Design of electric field meter to assess human exposure in environment with mobile base station

This paper proposes a design for an electric field (e-field) meter that enables evaluation of the total RF human exposure level in the frequency range from 30 MHz to 3 GHz considering when mobile base stations (BSs) transmit signals at the maximum transmission power in an environment where the transmission power due to the mobile communications traffic changes dynamically. The instantaneous exposure levels from all radio sources in the frequency range are evaluated based on frequency spectrum measurements and the integrals of the measured frequency spectrum expressed in units of a particular RF signal. The maximum exposure level from a mobile BS is evaluated based on decoding measurements of a particular constant transmission power channel in each carrier and extrapolation based on the power ratio of the maximum transmission power for each carrier to each constant transmission power channel. Furthermore, a part of the instantaneous exposure levels corresponding to the signals from the mobile BSs are replaced with the maximum exposure levels. Therefore, the proposed e-field meter can evaluate the total exposure level in the frequency range considering the maximum exposure levels from the mobile BSs. The sensitivity level of less than 1 mV/m in the frequency range is achieved using a 3-axis isotropic e-field sensor constructed from novel sleeve dipole elements.