Effect of duty-cycle on temperature elevation in a model of the human eye due to portable transceivers

The potential influences of electromagnetic fields on living tissues are studied numerically using the implicit alternating-direction (IAD) algorithm to solve the heat conduction equation in a model of the human eye. A detailed model representing the eyeball, in its bony orbit, exposed to the near-fields of a /spl lambda//2 dipole antenna is used for computations. The spatial SARs, locally averaged over one cm/sup 3/, at frequencies of 840, 915, 1500 and 1800 MHz were calculated previously for near-field exposures. The results showed that the amount of energy deposition in the eye can reach values in excess of the presently accepted standard for portable communication equipment and led one to pursue the analysis in the thermal domain. The heating potential, derived from the electric field values, is used to calculate the temperature distribution induced within the model. Results are given for continuous-wave exposure and intermittent exposure, modelling accurately the north American system (USDC), the Japanese system (JDC) and the European system (GSM). It is found that the power limits, defined by ANSI C95.1 for the uncontrolled environment, appear to be safe for the general public.