University of Oulu

Kissi, C., Särestöniemi, M., Kumpuniemi, T. et al. On-body Cavity-Backed Low-UWB Antenna for Capsule Localization. Int J Wireless Inf Networks 27, 30–44 (2020).

On-body cavity-backed low-UWB antenna for capsule localization

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Author: Kissi, Chaïmaâ1; Särestöniemi, Mariella2; Kumpuniemi, Timo2;
Organizations: 1Electronics and Telecommunication Systems Research Group, National School of Applied Sciences (ENSA), Ibn Tofai University, Kenitra, Morocco
2Centre for Wireless Communications, Faculty of Information Technology and Electrical Engineering, University of Oulu, Oulu, Finland
3Microelectronics Research Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu, Oulu, Finland
4Department of Electrical and Computer Engineering, Purdue University, Fort Wayne, USA
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 3.8 MB)
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Language: English
Published: Springer Nature, 2020
Publish Date: 2019-10-24


The paper presents a novel antenna operating at the lower UWB band (3.75–4.25 GHz), defined originally in IEEE 802.15.6 standard for Body Area Networks (BAN) applications. The proposed antenna is designed for biomedical application, wireless capsule endoscopy localization. In other words, the concerned application is dedicated to track a capsule, by means of an external device, swallowed by the patient to provide captured images of the Small Intestine (SI), essential part of the GastroIntestinal (GI) tract, and transfer them in real-time to the external device. In this context, antenna with and without cavity-backed structures, are presented and compared with the requirements for a receiving antenna in terms of directivity and bandwidth coverage in question. It was revealed that the cavity approach improved the antenna gain up to 8 dBi, at the 4 GHz center frequency, compared to 6 dBi without the cavity presence. Simulations were carried out using CST Microwave Studio, and the results were validated by measurements in proximity to human body. The antenna safety issue was assessed with CST SAR (Specific Absorption Rate) calculation, in compliance with IEEE/IEC 62704-1 standard. Results showed a maximum SAR of 0.112 W/kg and 0.005 W/kg at 4 mm and 30 mm antenna-skin distance, in the range of the SAR limit guidelines defined by safety standards. The cavity-backed antenna ability to penetrate the human tissues, to reach the small intestine layer was studied by means of CST voxel model and compared to a multi-layer model emulating the dielectric properties of the human tissues at 4 GHz. This analysis was conducted using power flow results and completed by the power field probes at the several tissue interfaces.

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Series: International journal of wireless information networks
ISSN: 1068-9605
ISSN-E: 1572-8129
ISSN-L: 1068-9605
Volume: 27
Pages: 30 - 44
DOI: 10.1007/s10776-019-00460-9
Type of Publication: A1 Journal article – refereed
Field of Science: 213 Electronic, automation and communications engineering, electronics
Funding: Open access funding provided by University of Oulu including Oulu University Hospital. Authors would like to thank Professor Heli Jantunen and all in Microelectronics research unit team for the help on antenna design and measurements. This research has been financially supported in part by Academy of Finland 6GGenesis Flagship (Grant 318927).
Academy of Finland Grant Number: 318927
Detailed Information: 318927 (Academy of Finland Funding decision)
Copyright information: © The Author(s) 2019. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.