Electromagnetic Safety Research Articles

Prediction of Equipment-to-Equipment Coupling Through Antennas Mounted on An Aircraft

Modern military and civil aircraft have various radar and communication equipments placed on them for different actions. Electromagnetic interference (EMI) can be easily coupled through various antennas which are mounted on the aircraft. It is therefore desirable to exactly predict their effect on one another as much as possible. In this paper the equipment-to-equipment coupling (ETEC) is proposed which is suitable to accurately determine the electromagnetic compatibility (EMC) safety margin of the aircraft radio system. By employing the microwave network theory the equivalent circuit model of the Identification Friend or Foe System (IFFS) and the Ground-to-Air (GTA) communication system of the aircraft can be obtained and then the ETEC is accurately calculated. In this way the electromagnetic coupling level between the two subsystems can be easily determined. Basing on the accurate coupling, it is allowed to simply and exactly evaluate the electromagnetic interference safety margin of the receiver.

Mobile phones, mobile phone base stations and cancer: a review

There have been reports in the media and claims in the courts that radiofrequency (RF) emissions from mobile phones are a cause of cancer, and there have been numerous public objections to the siting of mobile phone base antennas because of a fear of cancer. This review summarizes the current state of evidence concerning whether the RF energy used for wireless communication might be carcinogenic. Relevant studies were identified by searching MedLine with a combination of exposure and endpoint terms. This was supplemented by a review of the over 1700 citations assembled by the Institute of Electrical and Electronics Engineers (IEEE) International Committee on Electromagnetic Safety as part of their updating of the IEEE C95.1 RF energy safety guidelines. Where there were multiple studies, preference was given to recent reports, to positive reports of effects and to attempts to confirm such positive reports. Biophysical considerations indicate that there is little theoretical basis for anticipating that RF energy would have significant biological effects at the power levels used by modern mobile phones and their base station antennas. The epidemiological evidence for a causal association between cancer and RF energy is weak and limited. Animal studies have provided no consistent evidence that exposure to RF energy at non-thermal intensities causes or promotes cancer. Extensive in vitro studies have found no consistent evidence of genotoxic potential, but in vitro studies assessing the epigenetic potential of RF energy are limited. Overall, a weight-of-evidence evaluation shows that the current evidence for a causal association between cancer and exposure to RF energy is weak and unconvincing. However, the existing epidemiology is limited and the possibility of epigenetic effects has not been thoroughly evaluated, so that additional research in those areas will be required for a more thorough assessment of the possibility of a causal connection between cancer and the RF energy from mobile telecommunications.

Electromagnetic safety of children using wireless phones: A literature review

In this article, several issues related to the safety of electromagnetic field exposure of children when using wireless devices such as mobile phones are described. The information available in the literature is reviewed and open areas that need to be subject of future research are identified. A lack of proof that dielectric properties change with age and an inconsistency in absorption studies in children is reported. The number of biological studies relevant to children is limited. Only some of the cognitive studies specifically target children and these show no significant effect of exposure. There is also a need to investigate the impact of electromagnetic fields on the developmental process of children. All this makes a definitive answer to the question if children are more sensitive to electromagnetic fields than adults impossible. More consistent research will be needed. This study is part of the European COST281 project "Potential Health Implications from Mobile Communication Systems."

Reply to “A biological guide for electromagnetic safety: The stress response” by M. Blank and R. Goodman

Reply to “A biological guide for electromagnetic safety: The stress response” by M. Blank and R. Goodman

Comment: A biological guide for electromagnetic safety: the stress response

Questions of safety of electromagnetic (EM) fields should be based on relevant biological properties, i.e., specific cellular reactions to potentially harmful stimuli. The stress response is a well documented protective reaction of plant and animal cells to a variety of environmental threats, and it is stimulated by both extremely low frequency (ELF) and radio frequency (RF) EM fields. It involves activation of DNA to initiate synthesis of stress proteins. Thermal and non-thermal stimuli affect different segments of DNA and utilize different biochemical pathways. However, both ELF and RF stimulate the same non-thermal pathway. Since the same biochemical reactions are stimulated in different frequency ranges with very different specific absorption rates (SARs), SAR level is not a valid basis for safety standards. Studies of EM field interactions with DNA and with model systems provide insight into a plausible mechanism that can be effective in ELF and RF ranges.

電磁環境計測と安全性 第1回: 電磁環境の計測技術

電磁環境計測と安全性 第1回: 電磁環境の計測技術

Historical review of RF exposure standards and the International Committee on Electromagnetic Safety (ICES).

