Design, fabrication and evalation of textile based band-stop frequency selective surface at 3,5 and 5 ghz

In this dissertation, a flexible, lightweight and conformal frequency selective surface (FSS) is developed with band-stop filter characteristic in Wi-Fi, LTE and WiMAX bands where electromagnetic pollution is intense. Textile materials are used so that FSS can meet the desired properties. The components of the FSS, the dielectric substrate and the conductive patch, are designed entirely on textile basis. Fabrics frequently used in the market are preferred as dielectric substrate. Silver-coated conductive yarn is embroidered as a conductive patch and silver-containing dye is printed by screen printing method. In the study, the effect of embroidery parameters (embroidery direction and density) on the FSS transmission coefficient is investigated. There is no resonance at the respective frequencies in horizontally and vertically embroidered FSSs. However, the resonance is observed below -10 dB at the relevant frequencies in horizontal+vertical form of embroidery. In addition, modeling and simulation are carried out in embroidery form with the CST MWS software. A strong agreement is observed between embroidery modeling results and embroidery production results. In the screen printing method, cotton, cotton/PES, PES and Cordura fabrics are evaluated as substrate and the effect of fabric content on the FSSs transmission coefficient is investigated. Successful results are obtained in the fabrics except PES fabric. In addition, FSS is produced by applying thermoplastic polyurethane (TPU) lamination on the fabrics. TPU coating negatively affecs the FSS transmission coefficient.