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Wearable Antennas and Sensors for Microwave Applications

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Wearables".

Deadline for manuscript submissions: 31 August 2024 | Viewed by 6679

Special Issue Editor

Department of Electrical and Electronic Engineering, University of Cagliari, Piazza d’armi, 09123 Cagliari, Italy
Interests: low-cost RFID tag design in the UHF band; wearable antennas design and interaction with the human body; design of substrate integrated waveguides slot antennas in the UHF band; microwave antennas design using genetic programming; periodic structures design (EBG and AMC) through evolutionary programming; printed log-periodic dipole antennas design using innovative feeding techniques and inkjet printing; synthesis, analysis, and design of wire; patch and slot antennas
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

In recent years, the continuous development of modern technologies and the Internet has pushed researchers to design devices continuously connected to the network, and the main purpose of the telecommunications industry is to achieve the highest possible level of portability. The use of devices, applications, and gadgets of various types, integrated into clothes or the body (such as smartwatches, hi-tech bracelets, and smart glasses), offers greater freedom to the users in their daily activities. Wearable devices can communicate with each other, allowing the user to monitor everyday activities and to obtain information about the surrounding environment.

Several design challenges are associated with wearable devices, including operation frequencies, the influence of the surrounding biological tissues, antenna design and miniaturization, efficient integration into garments, mechanical robustness, easy manufacturing, low cost, reduced size, light weight, flexibility, reliability in the proximity of the human body, and conformation to international safety guidelines with an adequate specific absorption rate. Different fabrication methods are available for realizing flexible, conformal, and robust device prototypes. The presence of the human body in close proximity to the device is probably the most critical difficulty in terms of design, fabrication, and testing, which must be faced in order to allow appropriate developments in the field of health care and of body-area applications in general.

Authors are invited to submit articles reporting recent advances in wearable antennas and sensors for microwave applications. The Special Issue is mainly focused on new design methodologies and simulation techniques of wearable devices to face the problems imposed by the human body proximity, and on new materials, fabrication, and miniaturization methods for single and multi-band applications. The scope of this Special Issue will be the collection of new full research and/or review results, and highly rated manuscripts exploring the above topics.

We encourage submissions on areas related to:

  • Textile antennas;
  • Flexible microstrip and printed antennas;
  • Epidermal antennas;
  • 3D printed antennas;
  • Origami wearable antennas;
  • Wearable antennas fabrication technology;
  • Wearable antennas testing and measurements.

Prof. Dr. Giovanni Andrea Casula
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access semimonthly journal published by MDPI.

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

  • microwave applications
  • wearable antennas
  • wearable sensors
  • body–antenna coupling
  • additive manufacturing
  • textile antennas
  • epidermal antennas

Published Papers (6 papers)

