In order to efficiently mitigate emissions radiated from electrical equipment, emission source visualization methods need to be studied. In this paper, we propose a new macroscopic visualization method based on an optimization process which uses only cylindrically-scanned electric field amplitude data from an EMI test facility as specified by CISPR, and so does not need a special measurement system. The presented method divides the visualization space into three-dimensional rectangular cells, and estimated current values through the optimization process are sorted into each corresponding cell. By displaying the summed value of every cell, the emission source can be visualized. For this study, the spatial resolution was evaluated by computer simulation, with a result of around 0.2 m using a cell size of 0.1 m. With subsequent experimental verification using a comb generator in a semi-anechoic chamber, the visualization deviation was found to be less than 0.1 m in a frequency range of 100 MHz to 800 MHz. When two spherical dipole antennas were used, the deviation was less than 0.15 m. Finally, visualization results from a facsimile unit and a PC as real EUTs were shown and basic applicability of this method demonstrated.

The site attenuation is an important parameter to evaluate an anechoic chamber. The ray-tracing method has been applied to analyze it. However, the lowest applicable frequency has not been cleared. In this paper, the FDTD method has been applied to analyze the site attenuation of a compact anechoic chamber from 30 MHz to 250 MHz, and this has been compared with the calculated one by the ray-tracing method to evaluate the lowest frequency where the ray-tracing method could be applied. The compact anechoic chamber, where the absorbers are placed on the all walls, has been used for the calculation. For FDTD analysis, the dipole antenna and the absorber have been modeled by using the large cell, whose size is larger than the diameter of the antenna element. For verification, the site attenuation of a compact anechoic chamber has been measured and compared with the calculated values by the FDTD method and the ray-tracing method. As the results, the calculated values by the ray-tracing method have larger deviation than the ones by the FDTD method when the frequency is less than 180 MHz.

In the spatial network method (SNM) for the vector potential, both the current continuity law including polarization vector and the conservation law of generalized momentum including vector potential field can introduce simpler expressions for dispersive property than that by the electromagnetic field variables. But for the anisotropic medium conditions, the conventional expanded node expression has some difficulties in treating the coupling mechanism among field variables. On the other hand, in the condensed node expression, in which all field components exist at each node, every connections among field components can be simply formulated. In this paper, after proposing the condensed node spatial network method for the vector potential, the advantage of the method such as performing the simplified formulation by utilization of both the vector potential and the condensed node expressions is presented for the magnetized plasma which has the gyro-anisotropy. The validity of the computation is shown by some examples such as Faraday rotation.

The electromagnetic field emitted from UTP cable has been calculated by the 4-port network method from 30 MHz to 1 GHz. However it has not been clarified as to whether this method was effective in the frequency range of more than 1 GHz or not. In this paper, the electromagnetic field emitted from UTP cable was calculated by the moment method and it was compared with the calculated results by the 4-port network method. The wire grid model was developed to represent the propagation constants of UTP cable. The comparison of calculated and measured results confirms the validity of the model. A hybrid coupler was used to generate differential mode signal for the measurement. The comparison indicated that the calculated results by the moment method closely agreed with the measured results in the frequency range of 0.3 to 2 GHz and the difference was smaller than the results by the 4-port network method.