A New Measurement Method of Shielding Effectiveness

A new method for measuring the shielding effectiveness of a shielding material is proposed The apparatus consists of an enlarged diameter inner conductor with tapered ends fitting into sleeves at the ends to make connection with the inner pin of an N-type connector. The outer conductor has been expanded to the appropriate dimensions to maintain 50 Ohm impedance. Two outer conductors may be jointed with flanges which have a tongue along the one outer conductor and groove ring along the other outer conductor. Inner conductors consist of two parts having a convexity at the end of one inner conductor and having a concavity at the end of other inner conductor. The convexity of one inner conductor is inserted in the center of the concavity of other inna conductor to joint two inner conductors. Electrical connections are made via these contact between the groove and tongue of outer conductor and between convexity and concavity of the inna conductors. They allow to transmit the signal, whether sample exists or not. Because the sample is sandwiched between flanges on the outer conductor and between the inna conductors, the apparatus maintains good electrical contact between the sample and the inna and outer conductors. An amorphous magnetic film (CoZrTaNb) fomed on 7- µ m-thick polyamide film by sputtering methord was selected for use in this test method evaluation. Measurements of the shielding effectiveness were made for the frequency range from 0.3 MHz to 6 GHz with a network analyzer. The shielding effectiveness obtained using the proposed flanged coaxial apparatus show excellent reproduction.