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Antenna Technologies for Millimeter and Terahertz Sensing

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

Deadline for manuscript submissions: closed (31 May 2022) | Viewed by 23815

Special Issue Editors


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Guest Editor
Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield S1 4AE, UK
Interests: computational electromagnetics; dielectric resonator antennas; mm-Wave and THz communications; plasmonic antennas
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Department of Physics, University Putra Malaysia, 43400 UPM Serdang, Malaysia
Interests: theory, simulation, and instrumentation of electromagnetic wave propagation at microwave frequencies focusing on the development of microwave sensors for agricultural applications

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Guest Editor
Head of the Communication Engineering Department, Al-Ma’moon University College, Baghdad, Iraq
Interests: artificial and nanoscale structures; mm-Wave antennas; antennas for medical applications; neural and artificial intelligent optimization analysis

Special Issue Information

Dear Colleagues,

At present, many applications in medical, environmental, and industrial fields have attracted researchers, who have proposed various sensor technologies. In particular, microwave and millimeter-wave sensors have drawn substantial attention due to their unique detecting process which can be done remotely in destructive and non-destructive aspects. Such technology offers several advantages such as compact size and sub-millimeter accuracy owing to the corresponding short wavelengths. This technology has been utilized in mmWave radars, wireless sensor networks, miniature biosensors, intelligent transport systems, THz security scanners, and in various other applications. Such unique properties are achieved due to the natural propagation properties of such frequencies and their ability to penetrate through many surfaces.

Currently, such sensor technologies face the same challenges as any advanced system, including: availability, immune-ability, maintainability, integrability, updatability, reconfigurability, sensitivity, detectability, and effective cost–mass production process. However, there are challenges associated with such technology, such as:

  1. Size reduction and miniaturization for wearable and implantable portable systems;
  2. Degradation of detecting function and sensing operation with long-term usage;
  3. Depth limitations of waves’ penetration in different objects and materials;
  4. Effects of surrounding objects on their performance when applied in integrated systems;
  5. Sensors’ connectivity to the outside world through wireless communication channels;
  6. Analysis process of evaluating the detecting measurements quantitatively and qualitatively;
  7. Energy consumption and difficulty of sharing data to and out of the sensor device;
  8. Operation limitations to certain processing conditions.

On the other hand, marginal fabrication errors could have a significant impact on the operational characteristics of such sensors. Such unprecedented challenges consequently necessitate the use of high-precision fabrication processes, which in turn leads to increased manufacturing time and hence production costs. Therefore, the challenge is to generate innovative designs which would significantly relax fabrication tolerance requirements.

For this Special Issue, we invite researchers and developers to submit their novel research papers on millimeter-wave and terahertz sensors with relevant characteristics and fabrication cost effectiveness. Nevertheless, this Issue is also extended to include research focused on the propagation at these bands as well as material characterizations for object detection and imaging. Therefore, it is preferred that manuscripts submitted for this Special Issue fall within the following topics (not an exhaustive list):

  • Antenna arrays and beamforming;
  • Millimeter-wave radars and transmitters;
  • Terahertz and millimeter-wave antenna designs;
  • Material characterization and detection;
  • Manufacturing error characterization;
  • Smart sensing developments and implementations;
  • Sensing systems design;
  • Metasurface-based antenna sensors;
  • On-chip antennas;
  • Antenna in package sensors;
  • Wireless sensor networks;
  • Sensors-based body area networks;
  • EEG-based biomedical sensors;
  • Integrated sensors-based human–computer interfaces;
  • Smart algorithms based on neural and artificial networks;
  • IoT-based sensor networks;
  • Functionalized based on bulk and nanomaterials for wireless sensor devices;
  • Energy harvesting technologies for self-powered sensors.

