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The specific absorption rate (SAR) characteristics of the studied antenna were evaluated by simulations which were performed using a commercial FDTD program (XFDTD, version 5.0 Bio-Pro by Remcom, Inc.). An FDTD mesh of a male head and shoulders with the voxel resolution of 2.5 mm was used. This was based on the standard human head and shoulders mesh (3 mm voxel) obtained from Remcom. The values of the tissue parameters (er´, seff) were interpolated from the values given in [5]. The tissue density values were those provided with the original mesh. The phone model (antenna and thin ground plane) was placed beside the head model according to the intended use position specified by CENELEC [6]. This was obtained by rotating the head model forward by 74° and to the right by 10° while keeping the phone model vertical in the mesh. The distance of 11.9 mm (5 cells) was left between the head and phone model. The SARs were calculated at 915 MHz, 1730 MHz, and 2100 MHz using a steady-state sinusoidal excitation. Due to the limitations of the 2.5 mm grid, the dimensions of the antenna, and thus also its resonant frequencies, were slightly different from those of the measured antenna. The frequencies used in SAR simulations were adjusted accordingly. The simulation space enclosing the head and the handset consisted of 207 *187 * 206 cells. The simulations were run for 4000 timesteps to ensure converged results.
这两天看英文资料,这段始终看不懂,向高手请教,谢谢 |
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