode electromagnetic wave propagating normally into an overdense magnetised plasma with a smooth density gradient leading to excitation of Langmuir turbulence in the vicinity of the reflection point. The simulation parameters are chosen to represent an ionospheric radio frequency heating experiment but may have relevance to other situations. The simulation model is one-dimensional for large-scale electromagnetic waves and two-dimensional for short-scale electrostatic waves. This allows consideration of local modulational and parametric-decay instabilities as well as the larger scale depletion of the driver electromagnetic wave by anomalous absorption due to the excited turbulence. Simulated growth rates are shown to be in broad agreement with expected values and the evolution of the spatial distribution of the turbulence and driver field profile are presented along with simulated scatter radar spectra.

Computer simulated assessment of radio frequency electromagnetic waves for the detection of obstructive sleep apnea

Abstract Obstructive sleep apnea/hypopnea syndrome (OSAHS) is the most common form of sleep-disorder breathing (SDB). Recurring restriction or occlusion of the upper airway throughout the night concurrent with continued respiratory efforts lasting more than 10 s characterizes the disorder. Prevalence of OSAHS is increasing globally, with a high association with obesity, hypertension, and heart failure. Nocturnal polysomnography (NPSG), which is the gold standard for OSAHS diagnosis, is scarce, expensive, and cumbersome. Methods for home screening and diagnosis of the disorder, directly and indirectly, are highly sought after to amend or replace NPSG. Well-established norms and procedures for electromagnetic (EM) antenna design, radiation pattern and characterization, and signal reception and measurements can be employed for the direct detection of upper airway occlusion. The utilization of radio-frequency (RF) EM antennas is desirable, as it is inexpensive, and simple to design and implement. In this paper, a computerized simulation of a new EM sensing system for direct detection of the occlusion in the upper airway is presented. Electromagnetic, anatomical, and RF safety constraints are taken into consideration. The theoretical basis of EM, antenna design, and physiological interactions with EM waves are presented. The proposed methodology for creating an anatomically-correct neck and airway simulated phantoms to test the hypothesis and the results of the tests are presented. Hypothesis Radio-frequency electromagnetic waves transmitted through an open airway will have different energy levels at the distal side of the neck compared to those associated with a fully occluded airway. Methodology A system is designed comprising a simulated phantom model of the upper airway and neck with the approximate anatomical dimensions and dielectric properties of homogenous neck tissue. Additionally, an RF patch antenna is designed and matched to the phantom neck. An iterative process is developed and implemented for the patch antenna design and coupling with a tissue. Simulation of the EM wave propagation and dissipation throughout the neck in the open and closed airway cases is provided and calculated based on the specific absorption ratios (SAR). The results of several permutations of antenna orientation with respect to the neck and several gaps between the antenna and the neck are provided. Results the Computer simulations for all antenna orientation and location have shown that the EM energy levels recorded from open airway phantom models are statistically different and lower than those recorded from the occluded airway phantom models. Conclusions The results of this study support the hypothesis that it is theoretically feasible to use electromagnetic energy to distinguish between open and occluded upper airway.

Ultrasonic through-tissue communication with video capabilities

The use of wireless implanted medical devices (IMDs), which communicate data wirelessly from sensors within the body to a receiver outside of the body, are gaining significant momentum in medical diagnosis and treatment procedures. Currently, radio frequency (RF) electromagnetic waves are the most frequently used communication method for wireless IMDs. However, there are various drawbacks of using RF electromagnetic waves in such applications such as high attenuation in the body and strictly regulated frequency spectrum, which consequently limit data rates of these devices. An alternative approach to RF transmission for IMDs uses ultrasonic waves, which experience lower attenuation in the body and have higher available bandwidth. In our work, we aim to demonstrate high data rate (>1.2 Mbps) through tissue communication using ultrasonic waves that will allow us to stream video with an IMD while actively controlling it inside the body. Initial experiments performed with 2mm biocompatible sonomicrometry transducers, where 2.4 Mbps data rate BER less than 5E-5 through water is achieved, demonstrating the capability of this method for high speed data transmission. Additional targets of this work include data transmission through beef liver and a live rabbit abdominal wall with high enough data rates capable of video streaming.The use of wireless implanted medical devices (IMDs), which communicate data wirelessly from sensors within the body to a receiver outside of the body, are gaining significant momentum in medical diagnosis and treatment procedures. Currently, radio frequency (RF) electromagnetic waves are the most frequently used communication method for wireless IMDs. However, there are various drawbacks of using RF electromagnetic waves in such applications such as high attenuation in the body and strictly regulated frequency spectrum, which consequently limit data rates of these devices. An alternative approach to RF transmission for IMDs uses ultrasonic waves, which experience lower attenuation in the body and have higher available bandwidth. In our work, we aim to demonstrate high data rate (>1.2 Mbps) through tissue communication using ultrasonic waves that will allow us to stream video with an IMD while actively controlling it inside the body. Initial experiments performed with 2mm biocompatible sonomicrometry tran...

