Indoor radio-wave behavior at 850 and 1900 MHz with electromagnetic compatibility applications in hospitals: An experimental, theoretical, statistical and morphological characterization.

摘要

This thesis aimed to provide a knowledge base and methodologies to help minimize electromagnetic interference (EMI) in healthcare. Two methods were developed, for the first time, to quantify EMI risk due to radio frequency (RF) sources in hospitals. The first method used contour maps and cumulative distributions of field strength to compute the risk of EMI from an RF source of known power operating near a medical device of known immunity. The second method, "minimal separation with risk", used power law models and cumulative distributions of the residuals from such models to compute the risk of EMI from an RF source of known power operating near a medical device of known immunity, both situated in a known electromagnetic environment.; Field structures within a hospital were extensively characterized using straight-line trajectories or planar surfaces, sampled individually or in 3-dimensional arrays. Data was obtained both experimentally (850 and 1900 MHz) and through simulations (850, 1900 and 2400 MHz). Both the structure (morphology) and the statistics of fields were characterized. Field behavior was characterized in corridors (e.g. fields fell more rapidly near walls, but remained unexpectedly constant near the floor) and in clay-block rooms (e.g. extensive standing wave patterns).; The methods permitted computation of the actual risk of EMI for a given hospital electromagnetic compatibility (EMC) policy in a hospital environment, rather than the safe-unsafe recommendations commonly recommended, even in medical device standards. This provides a more realistic assessment of the effectiveness of a particular hospital EMC policy.; Finally, a theoretical development employing scalar theory approach led to an approximate estimate of the average electric field in a room. The relationship between this average field strength and the room's average reflection coefficient provided an approximate gauge useful for rapid preliminary EMI risk assessment within a room.