In-situ measurement procedures for temporal RF electromagnetic field exposure of the general public

In this paper, the general public's exposure to FM, GSM, and UMTS over 7 day's time is investigated. The purpose of this paper is to investigate how short-period measurements can be representative for the actual maximal and average exposure during longer periods such as 1 week. Locations of public RF exposure have been categorized according to the type of environment, population density, and the amount of mobile phone traffic. Five different sites have been selected to perform measurements of the electric fields over time. In total 352,800 time samples of the electric field were obtained from the measurement campaign. A factor X is defined as the ratio between the actual maximal value of the temporal measurements and the estimated maximal value from short-period data. Three different methods to assess X are compared and an optimal method is proposed for an in-situ measurement procedure. Median values of X according to the proposed method are 1.05, 0.47, and 0.96, for FM, GSM, and UMTS, respectively. Moreover a factor R is defined as the ratio between the median and maximal value of the momentary temporal field measurements, indicating the level of variation of a certain signal over time. R enables to calculate maximal values from median values and vice versa. Median values of R are 0.92, 0.66, and 0.71 for FM, GSM, and UMTS, respectively. By combining X and R one can estimate the actual maximal and median exposure during longer periods from short-period measurements.