Database Management using Embedded System and CAD

An aim of this paper is to use Radio Frequency Identification (RFID) technology in facilitating efficient file management system. RFID is an abbreviation of radio frequency identification, RFID was poised to take off and become a standard piece of library technology. An RFID transmitter is also needed to capture the radio frequency signal from the tag for turn out to be giving out by the RFID reader. Therefore RFID has been referred to as “a non-contact method of using radio frequency electromagnetic waves for communication between two remote entities”. An Objective of this paper is to design 3D modeling of file rack using Creo software, manage the files using RFID tag, read the files from RFID using microcontroller through embedded code and to display the files using 16x2 Liquid Crystal Display and 4x4 keypad. The position of the files in the rack will be identified using Light Emitting Diode.

Fair and Throughput-Optimal Routing in Multimodal Underwater Networks

While acoustic communications are still considered the most prominent technology to communicate under water, other technologies are being developed based, e.g., on optical and radio-frequency electromagnetic waves. Each technology has its own advantages and drawbacks: for example, acoustic signals achieve long communication ranges at order-of-kbit/s rates, whereas optical signals offer order-of-Mbit/s transmission rates, but only over short ranges. Such diversity can be leveraged by multimodal systems, which integrate different technologies and provide the intelligence required to decide which one should be used at any given time. In this paper, we address a fundamental part of this intelligence by proposing optimal multimodal routing (OMR), a novel routing protocol for underwater networks of multimodal nodes. OMR makes distributed decisions about the flow in each link and over each technology, at any given time, in order to advance a packet toward its destination; in doing so, it prevents bottlenecks and allocates resources fairly to different nodes. We analyze the performance of OMR via simulations and in a field experiment. The results show that OMR successfully leverages all technologies to deliver data, even in the presence of imperfect topology information. To permit the reproduction of our results, we share our simulation code.

Assessment of exposure to radio frequency electromagnetic fields from smart utility meters in GB; part II) numerical assessment of induced SAR within the human body.

Human body exposure to radiofrequency electromagnetic waves emitted from smart meters was assessed using various exposure configurations. Specific energy absorption rate distributions were determined using three anatomically realistic human models. Each model was assigned with age- and frequency-dependent dielectric properties representing a collection of age groups. Generalized exposure conditions involving standing and sleeping postures were assessed for a home area network operating at 868 and 2,450 MHz. The smart meter antenna was fed with 1 W power input which is an overestimation of what real devices typically emit (15 mW max limit). The highest observed whole body specific energy absorption rate value was 1.87 mW kg-1 , within the child model at a distance of 15 cm from a 2,450 MHz device. The higher values were attributed to differences in dimension and dielectric properties within the model. Specific absorption rate (SAR) values were also estimated based on power density levels derived from electric field strength measurements made at various distances from smart meter devices. All the calculated SAR values were found to be very small in comparison to International Commission on Non-Ionizing Radiation Protection limits for public exposure. Bioelectromagnetics. 39:200-216, 2018. © 2017 Wiley Periodicals, Inc.

Zastosowanie wybranych bodźców fizykalnych podczas profesjonalnych zabiegów kosmetologicznych. Część III. Prąd niskiej częstotliwości i fale elektromagnetyczne o częstotliwości radiowej jako alternatywa inwazyjnych zabiegów z zakresu medycyny estetycznej

Zastosowanie różnych bodźców fizykalnych wpływa na podniesienie skuteczności zabiegów kosmetycznych. Opracowanie optymalnej metodyki zabiegów kosmetycznych z użyciem elektrostymulacji i metodyki zabiegów z zastosowaniem fal elektromagnetycznych o częstotliwości radiowej oraz zastosowanie substancji aktywnych stymulujących regenerację kolagenu, elastyny i kwasu hialuronowego może wpłynąć na poprawę struktury skóry.

