E-Textiles have gained enormous attention due to their specific characteristics in various non-conventional applications such as electromagnetic shielding materials. With the advent of various high frequency-driven devices, the need to restrict the non-ionizing radiations from their undesired effects became imperative. Due to the ease of production, better electrical conductivity and durability, the conductive hybrid cover yarns with continuous metallic filaments have earned its place as the most convenient form of yarns to develop E-textiles. However, controlling the amount of conducting material in yarns poses a challenge as the increase in size of the metallic filaments are associated with reduced electromagnetic shielding effectiveness due to increased stiffness of yarns, which resists in proper interlacement and hence causes openness in fabrics. The proposed design of conductive hybrid cover yarns is proven to have better tensile properties and modulus, therefore this design is more suitable to produced fabrics with higher cover factors. The amount of conducting material in the proposed design increased significantly without changing the size of the continuous filaments. Moreover, 99.9% shielding effectiveness is achieved with this increased metal content in fabrics in S-band and partly C-band microwave frequencies.
Of late, a significant amount of research has been carried out using metals for conductive fabrics and composites to obtain the desired level of electromagnetic shielding along with physical and
mechanical properties for its durability. However, incorporating these metallic filaments as core or as an integral part of core deteriorate the mechanical properties of textile yarns and ultimately the fabrics’. Moreover, the transparency of fabrics to high frequency/smaller wavelength waves further increases with the attempt to increase the metallic filament diameter. This study, therefore analyses the effects of metallic filament alignment in order to improve the mechanical properties of the resultant hybrid yarns, and devises an alternative method to increase the amount of conductive filament without increasing the diameter of the conducting wire in hybrid yarn structures. The results suggest that the tensile properties of the proposed hybrid cover yarns with conductive filament as covering component is superior as compared to the yarns having a conductive filament in the core, however, the electrical resistance increases with an increase in conductive filament length. The tenacity, elongation and initial modulus values were enhanced several times by incorporating the conductive filament as spiral covering. Moreover, with the proposed alignment method, the amount of copper in hybrid yarn can be increased up to some extent by changing the number of turns of covering component.
In this paper, three antennas with different designs, which are square, circle and edgy patch (flower) were simulated and fabricated. The experiment was carried out to study the effects of bending on these three different shapes of antennas. Two bending conditions which are H-plane and E-plane were used. The antenna was designed to resonate at 1.575 GHz for GPS application and to be incorporated with human arm. Thus, the bending angle was specified to be 135o which is about the size of a typical human arm. As the paper focusing on the bending effects only, the characteristic of the bending structure was set to be equal to the air, with Ɛr=1. The antenna characteristics such as gain, resonant frequency and radiation pattern were analyzed for these three shapes of antennas. As a result, the shape of the radiating patch has significant impact on the antenna performance under bending conditions. Based on the comparison of E-plane and H-plane data, the edgy shape was found to be more affected in term of gain performance as compared to other shapes. Bending on E-plane has shown severe degradation in antenna gain performance, whereby at H-plane, significant improvement in gain was observed
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