Design And Research On Near-field Irradiation System Based On Post-wall Waveguide Technology

In recent years, with the rapid development of science and technology, people make all kinds of millimeter wave(MMW) irradiation devices in vitro and improve the applicator for research. In this paper, a novel in vitro millimeter wave applicator is developed for study of irradiation efficiency and quality. The millimeter wave frequency is 60 GHz. The applicator is fed by using post-wall waveguide technique. Adaptive grid resolution is used for research. And we adopt the dosimetry of millimeter wave in vitro on cells. The paper has finished the following three parts:Firstly, a high efficiency applicator in millimeter-wave region is constructed. The irradiation system is integrated on a dielectric substrate. And the substrate is made through printed circuit board technology. A copper foil is covered on the surface of the substrate. Then we design two columns of via hole and coupling apertures according to a certain distance. The MMWs propagate inside the substrate and leak out from the applicator through the coupling apertures. A culture dish is placed on the applicator to be fed with MMWs from below. At the same time, the problem space is optimized to a quarter of the original size according to the symmetrical boundary.Secondly, the specific absorption rate(SAR) distribution of cells is simulated and analyzed. 0.125 mm grid resolution is chosen for usual research. SAR distribution achieve the purpose of accurate calculation by adjusting the computing space to 0.1mm and the surrounding space to 0.5mm. The millimeter wave frequency is 60 GHz and amplitude is 1V/m. Also the discrete source is used as excitation source and the source impedance is 50 ohms. We calculate and analysis the SAR distribution of cells to get irradiation efficiency of culture medium.Finally, we optimize the SAR distribution of cells. Through 140 period of simulation, a 120 percents of the ralative standard deviation(RSD) within the culture medium is obtained. For the suppression of the RSD in SAR of cell, the influencing factors are studied and adjusted to the optimum. First, considering the computation period inadequate, a stable calculation period of 1000 by increasing period is adopted. Then the influence of the thickness of petri dish stage is studied and a best thickness of 4.5mm and lowest RSD isacquired. At last the paper discusses the effect of the dielectric characteristics and a best value 2.17 is obtained. The result shows that the best SAR distribution with the RSD in the cells is 75%.