Estimates of electromagnetic compatibility requirements in health care environments

The characteristics of electromagnetic (E.M.) fields due to portable/mobile radio-frequency (R.F.) sources inside buildings are examined with particular attention to health care environments snch as in hospital rooms. Attention is given in particular to the identification of high field levels which might exceed proposed susceptibility thresholds for medical electronic equipment. Effects of the room geometry, surface material properties and R.F. source location are examined, using geometric-optics ray modelling along with the image technique. It is found that the interference patterns generated can exhibit field levels substantially above simplistic free-space estimates. The magnitude and distribution of such high field conditions are increasingly serious with the occurances of multiple high conductivity reflective surfaces.