Increase of Input Resistance of a Normal-Mode Helical Antenna (NMHA) in Human Body Application

Zainudin, Norsiha and Latef, Tarik Abdul and Aridas, Narendra Kumar and Yamada, Yoshihide and Kamardin, Kamilia and Abd Rahman, Nurul Huda (2020) Increase of Input Resistance of a Normal-Mode Helical Antenna (NMHA) in Human Body Application. Sensors, 20 (4). p. 958. ISSN 1424-8220, DOI

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In recent years, the development of healthcare monitoring devices requires high performance and compact in-body sensor antennas. A normal-mode helical antenna (NMHA) is one of the most suitable candidates that meets the criteria, especially with the ability to achieve high efficiency when the antenna structure is in self-resonant mode. It was reported that when the antenna was placed in a human body, the antenna efficiency was decreased due to the increase of its input resistance (Rin). However, the reason for Rin increase was not clarified. In this paper, the increase of Rin is ensured through experiments and the physical reasons are validated through electromagnetic simulations. In the simulation, the Rin is calculated by placing the NMHA inside a human’s stomach, skin and fat. The dependency of Rin to conductivity (σ) is significant. Through current distribution calculation, it is verified that the reason of the increase in Rin is due to the decrease of antenna current. The effects of Rin to bandwidth (BW) and electrical field are also numerically clarified. Furthermore, by using the fabricated human body phantom, the measured Rin and bandwidth are also obtained. From the good agreement between the measured and simulated results, the condition of Rin increment is clarified. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

Item Type: Article
Funders: Ministry of Higher Education, Malaysia (MoHE‐MyPhD), University of Malaya grant (GPF015A‐2019), MJIIT Fundamental Research Grant Scheme (FRGS) vote number 5F046
Uncontrolled Keywords: normal-mode helical antenna (NMHA); input resistance; conductivity; human body
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering
Divisions: Faculty of Engineering
Depositing User: Ms. Juhaida Abd Rahim
Date Deposited: 03 Jun 2020 02:37
Last Modified: 03 Jun 2020 02:37

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