Design, Analysis and Applications of Wearable Antennas: A Review

Abstract

Wearable antennas are the vital components for Body Centric Communication (BCC). These antennas have recently gained the attention of researchers and have received a great deal of popularity due to their attractive characteristics and opportunities. They are fundamental in the Wireless Body Area Networks (WBANs) for health care, military, sports, and identification purposes. Compared to traditional antennas, these antennas work in close proximity to the human body, so their performance in terms of return loss, gain, directivity, bandwidth, radiation pattern, efficiency, and Specific Absorption Rate (SAR) is influenced by the coupling and absorption of the human body tissues. Additionally, in the design of these antennas, size, power consumption, and speed can also play a paramount role. In most cases, these antennas are integrated into the clothes, or in some cases, they may be fixed over the skin of the users. When these characteristics are considered, the design of wearable antennas becomes challenging, particularly when textile materials are examined, high conductivity materials are used during the manufacturing process, and various deformation scenarios have an impact on the design's performance. To enhance the overall performance of the wearable antennas and to reduce the backward radiation towards the human body, metamaterial surfaces are introduced that provide a high degree of isolation from the human body and significantly reduce the SAR. This paper discusses the state-of-the-art wearable/textile/flexible antennas integrated with metamaterial structures composed of wearable/flexible substrate materials, with a focus on single and dual band antenna designs. The paper also reviews the critical design issues, various fabrication techniques, and other factors that need to be considered in the design of wearable/textile/flexible antennas. All the designs presented in this work are of the recent developments in wearable technology. INDEX TERMS BCC, WBAN, SAR, metamaterial, and wearable/textile/flexible antennas I. INTRODUCTIONRecently, Body Centric Wireless Communication (BCWC) has become one of the most important parts of the fourth generation (4G) mobile communication systems. The fifth generation (5G) is an encouraging technology which will not only fulfil the need of a high data rate for mobile phones and similar devices but also enable incorporation with different high added value services [1]. The IEEE 802.15 standardization group has been established to standardize applications intended for on, off, and in-body communication due to the growing interest in antennas and wave propagation for body centric communication systems [2]. BCWC is a type of communication which is used to connect devices which are worn on or in the body, or between the two people in close proximity. It is further divided into three different categories according to the mean of communication, they are on-body, in-body and off-body communication [3][4][5]. On-body communication describes the wireless communication between the body-mou...

Screen‐printed dual‐band wearable textile antenna incorporated with EBG structure for WBAN communications

“…15 To reduce the λ/4 distance between the antenna and reflector, PEC reflector is replaced by the EBG or AMC structure to obtain in phase reflection with lesser than the λ/4 distance. 16 Defective circular pores 17 are loaded on the EBG ground plane to improve breathability and wearable comfortability. However, porous in the bottom ground allows to pass sweat and moisture to the substrate, which may degrade antenna performance.…”

“…In order to reduce the electromagnetic coupling, a full ground plane or perfect electric conductor (PEC) is employed below the antenna at λ/4 distance, which leads to a larger size 15 . To reduce the λ/4 distance between the antenna and reflector, PEC reflector is replaced by the EBG or AMC structure to obtain in phase reflection with lesser than the λ/4 distance 16 . Defective circular pores 17 are loaded on the EBG ground plane to improve breathability and wearable comfortability.…”

Silicon elastomer as flexible substrate: dielectric characterization and applications for wearable antenna

“…The wearable antennas are designed on flexible substrates to allow communication with the on-body electronic devices for wireless health monitoring while remaining agile. The newly developed flexible and elastic substrates have now replaced the traditional rigid substrates because they provide superior adaptation, like twisting and bending, in challenging conditions [1][2][3]. The choice of substrate for the fabrication of the flexible antennas is based on the substrate's dielectric properties and forbearance to mechanical deformation.…”

“…Furthermore, in recent times, scholars have presented the concept of smart fabrics comprising diverse pliable materials that are viable for the development of wearable antennas [1][2][3]. The wearable substrates encompass a range of materials, such as silk, Cordura, Quartz fabric, Moleskin, fleece, and Perspex [3]. Nevertheless, wearable substrates have an impact on antenna performance due to their relative permittivity and dielectric losses.…”

Wearable Flexible Jeans Textile Microstrip Patch Antenna for ISM band Application

“…Wireless Body Area Networks (WBANs) depend heavily on antennas since they serve as the link between the human body and wireless communication technology [6]. Sensors installed on or inside the body communicate wirelessly with an external device or gateway using antennas to send and receive signals [7].…”