Textile loop antenna and TFT channel-select circuit for fully bendable TFT receivers

In this paper we present the design, measurements, simulation, and modelling of a flexible textile loop antenna. Using embroidering techniques, a stranded copper wire is integrated onto a textile substrate, which in turn can be part of a garment or wearable accessory. The targeted application is a textile antenna integrated into the sides of a messenger bag next to fully flexible a-IGZO TFT receiver circuitry. The carrier frequency is dictated by the relatively slow TFTs, which limit the operation frequency of the receiver. As a result, a compact antenna for frequencies in the range of 100 kHz to 10 MHz is required. For this purpose loop antennas are suited. They usually provide only a limited gain, yet they allow for a low profile. Since the performance of thin and organic large area electronics (TOLAE) technologies improves steadily, we also investigate their applicability for higher carrier frequencies, which will enable smaller antenna dimensions. Finally we present a fully flexible TFT circuit to tune the antenna characteristics.