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Research

12 pages, 4174 KiB  
Article
A Compact and Robust RFID Tag Based on an AMC Structure
by Giovanni Andrea Casula, Giacomo Muntoni, Paolo Maxia and Giorgio Montisci
Sensors 2024, 24(5), 1468; https://0-doi-org.brum.beds.ac.uk/10.3390/s24051468 - 24 Feb 2024
Viewed by 380
Abstract
A platform-tolerant RFID (Radio-Frequency Identification) tag is presented, designed to operate across the entire RFID band. This tag utilizes a small Artificial Magnetic Conductor (AMC) structure as a shielding element for an ungrounded RFID tag antenna. It can be easily mounted on various [...] Read more.
A platform-tolerant RFID (Radio-Frequency Identification) tag is presented, designed to operate across the entire RFID band. This tag utilizes a small Artificial Magnetic Conductor (AMC) structure as a shielding element for an ungrounded RFID tag antenna. It can be easily mounted on various surfaces, including low permittivity dielectric materials, metal objects, or even attached to the human body for wearable applications. The key features of this RFID tag include its ability to be tuned within the worldwide RFID band, achieving a maximum theoretical read range of over 11 m. Despite its advanced capabilities, the design emphasizes simplicity and cost-effective manufacturing. The design and simulations were conducted using CST Studio Suite. Full article
(This article belongs to the Special Issue Wearable Antennas and Sensors for Microwave Applications)
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15 pages, 3797 KiB  
Article
Three-Dimensional Printed Annular Ring Aperture-Fed Antenna for Telecommunication and Biomedical Applications
by Khaled Alhassoon, Yaaqoub Malallah, Fahad N. Alsunaydih and Fahd Alsaleem
Sensors 2024, 24(3), 949; https://0-doi-org.brum.beds.ac.uk/10.3390/s24030949 - 01 Feb 2024
Viewed by 554
Abstract
The design of the aperture-fed annular ring (AFAR) microstrip antenna is presented. This proposed design will ease the fabrication and usability of the 3D-printed and solderless 2D materials. This antenna consists of three layers: the patch, the slot within the ground plane as [...] Read more.
The design of the aperture-fed annular ring (AFAR) microstrip antenna is presented. This proposed design will ease the fabrication and usability of the 3D-printed and solderless 2D materials. This antenna consists of three layers: the patch, the slot within the ground plane as the power transfer medium, and the microstrip line as the feeding. The parameters of the proposed design are investigated using the finite element method FEM to achieve the 50 Ω impedance with the maximum front-to-back ratio of the radiation pattern. This study was performed based on four steps, each investigating one parameter at a time. These parameters were evaluated based on an initial design and prototype. The optimized design of 3D AFAR attained S11 around 17 dB with a front-to-back ratio of more than 30 dB and a gain of around 3.3 dBi. This design eases the process of using a manufacturing process that involves 3D-printed and 2D metallic materials for antenna applications. Full article
(This article belongs to the Special Issue Wearable Antennas and Sensors for Microwave Applications)
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20 pages, 5545 KiB  
Article
Design and Realization of Wearable Textile Slotted Waveguide Antennas
by Davorin Mikulić, Evita Šopp, Davor Bonefačić, Juraj Bartolić and Zvonimir Šipuš
Sensors 2023, 23(17), 7509; https://0-doi-org.brum.beds.ac.uk/10.3390/s23177509 - 29 Aug 2023
Cited by 1 | Viewed by 629
Abstract
The design of wearable antennas presents a challenge from multiple perspectives, as they must meet technical requirements and satisfy safety standards while also being suitable for integration into clothing and aesthetically pleasing. In recent years, the development of conductive fabrics has, in many [...] Read more.
The design of wearable antennas presents a challenge from multiple perspectives, as they must meet technical requirements and satisfy safety standards while also being suitable for integration into clothing and aesthetically pleasing. In recent years, the development of conductive fabrics has, in many ways, allowed for significant progress in the manufacturing of wearable antennas, and in previous work, we developed textile slotted waveguide antennas using conductive textiles and traditional sewing processes. However, various aspects of the design and realization of such antennas remain challenging. In particular, this work investigates the issue of using foam-based molds, which enables the realization of thin, flexible, wearable antennas, as well as the issue of antenna feed, specifically the transition from a classic coaxial transmission line to a waveguide. The design of the transition was focused on simplicity and robustness, due to which we limited the number of degrees of freedom in the design process in order to achieve a structure suitable for mounting on textile waveguide antennas. In addition, the antenna design procedure and the body-channel model were considered in order to optimize the performance of the antennas and the wireless body-centric system itself. Several prototypes of different kinds were developed in the 5.8 GHz ISM band, confirming the feasibility of the proposed concepts through experimental results. Full article
(This article belongs to the Special Issue Wearable Antennas and Sensors for Microwave Applications)
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12 pages, 1070 KiB  
Article
A Subtlety of Sizing the Inset Gap Width of a Microstrip Antenna When Built on an Ultra-Thin Substrate in the S-Band
by Miroslav Joler and Leo Mihalić
Sensors 2023, 23(1), 213; https://0-doi-org.brum.beds.ac.uk/10.3390/s23010213 - 25 Dec 2022
Cited by 1 | Viewed by 1332
Abstract
