Research On Optimization Of SAR Uniformity For Irradiation System At1800MHz

A rectangular waveguide (WG) and a TEM cells are used in the study onimproving the irradiation uniformity of cell layer in a culture dish in this thesis, inwhich the standing waves at1800MHz is generated.Firstly, the model of WG irradiation system, TEM cells irradiation system andculture dish are built with the XFDTD software based on Finite Difference TimeDomain (FDTD) method. Secondly, the characteristics of SAR distribution arecalculated and analyzed with different experimental conditions. Great much emulationindicates that the closer to the source, the bigger value of cell layer SAR. We also findthat magnetic and electric field play main role on SAR of cell layer while the culturedish selects E polarization and H polarization respectively. According to thesecharacteristics, it is possible to improve the SAR uniformity by adding symmetric port,rotating WG and adjusting the position of culture dish along the broad and narrow sideof WG. The design of the best SAR uniformity of cell layer is obtained with theoptimization method on condition of single culture dish in WG. To verify the accuracyof the optimization method we just proposed, the WG and TEM cells irradiation systemwith multiple culture dishes are emulated, and the optimization effect of the method toSAR distribution uniformity of cell layer is tested for multiple culture dishes.As to the WG irradiation system with single culture dish, the SAR relative standarddeviation(RSD) of cell layer are33.27%and35.24%in E polarization and Hpolarization respectively. The SAR RSD is18.65%by using optimization method thatsymmetric port is added, WG is rotated6degrees and the culture dish is moved19.5mm and2.75mm along broad and narrow side from the center. The SAR RSD is32.77%when culture dish is E polarization in multiple culture dishes WG irradiationsystem. After the same method as single culture is adopted, it can reach18.45%withoptimization. For TEM cells irradiation system, the SAR RSD are71.73%and42.12%when culture dish is arranged with E polarization and H polarization respectively. TheSAR RSD is22.07%after TEM cells is rotated27.5degrees. By the emulation resultscan be seen that the optimization method in this thesis is helpful to improve the SARdistribution uniformity of cell layer.