Dr. Salam Khamas
Prof. Zulkifly Abbas
Prof. Taha Elwi
Guest Editors

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

  • Antenna arrays
  • Millimeter-wave radars
  • Sensing systems design
  • On-chip antennas
  • Wireless sensor networks
  • IoT-based sensor networks

Published Papers (9 papers)

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Research

15 pages, 6915 KiB  
Article
A Compact Dual Band MIMO Dielectric Resonator Antenna with Improved Performance for mm-Wave Applications
by Meshari D. Alanazi and Salam K. Khamas
Sensors 2022, 22(13), 5056; https://doi.org/10.3390/s22135056 - 05 Jul 2022
Cited by 20 | Viewed by 2464
Abstract
A compact multiple-input-multiple-output (MIMO) dielectric resonator antenna (DRA) that is suitable for internet of things (IoT) sensor networks is proposed with reduced coupling between elements. Two rectangular-shaped DRAs have been placed on the opposite sides of a Rogers substrate and each is fed [...] Read more.
A compact multiple-input-multiple-output (MIMO) dielectric resonator antenna (DRA) that is suitable for internet of things (IoT) sensor networks is proposed with reduced coupling between elements. Two rectangular-shaped DRAs have been placed on the opposite sides of a Rogers substrate and each is fed using a coplanar waveguide (CPW) feed with slots etched in a dedicated metal ground plane that is located under the DRA. Moreover, locating the elements at the opposite sides of the substrate has improved the isolation by 27 dB without the need to incorporate additional complex structures, which has reduced the overall antenna size. Furthermore, a dual band operation is achieved since each antenna resonates at two frequencies: 28 GHz and 38 GHz with respective impedance matching bandwidths of 18% and 13%. As a result, the corresponding data rates are also increased independently. In addition to the advantages of improved isolation, compact size and dual band operation, the proposed configuration offers a diversity gain (DG), envelope correlation coefficient (ECC) and channel capacity loss (CCL) of 9.98 dB, 0.007, 0.06 bits/s/Hz over the desired bands, respectively. A prototype has been built with good agreement between simulated and measured results. Full article
(This article belongs to the Special Issue Antenna Technologies for Millimeter and Terahertz Sensing)
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13 pages, 34365 KiB  
Communication
Refractive Index-Based Terahertz Sensor Using Graphene for Material Characterization
by Aruna Veeraselvam, Gulam Nabi Alsath Mohammed, Kirubaveni Savarimuthu, Jaume Anguera, Jessica Constance Paul and Ram Kumar Krishnan
Sensors 2021, 21(23), 8151; https://doi.org/10.3390/s21238151 - 06 Dec 2021
Cited by 16 | Viewed by 2765
Abstract
In this paper, a graphene-based THz metamaterial has been designed and characterized for use in sensing various refractive index profiles. The proposed single-band THz sensor was constructed using a graphene-metal hybridized periodic metamaterial wherein the unit cell had a footprint of 1.395λeff [...] Read more.
In this paper, a graphene-based THz metamaterial has been designed and characterized for use in sensing various refractive index profiles. The proposed single-band THz sensor was constructed using a graphene-metal hybridized periodic metamaterial wherein the unit cell had a footprint of 1.395λeff × 1.395λeff and resonated at 4.4754 THz. The realized peak absorption was 98.88% at 4.4754 THz. The sensitivity of the proposed metamaterial sensor was estimated using the absorption characteristics of the unit cell. The performance of the sensor was analyzed under two different categories, viz. the random dielectric loading and chemical analytes, based on the refractive index. The proposed THz sensor offered a peak sensitivity of 22.75 GHz/Refractive Index Unit (RIU) for the various sample loadings. In addition, the effect of the sample thickness on the sensor performance was analyzed and the results were presented. From the results, it can be inferred that the proposed metamaterial THz sensor that was based on a refractive index is suitable for THz sensing applications. Full article
(This article belongs to the Special Issue Antenna Technologies for Millimeter and Terahertz Sensing)
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18 pages, 7223 KiB  
Article
A Flexible Metamaterial Based Printed Antenna for Wearable Biomedical Applications
by Ammar Al-Adhami and Ergun Ercelebi
Sensors 2021, 21(23), 7960; https://doi.org/10.3390/s21237960 - 29 Nov 2021
