Characterization of metals as EMC shields

The authors describe a test fixture and method used for about five years to characterize the shielding performance of both monometallic and composite sheets, over a frequency range of 50 Hz-300 kHz, with effectiveness values up to 90 dB. Calculation methods were developed to permit extrapolation of the test results to different geometries and wave impedance; data are presented showing the correlation with more difficult tests. The procedure could be made a standard test method capable of providing all the information needed for the selection of an economical and effective metal shield under a variety of field conditions.