scholarly journals Effects of the permittivity and conductivity of human body for normal-mode helical antenna performance

2019 ◽  
Vol 16 (16) ◽  
pp. 20190395-20190395 ◽  
Author(s):  
Rasyidah Hanan Mohd Baharin ◽  
Toru Uno ◽  
Takuji Arima ◽  
Norsiha Zainuddin ◽  
Yoshihide Yamada ◽  
...  
Keyword(s):  
Normal Mode ◽  
Human Body ◽  
Helical Antenna ◽  
Antenna Performance

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

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 958 ◽  
Author(s):  
Norsiha Zainudin ◽  
Tarik Abdul Latef ◽  
Narendra Kumar Aridas ◽  
Yoshihide Yamada ◽  
Kamilia Kamardin ◽  
...  
Keyword(s):  
Normal Mode ◽  
Human Body ◽  
High Performance ◽  
High Efficiency ◽  
Input Resistance ◽  
Resonant Mode ◽  
Helical Antenna ◽  
Antenna Structure ◽  
Electromagnetic Simulations ◽  
Physical Reasons

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.

Changes of electric current on a normal-mode helical antenna inside a human body

2017 ◽  
Author(s):  
Rasyidah Hanan Binti Mohd Baharin ◽  
Yoshihide Yamada ◽  
Kamilia Binti Kamardin ◽  
Naobumi Michishita
Keyword(s):  
Electric Current ◽  
Normal Mode ◽  
Human Body ◽  
Helical Antenna

Performance Analysis of Normal Mode Helical Antenna in Seawater

2020 ◽  
Author(s):  
Siti Harliza Mohd Razali ◽  
Razali Ngah ◽  
Kamalia Kamardin ◽  
Yoshihide Yamada
Keyword(s):  
Performance Analysis ◽  
Normal Mode ◽  
Helical Antenna

scholarly journals Design of Cavity-Backed Bow-Tie Antenna with Matching Layer for Human Body Application

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 4015 ◽  
Author(s):  
Jeong ◽  
Park ◽  
Lee
Keyword(s):  
Reflection Coefficient ◽  
Human Body ◽  
Electromagnetic Interference ◽  
Impedance Matching ◽  
Human Head ◽  
Impedance Match ◽  
Broadband Antenna ◽  
Matching Layer ◽  
Antenna Performance ◽  
Bow Tie

This paper presents the broadband antenna for the microwave radiometric sensing of internal body temperature. For broadband operation, the bow-tie antenna was designed and backed with a cylindrical cavity, which decreased environmental electromagnetic interference and also improved the directivity of the antenna. The broadband impedance-transforming balun in microstrip form was also designed to feed the bow-tie antenna, and was located inside the cavity. An impedance-matching dielectric layer (IMDL) was introduced on top of the bow-tie antenna, for impedance match with the human body with high permittivity. The fabricated antenna was measured in free space with the IMDL removed, showing an input reflection coefficient lower than −10 dB from 2.64 to > 3.60 GHz with antenna gain over 6.0 dBi and radiation efficiency over 74.7% from 2.7 to 3.5 GHz. The IMDL was re-installed on the cavity-backed bow-tie antenna to measure the antenna performance for the human head with relative permittivity of about 40. The measured reflection coefficient was as low as −28.9 dB at 2.95 GHz and lower than −10 dB from 2.65 to > 3.5 GHz. It was also shown that the designed antenna recovered a good impedance match by adjusting the permittivity and thickness of the IMDL for the different parts of the human body with different permittivities.

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