A Miniaturized Tri-Band Implantable Antenna for ISM/WMTS/Lower UWB/Wi-Fi Frequencies

Anupma Gupta; Vipan Kumar; Shonak Bansal; Mohammed H Alsharif; Abu Jahid; Ho-Shin Cho

doi:10.3390/s23156989

A Miniaturized Tri-Band Implantable Antenna for ISM/WMTS/Lower UWB/Wi-Fi Frequencies

Sensors (Basel). 2023 Aug 7;23(15):6989. doi: 10.3390/s23156989.

Authors

Anupma Gupta¹, Vipan Kumar², Shonak Bansal³, Mohammed H Alsharif⁴, Abu Jahid⁵, Ho-Shin Cho⁶

Affiliations

¹ Department of Interdisciplinary Courses in Engineering, Chitkara University Institute of Engineering and Technology, Chitkara University, Rajpura 140401, India.
² Department of ECE, Sri Sai College of Engineering and Technology, Badhani, Pathankot 145001, India.
³ Department of ECE, Chandigarh University, Mohali 140413, India.
⁴ Department of Electrical Engineering, College of Electronics and Information Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 05006, Republic of Korea.
⁵ School of Electrical Engineering and Computer Science, University of Ottawa, 25 Templeton St., Ottawa, ON K1N 6N5, Canada.
⁶ School of Electronic and Electrical Engineering, Kyungpook National University, Daegu 41566, Republic of Korea.

Abstract

This study aims to design a compact antenna structure suitable for implantable devices, with a broad frequency range covering various bands such as the Industrial Scientific and Medical band (868-868.6 MHz, 902-928 MHz, 5.725-5.875 GHz), the Wireless Medical Telemetry Service (WMTS) band, a subset of the unlicensed 3.5-4.5 GHz ultra-wideband (UWB) that is free of interference, and various Wi-Fi spectra (3.6 GHz, 4.9 GHz, 5 GHz, 5.9 GHz, 6 GHz). The antenna supports both low and high frequencies for efficient data transfer and is compatible with various communication technologies. The antenna features an asynchronous-meandered radiator, a parasitic patch, and an open-ended square ring-shaped ground plane. The antenna is deployed deep inside the muscle layer of a rectangular phantom below the skin and fat layer at a depth of 7 mm for numerical simulation. Furthermore, the antenna is deployed in a cylindrical phantom and bent to check the suitability for different organs. A prototype of the antenna is created, and its reflection coefficient and radiation patterns are measured in fresh pork tissue. The proposed antenna is considered a suitable candidate for implantable technology compared to other designs reported in the literature. It can be observed that the proposed antenna in this study has the smallest volume (75 mm³) and widest bandwidth (181.8% for 0.86 GHz, 9.58% for 1.43 GHz, and 285.7% for the UWB subset and Wi-Fi). It also has the highest gain (-26 dBi for ISM, -14 dBi for WMTS, and -14.2 dBi for UWB subset and Wi-Fi) compared to other antennas in the literature. In addition, the SAR values for the proposed antenna are well below the safety limits prescribed by IEEE Std C95.1-1999, with SAR values of 0.409 W/Kg for 0.8 GHz, 0.534 W/Kg for 1.43 GHz, 0.529 W/Kg for 3.5 GHz, and 0.665 W/Kg for 5.5 GHz when the applied input power is 10 mW. Overall, the proposed antenna in this study demonstrates superior performance compared to existing tri-band implantable antennas in terms of size, bandwidth, gain, and SAR values.

Keywords: ISM/WMTS bands; asynchronous–spiral radiator; communication technologies; implantable antenna; parasitic patch; smart antennas; tri-band.

Grants and funding

2021R1A2C1003507/National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT)