Wireless communication systems in healthcare: Development of a new multi-source electromagnetic-compatibility criterion

Future healthcare informatics needs at the point of care will require the usage of multiple radio-frequency (RF) sources near medical devices. Current electromagnetic compatibility (EMC) criteria in hospitals recommend that a minimum separation be maintained between a single RF source and a medical device, but they say nothing about multiple RF sources, and are therefore inadequate when multiple sources are present. This paper describes a new EMC separation criterion specifying a minimum separation distance when N RF sources operate in an indoor-propagation scenario. The new separation criterion is based on the direct field of N nearby sources, which increases the separation distance by √N, and the indirect or reverberant field of these sources, which depends on the combined power of all sources in the room and the room absorption. Simulations are shown to illustrate the usefulness and validity of the new criterion.