Validation of a measurement method for magnetic shielding effectiveness of a wire mesh enclosure with comparison to an analytical model

[摘要] This paper deals with the validation of a measurement method for determiningthe magnetic shielding effectiveness of a wire mesh enclosure in thefrequency range from 10 kHz to 150 kHz. The comparison with an analyticalmodel (parallel-plate-shield, see Kaden, 1959) for magnetic shieldingeffectiveness of wire mesh is also part of this contribution. To measure theshielding effectiveness of an enclosure in general, two steps are necessary:

1. Reference measurement of the incidentelectro-magnetic field.
2. Measurement of the incident electro-magnetic field inthe enclosure by same conditions.

This method presented in the contribution uses a Helmholtz coil as magneticfield source, controlled by a signal generator and an amplifier in voltagemode. At first, a field meter was used to measure the frequency dependentmagnetic field in the center of the Helmholtz coil. The magnetic fieldstrength was also analytically calculated and compared to the measurementresults. The next step was to measure the induction voltage caused by themagnetic field with a magnetic field probe, which was later used for themeasurements of the shielding effectiveness either. A signal amplifier wasneeded to raise the signal-to-noise-ratio (SNR). The gain of the signalamplifier was also determined and measured. Two positions of the enclosure inthe Helmholtz coil were considered, horizontal and vertical. The verticalposition of the enclosure approaches the analytical model ofKaden (1959) closely and the results show a good match with theanalytical model.

[学科分类] 电子、光学、磁材料