ID: 1044 DNA origami nanobot for sensitive drug delivery chemotherapy

The cutting-edge technology of constructing nanoscale objects using DNA origami has opened new directions for drug delivery in cancer chemotherapy research [1, 2]. This project aims to develop a novel DNA origami nanobot for drug delivery, with high selectivity and specificity for chemotherapy. It is important to be able to control the rate of drug release to maintain the concentration of chemotherapeutic agents at the desirable set-point [3]. This control can be achieved through various activation methods, similar to those used in liposome drug delivery systems, e.g. magnetism, radiation, ultrasound, heating etc. [4]. These stimuli can deliver specific types of energy (e.g. thermal), which can then activate a pre-designed nanobot- topology variation. For example, thermal energy can cause local DNA strands to melt and partially distort some local regions of the DNA topology, releasing drug molecules. One mechanism to activate the drug release is via radio frequency (RF) electromagnetic wave induced heating of gold nanoparticles [6]. A prototype nanobot will be developed and tested for heat-triggered nanobot switching between open and closed configurations. It is hypothesized that upon RF heating, the gold nanoparticles will concentrate the heat and cause the local DNA strands to melt, leading to the open configuration, without melting the rest of the nanobot structure. Heating time and power will be tuned to regulate the drug release rate. This work will develop an effective process control strategy for enhanced performance of nanoscale drug delivery systems.

The use of RFID technology to measure the compositions of diethyl ether-oil-brine mixtures in enhanced imbibition experiments

Recent developments in Radio Frequency (800 MHz–1000 MHz) Identification (RFID) devices suggest that it is possible to use them for wireless laboratory measurements of the dielectric coefficients (or compositions) of fluid mixtures with possible spin-off for their use in the petroleum engineering practice. The advantage of RFID devices is their small size (0.095×0.008×0.001 m3), the developments to make them increasingly smaller and that they do not require the use of leak prone connecting cables. RFID measures the response of a sample volume of interest irradiated by a radio frequency electromagnetic (EM) wave. The response can be expressed in terms of various response functions, e.g. two scattering functions (S11 and S21) or the minimum irradiated power (Pmin). The response functions can be measured using a state-of-the-art RFID device (CISC RFID Xplorer-200), which operates in the range between 800 and 1000 MHz. The effect of the dielectric coefficient on the RFID response was tested by placing the RFID tag in different media with various dielectric coefficients ε ranging from 1 to 80. The overall purpose is to develop a work-flow to relate the response functions obtained with RFID technology to the dielectric coefficient and thus the composition of fluid mixtures in which an RFID tag can be immersed. An application is to measure fluid compositions during a spontaneous imbibition experiment in an Amott-cell. As an intermediate step we measure the composition dependence of the partial molar volume of diethyl ether (DEE) in brine and the partial molar volume of DEE in oil by using an Anton Paar density meter. The relation between the dielectric coefficients and the volume fraction can be obtained with the Böttcher mixing rule. The DEE volume fraction range of interest is 0–8% volume fraction in the aqueous solution whereas DEE volume fraction range of interest is 0–100% volume fraction in oleic solutions. For better understanding of the measurement results, we used COMSOL™ simulations, which show that the response functions depend on the dielectric coefficient in a vessel of appropriate dimensions filled with a fluid of choice. The measurements show that the minimum power at the tag position Pmin is the preferred response function and that the sensitivity of Pmin was highest at 915 and 868 MHz for aqueous (8.547×10−6) and oleic (1.905×10−4) solutions respectively. The measurement error is of the same order of magnitude as the errors mentioned above (Hon, 1989) ensuing from evaporation of DEE during the preparation of the calibration fluids or the approximate nature of the Böttcher mixing rule. We conclude that it is possible to use RFID technology for contact-less measurements of the compositions of fluids in imbibition experiments.

Influence of radiofrequency-electromagnetic waves from 3rd-generation cellular phones on fertilization and embryo development in mice.

