Electromagnetic radiation from selected telecommunications systems

Because of the growing interest in potential health effects associated with exposure to electromagnetic (EM) radiation at microwave and radio frequencies (RF's), a study was initiated within the Bell System to document existing levels of EM energy associated with various radio transmission systems. To this end, power density and electric field strength measurements were made at selected facilities, particularly at locations judged to be representative of those frequently encountered by various crafts personnel. For the case of point-to-point microwave radio, measurements were made in the vicinity of various antenna towers in order to obtain information that could be compared with the corresponding levels predicted by analytical techniques. These data allow one to assess the environmental impact, with respect to EM radiation, of the microwave radio system as well as the impact of future standards and guidelines on the system. This paper describes the instrumentation and measurement techniques used for this study and provides a summary of the results obtained for several different types of radio systems including high frequency (HF) radio, tropospheric scatter, earth-satellite and ubiquitous microwave radio relay.