Electromagnetic interference on medical equipment by low-power mobile telecommunication systems

There have been a number of reports of electromagnetic interference (EMI) on electronic medical equipment caused by mobile telecommunication systems. In Japan, the use of the personal handy-phone system (PHS) has greatly expanded within urban areas, PHS handsets transmit EM signals at a frequency of 1.9 GHz and have a peak radiated power of 80 mW. This power level is lower than that of other mobile telecommunication systems. Two studies were carried out. One was to determine whether or not PHS interferes with electronic medical equipment in hospitals. We observed no EMI on electronic medical equipment when the PHS handset was in either the speaking mode or on standby. The second study was to observe EMI from 1.9-GHz signals at several radiation power levels. Although EMI was not observed at the radiated peak power of the PHS handset, EMI on some of the tested equipment was observed when the radiated power was ten or more times higher than that of the PHS handset.