Measurement, prediction and analysis of the radio frequency electromagnetic environment outside and inside hospitals

The electromagnetic environment outside and inside five urban hospitals, due to fixed, EXTERNAL TRANSMTTERS (30-1000 MHz range), was characterized by measurement. Measured fields generally remained below 130 dB$ mu$V/m (3 V/m). Four computational prediction methods, based on line-of-site free-space propagation, Uniform Geometric Theory of Diffraction, and urban clutter models, were evolved. Fields predicted outside these hospitals were compared to the measured fields. A simple line-of-sight method predicted fields within 20 dB of those measured, thereby easily providing an estimate of the worst-case fields at a hospital. The most complex of these prediction methods estimated field levels to within 10 dB.Measurements were also used to analyze signal propagation characteristics inside buildings due to INTERNAL SOURCES operating at 433, 861, and 1705 MHz. Cross-floor propagation paths, where multiple floors and walls were traversed, showed fields were independent of the transmitter-receiver separation distance. Signals measured for a separation of one floor were higher than same-floor signal levels