On-Body and SAR analysis of a Polyester Textile antenna for Wearable Applications

An polyester substrate textile antenna is proposed for wearable body applications at 4.6 and 5.8 GHz frequencies. The antenna has the required compact design for wearable applications. The X-mass tree-shaped patch, supported by the staircase structure, aids the antenna in operating at treble bands. The antenna's polyester has hydrophobic properties, and the conductive ground patch layers were portrayed by means of the conductive adhesive copper film. A prototype was developed with the polyester material as the substrate, and the total footprints of the antenna are 30x20 mm². This model was meant for wearable applications, so it was intensively tested in many horizontal and vertical bending positions. Thus the conformability of the antenna was validated. The specific absorption rate (SAR) analysis was also done on a three-level human phantom prototype; comprising muscle, fat and skin. The dual wearable application frequencies of 4.6 and 5.8 GHz applications are validated. The results from the SAR analysis conclude that the antenna is safe to use on the human body with a max SAR of 0.762 and 0.698 w/kg for 1 gram of tissue. The compact design with conformability and safe SAR thresholds aid the antenna for wearable body application.

I. Introduction

To address the need for wearable and conformal antennas, researchers have developed several types of flexible antennas that can conform to the contours of the human body and are more skin-friendly. These antennas can be made using flexible materials such as polymer films, fabrics, and even paper [1]. One type of flexible antenna that has gained popularity is the flexible microstrip antenna. These antennas use a thin, flexible substrate that can be bent and shaped to fit the curvature of the body [2]. The flexible substrate is typically made of materials such as polyimide or liquid crystal polymer, which have good mechanical strength, flexibility, and temperature stability. Another type of flexible antenna is the textile antenna, which is made using conductive textiles such as silver-coated nylon or copper-coated polyester. These antennas can be woven into the fabric of clothing, making them unobtrusive and comfortable to wear [3–5]. Yet another type of flexible antenna is the inkjet-printed antenna, which is made by printing conductive ink onto a flexible substrate such as paper or plastic. Inkjet printing allows for precise control over the antenna design and can be used to create complex antenna shapes that conform to the body. Overall, the development of flexible and conformal antennas has opened up new possibilities for wearable electronics, enabling the creation of devices that can be comfortably worn for extended periods of time. These antennas have numerous applications, including in the fields of healthcare, sports, and military, where they can be used for remote monitoring, communication, and sensing [6].