Embroidered wideband wearable slot antennas using conductive yarn with different yarn-spacing densities

The radiation characteristics of two embroidered wideband wearable slot antennas covering 3.1-10.6 GHz: Ultra Wide Band (UWB) with different yarn-spacing densities have been presented and compared with a same-size reference copper antenna. When a wearable antenna is fabricated by a conductive yarn, it is important to assess the level of loss in respect to the yarn-spacing density [yarns/mm]. Therefore, the radiation characteristics of the proposed antennas with different yarn-spacing densities have been evaluated experimentally to assess the radiation efficiencies both with and without a human equivalent phantom. Compared to the same-size copper reference antenna, the additional loss in radiation efficiency of the proposed antenna with yarn-spacing density 4 [yarns/mm] is about 10-15 % even when the embroidered antenna is placed in the vicinity of the phantom.