Miniaturized Wearable Antennas

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "E:Engineering and Technology".

Deadline for manuscript submissions: closed (30 April 2023) | Viewed by 9189

Special Issue Editor

Department of Communication and Computer Engineering, South-West University “Neofit Rilski”, 2700 Blagoevgrad, Bulgaria
Interests: electromagnetic fields; microwave engineering; computational electromagnetics; electromagnetics; electromagnetic engineering; antennas and propagation; antenna engineering; RF engineering
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Special Issue Information

Dear Colleagues,

Wearable technology has undergone rapid development and has been identified as one of the leading technologies that can make human life more productive, safe, and healthy. Today, wearable devices such as smartwatches, fitness trackers, skin patches, and virtual reality headsets are widely used in everyday life. The antenna is one of the essential elements of any wearable gadget, which enables the device to exchange information with other devices and physical objects around it. In the Internet of Things (IoT) era, with the development of the 5G and 6G networks, a need for new miniaturized antennas with unique shapes made on unconventional materials for unobtrusive integration in next-generation wearable devices is occurring.

This Special Issue invites researchers from industry and academia to contribute original research and review articles that focus on new antenna topologies, new materials, the design, simulation, and modeling techniques of wearable antennas, and applications for next-generation wearables.

Research areas may include (but are not limited to) the following:

  • Design and technology for miniaturized wearable antennas;
  • Antennas for IoT wearable devices;
  • Antennas for biomedical telemetry;
  • Antennas for precision farming and agriculture;
  • Rectennas for low-power wireless devices;
  • Composites applicable in wearable antennas;
  • Dosimetry, exposure, and SAR assessment;
  • Wearable antenna characterization;
  • Evaluation of biological effects of wearable antennas.

Dr. Gabriela Atanasova
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • wearable antenna
  • flexible antenna
  • textile antenna
  • rectenna
  • Internet of Wearable Things
  • wearable antenna measurements
  • dosimetry
  • exposure
  • SAR
  • composite and biocompatibility materials

Published Papers (5 papers)

