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Report on: Measurement of Cellular Base-station Emissions Using a Newly Developed RF Field Mapping System*

Motivation

The motivation for this work was to construct and utilize an instrument designed to explore the spatial (i.e. over an area) and temporal (i.e. with time) variations in exposure levels in locations around cellular base stations. The requirements for the instrument were that it would be lightweight, portable and easy to use. It must be able to record exposure level and geographic position all while mounted on a vehicle and moving.

Previously, measurements of exposure levels (more precisely known as power density) from base stations required the use of a spectrum analyzer and a probe antenna [Thansandote, et al, 1999]. Owing to the size and complexity of the equipment, measurements could only be made at fixed locations (spot measurements). Although very sensitive, a spectrum analyzer is essentially a swept-tuned radio receiver, which must be tuned to each transmitted carrier frequency in the cellular band while the amplitudes are recorded. Even with automated equipment, this method was slow and only a few measurement locations could be surveyed in an hour. With only a small number of resulting measurements, the data could not reveal patterns or geographic distributions of the power density.