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Microwave Sensing Systems

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

Deadline for manuscript submissions: closed (30 June 2024) | Viewed by 20756

Special Issue Editors


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Guest Editor
Institute of Electrodynamics, Microwave and Circuit Engineering, TU Wien, 1040 Vienna, Austria
Interests: microwave sensing; nonlinear RF measurement techniques; indoor localization; antenna design/measurement; RF material characterization; RF power amplifiers; RFID

E-Mail Website
Guest Editor
Institute of Telecommunications, TU Wien, 1040 Vienna, Austria
Interests: sparse signals and channels; localisation and positioning; dependable vehicular connectivity; ultra-wideband radio systems; joint communications and sensing

Special Issue Information

Dear Colleagues,

The use of microwave sensing systems has received growing interest in recent years. Identifying/localizing UHF RFID tags, measurement of physical properties, or radar imaging are just some examples of their current applications. Microwave systems are insensitive to dust, allow non-line-of-sight applications, and often allow for easier and less expensive integration. Steadily increasing frequencies, more powerful signal processors, and higher integration densities have recently opened up new possibilities in scientific, production, logistics, and medical applications.

This Special Issue aims to present original research and review articles on recent advances, technologies, solutions, applications, and new challenges in the field of microwave sensing.

Potential topics include but are not limited to:

  • Microwave based positioning/localization;
  • Radio frequency identification (RFID)-based sensors;
  • Microwave material characterization;
  • Distributed/cooperative sensing;
  • Antennas for microwave sensing;
  • Ultra-wideband (UWB) sensing;
  • Radar systems;
  • Microwave sensing circuits;
  • Sensor fusion in microwave sensing applications;
  • Calibration techniques;
  • Integration of microwave sensors;
  • Microwave imaging techniques;
  • Joint sensing and communications;
  • Spectral sharing concepts.

Dr. Holger Arthaber
Prof. Dr. Christoph Mecklenbraeuker
Guest Editors

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Published Papers (12 papers)

