Analysis of the Near Field Emission from the PCB of a Car Deck Player

摘要

The advanced system in an automobile tends to incorporate within a confined space to save some place inside the automobile. However, the components interfere with each other, which produces EMI related problems. Hence, to overcome such EMI associated glitches, it is necessary to carry out an investigation and a detailed EMI/EMC analysis of the equipment. This paper deals with the detailed analysis of a Car Deck player. The Near Field Emissions from the PCB of a car Deck player was investigated within the frequency range from 9 KHz to 3 GHz. This test was performed from 9 KHz to 30 MHz by an Agilent Close Field Probe HP11941 A at DIT, Pimpri and from 30 MHz to 3 GHz by EMC Precision Scan Tool at ARAI, Pune. All of the measured radiations were plotted using MATLAB. In the near field, E and H fields are separated. The estimation of E field is necessary to compare near field radiations with the automotive standard CISPR 25. Hence E field, H field and Power Density are estimated from the measured near field radiations. The comparison between E field and CISPR 25 standard is plotted in MATLAB which shows that the level of E field is far above the specified standard limit. Shielding methodology is proposed to suppress radiation within a specified limit. Shielding materials such as Cu, Al, Mild Steel and Mumetal are selected to decrease the near field radiations. This paper recommends Al as an effective enclosure material to mitigate the near field radiations.