Multimedia products for automotive applications consist of various subsystems, including CPU, peripherals, clock domains, and interfaces, that are combined in a single multimedia housing. The resulting device needs to be EMC compliant according to automotive regulatory. In addition electromagnetic interference to the device electronics needs to be kept low to ensure functionality. Therefore the device housing is often used as a shielding box. An undesired effect is that the housing introduces resonances and acts as a radiation source. Similar to the effect of a microwave circuit, the housing might resonate on a higher harmonic of a signal and mechanically amplify it to a critical field radiation. At Continental we simulate the EM behavior of multimedia device housings by introducing a radiation source inside the housing and probing the field at various locations at a defined distance. 3D E-field distribution and surface current simulations lead to the radiation source at the frequency of interest. This approach allows for optimization already in the development phase regarding performance, EMC compliance, ground and shielding concepts, and cost. The simulation models are continuously calibrated by measurements that are performed by the EMC lab.
Ralf Kakerow, Continental Automotive GmbH