This paper provides a detailed review and classification of exposure systems used in RF in vitro research from 1999 up to 2009. Since different endpoints and protocols are used in bioelectromagnetics studies, exposure systems cannot be standardized. However, a standardized procedure to achieve the optimum design of the exposure system is suggested. Following this procedure will lead to a known dose distribution within the biological sample and allow a better comparison with other in vitro studies. In addition, the quality of the study will be such that it will be more likely to be included in assessment procedures such as health-risk assessments.

Considerations for Developing an RF Exposure System: A Review for in vitro Biological Experiments

An embedded antenna for facilitating wireless transmission of utility meter data is disclosed, where in one embodiment an RF antenna is a part of the faceplate of the utility meter. In another embodiment the utility meter faceplate is a single-layer or a multi-layer printed circuit board (PCB) with the RF antenna printed on any desired layer. Such faceplates may be labeled to be viewable from outside of the meter housing and/or have openings to accommodate visual access to an output display of the meter consumption information.

Embedded antenna apparatus for utility metering applications

We conducted a large-scale in vitro study focused on the effects of low level radiofrequency (RF) fields from mobile radio base stations employing the International Mobile Telecommunication 2000 (IMT-2000) cellular system in order to test the hypothesis that modulated RF fields may act as a DNA damaging agent. First, we evaluated the responses of human cells to microwave exposure at a specific absorption rate (SAR) of 80 mW/kg, which corresponds to the limit of the average whole body SAR for general public exposure defined as a basic restriction in the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines. Second, we investigated whether continuous wave (CW) and Wideband Code Division Multiple Access (W-CDMA) modulated signal RF fields at 2.1425 GHz induced different levels of DNA damage. Human glioblastoma A172 cells and normal human IMR-90 fibroblasts from fetal lungs were exposed to mobile communication frequency radiation to investigate whether such exposure produced DNA strand breaks in cell culture. A172 cells were exposed to W-CDMA radiation at SARs of 80, 250, and 800 mW/kg and CW radiation at 80 mW/kg for 2 and 24 h, while IMR-90 cells were exposed to both W-CDMA and CW radiations at a SAR of 80 mW/kg for the same time periods. Under the same RF field exposure conditions, no significant differences in the DNA strand breaks were observed between the test groups exposed to W-CDMA or CW radiation and the sham exposed negative controls, as evaluated immediately after the exposure periods by alkaline comet assays. Our results confirm that low level exposures do not act as a genotoxicant up to a SAR of 800 mW/kg.

DNA strand breaks are not induced in human cells exposed to 2.1425 GHz band CW and W-CDMA modulated radiofrequency fields allocated to mobile radio base stations.

This article reviews recent standardization activities and scientific studies related to the assessment of human exposure to electromagnetic fields (EMF). The differences of human exposure standards and assessment of consumer products and medical applications are summarized. First, we reviewed human body modeling and tissue dielectric properties. Then, we explain the rationale of current exposure standards from the viewpoint of EMF and the standardization process for product compliance based on these exposure standards. The assessment of wireless power transfer, as an example of emerging wireless devices, and environmental EMFs in our daily lives are reviewed. Safety in magnetic resonance systems, where the EMF exposure is much larger than from typical consumer devices, is also reviewed. Finally, we summarize future research directions and research needs for EMF safety.

Assessment of Human Exposure to Electromagnetic Fields: Review and Future Directions

A near field microwave scanning system includes a switched array of antenna elements forming an array surface, a scan surface substantially parallel to the array surface and separated by a distance less than about 1 wavelength of the measured frequency, and a processing engine for obtaining and processing near field data, without the use of an absorber.

Multichannel absorberless near field measurement system

Averaging Area of Incident Power Density for Human Exposure from Patch Antenna Arrays

In an apparatus for measuring absorbed power including an electromagnetic field probe 1 fixedly mounted within a head simulation phantom 2 which simulates the configuration and the electromagnetic characteristics of a head of a human body, and wherein the strength of an electric field or a magnetic field of a radio wave externally irradiated upon the head simulation phantom 2 is measured by the electromagnetic field probe 1, and the power of the radio wave absorbed by the head is estimated on the basis of measured values, the head simulation phantom 2 comprises a solid dielectric 10′ which simulates the configuration and the electromagnetic characteristics of a head of a human body or a liquid dielectric 10 which simulates the electromagnetic characteristics of a head of a human body and which is filled in an enclosed vessel 10 which simulates the configuration of a head of a human body The volume of the solid dielectric 10′ or the volume of the enclosed vessel 11 is equal to or less than 5×105 mm3

