The millimeter wave (mmWave) bands between 30 and 300 GHz offer massive amounts of raw bandwidth to enable multi-Gigabit-per-second (Gbps) wireless data rates. However, the potential health effects of transmissions in these new frequencies need to be carefully understood for use in consumer devices. NYU WIRELESS, in a unique collaboration with the NYU Radiology department, has been leading research in understanding interactions between the human body and millimeter-wave radiation and the biological effects of mmWave exposures.
Unlike much higher frequency ultraviolet, X-ray, and gamma radiation, mmWave radiation is non-ionizing. Thus, the main safety concern is heating of the eyes and skin caused by the absorption of mmWave energy in the human body. Our recent research shows that current methods based on estimating power density are not suitable to determine exposure compliance when millimeter wave devices are used very close to the body. We have developed the first temperature-based technique for the evaluation of safety compliance using magnetic resonance imaging (MRI)-based systems for mapping thermal changes. In recent years, the cost of operation of MRI has been decreasing, and MRI-based systems for mapping thermal changes are becoming affordable to wireless manufacturers and regulatory bodies. They provide wideband capabilities, high 3-dimensional resolution, and scan speeds that are unparalleled to the current SAR measurement systems. MRI can accurately measure heating of the skin caused by mmWave radiations.
With increasing interest in millimeter wave wireless communications, investigations on interactions between the human body and millimeter wave devices are becoming important. Our research provides examples of current regulatory requirements, and provides an example for a 60 GHz transceiver. Also, the propagation characteristics of millimeter-waves in the presence of the human body are studied, and four models representing different body parts are considered to evaluate thermal effects of millimeter-wave radiation on the body.
|T. Wu, T. S. Rappaport, C. M. Collins, “Safe for generations to come: considerations of safety for millimeter waves in wireless communications”, IEEE Microwave Magazine, vol. 16, no. 2, pp. 65-84, Mar. 2015.||mmWave Radiation, mmwave rappaport, Wireless Comm||2015/02/05|
|L. Alon, G. Y. Cho, X. Yang, D. K. Sodickson, C. M. Deniz, “A method for safety testing of radiofrequency/microwave-emitting devices using MRI”,Magnetic Resonance in Medicine, Nov 2014.||mmWave Radiation||2014/11/25|