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Research

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21 pages, 2358 KiB  
Article
Trustworthiness for an Ultra-Wideband Localization Service
by Philipp Peterseil, Bernhard Etzlinger, Jan Horáček, Roya Khanzadeh and Andreas Springer
Sensors 2024, 24(16), 5268; https://doi.org/10.3390/s24165268 - 14 Aug 2024
Cited by 1 | Viewed by 285
Abstract
Trustworthiness assessment is an essential step to assure that interdependent systems perform critical functions as anticipated, even under adverse conditions. In this paper, a holistic trustworthiness assessment framework for ultra-wideband self-localization is proposed, including the attributes of reliability, security, privacy, and resilience. Our [...] Read more.
Trustworthiness assessment is an essential step to assure that interdependent systems perform critical functions as anticipated, even under adverse conditions. In this paper, a holistic trustworthiness assessment framework for ultra-wideband self-localization is proposed, including the attributes of reliability, security, privacy, and resilience. Our goal is to provide guidance for evaluating a system’s trustworthiness based on objective evidence, i.e., so-called trustworthiness indicators. These indicators are carefully selected through the threat analysis of the particular system under evaluation. Our approach guarantees that the resulting trustworthiness indicators correspond to chosen real-world threats. Moreover, experimental evaluations are conducted to demonstrate the effectiveness of the proposed method. While the framework is tailored for this specific use case, the process itself serves as a versatile template, which can be used in other applications in the domains of the Internet of Things or cyber–physical systems. Full article
(This article belongs to the Special Issue Microwave Sensing Systems)
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22 pages, 3579 KiB  
Article
Realistic 3D Phantoms for Validation of Microwave Sensing in Health Monitoring Applications
by Mariella Särestöniemi, Daljeet Singh, Rakshita Dessai, Charline Heredia, Sami Myllymäki and Teemu Myllylä
Sensors 2024, 24(6), 1975; https://doi.org/10.3390/s24061975 - 20 Mar 2024
Cited by 3 | Viewed by 1288
Abstract
The development of new medical-monitoring applications requires precise modeling of effects on the human body as well as the simulation and the emulation of realistic scenarios and conditions. The first aim of this paper is to develop realistic and adjustable 3D human-body emulation [...] Read more.
The development of new medical-monitoring applications requires precise modeling of effects on the human body as well as the simulation and the emulation of realistic scenarios and conditions. The first aim of this paper is to develop realistic and adjustable 3D human-body emulation platforms that could be used for evaluating emerging microwave-based medical monitoring/sensing applications such as the detection of brain tumors, strokes, and breast cancers, as well as for capsule endoscopy studies. New phantom recipes are developed for microwave ranges for phantom molds with realistic shapes. The second aim is to validate the feasibility and reliability of using the phantoms for practical scenarios with electromagnetic simulations using tissue-layer models and biomedical antennas. The third aim is to investigate the impact of the water temperature in the phantom-cooking phase on the dielectric properties of the stabilized phantom. The evaluations show that the dielectric properties of the developed phantoms correspond closely to those of real human tissue. The error in dielectric properties varies between 0.5–8%. In the practical-scenario simulations, the differences obtained with phantoms-based simulations in S21 parameters are 0.1–13 dB. However, the differences are smaller in the frequency ranges used for medical applications. Full article
(This article belongs to the Special Issue Microwave Sensing Systems)
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20 pages, 7480 KiB  
Article
Microwave Receiving System Based on Cryogenic Sensors for the Optical Big Telescope Alt-Azimuth
by Yurii Balega, Grigory Bubnov, Artem Chekushkin, Victor Dubrovich, Valerian Edelman, Aleksandra Gunbina, Sergey Kapustin, Tatyana Khabarova, Dmitrii Kukushkin, Igor Lapkin, Maria Mansfeld, Andrei Maruhno, Vladimir Parshin, Aleksey Raevskiy, Vladislav Stolyarov, Mikhail Tarasov, Gennady Valyavin, Vyacheslav Vdovin, Grigory Yakopov, Renat Yusupov, Petr Zemlyanukha and Igor Zinchenkoadd Show full author list remove Hide full author list
Sensors 2024, 24(2), 359; https://doi.org/10.3390/s24020359 - 7 Jan 2024
Cited by 1 | Viewed by 1197
Abstract
This article presents the results of evaluating the possibility of conducting radio astronomy studies in the windows of atmospheric transparency ~100, ~230, and ~350 GHz using the optical Big Telescope Alt-Azimuthal (BTA) of the Special Astrophysical Observatory of the Russian Academy of Sciences [...] Read more.
This article presents the results of evaluating the possibility of conducting radio astronomy studies in the windows of atmospheric transparency ~100, ~230, and ~350 GHz using the optical Big Telescope Alt-Azimuthal (BTA) of the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS). A list of some promising astronomical tasks is proposed. The astroclimat conditions at the BTA site and possible optical, cryogenic, and mechanical interfaces for mounting a superconducting radio receiver at the focus of the optical telescope are considered. As a receiving system, arrays of detectors cooled to ~0.3 K based on the superconductor–insulator–normal metal–insulator–superconductor (SINIS) structure are proposed. The implementation of the project will make it possible to use the BTA site of the SAO RAS not only to solve some astronomical problems (it is possible to consider the implementation of a single observatory, the VLBI (very-long-baseline interferometry) mode in the Suffa, EHT (Event Horizon Telescope), and Millimetron projects), but it will also be used to test various cryogenic detectors in a real observatory. Full article
(This article belongs to the Special Issue Microwave Sensing Systems)
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30 pages, 15781 KiB  
Article
Dual-Polarization Ambient Backscatter Communications and Signal Detection
by Youze Yang and Sen Yan
Sensors 2024, 24(1), 223; https://doi.org/10.3390/s24010223 - 30 Dec 2023
Viewed by 965
Abstract
Ambient backscatter communication (AmBC), an emerging mechanism for batteryless communications that can utilize ambient radio-frequency signals to modulate information and thus reduce power consumption, has attracted considerable attention and has been considered as a critical technology in green “Internet of Things” sensor networks [...] Read more.