Cited by 17 | Viewed by 2911
Abstract
This paper presents a microstrip antenna based on metamaterials (MTM). The proposed antenna showed several resonances around the BAN and ISM frequency bands. The antenna showed a suitable gain for short and medium wireless communication systems of about 1 dBi, 1.24 dBi, 1.48 [...] Read more.
This paper presents a microstrip antenna based on metamaterials (MTM). The proposed antenna showed several resonances around the BAN and ISM frequency bands. The antenna showed a suitable gain for short and medium wireless communication systems of about 1 dBi, 1.24 dBi, 1.48 dBi, 2.05 dBi, and 4.11 dBi at 403 MHz, 433 MH, 611 Mz, 912 MHz, and 2.45 GHz, respectively. The antenna was printed using silver nanoparticle ink on a polymer substrate. The antenna size was reduced to 20 × 10 mm2 to suit the different miniaturized wireless biomedical devices. The fabricated prototype was tested experimentally on the human body. The main novelty with this design is its ability to suppress the surface wave from the patch edges, significantly reducing the back radiation toward the human body when used close to it. The antenna was located on the human head to specify the specific absorption rate (SAR). It was found in all cases that the proposed antenna showed low SAR effects on the human body. Full article
(This article belongs to the Special Issue Antenna Technologies for Millimeter and Terahertz Sensing)
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20 pages, 12443 KiB  
Article
Differential Microstrip Sensor for Complex Permittivity Characterization of Organic Fluid Mixtures
by Amer Abbood al-Behadili, Iulia Andreea Mocanu, Teodor Mihai Petrescu and Taha A. Elwi
Sensors 2021, 21(23), 7865; https://doi.org/10.3390/s21237865 - 26 Nov 2021
Cited by 9 | Viewed by 2124
Abstract
A microstrip highly sensitive differential sensor for complex permittivity characterization of urine samples was designed, fabricated and tested. The sensing area contains two pairs of open-stub resonators, and the working frequency of the unloaded sensor is 1.25 GHz. The sensor is easily implemented [...] Read more.
A microstrip highly sensitive differential sensor for complex permittivity characterization of urine samples was designed, fabricated and tested. The sensing area contains two pairs of open-stub resonators, and the working frequency of the unloaded sensor is 1.25 GHz. The sensor is easily implemented on an affordable substrate FR-4 Epoxy with a thickness of 1.6 mm. A Teflon beaker is mounted on the sensor without affecting the measurements. Numerically, liquid mixtures of water and urine at different percentages were introduced to the proposed sensor to evaluate the frequency variation. The percentage of water content in the mixture varied from 0% (100% urine) to 100% (0% urine) with a step of 3.226%, thus giving 32 data groups of the simulated results. Experimentally, the mixtures of: 0% urine (100% water), 20% urine (80% water), 33% urine (66% water), 50% urine (50% water), 66% urine (33% water), and 100% urine (0% water) were considered for validation. The complex permittivity of the considered samples was evaluated using a nonlinear least square curve fitting in MATLAB in order to realize a sensing sensitivity of about 3%. Full article
(This article belongs to the Special Issue Antenna Technologies for Millimeter and Terahertz Sensing)
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17 pages, 6571 KiB  
Article
Field Decorrelation and Isolation Improvement in an MIMO Antenna Using an All-Dielectric Device Based on Transformation Electromagnetics
by Usman Qureshi, Muhammad Umar Khan, Mohammad S. Sharawi, Shah Nawaz Burokur and Raj Mittra
Sensors 2021, 21(22), 7577; https://doi.org/10.3390/s21227577 - 15 Nov 2021
Cited by 4 | Viewed by 1601
Abstract
This work presents a new technique for enhancing the performance of a multiple-input multiple-output (MIMO) antenna by improving its correlation coefficient ρ. A broadband dielectric structure is designed using the transformation electromagnetics (TE) concept to decorrelate the fields of closely placed radiating [...] Read more.
