The influence of seaming stitches on the shielding effectiveness (SE) of electromagnetic shielding (EMS) fabric is huge, but there is not an ideal computation model for the SE of the EMS fabric with the seaming stitch at present. This paper proposes a computation model of the SE based on the equivalent seaming gap. Firstly, a structure model of the equivalent seaming gap is constructed according to the equivalent dielectric principle. The computation method of the structural size of the equivalent seaming gap model is determined by the parameters of the stitch length, number of the stitch type, needle number, and sewing thread. A computation model of the SE based on the equivalent seaming gap structure is built according to the EMS theory. The method of the correction coefficient of the model determination is given. Finally, the samples with seaming stitches are made to test the SE using the waveguide method. The computation results with the proposed model are compared with the experimental ones. The results show that the proposed model can well calculate the SE of the EMS fabric with the seaming stitch. The study in this paper can provide a foundation for further study of the influence of seaming stitches on the SE of the EMS fabric and possesses reference significance for the design, production, evaluation and related theoretical research of the EMS clothing.
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