EVALUATION OF EMI RISK DUE TO THE INTERACTION BETWEEN CELLULAR PHONES AND MEDICAL DEVICES

摘要

The FDTD method was used to calculate the electric fields emitted from cellular phones. Cellular phones were modeled by a quarter-wavelength monopole antenna mounted on a rectangular box with equivalent material in the interior of the rectangular box and a dielectric coating in the exterior of the rectangular box. Measurements of the electric fields emitted from cellular phones were also performed by using a Narda Model SRM-3000 high frequency selective radiation meter with an isotropic E-field probe. From measurement and simulation results, electric fields emitted from cellular phones are in the range of 0.02-39.0 V/m for separation distances of 0-3 m between handsets and test points. It is found that field strengths emitted from cellular phones may meet the recommended EMI immunity level of 3 V/m set by the IEC for medical equipment keeping a separation distance of more than 1 m from cellular phones. An interference threshold separation distance of 3 m is proposed for evaluating the interaction between cellular phones and medical devices.