Focused research on the biological effects of exposure of humans and animals to radio frequency (RF) and microwave energy goes back at least five decades. The history of committees that develop safety standards based on the results of this research goes back almost as far. One such committee that has played a major role in developing such standards is the International Committee on Electromagnetic Safety (ICES), which began in 1960 as the American Standards Association C95 Committee. This paper briefly reviews the history of this committee and its role in the development of RF safety standards. The process now being followed by ICES and its sponsor, the IEEE Standards Association Standards Board (SASB), is discussed, as are a number of issues related to standards setting, such as the poor quality of much of the research and the seemingly endless speculation and search for mechanisms of interaction other than heating. Finally, a tribute is given to Dr. Eleanor Adair, a long-time researcher and supporter of science-based standards. As Chairman of ICES, she makes it clear that her goal and the goal of ICES is to establish rational standards that will make future beneficial applications of RF energy credible to humanity.

Radio frequency electromagnetic fields: cancer, mutagenesis, and genotoxicity.

We present critiques of epidemiologic studies and experimental investigations, published mostly in peer-reviewed journals, on cancer and related effects from exposure to nonionizing electromagnetic fields in the nominal frequency range of 3 kHz to 300 GHz of interest to Subcommittee 4 (SC4) of the International Committee on Electromagnetic Safety (ICES). The major topics discussed are presented under the headings Epidemiologic and Other Findings on Human Exposure, Mammals Exposed In Vivo, Mammalian Live Tissues and Cell Preparations Exposed In Vitro, and Mutagenesis and Genotoxicity in Microorganisms and Fruit Flies. Under each major topic, we present minireviews of papers on various specific endpoints investigated. The section on Epidemiologic and Other Findings on Human Exposure is divided into two subsections, the first on possible carcinogenic effects of exposure from emitters not in physical contact with the populations studied, for example, transmitting antennas and other devices. Discussed in the second subsection are studies of postulated carcinogenic effects from use of mobile phones, with prominence given to brain tumors from use of cellular and cordless telephones in direct physical contact with an ear of each subject. In both subsections, some investigations yielded positive findings, others had negative findings, including papers directed toward experimentally verifying positive findings, and both were reported in a few instances. Further research on various important aspects may resolve such differences. Overall, however, the preponderance of published epidemiologic and experimental findings do not support the supposition that in vivo or in vitro exposures to such fields are carcinogenic.

Reviews of effects of RF fields on various aspects of human health: Introduction

The IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz, C95.1-1991, was published in 1991, reaffirmed in 1997, and amended in 1999 with no changes in the exposure limits. A complete revision of the standard by the subcommittee we co-chair, now in progress, will be based on the peer reviewed literature identified by the Literature Surveillance Working Group. More than 1300 relevant research papers have been evaluated by two randomly selected members of the subcommittee’s Engineering Evaluation Working Group and by two members of the appropriate Biological EvaluationWorking Group (in vitro, in vivo, and epidemiology). Summaries of the working group evaluations are forwarded to the Risk Assessment Working Group (RAWG) to evaluate the levels of possible risk to humans and define the lowest threshold SAR above which potentially adverse effects are likely to occur. A Mechanisms Working Group works in parallel with the RAWG to evaluate possible mechanisms of interaction, both nonthermal and thermal mechanisms. In addition, review papers have been prepared on cancer, reproduction, calcium efflux, behavior, thermoregulation, nervous system, ocular and auditory effects, homeostasis and metabolism, survival, epidemiology, and in vitro studies. During the 2002 U.S. Air Force Research Laboratory Workshop ‘‘Setting a Science-Based Standard for Safe Human Exposure to RF Electromagnetic Fields: A Tribute to Dr. Eleanor R. Adair,’’ held in Quebec City, Que., Canada, 14 review papers were presented to a large audience. These 14 papers were commissioned by Subcommittee 4 (SC4) of the IEEE International Committee on Electromagnetic Safety (ICES) to assist with the Working Group’s assessment of the extensiveRF bioeffect literature database. Except for the epidemiology paper, each paper was written by SC4 members who were experts in the subject matter, and all subcommittee members were encouraged to work with the lead authors. Dr. Mark Elwood, an Australian epidemiologist, wrote the epidemiology paper at the request of the Co-Chairs of SC4. After the workshop, the available preliminary papers were posted on the ICES SC4 public website (http://grouper.ieee.org/groups/scc28/sc4), soliciting comments prior to completion of the manuscripts. Thirteen papers were submitted to Bioelectromagnetics for publication; 12 of these technical papers are included in this special issue. The subjects of the two papers that are not included are calcium efflux and onevs. two-tier standard. These two manuscripts may appear in future regular issues of the Journal. Some topics in the Literature Surveillance Working Group database (posted on the ICES website http:// grouper.ieee.org/groups/scc28/) are not covered in this special issue. For example, electrostimulation by low frequencyRF current is not included.However, the final published standard will include an ‘‘Informative Annex (Annex B)’’ that summarizes all topics covered in the database. In addition to Annex B, Annex A describes the approach adopted during the revision and Annex C explains the rationale of the revision. Other annexes include a bibliography and practical applications of the standard. The exposure limits are set forth in the normative section of the standard. At this writing, SC4 still has work to do to complete the revision of IEEE Standard C95.1-1991. On January 19, 2002, SC4 adopted 12 criteria to focus

