FI法による電波暗室のサイトアッテネーション解析

抄録

In this paper, to calculate site attenuation of anechoic chamber, we applied the FI method that was used Maxwell's relations with the integration form. First, in order to examine the influence of the cell size on the site attenuation calculation, we compared with the difference between the calculations values of a 30MHz tuned dipole antenna and a shortened dipole antenna using 40MHz tuned dipole antenna at the frequency of 30MHz. As a result, it was necessary for the 30MHz tuned dipole antenna to be 50 divisions to the wavelength of 30MHz, but, for the shortened dipole antenna to be 300 divisions to the wavelength. In order to examine this cause, we calculated the electric field in the antenna surroundings by the moment method (NEC2), and found that the change of the electric field distribution around the shortened dipole antenna was steeper than that around the tuned dipole antenna. Therefore, it is thought that the difference of the electric field distribution with this antenna was the cause mentioned above. The best size of the cell was presumed from the examination mentioned above, and we calculated the site attenuations of an open area test site and an anechoic chamber by the FI method. As for the open area test site, the calculation value by the FI method agreed with that by the moment method within 0.4dB. As for the anechoic chamber, the calculation value by the FI method was corresponding to the actual measurement value within 0.5dB by setting the cell size of 2cm. Therefore, it was confirmed that the FI method is effective for the calculation of site attenuation on the anechoic chamber.