This work presents a new technique for enhancing the performance of a multiple-input multiple-output (MIMO) antenna by improving its correlation coefficient ρ. A broadband dielectric structure is designed using the transformation electromagnetics (TE) concept to decorrelate the fields of closely placed radiating elements of an MIMO antenna, thereby decreasing ρ and mutual coupling. The desired properties of the broadband dielectric wave tilting structure (DWTS) are determined by using quasi-conformal transformation electromagnetics (QCTE). Next, the permittivity profile of the DWTS is realized by employing air-hole technology, which is based on the effective medium theory, and the DWTS is fabricated using the additive manufacturing (3D printing) technique. The effectiveness of the proposed technique is verified by designing two-element patch-based MIMO antenna prototypes operating at 3 GHz, 5 GHz, and 7 GHz, respectively. The proposed technique helped to reduce the correlation coefficient ρ in the range of 37% to 99% in the respective operating bandwidth of each MIMO antenna, thereby, in each case, improving the isolation between antenna elements by better than 3 dB, which is an excellent performance. Full article
(This article belongs to the Special Issue Antenna Technologies for Millimeter and Terahertz Sensing)
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12 pages, 4856 KiB  
Article
A 16-Channel Dipole Antenna Array for Human Head Magnetic Resonance Imaging at 10.5 Tesla
by Myung Kyun Woo, Lance DelaBarre, Matt Waks, Jerahmie Radder, Uk-Su Choi, Russell Lagore, Kamil Ugurbil and Gregor Adriany
Sensors 2021, 21(21), 7250; https://doi.org/10.3390/s21217250 - 30 Oct 2021
Cited by 9 | Viewed by 2599
Abstract
For ultra-high field and frequency (UHF) magnetic resonance imaging (MRI), the associated short wavelengths in biological tissues leads to penetration and homogeneity issues at 10.5 tesla (T) and require antenna transmit arrays for efficiently generated 447 MHz B1+ fields (defined as [...] Read more.
For ultra-high field and frequency (UHF) magnetic resonance imaging (MRI), the associated short wavelengths in biological tissues leads to penetration and homogeneity issues at 10.5 tesla (T) and require antenna transmit arrays for efficiently generated 447 MHz B1+ fields (defined as the transmit radiofrequency (RF) magnetic field generated by RF coils). Previously, we evaluated a 16-channel combined loop + dipole antenna (LD) 10.5 T head array. While the LD array configuration did not achieve the desired B1+ efficiency, it showed an improvement of the specific absorption rate (SAR) efficiency compared to the separate 8-channel loop and separate 8-channel dipole antenna arrays at 10.5 T. Here we compare a 16-channel dipole antenna array with a 16-channel LD array of the same dimensions to evaluate B1+ efficiency, 10 g SAR, and SAR efficiency. The 16-channel dipole antenna array achieved a 24% increase in B1+ efficiency in the electromagnetic simulation and MR experiment compared to the LD array, as measured in the central region of a phantom. Based on the simulation results with a human model, we estimate that a 16-channel dipole antenna array for human brain imaging can increase B1+ efficiency by 15% with similar SAR efficiency compared to a 16-channel LD head array. Full article
(This article belongs to the Special Issue Antenna Technologies for Millimeter and Terahertz Sensing)
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18 pages, 6868 KiB  
Article
A New Microwave Sensor Based on the Moore Fractal Structure to Detect Water Content in Crude Oil
by Russul Khalid Abdulsattar, Taha A. Elwi and Zaid A. Abdul Hassain
Sensors 2021, 21(21), 7143; https://doi.org/10.3390/s21217143 - 28 Oct 2021
Cited by 21 | Viewed by 2361
Abstract
This paper presents a microwave sensor based on a two-ports network for liquid characterizations. The proposed sensor is constructed as a miniaturized microwave resonator based on Moore fractal geometry of the 4th iteration. The T-resonator is combined with the proposed structure to increase [...] Read more.
This paper presents a microwave sensor based on a two-ports network for liquid characterizations. The proposed sensor is constructed as a miniaturized microwave resonator based on Moore fractal geometry of the 4th iteration. The T-resonator is combined with the proposed structure to increase the sensor quality factor. The proposed sensor occupies an area of 50 × 50 × 1.6 mm3 printed on an FR4 substrate. Analytically, a theoretical study is conducted to explain the proposed sensor operation. The proposed sensor was fabricated and experimentally tested for validation. Later, two pans were printed on the sensor to hold the Sample Under Test (SUT) of crude oil. The frequency resonance of the proposed structure before loading SUT was found to be 0.8 GHz. After printing the pans, a 150 MHz frequency shift was accrued to the first resonance. The sensing part was accomplished by monitoring the S-parameters in terms of S12 regarding the water concentration change in the crude oil samples. Therefore, 10 different samples with different water percentages were introduced to the proposed sensor to be tested for detecting the water content. Finally, the measurements of the proposed process were found to agree very well with their relative simulated results. Full article
