An Extrapolation Method for Efficient and Accurate Numerical Dosimetry of Resonant Exposure Setups

An extrapolation method was proposed to increase the calculation efficiency and the accuracy of the incident power and specific absorption rate (SAR) in resonant exposure setups. The stable incident power and SAR were derived by observing the oscillating E-field envelope recorded during the finite-difference time-domain calculation. The extrapolation method was validated when applied to a waveguide loaded with two or four 35-mm-diameter Petri dishes at the H-field maximum for the resonant exposure at 1800 MHz. With the extrapolation, the computational time was reduced by 80% to derive the incident power with the error reduction of 93%, as compared to the calculation with the current mechanism until the accepted wave stability. For the SAR, the computational time was reduced by 77%. With the proper position and weighting of the E-field samples, the error of the averaged SAR in the cell monolayer was reduced from 4.62% to 1.31%. The proposed method applies to the scenario where the resonant frequency of the loaded setup drifts away from the driven frequency so that an oscillating E-field envelope is available.