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Research

18 pages, 13530 KiB  
Article
A Simulation Study of Triband Low SAR Wearable Antenna
by Wazie M. Abdulkawi, Asad Masood, N. Nizam-Uddin and Mohammad Alnakhli
Micromachines 2023, 14(4), 819; https://doi.org/10.3390/mi14040819 - 05 Apr 2023
Cited by 6 | Viewed by 1573
Abstract
The proposed paper presents a flexible antenna that is capable of operating in several frequency bands, namely 2.45 GHz, 5.8 GHz, and 8 GHz. The first two frequency bands are frequently utilized in industrial, scientific, and medical (ISM) as well as wireless local [...] Read more.
The proposed paper presents a flexible antenna that is capable of operating in several frequency bands, namely 2.45 GHz, 5.8 GHz, and 8 GHz. The first two frequency bands are frequently utilized in industrial, scientific, and medical (ISM) as well as wireless local area network (WLAN) applications, whereas the third frequency band is associated with X-band applications. The antenna, with dimensions of 52 mm × 40 mm (0.79 λ × 0.61 λ), was designed using a 1.8 mm thick flexible kapton polyimide substrate with a permittivity of 3.5. Using CST Studio Suite, full-wave electromagnetic simulations were conducted, and the proposed design achieved a reflection coefficient below −10 dB for the intended frequency bands. Additionally, the proposed antenna achieves an efficiency value of up to 83% and appropriate values of gain in the desired frequency bands. In order to quantify the specific absorption rate (SAR), simulations were conducted by mounting the proposed antenna on a three-layered phantom. The SAR1g values recorded for the frequency bands of 2.45 GHz, 5.8 GHz, and 8 GHz were 0.34, 1.45, and 1.57 W/Kg respectively. These SAR values were observed to be significantly lower than the 1.6 W/Kg threshold set by the Federal Communication Commission (FCC). Moreover, the performance of the antenna was evaluated by simulating various deformation tests. Full article
(This article belongs to the Special Issue Miniaturized Wearable Antennas)
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14 pages, 6754 KiB  
Article
Evaluation of Polydimethylsiloxane (PDMS) as a Substrate for the Realization of Flexible/Wearable Antennas and Sensors
by Praveen Kumar Sharma and Jae-Young Chung
Micromachines 2023, 14(4), 735; https://doi.org/10.3390/mi14040735 - 26 Mar 2023
Cited by 8 | Viewed by 2056
Abstract
To demonstrate that the silicone-based polymer polydimethylsiloxane (PDMS) is suitable as a substrate for flexible/wearable antennae and sensors, an investigation of its various properties was carried out. The substrate was first developed in compliance with the requirements, and then its anisotropy was investigated [...] Read more.
To demonstrate that the silicone-based polymer polydimethylsiloxane (PDMS) is suitable as a substrate for flexible/wearable antennae and sensors, an investigation of its various properties was carried out. The substrate was first developed in compliance with the requirements, and then its anisotropy was investigated using an experimental bi-resonator approach. This material exhibited modest but discernible anisotropy, with values of ~6.2/25 % for the dielectric constant and loss tangent, respectively. Its anisotropic behavior was confirmed by a parallel dielectric constant (εpar) ~2.717 and an evaluated perpendicular dielectric constant (εperp) ~2.570—εpar > εperp by 5.7%. Temperature affected PDMS’s dielectric properties. Lastly, the simultaneous impact of bending and anisotropy of the flexible substrate PDMS on the resonance properties of planar structures was also addressed, and these had diametrically opposed effects. PDMS appears to be a good contender as a substrate for flexible/wearable antennae and sensors based on all experimental evaluations conducted for this research. Full article
(This article belongs to the Special Issue Miniaturized Wearable Antennas)
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13 pages, 5372 KiB  
Article
Flexible and Small Textile Antenna for UWB Wireless Body Area Network
by Peng Chen, Dan Wang and Zongsheng Gan
Micromachines 2023, 14(4), 718; https://doi.org/10.3390/mi14040718 - 24 Mar 2023
Cited by 4 | Viewed by 1391
Abstract
In this paper, a miniaturized textile microstrip antenna is proposed for wireless body area networks (WBAN). The ultra-wideband (UWB) antenna used a denim substrate to reduce the surface wave losses. The monopole antenna consists of a modified circular radiation patch and an asymmetric [...] Read more.
In this paper, a miniaturized textile microstrip antenna is proposed for wireless body area networks (WBAN). The ultra-wideband (UWB) antenna used a denim substrate to reduce the surface wave losses. The monopole antenna consists of a modified circular radiation patch and an asymmetric defected ground structure, which expands impedance bandwidth (BW) and improves the radiation patterns of the antenna with a small size of 20 × 30 × 1.4 mm3. An impedance BW of 110% (2.85–9.81 GHz) frequency boundaries was observed. Based on the measured results, a peak gain of 3.28 dBi was analyzed at 6 GHz. The SAR values were calculated to observe the radiation effects, and the SAR values obtained from the simulation at 4/6/8 GHz frequencies followed the FCC guideline. Compared to typical wearable miniaturized antennas, the antenna size is reduced by 62.5%. The proposed antenna has good performance and can be integrated on a peaked cap as a wearable antenna for indoor positioning systems. Full article
(This article belongs to the Special Issue Miniaturized Wearable Antennas)
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13 pages, 9199 KiB  
Article
A Flexible Miniature Antenna for Body-Worn Devices: Design and Transmission Performance
by Abdullah Al-Sehemi, Ahmed Al-Ghamdi, Nikolay Dishovsky, Nikolay Atanasov and Gabriela Atanasova
Micromachines 2023, 14(3), 514; https://doi.org/10.3390/mi14030514 - 23 Feb 2023
Cited by 6 | Viewed by 1537
Abstract
The last few years have seen a rapid increase in body-worn devices because these devices cover a broad spectrum of potential uses. Moreover, body-worn devices still require improvements in their flexibility, size, and weight that necessitate the development of flexible and miniature antennas. [...] Read more.
The last few years have seen a rapid increase in body-worn devices because these devices cover a broad spectrum of potential uses. Moreover, body-worn devices still require improvements in their flexibility, size, and weight that necessitate the development of flexible and miniature antennas. In this paper, we present a new flexible miniature antenna for body-worn devices. To ensure flexibility and comfort when the antenna is in contact with the human body, a substrate from natural rubber filled with TiO2 is developed. The miniaturization is achieved using the quadratic Koch curve. The antenna design, optimization, and characterization are performed on a human body model. The performance of the antenna is analyzed in two scenarios: (1) in- to on-body, and (2) on- to off-body wireless communications. The results show that the antenna realized the maximum telemetry range of more than 80 mm for in-body communications and more than 2 m for off-body communications. Moreover, the highest 10 g specific absorption rate value was 0.62 W/kg. These results, in addition to the antenna’s compact dimensions (12 mm × 26 mm × 2.5 mm) and the low manufacturing price, make the proposed antenna an ideal candidate for health telemetry applications. Full article
(This article belongs to the Special Issue Miniaturized Wearable Antennas)
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12 pages, 4582 KiB  
Article
An EBG-Based Triple-Band Wearable Antenna for WBAN Applications
by Rongqiang Li, Chuan Wu, Xiaofeng Sun, Yuan Zhao and Wei Luo
Micromachines 2022, 13(11), 1938; https://doi.org/10.3390/mi13111938 - 10 Nov 2022
Cited by 11 | Viewed by 1577
Abstract
In this article, a triple-band wearable monopole antenna fed by a coplanar waveguide (CPW) with an integrated electromagnetic bandgap (EBG) array is proposed. The monopole antenna consists of an asymmetric inverted U-shaped strip, a horizontal branch, and an L-shaped ground stub, which can [...] Read more.
In this article, a triple-band wearable monopole antenna fed by a coplanar waveguide (CPW) with an integrated electromagnetic bandgap (EBG) array is proposed. The monopole antenna consists of an asymmetric inverted U-shaped strip, a horizontal branch, and an L-shaped ground stub, which can generate the 2.45/5.8 GHz wireless local area network (WLAN) band and the 3.5 GHz worldwide interoperability for microwave access (WiMAX) band. To reduce the influence of antenna radiation on the human body, a triple-band 3 × 3 EBG array has been integrated into the back of the monopole antenna. The EBG unit is composed of two rectangular rings and a circular ring, and the operating frequencies correspond to the triple bands of the monopole antenna. In this paper, the impedance and radiation performances of the stand-alone monopole antenna and the integrated antenna are analyzed, and the safety for the human body is evaluated based on specific absorption rate (SAR) values. The proposed triple-band antenna can be used in wearable devices in wireless body area networks (WBANs). Full article
(This article belongs to the Special Issue Miniaturized Wearable Antennas)
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