(This article belongs to the Special Issue Antenna Technologies for Millimeter and Terahertz Sensing)
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12 pages, 29008 KiB  
Article
Evaluation of 8-Channel Radiative Antenna Arrays for Human Head Imaging at 10.5 Tesla
by Myung Kyun Woo, Lance DelaBarre, Matt Thomas Waks, Young Woo Park, Russell Luke Lagore, Steve Jungst, Yigitcan Eryaman, Se-Hong Oh, Kamil Ugurbil and Gregor Adriany
Sensors 2021, 21(18), 6000; https://doi.org/10.3390/s21186000 - 08 Sep 2021
Cited by 5 | Viewed by 2487
Abstract
For human head magnetic resonance imaging at 10.5 tesla (T), we built an 8-channel transceiver dipole antenna array and evaluated the influence of coaxial feed cables. The influence of coaxial feed cables was evaluated in simulation and compared against a physically constructed array [...] Read more.
For human head magnetic resonance imaging at 10.5 tesla (T), we built an 8-channel transceiver dipole antenna array and evaluated the influence of coaxial feed cables. The influence of coaxial feed cables was evaluated in simulation and compared against a physically constructed array in terms of transmit magnetic field (B1+) and specific absorption rate (SAR) efficiency. A substantial drop (23.1% in simulation and 20.7% in experiment) in B1+ efficiency was observed with a tight coaxial feed cable setup. For the investigation of the feed location, the center-fed dipole antenna array was compared to two 8-channel end-fed arrays: monopole and sleeve antenna arrays. The simulation results with a phantom indicate that these arrays achieved ~24% higher SAR efficiency compared to the dipole antenna array. For a human head model, we observed 30.8% lower SAR efficiency with the 8-channel monopole antenna array compared to the phantom. Importantly, our simulation with the human model indicates that the sleeve antenna arrays can achieve 23.8% and 21% higher SAR efficiency compared to the dipole and monopole antenna arrays, respectively. Finally, we obtained high-resolution human cadaver images at 10.5 T with the 8-channel sleeve antenna array. Full article
(This article belongs to the Special Issue Antenna Technologies for Millimeter and Terahertz Sensing)
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12 pages, 4277 KiB  
Communication
CPW Fed Compact UWB 4-Element MIMO Antenna with High Isolation
by Wenfei Yin, Shaoxiang Chen, Junjie Chang, Chunhua Li and Salam K. Khamas
Sensors 2021, 21(8), 2688; https://doi.org/10.3390/s21082688 - 11 Apr 2021
Cited by 27 | Viewed by 2834
Abstract
In the paper, an extremely compact multiple-input-multiple-output (MIMO) antenna is proposed for portable wireless ultrawideband (UWB) applications. The proposed prototype consists of four monopole antenna elements, which are placed perpendicularly to achieve polarization diversity. In addition, the mutual coupling between antenna elements is [...] Read more.
In the paper, an extremely compact multiple-input-multiple-output (MIMO) antenna is proposed for portable wireless ultrawideband (UWB) applications. The proposed prototype consists of four monopole antenna elements, which are placed perpendicularly to achieve polarization diversity. In addition, the mutual coupling between antenna elements is suppressed by designing the gap between the radiation element and the ground plane. Moreover, a matching stub has been connected to the feedline to ensure impedance matching in high frequency. Both simulated and measured results indicate that the proposed antenna has a bandwidth of 3–20 GHz, with a high isolation better than 17 dB. In addition, the designed MIMO antenna offers excellent radiation characteristics and stable gain over the whole working band. The envelope correlation coefficient (ECC) is less than 0.1, which shows that the antenna can meet the polarization diversity characteristics well. Full article
(This article belongs to the Special Issue Antenna Technologies for Millimeter and Terahertz Sensing)
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