In this paper, Pyralux—a modern, ultra-thin, and acrylic-based laminate—was tested as a substrate of a microstrip antenna to examine the antenna characteristics when it is built on such a thin, flexible, and robust dielectric material, with the idea of eventually serving in wearable [...] Read more.
In this paper, Pyralux—a modern, ultra-thin, and acrylic-based laminate—was tested as a substrate of a microstrip antenna to examine the antenna characteristics when it is built on such a thin, flexible, and robust dielectric material, with the idea of eventually serving in wearable antennas in the context of smart-clothing applications. We particularly discuss the sensitivity of the design and fabrication of an inset-fed rectangular microstrip antenna (IRMA) in terms of its inset gap width when it is designed in the S-frequency band. The simulated and measured results showed a very small feasible range for the inset gap dimension with respect to the feed line width. Ultimately, an IRMA was successfully designed, fabricated, and tested with both SMA and U.FL connectors. The impedance bandwidth, in either case, was about 2%, the average value of directivity was 5.8 dB, and the realized efficiency was 2.67%, while the 3-dB beamwidths in the E-plane and the H-plane were 90° or wider. Full article
(This article belongs to the Special Issue Wearable Antennas and Sensors for Microwave Applications)
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11 pages, 3478 KiB  
Article
Wireless Communication Platform Based on an Embroidered Antenna-Sensor for Real-Time Breathing Detection
by Mariam El Gharbi, Raúl Fernández-García and Ignacio Gil
Sensors 2022, 22(22), 8667; https://0-doi-org.brum.beds.ac.uk/10.3390/s22228667 - 10 Nov 2022
Cited by 5 | Viewed by 1378
Abstract
Wearable technology has been getting more attention for monitoring vital signs in various medical fields, particularly in breathing monitoring. To monitor respiratory patterns, there is a current set of challenges related to the lack of user comfort, reliability, and rigidity of the systems, [...] Read more.
Wearable technology has been getting more attention for monitoring vital signs in various medical fields, particularly in breathing monitoring. To monitor respiratory patterns, there is a current set of challenges related to the lack of user comfort, reliability, and rigidity of the systems, as well as challenges related to processing data. Therefore, the need to develop user-friendly and reliable wireless approaches to address these problems is required. In this paper, a novel, full, compact textile breathing sensor is investigated. Specifically, an embroidered meander dipole antenna sensor integrated into an e-textile T-shirt with a Bluetooth transmitter for real-time breathing monitoring was developed and tested. The proposed antenna-based sensor is designed to transmit data over wireless communication networks at 2.4 GHz and is made of a silver-coated nylon thread. The sensing mechanism of the proposed system is based on the detection of a received signal strength indicator (RSSI) transmitted wirelessly by the antenna-based sensor, which is found to be sensitive to stretch. The respiratory system is placed on the middle of the human chest; the area of the proposed system is 4.5 × 0.48 cm2, with 2.36 × 3.17 cm2 covered by the transmitter module. The respiratory signal is extracted from the variation of the RSSI signal emitted at 2.4 GHz from the detuned embroidered antenna-based sensor embedded into a commercial T-shirt and detected using a laptop. The experimental results demonstrated that breathing signals can be acquired wirelessly by the RSSI via Bluetooth. The RSSI range change was from −80 dBm to −72 dBm, −88 dBm to −79 dBm and −85 dBm to −80 dBm during inspiration and expiration for normal breathing, speaking and movement, respectively. We tested the feasibility assessment for breathing monitoring and we demonstrated experimentally that the standard wireless networks, which measure the RSSI signal via standard Bluetooth protocol, can be used to detect human respiratory status and patterns in real time. Full article
(This article belongs to the Special Issue Wearable Antennas and Sensors for Microwave Applications)
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11 pages, 2575 KiB  
Communication
Slot Antennas Integrated into 3D Knitted Fabrics: 5.8 GHz and 24 GHz ISM Bands
by Miroslav Cupal and Zbynek Raida
Sensors 2022, 22(7), 2707; https://0-doi-org.brum.beds.ac.uk/10.3390/s22072707 - 01 Apr 2022
Cited by 4 | Viewed by 1596
Abstract
In the paper, a 3D knitted fabric is used for the design of a circularly polarized textile-integrated antenna. The role of the radiating element is played by a circular slot etched into the conductive top wall of a textile-integrated waveguide. Inside the circular [...] Read more.
In the paper, a 3D knitted fabric is used for the design of a circularly polarized textile-integrated antenna. The role of the radiating element is played by a circular slot etched into the conductive top wall of a textile-integrated waveguide. Inside the circular slot, a cross slot rotated for about 45° is etched to excite the circular polarization. The polarization of the antenna can be changed by the rotation of the cross slot. The antenna has a patch-like radiation pattern, and the gain is about 5.3 dBi. The textile-integrated feeder of the antenna is manufactured by screen printing conductive surfaces and sewing side walls with conductive threads. The antenna was developed for ISM bands 5.8 GHz and 24 GHz. The operation frequency 24 GHz is the highest frequency of operation for which the textile-integrated waveguide antenna has been manufactured. Full article
(This article belongs to the Special Issue Wearable Antennas and Sensors for Microwave Applications)
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