The purpose of this study was to evaluate the effects of 3rd-generation (3G) cellular phone radiofrequency-electromagnetic wave (RF-EMW) exposure on fertilization and embryogenesis in mice. Oocytes and spermatozoa were exposed to 3G cellular phone RF-EMWs, 1.95 GHz wideband code division multiple access, at a specific absorption rate of 2 mW/g for 60 min, or to sham exposure. After RF-EMW exposure, in vitro fertilization and intracytoplasmic sperm injection were performed. Rates of fertilization, embryogenesis (8-cell embryo, blastocyst), and chromosome aberration were compared between the combined spermatozoa and oocyte groups: both exposed, both non-exposed, one exposed, and the other non-exposed. Rates of fertilization, embryogenesis, and blastocyst formation did not change significantly across the four groups. Considering that the degree of exposure in the present study was ≥100 times greater than daily exposure of human spermatozoa and even greater than daily exposure of oocytes, the present results indicate safety of RF-EMW exposure in humans. Bioelectromagnetics. 38:466-473, 2017. © 2017 Wiley Periodicals, Inc.

A Software-Defined Ultrasonic Networking Framework for Wearable Devices

Wearable medical devices with wireless capabilities have become the cornerstone of many revolutionary digital health applications that promise to predict and treat major diseases by acquiring and processing physiological information. Existing wireless wearable devices are connected through radio frequency electromagnetic wave carriers based on standards, such as Bluetooth or Wi-Fi. However, these solutions tend to almost blindly scale down traditional wireless technologies to the body environment, with little or no attention to the peculiar characteristics of the human body and the severe privacy and security requirements of patients. We contend that this is not the only possible approach, and we introduce U-Wear, the first networking framework for wearable medical devices based on ultrasonic communications. U-Wear encloses a set of physical, data link, and network layer functionalities that can flexibly adapt to application and system requirements to efficiently distribute information between ultrasonic wearable devices. U-Wear also offers reconfiguration functionalities at the application layer to provide a flexible platform to develop medical applications. We design two prototypes that implement U-Wear and operate in the near-ultrasonic frequency range using commercial-off-the-shelf (COTS) speakers and microphones. Despite the limited bandwidth, i.e., about $2~{kHz}$ , and COTS hardware components not optimized for operating at high frequency, our prototypes: 1) achieve data rates up to $2.76~{kbit/s}$ with bit-error-rate lower than $10^{-5}$ using a transmission power of $13~{dBm}$ ( $20~{mW}$ ); 2) enable multiple nodes to share the medium; and 3) implement reconfigurable processing to extract medical parameters from sensors with high accuracy.

Exposure to radio-frequency electromagnetic waves alters acetylcholinesterase gene expression, exploratory and motor coordination-linked behaviour in male rats.

Humans in modern society are exposed to an ever-increasing number of electromagnetic fields (EMFs) and some studies have demonstrated that these waves can alter brain function but the mechanism still remains unclear. Hence, this study sought to investigate the effect of 2.5Ghz band radio-frequency electromagnetic waves (RF-EMF) exposure on cerebral cortex acetylcholinesterase (AChE) activity and their mRNA expression level as well as locomotor function and anxiety-linked behaviour in male rats. Animals were divided into four groups namely; group 1 was control (without exposure), group 2-4 were exposed to 2.5Ghz radiofrequency waves from an installed WI-FI device for a period of 4, 6 and 8 weeks respectively. The results revealed that WiFi exposure caused a significant increase in anxiety level and affect locomotor function. Furthermore, there was a significant decrease in AChE activity with a concomitant increase in AChE mRNA expression level in WiFi exposed rats when compared with control. In conclusions, these data showed that long term exposure to WiFi may lead to adverse effects such as neurodegenerative diseases as observed by a significant alteration on AChE gene expression and some neurobehavioral parameters associated with brain damage.

