Absorber Lined Shielded Enclosure Research Articles

Field‐circuit simulation of electromagnetic interference and optimisation design in vehicle navigation system

With the rapid development of the vehicle navigation system (VNS), the functions of VNS are improved, while the design becomes very complicated. The conventional field-circuit simulation method is not precise enough to evaluate the VNS design. It is difficult to ensure that the electromagnetic compatibility index of VNS meets the GMW 3097 standard, resulting in electromagnetic interference (EMI) testing in an absorber lined shielded enclosure (ALSE). If the VNS does not comply with the GMW 3097 standard, it needs to be debugged repeatedly in the expensive ALSE. Therefore, a more accurate simulation method is highly desired, which can be used for improving the designed system to avoid using the expensive ALSE solution. In this study, an advanced field-circuit simulation method utilising actual parameters of the working printed circuit board is proposed to improve the simulation accuracy. The system is debugged by the proposed simulation method. Meanwhile, the optimisation method is proposed to enhance the EMI performance. Finally, by suppressing noise on the transmission path, the emission level of the VNS at 1.6 GHz is reduced from 5.9 dBμV to below−4 dBμV, which is ∼8 dBμV lower than the GMW 3097 standard.

Predicting the Radiated Emissions of Automotive Systems According to CISPR 25 Using Current Scan Methods

According to automotive standard CISPR 25, electronic components or modules are required to be connected to a specific test cable bundle in order to evaluate the radiated emissions. In the absorber-lined shielded enclosure (ALSE) method, also called the antenna method, the cable bundle is often the dominant radiation structure due to its length. This measurement method requires a large anechoic chamber, but often, it is only the impact of the test cable bundle's common-mode (CM) current distribution that is measured. Since the current distribution can be measured easily with current clamps, and with much lower demands to the environment, it is advantageous that the level of radiated fields can be estimated from the measured current distribution. This paper presents a field prediction method, which combines a measured CM current distribution with numerical computations for the radiated fields in the frequency range of 30–1000 MHz. Applicability is discussed based on several complex test cases. Three major problems had to be solved. First, appropriate current phase measurement methods had to be developed since the current amplitudes are not sufficient for estimating the electric fields. Second, a CM radiation model of a cable bundle had to be found. Third, in order to get comparable data for the ALSE test environment, a method had to be developed that could take this influence into account. Different solution approaches are examined here for the problems mentioned above.

CISPR25의 ALSE(Absorber-Lined Shielded Enclosure) 성능 검증 방법에 관한 연구

본 논문은 자동차 부품의 EMC 규격인 CISPR25의 ALSE 검증 방법에 관하여 새로운 제안을 하였다. CISPR-16은 NSA와 VSWR 방법을 이용하여 챔버 성능을 검증하도록 하고 있다. 그러나 CISPR25의 ALSE는 아직까지 챔버 검증에 관한 표준 방법이 없다. 본 논문은 이러한 관점에서 CISPR D/A JTF에서 논의가 되고 있는 롱-와이어 안테나 방식의 검증 방법을 기반으로 개선된 성능 검증 방법을 제안하고자 한다. 기존에 논의된 롱-와이어 안테나 방식은 길이 500 mm의 안테나를 제안했지만, 본 논문에서는 1,700 mm 안테나 길이를 제안하였으며, 정합 조건에 따른 영향도 평가와 기존에 제안된 방법과 관련된 문제점 및 중요 파라미터들에 관하여 검증 및 개선 방안을 제안하였다. This paper proposes a new way to verify the performance of an absorber lined shielded enclosure(ALSE) in accordance with CISPR25, EMC standards dedicated to testing automotive components. CISPR16 requires the use of NSA and VSWR methods to test the performance of a chamber. As for CISPR25, however, there hasn't been standardized ways to verify the performance of ALSE. This paper purports to present an improved method for the verification based on a long-wire antenna method under discussion at CISPR25 JFT. Existing discussions on a long-wire antenna method proposes that an antenna should reach 500 millimeters in length, while this paper adopts the antenna length of 1,700 millimeters. This paper also assesses the effects of matching conditions and studies problems related to methods which have been already proposed and key parameters in order to improve verification methods.