Absorption power measuring device

A beam formed radiofrequency (RF) exposure-incubator employing a horn antenna, a dielectric lens, and a culture case in an anechoic chamber is developed for large scale in vitro studies. The combination of an open type RF exposure source and a culture case through which RF is transmitted realizes a uniform electric field (±1.5 dB) in a 300 × 300 mm area that accommodates 49 35 mm diameter culture dishes. This large culture dish area enables simultaneous RF exposure of a large number of cells or various cell lines. The RF exposure source operates at 2142.5 MHz corresponding to the middle frequency of the downlink band of the International Mobile Telecommunication 2000 (IMT-2000) cellular system. The dielectric lens, which has a gain of 7 dB, focuses RF energy in the direction of the culture case and provides a uniform electric field. The culture case is sealed and connected to the main unit for environmental control, located outside the anechoic chamber, via ducts. The temperature at the center of the tray, which contains the culture dishes in the culture room, is maintained at 37.0 ± 0.2 °C by air circulation. In addition, the appropriate CO2 density and humidity supplied to the culture case realizes stable long term culture conditions. Specific absorption rate (SAR) dosimetry is performed using an electric field measurement technique and the Finite Difference Time Domain (FDTD) calculation method. The results indicate that the mean SAR of the culture fluid at the bottom of the 49 (7 × 7 array) culture dishes used in the in vitro experiments is 0.175 W/kg for an antenna input power of 1 W and the standard deviation of the SAR distribution is 59%. When only 25 culture dishes (5 × 5 array) are evaluated, the mean SAR is 0.139 W/kg for the same antenna input power and the standard deviation of the SAR distribution is 47%. The proliferation of the H4 cell line in 72 h in a pair of RF exposure-incubators reveals that the culture conditions are equivalent to those of a common CO2 incubator. Bioelectromagnetics 25:599–606, 2004. © 2004 Wiley-Liss, Inc.

Large scale in vitro experiment system for 2 GHz exposure.

This paper aims to clarify the accuracy of a method for assessing the power density in close proximity to a wireless communication device operating above 6 GHz for the assessment of compliance with radio-frequency exposure guidelines. We focused on a near-field reconstruction technique that estimates the power density in close proximity to a wireless communication device using the results of electric field measurement at a plane several wavelengths away from the device. In this paper, the reconstruction technique was first validated by comparing the results evaluated using this technique with those obtained by computational simulation for the case of a standard horn antenna. Second, the reconstruction errors of the technique were assessed using ten planar array antennas at frequencies from 15 to 100 GHz. Reconstruction errors no larger than 0.35 dB were obtained for the maximum spatially averaged power density at a separation distance of over <inline-formula> <tex-math notation=\"LaTeX\">$0.15\\lambda $ </tex-math></inline-formula> from the antennas using an averaging area of <inline-formula> <tex-math notation=\"LaTeX\">$\\lambda ^{2}$ </tex-math></inline-formula> or larger, where <inline-formula> <tex-math notation=\"LaTeX\">$\\lambda $ </tex-math></inline-formula> denotes the wavelength. Finally, the requirement for electric field measurement was also examined, where the combined error for the compliance assessment of the power density was suggested for an actual testing scenario. These results support the standardization of compliance assessment techniques for wireless communication devices operating above 6 GHz, which are expected to be introduced in the near future.

Error Analysis of a Near-Field Reconstruction Technique Based on Plane Wave Spectrum Expansion for Power Density Assessment Above 6 GHz

A novel specific absorption rate (SAR) measurement method is presented that employs a flat solid phantom with multiple embedded E-field probes. A radio device under test traverses over them during the scanning process. The solid phantom provides stable dielectric properties and easy handling, while the multiple E-field probes contribute to shortening the time for measuring the SAR distribution. This method can also be used as an alternative to that employing flat phantoms filled with liquid. Based on the numerical approach, the measurement system configuration is designed to obtain the SAR distributions with an error of within 10% at 900 and 1950 MHz, focusing on the following points: dimensions of the flat solid phantom, size of the E-field probe, and distance between the E-field probes. The experimental setup for the frequency of 1950 MHz confirms that the proposed measurement method obtains the average SARs over 10 and 1 g with an error of within 10% compared to the computed values.

Takahiro Iyama

Papers

Averaging Area of Incident Power Density for Human Exposure from Patch Antenna Arrays

Absorption power measuring device

Large scale in vitro experiment system for 2 GHz exposure.

Error Analysis of a Near-Field Reconstruction Technique Based on Plane Wave Spectrum Expansion for Power Density Assessment Above 6 GHz

Novel Specific Absorption Rate (SAR) Measurement Method Using a Flat Solid Phantom