Wireless Body Area Networks: UWB Wearable Textile Antenna for Telemedicine and Mobile Health Systems

• Main Authors: Ashok Yadav, Vinod Kumar Singh, Akash Kumar Bhoi, Gonçalo Marques, Begonya Garcia-Zapirain, Isabel de la Torre Díez
• Format: Article
• Language: English
• Published: MDPI AG 2020-05-01
• Series: Micromachines
• Subjects: textile antenna; ultra-wideband; circuit theory; frequency domain; time domain; SAR
• Online Access: https://www.mdpi.com/2072-666X/11/6/558

A compact textile ultra-wideband (UWB) antenna with an electrical dimension of 0.24λ_o × 0.24λ_o × 0.009λ_o with microstrip line feed at lower edge and a frequency of operation of 2.96 GHz is proposed for UWB application. The analytical investigation using circuit theory concepts and the cavity model of the antenna is presented to validate the design. The main contribution of this paper is to propose a wearable antenna with wide impedance bandwidth of 118.68 % (2.96–11.6 GHz) applicable for UWB range of 3.1 to 10.6 GHz. The results present a maximum gain of 5.47 dBi at 7.3 GHz frequency. Moreover, this antenna exhibits Omni and quasi-Omni radiation patterns at various frequencies (4 GHz, 7 GHz and 10 GHz) for short-distance communication. The cutting notch and slot on the patch, and its effect on the antenna impedance to increase performance through current distribution is also presented. The time-domain characteristic of the proposed antenna is also discussed for the analysis of the pulse distortion phenomena. A constant group delay less than 1 ns is obtained over the entire operating impedance bandwidth (2.96–11.6 GHz) of the textile antenna in both situations, i.e., side by side and front to front. Linear phase consideration is also presented for both situations, as well as configurations of reception and transmission. An assessment of the effects of bending and humidity has been demonstrated by placing the antenna on the human body. The specific absorption rate (SAR) value was tested to show the radiation effect on the human body, and it was found that its impact on the human body SAR value is 1.68 W/kg, which indicates the safer limit to avoid radiation effects. Therefore, the proposed method is promising for telemedicine and mobile health systems.