Electro Magnetic Compatibility Measurement and Safety #4: Recent Topics on the Guidelines on Limiting Exposures to Electromagnetic Fields

Electro Magnetic Compatibility Measurement and Safety #4: Recent Topics on the Guidelines on Limiting Exposures to Electromagnetic Fields

Electro Magnetic Compatibility Measurement and Safety #2: Wave Absorbers and their Measurement Technologies

Electro Magnetic Compatibility Measurement and Safety #2: Wave Absorbers and their Measurement Technologies

The dependence of electromagnetic energy absorption upon human head tissue composition in the frequency range of 300-3000 MHz

The requirements for testing compliance of cellular phones with electromagnetic safety limits demand evaluation of the maximum exposure that may occur in the user group under normal operational conditions. Under these conditions, the tissues of the ear region are most exposed, the tissue composition of which is complex and varies considerably from user to user. The objective of this paper is to derive head tissue equivalent dielectric parameters that enable the utilization of one generic homogeneous head for testing compliance for the entire user group, i.e., granting no underestimation, but also not greatly overestimating the actual maximum user exposure. As a primary study, a simple analytical model of an infinite half-space layered tissue model exposed to a plane wave was utilized to investigate the impact of impedance matching standing waves, etc. On the spatial-peak specific absorption rate. The tissue layers were varied in composition and thickness, representing the anatomical variation of the exposed head region covering the user group including adults and children ( 90% percentile). Based on the worst-case tissue layer compositions with respect to absorption at each frequency, head tissue equivalent dielectric parameters for homogeneous modeling were derived, which result in the same spatial-peak absorption. The validity of this approach for near-field exposures was demonstrated by replacing the plane wave by different near-field sources (dipoles and generic phones) and the layered structure with magnetic-resonance-image-based nonhomogeneous human head models.

Safety Problems of Electric and Magnetic Fields and Experimental Magnetic Fusion Facilities. Health Protection Guidelines for Electromagnetic Field Exposures.

In order to protect human health from excessive exposure to electromagnetic fields safety guidelines have been established by national and international organizations. The International Commission on Nonionization Radiation Protection is one of these organizations, whose guidelines are briefly regarded as typical. The activities on this issue in various countries are reviewd. Recent situations and the problems still unsolved are also discussed.

Optical fibre-based goniometer for sensing patient position and movement within a magnetic resonance scanner using chromatic modulation.

An optical fibre-based goniometer is described. This instrument was designed to measure the angular position of patients' limbs within the core of a magnetic resonance body scanner, via a 40 m remote fibre-optic link. The sensor exploits the advantages of optical fibre-based sensing, which include immunity to electromagnetic interference, intrinsic safety and chemical immunity. The detection electronics and signal processing are based on the principles of chromatic modulation, an inexpensive, intensity-independent technique in which a change in the spectral power distribution is measured over a broad bandwidth, by photodetectors with differing spectral responses. The optical fibre goniometer has an angular range of 90 degrees, with an average resolution of 2'. The long-term accuracy is within +/- 1 degree, the specified accuracy for the physiological application.

An overview of electromagnetic safety considerations associated with magnetic resonance imaging.

An overview of electromagnetic safety considerations associated with magnetic resonance imaging.

Electric field probes--A review

Electric field probes consisting of a dipole antenna, RF detector, nonperturbing transmission line, and readout device have been implemented in a variety of ways. Three orthogonal dipoles are generally used in an E -field probe to provide a response which is nearly isotropic for all polarizations of the incident field. Diode detectors have been used with electrically short or resistivity loaded dipoles to produce very broadband devices (0.2 MHz to 26 GHz). Thermocouple detectors are used to provide true time-averaged data for high peak-power modulated fields. Optical fibers, together with a suitably modulated light source, may be used to form a wide-band nonperturbing data link from the dipole and detector to a remote readout. Application of E -field probes range from the measurement of fields in living animals exposed to nonionizing radiation to the measurement of fields in air for electromagnetic compatability or radiation safety purposes. Probes are available that can measure field strengths from less than 1 V/m to over 1000 V/m (rms).

Fiber Optical Intensity Sensors

Fiber optical intensity sensors are made of optical fibers connected to a miniaturized optical sensor which is based on either a mechanical light valve, a light scattering process, a photoemission or photoabsorption process, or the transmission property of the optical fiber itself. Use of the optical fiber to transmit light to and from the optical sensor makes it possible to construct an electrically passive sensor with remotely located electronic readout capability. Major advantages of this type of sensors are electromagnetic interference immunity, electrical passiveness and safety, miniature size, and ruggedness, In this paper, the large variety of fiber optical intensity sensors reported to date will be classified by their sensing mechanism. Examples will be given for each category of sensors with reported performances.