The prediction of loss tangent of sewed multilayer fabric

The thickness and dielectric properties (dielectric constant and loss tangent) of fabric substrate play a key role in the design and properties of wearable antennas. Related research shows that a thicker substrate with a low dielectric constant and high loss tangent can enhance the bandwidth of antennas. Here, sewing multiple fabrics together was a good way to increase the thickness while maintaining flexibility, but it is hard to control the dielectric properties because of the lack of the relationship between the dielectric properties and that of the components. Although previous works have established the equivalent capacitance model of sewed multilayer fabric, they cannot obtain its dielectric properties completely. In this work, based on the circuit model proposed by Chin and Lee, the equivalent capacitance and resistance models of sewed multilayer fabric were established to predict its loss tangent. The sewed multilayer fabrics were fabricated and measured by split post dielectric resonator at 1.11 GHz to validate the model. From the comparison of the predicted and measured loss tangents of sewed multilayer fabrics, it was found that the predicted loss tangents agreed well with the experimental results. It is believed that the proposed model is beneficial to the rapid and rational configuration of the components for multilayer fabric according to thickness and dielectric properties of the components, and will provide a theoretical basis for the design of multilayer flexible electronic substrate.