Virtual HIRF tests in CST STUDIO SUITE™ : A Reverberant environment application

The prediction of the shielding performances of reverberant environments such as vehicle bodiesand metallic enclosure racks is an important part of the global design process of an electromagnetic system in order to ensure predefined performance specifications and fulfill the EMC standards. The desire for a reduced time-to-market means that there is often no time or budget for performing extensive prototyping and test measurements. These limitations make the reliable computation and prediction of the shielding properties of a given structure critical. To speed-up this time-consuming process numerical electromagnetic methods can be successfully adopted to analyze and characterize the system under test in terms of shielding performance. The data analysis and validation of results can be challenging due to rapid variation of data over a small frequency range and due to the high sensitivity to small geometric variations in such a strongly resonant environment. In this paper the studied test case consists of a metal enclosure, which is illuminated externally, and the internal response observed for different configurations of the internal structure including: coupling to straight and curved single wire lines; coupling through different types of aperture and material in the box walls and loading of the cavity by lossy materials to vary the Q-factor. The results are all presented as a reception aperture, a figure described by the ratio between the power received at a probe antenna and the power density of incident field. CST STUDIO SUITE™ was used to analyze the electromagnetic behavior of the aforementioned configurations. The different geometries have been constructed inside the frontend thanks to its powerful CAD capabilities. A plane wave has been used as excitation and receiving probes connected to a matched load (discrete ports) have been defined in order to calculate the reception aperture as a post processing step. Two different numerical EM methods have been applied to the case-study in order to cross-check the accuracy of the simulated results in the frequency range 1 - 6 GHz: 1) CST MICROWAVE STUDIO® Transient solver based on the Finite Integration technique (FIT). 2) CST MICROWAVE STUDIO® Frequency Domain solver based on the Finite Element method (FEM). The computed results showed a good agreement with the measured curves over the whole frequency range for all the examined configurations.