Measured electromagnetic shielding characteristics of fabric made from metal clad aramid yarn and wire

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 mΩ/square to 1.3 mΩ/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 mΩ/square. In this frequency range the current spreads across the fabric. A diffusion cut-off frequency was not observed in any of the samples