The electromagnetic shielding characteristics of four fabric samples made from metal clad aramid yarn and nickel plated copper wire were measured from 1 kHz to 3 GHz. Below 100 kHz, these measurements showed that the surface transfer impedance or surface resistivity ranged from 0.5 m/spl Omega//square to 1.3 m/spl Omega//square. This is extremely good. In this frequency range, the current flows on the wires. Between 10 and 100 MHz, the mid-frequency or limiting shielding effectiveness was greater than 70 dB. At 100 MHz and above, all samples were essentially equal at 45 m/spl Omega//square. In this frequency range the current spreads across the fabric. A diffusion cut-off frequency was not observed in any of the samples.
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