Site attenuation calculation of ferrite chamber

In a previous paper the authors measured the values of S parameter of radio-frequency (RF) absorbers, using a large square coaxial line at frequencies below 100 MHz and evaluated the results [S. Takeya, K. Shimada “New measurement of RF absorber characteristics by large square coaxial line”, 1993 IEEE International Symposium on EMC]. The present authors used the results obtained from the large coaxial line to simulate the site attenuation of a ferrite chamber and compared the simulation results with actually measured results. When the measurement results of a small coaxial line (39 mm diameter) were used, the accuracy of the calculation results was not high. Therefore, they adopted the results obtained from measurements made with the large coax, which represent the effects of gaps between ferrite tiles, and confirmed the improvement of simulation accuracy. This enabled to numerically analyze the site attenuation which varied depending on the sizes of gaps of the ferrite tiles, i.e., the difference in fabrication and placement conditions of RF absorbers. The authors were then able to apply this analysis to the design of ferrite chambers