Method for measuring radiated electric field excited by linear array antenna using near field to far field transformation

This paper proposes a novel method for measuring the radiated electric field excited by a linear array antenna using the near field to far field transformation. At a mobile radio base station, this measurement method aids in determining the compliance boundary that corresponds to the safety limit of human exposure to an RF electromagnetic field or the malfunction threshold level of an implantable medical device. The electric field strength and the phase are measured using a field sensor in the vicinity of the antenna radiation using one dimensional scanning. The two dimensional frequency spectrum of the wave is calculated from the combined electric field data that consist of the measured electric field and extrapolated electric field. The two dimensional electric field distribution of the radiated near field and far field is determined using the inverse Fourier transformation. This novel measurement method reduces the time for determining the compliance boundary with respect to the mobile base station antenna. The time required for this measurement is less than 30 minutes, while the conventional sensor scanning method requires approximately 9 hours.