Proposal for the validation of absorber lined shielded enclosures for CISPR 25 emission tests

CISPR 25 defines several methods and limit classes for emission measurements for vehicle components. With regard to the measurement of electric field strength the test set up consist of a table with metallic surface, on which the EUT and a specified length of cable harness is to be located. This set-up is placed in an absorber lined shielded enclosure (ALSE). The question of suitability of a certain ALSE for this measurement is not yet solved. A joint task force (JTF, between CISPR/D and CISPR/A) has been established to develop an appropriate validation method. In preparation of the international work in the JTF the authors of this paper propose a validation method, which is based on an arrangement similar to the test set-up. In contrast of a real cable harness the proposed radiator is well defined, which allows using results from numerical field computations as reference values. An ALSE including table and test set-up is suitable for measurements according CISPR 25, if the deviations between measurement results and theoretical results are within certain limits. In the paper the results of the field computations and measurement results obtained in different ALSEs are shown and evaluated.