A Miniature Feeding Network for Aperture-Coupled Wearable Antennas

Abstract

A miniature feeding network for aperture-coupled wearable antennas is proposed. In wearable systems, it allows to minimize the dimensions of the rigid printed circuit board (PCB) carrying the electronics and feeding the textile antenna. This optimizes the comfort of the user. Simultaneously, it avoids traditional probe feeding that has the disadvantage of requiring a single soldering point, which has a high risk of being broken with time due to movements of the user or washing. On top, since the aperture is implemented on the PCB, it can be fabricated with excellent dimensional tolerances that do not change during use. The proposed feeding topology is prototyped for applications in the industrial, scientific, and medical band (2.4-2.4835 GHz), resulting in dimensions of 0.073×0.061 λ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> 4 at 2.45 GHz, realized on a PCB substrate of 10 × 10 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (0.0817 × 0.0817 λ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at 2.45 GHz). The demonstration antenna incorporating the new feeding network has a realized gain of 5.6 dBi, a total efficiency of 47%, a low cross-polarization, and a high front-to-back ratio. Simulations and experiments agree well, proving the validity of the new concept.