Double-layer embroidery strategy for fabrication of textile antennas with improved efficiency

In this paper, two approaches in fabricating textile antennas with double-layer embroidery technique, as one of the way to increase the textile antennas' efficiency, are discussed and compared. In the first approach, a conductive thread is used for both the upper and lower (bobbin) threads, while in the second, the conductive thread is used only for the lower thread but the embroidery process is done twice. To study the effect of each approach, two embroidered rectangular patch antennas operating at 2.45 GHz ISM band were fabricated and measured. The embroidered layers were then placed on top of a 3.175 mm thick Rogers TMM3 substrate, tested, and compared with an etched copper version of the patch antenna. The results show that both approaches give a comparable radiation performance to the etched copper version with a slightly higher efficiency in the first one. However, the second approach allows faster and cost efficient fabrication.