Electromagnetic field level temporal variation in urban areas

Temporal variations of electric field levels have been continuously monitored over a period of a week at seven different urban locations and the results are presented and analysed. It has been found that the electric field level exhibits an important random variation with time. From the results analysis, it can be concluded that a single 'snapshot' measurement using a broadband field strength meter could underestimate the maximum averaged values by up to 9 dB. In urban environments, a continuous field meter using a portable datalogger would be required to obtain accurate measurements. Alternatively, compliance with the radiation limits for 99% of the time can be guaranteed from a single 'snapshot' measurement provided that an additional 8 dB margin under the maximum permissible values is considered.