A Technique for Determining Safe Separation Distances for Personnel and Electronic Equipment in the Near-Field of Short Dipole Antennas A Graphical Method - Its Development and Use

Abstract

ANSI C95.1-1982 establishes safety levels and guidelines with respect to human exposure to electromagnetic fields in the frequency range 300 kHz to 100 GHz, Nomograms have been developed for deter­ mining safe distances based on the familiar far-field equivalent plane-wave power density equation. How­ ever, for linear-type antennas, distances that were obtained which were less than about one-sixth (X/6) wavelength may not necessarily assure a "safe" dis­ tance. In these cases, other methods must be used to determine the field strengths from which appropriate distances could be determined. By using previously determined far-field "safe" distances, other nomo­ grams have been developed to determine "safe" dis­ tances for these near-field conditions. Example curves of normalized electric field intensities are used for developing the nomograms. These nomograms can be used to determine near-field distances for any other criteria for which far-field distances have been determined. The appendix describes the tech­ nique for developing the nomograms and could be fol­ lowed for developing nomograms from other curves where far-field distances need to be corrected for near-field conditions.