Modelling and testing the electromagnetic near field shielding effectiveness achieved by woven fabrics with conductive yarns

The current extensively development of electrical devices and telecommunication requires adequate solutions for ensuring electromagnetic compatibility (EMC). One of the main solutions provided by EMC is the shielding against electromagnetic (EM) radiation. Conventional screens for EM radiation are constructed from metallic plates, however, fabrics with conductive yarns may be used as well, with multiple advantages: lightweight, flexibility, mechanical resistance and 3D shape ability. The paper addresses the shielding of the electromagnetic near field, by proposing an analytic relation taking into account both geometrical and electrical parameters of the fabric, based on the circuit method. A validation study was performed, by measuring the shielding effectiveness of an enclosure with a cover from woven fabrics with conductive yarns. The experimental setup includes both the electrical measurement devices, as well as a set of five woven fabrics with conductive yarns from stainless steel and silver. The experimental results for the electromagnetic near field frequency range (1–20 MHz) present values in good relationship to the analytic relation. The simplified analytic relation allows the computing of the distance between the conductive yarns of the woven fabric in relation to the targeted shielding effectiveness. This relation supports the design process of a fabric, with balance between its costs and its target shielding effectiveness.