RF channel modelling and multi‐hop routing for wireless sensor networks located on oil rigs

This study presents a combined analytical and empirical model for predicting the signal loss effects of metallic drilling rig structures on radio-frequency electromagnetic waves used by wireless sensor networks (WSNs) installed on a drilling rig. The model is based on the combination of free space path loss and the excess loss caused by the metallic structure separately. The authors combine both losses to predict the overall loss of signal strength. The model has been validated against field data collected from multiple drilling rigs. Further modification of the model to include the effects of different signal frequencies is under way. They present simulation results from OMNeT++ based on their model, to establish the packet loss and energy consumption expected for a real WSN. They also present a novel dynamic multi-hop routing protocol, which improves network performance by removing the constraints of single-hop forwarding. The algorithm directs packets to their destination via a selected node within a routing ‘cluster’. By combining their channel model and routing protocol, they are able to achieve 100% packet success, while setting transmit power levels appropriately to achieve the longest possible network lifetime.

Distributed Algorithms for Joint Channel Access and Rate Control in Ultrasonic Intra-Body Networks

Most research in body area networks to date has focused on traditional RF wireless communications, typically along the body surface. However, the core challenge of enabling networked intra-body communications through body tissues is substantially unaddressed. RF waves are in fact known to suffer from high absorption and to potentially lead to overheating of human tissues. In this paper, we consider the problem of designing optimal network control algorithms for distributed networked systems of implantable medical devices wirelessly interconnected by means of ultrasonic waves, which are known to propagate better than radio-frequency electromagnetic waves in aqueous media such as human tissues. Specifically, we propose lightweight, asynchronous, and distributed algorithms for joint rate control and stochastic channel access designed to maximize the throughput of ultrasonic intra-body area networks under energy constraints. We first develop (and validate through testbed experiments) a statistical model of the ultrasonic channel and of the spatial and temporal variability of ultrasonic interference. Compared to in-air radio frequency (RF), human tissues are characterized by a much lower propagation speed, which further causes unaligned interference at the receiver. It is therefore inefficient to perform adaptation based on instantaneous channel state information (CSI). Based on this model, we formulate the problem of maximizing the network throughput by jointly controlling the transmission rate and the channel access probability over a finite time horizon based only on a statistical characterization of interference. We then propose a fully distributed solution algorithm, and through both simulation and testbed results, we show that the algorithm achieves considerable throughput gains compared with traditional algorithms.

Mobile phones electromagnetic radiation and NAD+-dependent isocitrate dehydrogenase as a mitochondrial marker in asthenozoospermia

NAD+-dependent Isocitrate Dehydrogenase (NAD+-IDH) could be one of the cell phone radiation targets. Enzyme activity alteration may lead to decline in sperm motility during radio-frequency electromagnetic waves (RF-EMW) exposure. The current case control study aimed to investigate the possible relationship between mitochondrial NAD+-IDH activity in human seminal plasma and sperm motility among asthenozoospermic cellular phone users. A total number of ninety idiopathic infertile males referred from the Department of Dermatology and Andrology, were enrolled in this study. NAD+-IDH activity was measured in human seminal plasma by spectrophotometer. Computer-aided sperm analysis (CASA) following WHO criteria has been used for semen analyses. The results showed that IDH activity was increased in patients with prolonged cell phone daily use ≥4 h/day. Its level, correlated negatively with either the motility ratio percentages (r = −0.46, p < 0.001) or the progressive motility percentages (r = −0.50, p < 0.001) in the study groups. The current study suggests that NAD+-IDH in human seminal plasma could be one of seminal plasma biomarkers reflecting the mitochondrial function of spermatozoa. Alteration of its level could reflect the defective motility of sperms among some cases of cellular phone users.

Can we estimate the cellular phone RF peak output power with a simple experiment?

Cellular phones are becoming increasingly useful tools for students. Since cell phones operate in the microwave bandwidth, they can be used to motivate students to demonstrate and better understand the properties of electromagnetic waves. However, since these waves operate at higher frequencies (L-band, from 800 MHz to 2 GHz) it is not simple to detect them. Usually, expensive real-time high frequency oscilloscopes are required. Indirect measurements are also possible through heat-based and diode-detector-based radio-frequency (RF) power sensors. Another didactic and intuitive way is to explore a simple and inexpensive detection system, based on the interference effect caused in the electronic circuit of TV and PC soundspeakers, and to try to investigate different properties of the cell phones’ RF electromagnetic waves, such as its power and modulated frequency. This manuscript proposes a trial to quantify these measurements, based on a simple Friis equation model and the time constant of the circuit used in the detection system, in order to show it didactically to the students and even allow them also to explore such a simple detection system at home.

