Study on the Characteristics of RF-EMI suppressing devices

近年来，移动无线电、无线局域网等个人无线系统发展非常迅速。另一方面，IT设备和其他设备的工作频率已提高到GHz频段，以实现更高的性能。因此，人们对这类设备发出的电磁干扰可能对无线系统造成的干扰感到强烈的担忧。为了控制干扰，IEC/CISPR一直在研究1 GHz以上辐射辐射的限值和测量方法。为了符合规定，电子设备中使用了各种EMI抑制装置，如铁氧体磁芯。因此，本课题从理论和实验上研究了1 GHz以上电磁干扰抑制装置的降噪能力和相关测量方法。1.宽带辐射发射量的测量方法电子设备辐射骚扰的测量要求按照相关规定使用天线进行测量。因此，电磁干扰测量天线是测量系统中最重要的设备之一。2.电磁干扰铁氧体磁芯的特性电磁干扰铁氧体磁芯通常用于减小电力设备电力线上的干扰电流。然而，到目前为止，铁氧体磁芯的还原机理和特性还没有得到充分的研究。因此，本项目研究了一种新的测量EMI铁氧体磁芯抑制干扰效果的方法，并试图开发出合适的铁氧体磁芯材料和结构的设计方法。

In recent years, personal wireless systems such as mobile radio and wireless LANs have been developed very rapidly. On the other hand, the operating frequency of IT equipment and other devices has been increased up to the GHz frequency band to achieve greater performance. Hence strong anxieties have been raised about the possible interference with wireless systems caused by electromagnetic disturbances emitted from such devices. To control interference, IEC/CISPR has been studying the limits and measurement methods of the radiated emissions above 1 GHz. To comply with the regulations, a variety of EMI suppressing devices such as ferrite cores are used in electronic equipment. But, design methods have not been established for such EMI suppressing devices.Thus, this research project theoretically and experimentally investigated the noise reduction capability of the EMI suppressing devices and the related measurement methods above 1 GHz.1.Measurement method of wideband radiated emissionsRadiated disturbances from electronic equipment are requested to be measured with antennas in accordance with the relevant regulations. Hence EMI measuring antennas are one of the most important equipment in the measurement system. Therefore, accurate calibration method has been developed in this project for characterizing various wide band EMI antennas.2.Characteristics of EMI ferrite coresEMI ferrite cores are commonly used for the purpose of reducing the disturbance current flowing on the power lines of electric equipment. However, reduction mechanism and characteristics of the ferrite cores have not been fully investigated so far. Accordingly, this project investigated a new method for measuring the effectiveness of EMI ferrite cores in reducing the disturbance, and then tried to develop the design method to yield suitable materials and structures of ferrite cores.