Ambient backscatter communication (AmBC), an emerging mechanism for batteryless communications that can utilize ambient radio-frequency signals to modulate information and thus reduce power consumption, has attracted considerable attention and has been considered as a critical technology in green “Internet of Things” sensor networks due to its ultra-low power consumption. This paper presents the first a complete dual-polarization AmBC (DPAm) system model, which can extend AmBC into polarization diversity and improve the data-transmission rate of backscatter symbols. We proposed two scenarios: direct dual-polarization-based DPAm node structures and polarization-conversion-based DPAm node structures. In addition, we consider a parallel backscatter mode with differential coding and develop corresponding detectors, which also give the analytical detection thresholds. Moreover, we consider a simultaneous backscatter mode with Manchester coding in order to avoid complex-parameter estimation. To address the power imbalance problem of the DPAm system that arises because the polarization deflection angle would cause the power level to change with different polarization patterns, we also develop a power-average detector and a clustering detector. Simulation results show the throughput performance on each DPAm node structure with each detector, demonstrating the feasibility and efficiency of the proposed DPAm nodes and detectors. Compared with single-polarization AmBC (SPAm), the proposed DPAm node can achieve higher throughput in most cases. Finally, the clustering detector is shown to be more robust to short training sequences and complex environments. Full article
(This article belongs to the Special Issue Microwave Sensing Systems)
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24 pages, 6160 KiB  
Article
Analysis and Implementation of Controlled Semiconductor Switch for Ultra-Wideband Radar Sensor Applications
by Patrik Jurik, Miroslav Sokol, Pavol Galajda and Milos Drutarovsky
Sensors 2023, 23(17), 7392; https://doi.org/10.3390/s23177392 - 24 Aug 2023
Cited by 5 | Viewed by 1424
Abstract
All ultra-wideband (UWB) sensor applications require hardware designed directly for their specific application. The switching of broadband radio frequency and microwave signals is an integral part of almost every piece of high-frequency equipment, whether in commercial operation or laboratory conditions. The trend of [...] Read more.
All ultra-wideband (UWB) sensor applications require hardware designed directly for their specific application. The switching of broadband radio frequency and microwave signals is an integral part of almost every piece of high-frequency equipment, whether in commercial operation or laboratory conditions. The trend of integrating various circuit structures and systems on a chip (SoC) or in a single package (SiP) is also related to the need to design these integrated switches for various measuring devices and instruments in laboratories, paradoxically for their further development. Another possible use is switching high-frequency signals in telecommunications devices, whether mobile or fixed networks, for example, for switching signals from several antennas. Based on these requirements, a high-frequency semiconductor integrated switch with NMOS transistors was designed. With these transistors, it is possible to achieve higher integration than with bipolar ones. Even though MOSFET transistors have worse frequency characteristics, we can compensate them to some extent with the precise design of the circuit and layout of the chip. This article describes the analysis and design of a high-frequency semiconductor integrated switch for UWB applications consisting of three series-parallel switches controlled by CMOS logic signals. They are primarily intended for UWB sensor systems, e.g., when switching and configuring the antenna MIMO system or when switching calibration tools. The design of the switch was implemented in low-cost 0.35 µm SiGe BiCMOS technology with an emphasis on the smallest possible attenuation and the largest possible bandwidth and isolation. The reason for choosing this technology was also that other circuit structures of UWB systems were realized in this technology. Through the simulations, individual parameters of the circuit were simulated, the layout of the chip was also created, and the parameters of the circuit were simulated with the parasitic extraction and the inclusion of parasitic elements (post-layout simulations). Subsequently, the chip was manufactured and its parameters were measured and evaluated. Based on these measurements, the designed and fabricated UWB switch was found to have the following parameters: a supply current of 2 mA at 3.3 V, a bandwidth of 6 GHz, an insertion loss (at 1 GHz) of −2.2 dB, and isolation (at 1 GHz) of 33 dB, which satisfy the requirements for our UWB sensor applications. Full article
(This article belongs to the Special Issue Microwave Sensing Systems)
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24 pages, 21691 KiB  
Article
Wideband TDoA Positioning Exploiting RSS-Based Clustering
by Andreas Fuchs, Lukas Wielandner, Daniel Neunteufel, Holger Arthaber and Klaus Witrisal
Sensors 2023, 23(12), 5772; https://doi.org/10.3390/s23125772 - 20 Jun 2023
Viewed by 1368
Abstract
The accuracy of radio-based positioning is heavily influenced by a dense multipath (DM) channel, leading to poor position accuracy. The DM affects both time of flight (ToF) measurements extracted from wideband (WB) signals—specifically, if the bandwidth is below 100 MHz—as well as received [...] Read more.
The accuracy of radio-based positioning is heavily influenced by a dense multipath (DM) channel, leading to poor position accuracy. The DM affects both time of flight (ToF) measurements extracted from wideband (WB) signals—specifically, if the bandwidth is below 100 MHz—as well as received signal strength (RSS) measurements, due to the interference of multipath signal components onto the information-bearing line-of-sight (LoS) component. This work proposes an approach for combining these two different measurement technologies, leading to a robust position estimation in the presence of DM. We assume that a large ensemble of densely-spaced devices is to be positioned. We use RSS measurements to determine “clusters” of devices in the vicinity of each other. Joint processing of the WB measurements from all devices in a cluster efficiently suppresses the influence of the DM. We formulate an algorithmic approach for the information fusion of the two technologies and derive the corresponding Cramér-Rao lower bound (CRLB) to gain insight into the performance trade-offs at hand. We evaluate our results by simulations and validate the approach with real-world measurement data. The results show that the clustering approach can halve the root-mean-square error (RMSE) from about 2 m to below 1 m, using WB signal transmissions in the 2.4 GHz ISM band at a bandwidth of about 80 MHz. Full article
(This article belongs to the Special Issue Microwave Sensing Systems)
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17 pages, 4764 KiB  
Article
Transmission-Based Vertebrae Strength Probe Development: Far Field Probe Property Extraction and Integrated Machine Vision Distance Validation Experiments
by Paul Meaney, Robin Augustine, Adrian Welteke, Bernd Pfrommer, Adam M. Pearson and Helena Brisby
Sensors 2023, 23(10), 4819; https://doi.org/10.3390/s23104819 - 17 May 2023
Viewed by 1261
Abstract
We are developing a transmission-based probe for point-of-care assessment of vertebrae strength needed for fabricating the instrumentation used in supporting the spinal column during spinal fusion surgery. The device is based on a transmission probe whereby thin coaxial probes are inserted into the [...] Read more.