Material Analysis and Application for Radio Frequency Electromagnetic Wave Shielding

In this study, after this introduction, in the second section the electromagnetic shielding concept is discussed. In the third section material selection and applications for an indoor environment, protection against electromagnetic radiation are explained and the results for curtain and fabrics tested for shielding eectiveness are provided. Finally, the paper ends with the conclusions section.

Non-ionizing radiofrequency electromagnetic waves traversing the head can be used to detect cerebrovascular autoregulation responses.

Monitoring changes in non-ionizing radiofrequency electromagnetic waves as they traverse the brain can detect the effects of stimuli employed in cerebrovascular autoregulation (CVA) tests on the brain, without contact and in real time. CVA is a physiological phenomenon of importance to health, used for diagnosis of a number of diseases of the brain with a vascular component. The technology described here is being developed for use in diagnosis of injuries and diseases of the brain in rural and economically underdeveloped parts of the world. A group of nine subjects participated in this pilot clinical evaluation of the technology. Substantial research remains to be done on correlating the measurements with physiology and anatomy.

Scattering of radio frequency waves by cylindrical density filaments in tokamak plasmas

In tokamak fusion plasmas, coherent fluctuations in the form of blobs or filaments are routinely observed in the scrape-off layer. Radio frequency (RF) electromagnetic waves, excited by antenna structures placed near the wall of a tokamak, have to propagate through the scrape-off layer before reaching the core of the plasma. While the effect of fluctuations on the properties of RF waves has not been quantified experimentally, it is of interest to carry out a theoretical study to determine if fluctuations can affect the propagation characteristics of RF waves. Usually, the difference between the plasma density inside the filament and the background plasma density is sizable, the ratio of the density difference to the background density being of order one. Generally, this precludes the use of geometrical optics in determining the effect of fluctuations, since the relevant ratio has to be much less than one, typically, of the order of 10% or less. In this paper, a full-wave, analytical model is developed for the scattering of a RF plane wave by a cylindrical plasma filament. It is assumed that the plasma inside and outside the filament is cold and uniform and that the major axis of the filament is aligned along the toroidal magnetic field. The ratio of the density inside the filament to the density of the background plasma is not restricted. The theoretical framework applies to the scattering of any cold plasma wave. In order to satisfy the boundary conditions at the interface between the filament and the background plasma, the electromagnetic fields inside and outside the filament need to have the same k∥, the wave vector parallel to the ambient magnetic field, as the incident plane wave. Consequently, in contrast to the scattering of a RF wave by a spherical blob [Ram et al., Phys. Plasmas 20, 056110-1–056110-10 (2013)], the scattering by a field-aligned filament does not broaden the k∥ spectrum. However, the filament induces side-scattering leading to surface waves and can also couple some power to the cold plasma wave different from the incident wave. The changes induced by a filament in the propagation of electron cyclotron waves and lower hybrid waves are illustrated by numerical results displaying the properties of the Poynting vector. The Poynting flux in the wake of the filament, and directed towards the core of the plasma, develops a spatial structure due to diffraction and shadowing. Thus, the fluctuations affect the uniformity of power flow into the plasma.

Estimation of state variables in the hyperthermia therapy of cancer with heating imposed by radiofrequency electromagnetic waves

One of the major difficulties in any cancer treatment is to kill the cells of the tumor without affecting healthy cells. Recently, with the advancement of nanotechnology, the localized hyperthermia treatment of cancer has again gained interest from the scientific community. In this technique, the application of electromagnetic waves, possibly even over the surface of the patient's body, causes temperature increases in the tissues. By concentrating nanoparticles in the tumorous tissues, cell damages can be inflicted mostly to the region of interest. This paper deals with numerical simulations under uncertainties of the treatment of cancer based on hyperthermia induced by radiofrequency electromagnetic waves, where the tumor is supposed to be loaded with nanoparticles. The focus of the paper is on the solution of the inverse problem dealing with the estimation of state variables, like the temperature distribution in the tissues. The state estimation problem is solved with the Particle Filter, by utilizing the Sampling Importance Resampling (SIR) algorithm. An excellent agreement between estimated and exact temperatures is obtained, which may help medical doctors in the future to prescribe treatment protocols and also opens the possibility of devising control strategies for the hyperthermia treatment of cancer.