Prediction of hybrid woven fabric electromagnetic shielding effectiveness

This paper deals with experimental verification of numerical models of fabric shielding effectiveness especially via analysis of leakage through the apertures (pores) in the textile structure. Equations for both solid shield and non-compact material were adopted from the literature, whereas an aperture equation based on waveguide conception was used. The experimental sample set was woven fabrics made of hybrid yarns composed of polypropylene fibers with different contents of staple stainless steel metal fibers in their structure. Geometrical characteristics of the aperture structure used for prediction were estimated with the aid of image analysis. Electric conductivity of the hybrid fabric was determined by measuring volume resistivity and plane-wave electromagnetic shielding properties of the sample set were measured by means of the coaxial transmission line method. The effect of metal fiber content on geometrical characteristics (e.g. area of pores, number of pores, cover factor), volume resistivity and electromagnetic shielding effectiveness was investigated. Results obtained by modeling of sample shielding effectiveness and experimental results achieved by measuring of shielding effectiveness were compared and discussed. It was confirmed that electromagnetic shielding effectiveness increased with a higher amount of metal fibers in the hybrid yarn structure. It was verified that the proposed numerical model is usable for predicting electromagnetic shielding effectiveness based on knowledge of dimensions of the structure apertures (pores), thickness of the fabric and volume resistivity of the material.