We are developing a transmission-based probe for point-of-care assessment of vertebrae strength needed for fabricating the instrumentation used in supporting the spinal column during spinal fusion surgery. The device is based on a transmission probe whereby thin coaxial probes are inserted into the small canals through the pedicles and into the vertebrae, and a broad band signal is transmitted from one probe to the other across the bone tissue. Simultaneously, a machine vision scheme has been developed to measure the separation distance between the probe tips while they are inserted into the vertebrae. The latter technique includes a small camera mounted to the handle of one probe and associated fiducials printed on the other. Machine vision techniques make it possible to track the location of the fiducial-based probe tip and compare it to the fixed coordinate location of the camera-based probe tip. The combination of the two methods allows for straightforward calculation of tissue characteristics by exploiting the antenna far field approximation. Validation tests of the two concepts are presented as a precursor to clinical prototype development. Full article
(This article belongs to the Special Issue Microwave Sensing Systems)
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15 pages, 4798 KiB  
Article
Propagation Constant Measurement Based on a Single Transmission Line Standard Using a Two-Port VNA
by Ziad Hatab, Arezoo Abdi, Gregor Steinbauer, Michael Ernst Gadringer and Wolfgang Bösch
Sensors 2023, 23(9), 4548; https://doi.org/10.3390/s23094548 - 7 May 2023
Cited by 1 | Viewed by 1708
Abstract
This study presents a new method for measuring the propagation constant of transmission lines using a single line standard and without prior calibration of a two-port vector network analyzer (VNA). The method provides accurate results by emulating multiple line standards of the multiline [...] Read more.
This study presents a new method for measuring the propagation constant of transmission lines using a single line standard and without prior calibration of a two-port vector network analyzer (VNA). The method provides accurate results by emulating multiple line standards of the multiline calibration method. Each line standard was realized by sweeping an unknown network along a transmission line. The network need not be symmetric or reciprocal, but must exhibit both transmission and reflection. We performed measurements using a slab coaxial airline and repeated the measurements on three different VNAs. The measured propagation constant of the slab coaxial airline from all VNAs was nearly identical. By avoiding disconnecting or moving the cables, the proposed method eliminates errors related to the repeatability of connectors, resulting in improved broadband traceability to SI units. Full article
(This article belongs to the Special Issue Microwave Sensing Systems)
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12 pages, 2788 KiB  
Communication
UWB-Modulated Microwave Imaging for Human Brain Functional Monitoring
by Youness Akazzim, Marc Jofre, Otman El Mrabet, Jordi Romeu and Luis Jofre-Roca
Sensors 2023, 23(9), 4374; https://doi.org/10.3390/s23094374 - 28 Apr 2023
Cited by 1 | Viewed by 1950
Abstract
Morphological microwave imaging has shown interesting results on reconstructing biological objects inside the human body, and these parameters represent their actual biological condition, but not their biological activity. In this paper, we propose a novel microwave technique to locate the low-frequency ( [...] Read more.
Morphological microwave imaging has shown interesting results on reconstructing biological objects inside the human body, and these parameters represent their actual biological condition, but not their biological activity. In this paper, we propose a novel microwave technique to locate the low-frequency (f1 kHz) -modulated signals produced by a microtag mimicking an action potential and proved it in a cylindrical phantom of the brain region. A set of two combined UWB microwave applicators, operating in the 0.5 to 2.5 GHz frequency band and producing a nsec interrogation pulse, is able to focus its radiated field into a small region of the brain containing the microtag with a modulated photodiode. The illuminating UWB microwave field was first modulated by the low-frequency (f1 kHz) electrical signal produced by the photodiode, inducing modulated microwave currents into the microtag that reradiating back towards the focusing applicators. At the receiving end, the low-frequency (f1 kHz) -modulated signal was first extracted from the full set of the backscattered signals, then focused into the region of interest and spatially represented in the corresponding region of the brain, resulting in a spatial resolution of the images in the order of 10 mm. Full article
(This article belongs to the Special Issue Microwave Sensing Systems)
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21 pages, 2027 KiB  
Article
Improving TDOA Radar Performance in Jammed Areas through Neural Network-Based Signal Processing
by Jakub Gotthans, Tomas Gotthans and David Novak
Sensors 2023, 23(6), 2889; https://doi.org/10.3390/s23062889 - 7 Mar 2023
Viewed by 2306
Abstract
This paper presents a method for estimating the position of a target under jammed conditions using the Time Difference of Arrival (TDOA) method. The algorithm utilizes a deep neural network to overcome the challenges posed by the jammed conditions. The simulations and results [...] Read more.
This paper presents a method for estimating the position of a target under jammed conditions using the Time Difference of Arrival (TDOA) method. The algorithm utilizes a deep neural network to overcome the challenges posed by the jammed conditions. The simulations and results indicate that the presented method is more accurate and efficient than the traditional TDOA methods. Full article
(This article belongs to the Special Issue Microwave Sensing Systems)
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17 pages, 11980 KiB  
Article
Persistent Homology Approach for Human Presence Detection from 60 GHz OTFS Transmissions
by Roman Maršálek, Radim Zedka, Erich Zöchmann, Josef Vychodil, Radek Závorka, Golsa Ghiaasi and Jiří Blumenstein
Sensors 2023, 23(4), 2224; https://doi.org/10.3390/s23042224 - 16 Feb 2023
Cited by 4 | Viewed by 1939
Abstract
Orthogonal Time Frequency Space (OTFS) is a new, promising modulation waveform candidate for the next-generation integrated sensing and communication (ISaC) systems, providing environment-awareness capabilities together with high-speed wireless data communications. This paper presents the original results of OTFS-based person monitoring measurements in the [...] Read more.
Orthogonal Time Frequency Space (OTFS) is a new, promising modulation waveform candidate for the next-generation integrated sensing and communication (ISaC) systems, providing environment-awareness capabilities together with high-speed wireless data communications. This paper presents the original results of OTFS-based person monitoring measurements in the 60 GHz millimeter-wave frequency band under realistic conditions, without the assumption of an integer ratio between the actual delays and Doppler shifts of the reflected components and the corresponding resolution of the OTFS grid. As the main contribution of the paper, we propose the use of the persistent homology technique as a method for processing gathered delay-Doppler responses. We highlight the advantages of the persistent homology approach over the standard constant false alarm rate target detector for selected scenarios. Full article
(This article belongs to the Special Issue Microwave Sensing Systems)
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Review

Jump to: Research

31 pages, 4981 KiB  
Review
Review of Microwave Near-Field Sensing and Imaging Devices in Medical Applications
by Cristina Origlia, David O. Rodriguez-Duarte, Jorge A. Tobon Vasquez, Jean-Charles Bolomey and Francesca Vipiana
Sensors 2024, 24(14), 4515; https://doi.org/10.3390/s24144515 - 12 Jul 2024
Viewed by 1358
Abstract
Microwaves can safely and non-destructively illuminate and penetrate dielectric materials, making them an attractive solution for various medical tasks, including detection, diagnosis, classification, and monitoring. Their inherent electromagnetic properties, portability, cost-effectiveness, and the growth in computing capabilities have encouraged the development of numerous [...] Read more.
Microwaves can safely and non-destructively illuminate and penetrate dielectric materials, making them an attractive solution for various medical tasks, including detection, diagnosis, classification, and monitoring. Their inherent electromagnetic properties, portability, cost-effectiveness, and the growth in computing capabilities have encouraged the development of numerous microwave sensing and imaging systems in the medical field, with the potential to complement or even replace current gold-standard methods. This review aims to provide a comprehensive update on the latest advances in medical applications of microwaves, particularly focusing on the near-field ones working within the 1–15 GHz frequency range. It specifically examines significant strides in the development of clinical devices for brain stroke diagnosis and classification, breast cancer screening, and continuous blood glucose monitoring. The technical implementation and algorithmic aspects of prototypes and devices are discussed in detail, including the transceiver systems, radiating elements (such as antennas and sensors), and the imaging algorithms. Additionally, it provides an overview of other promising cutting-edge microwave medical applications, such as knee injuries and colon polyps detection, torso scanning and image-based monitoring of thermal therapy intervention. Finally, the review discusses the challenges of achieving clinical engagement with microwave-based technologies and explores future perspectives. Full article
(This article belongs to the Special Issue Microwave Sensing Systems)
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