Antenna Sensor Research Articles

Human Muscle Mass Measurement through passive Flexible UWB-Myogram Antenna sensor to diagnose Sarcopenia

Sarcopenia disease is due to low muscle mass in humans. Sarcopenia leads to osteoporosis, metabolic syndrome and difficulty in performing day-to-day activities. At present, Dual-energy X-ray Absorptiometry (DXA) measures muscle mass with few limitations. They are variations in measurements according to region under investigation, irregularities in hydration status, and low precision in tall and obese persons. These limitations are due to low dosage level of X-ray radiations in certain muscle regions of human body such as heart, head, lower and upper extremities. This paper presents a non-invasive passive flexible Ultra Wide Band (UWB) Myogram antenna sensor for the prediction of Sarcopenia through human muscle mass measurement. This antenna is adhesively fixed on ventral surface of forearm and biceps for the measurement of skeletal and lean mass respectively. The proposed antenna sensor performs electromagnetic energy absorption from muscle tissues under radiating near-field condition. The muscle tissue signal from antenna is applied to blind source filtering-Non-negative Matrix Factorization (NMF), then subjected to Multi-Synchro Squeezing Transform (MSST), and finally correlated using linear regression machine learning algorithm to diagnose Sarcopenia. Furthermore, the proposed methodology is developed as a product through the MATLAB Mobile App compatible with Android devices. The proposed method of diagnosing Sarcopenia achieves an accuracy of 85% in fifty samples.

Design and experimental analysis of dual-band polarization converting metasurface for microwave applications

The manipulation of polarization state of electromagnetic waves is of great importance in many practical applications. In this paper, the reflection characteristics of a thin and dual-band metasurface are examined in the microwave frequency regime. The metasurface consists of a 22 × 22 element array of periodic unit cells. The geometry of the unit cell consists of three layers, including a 45° inclined dipole shape metal patch on top, which is backed by a 1.6 mm thick FR-4 substrate in the middle, and a fully reflective metallic mirror at the bottom. The proposed surface is exposed to horizontally (x) or vertically (y) polarized plane waves and the co and cross polarization reflection coefficients of the reflected waves are investigated experimentally in the 6–26 GHz frequency range. The metasurface is designed to convert incident waves of known polarization state (horizontal or vertical) to orthogonal polarization state (vertical and horizontal) in two distinct frequency bands, i.e. 7.1–8 GHz and 13.3–25.8 GHz. In these two frequency bands the simulated and experimental results are in good agreement. The polarization conversion ratio (PCR) of the surface is greater than 95% in the targeted frequency bands. A detailed parametric analysis of the metasurface is also discussed in this work and it has been estimated that the surface has the additional ability to convert linearly polarized waves to circularly polarized waves at several distinct frequencies. The proposed metasurface can be utilized in sensor applications, stealth technology, electromagnetic measurements, and antennas design.

A Capacitively-Fed Inverted-F Antenna for Displacement Detection in Structural Health Monitoring.

This paper presents a capacitive displacement sensor based on a capacitively fed inverted-F antenna (CFIFA) for displacement detection. The sensor is composed of a grounded L-shape patch and a rectangular upper patch, forming a capacitor between them. The asymmetric dipole model is adopted to explain the frequency shift and current distribution of the proposed antenna sensor at its first-order resonance. The numerical simulation of the CFIFA using the Ansoft high-frequency structure simulator (HFSS) software is carried out to optimize the dimensional parameters, allowing the antenna to perform better. Two sets of CFIFAs are fabricated and tested for verification. Results show that the CFIFA has a good linear relationship between its first resonant frequency and the relative displacement, and is capable of a long range of displacement measuring.

57–64 GHz Imaging/Detection Sensor—Part II: Experiments on Concealed Weapons and Threatening Materials Detection

In this paper, experimental evaluations over the frequency range of a 57–64 GHz for an improved millimeter wave (MMW) imaging/detection system have been conducted. The main objective behind this work is to examine the performance of a high gain and low profile multi sine corrugated AFTSA antenna sensor in the detection of metallic, non-metallic weapons and suspected liquids hidden by clothing, plywood, and plastics. A microwave holography technique based on time domain reflectometry (TDR), which utilizes amplitude information recorded over a 2D aperture, reconstructs a focused image of the target. 60 GHz ISM band imaging detection experiments elaborate the ability for the detection of concealed weapons or other threatening items placed on a body phantom, easily penetrating clothing material of different thicknesses, as well as able to detect through plywood and plastics. The MMW image is detected using a 2D linear scanning platform which generates XY movement, with a $30\times30$ cm2 mechanical range for the object field of view and oriented perpendicular with respect to a lens focal plane. This work is performed with a cross range resolution of $\delta {x}=\delta {y}= 3$ mm achieving a $100\times100$ pixels MMW image. The mechanical setup scanning method is similar to synthetic aperture array with a single AFTSA antenna element measurement, ideal for investigating the probe for 60 GHz band imaging and in detecting concealed threatening items at security surveillance checkpoints.

57-64 GHz Imaging/Detection Sensor–Part I: System Setup and Experimental Evaluations

A novel experimental evaluation of millimeter-wave imaging / detection system based on time domain reflectometry (TDR) is presented. The proposed 60 GHz-band system is characterized by high precision, lightweight, low profile, and utilization of low cost scanning probes. As a scanning sensor, multi sin-corrugation antipodal tapered slot antenna (MC-AFTSA-SC) with and without a grooved spherical probe is introduced. Although, the precise mechanical setup is especially designed and optimized to hold the proposed scanning probe antenna, it can handle a wide range of probes. The proposed antenna sensor is experimentally evaluated by integrating it in the proposed imaging / detection system. As a bench-marking process, multiple images for different targets are reconstructed using both the proposed probe and conventional standard gain horn (SGH) antenna. The images are generated using 2D linear scanning platform with a cross range resolution $\delta {x}=\delta {y}=3$ mm achieving a $100\times100$ pixels image. The obtained images indicate a superior performance of the proposed scanning probe over the bigger sized SGH. This paper is split into two parts because of its length: this paper (part I) describes the system setup and experimental evaluation of the probes, while part II will discuss experiments for detecting concealed weapons and threatening materials.

ACOUSTIC EMISSION CONTROL OF THE PROCESS OF DESTRUCTION OF CARBON FIBER SAMPLES AND THE WING BOX UNDER SHOCK LOADS

Investigations of three groups of samples from carbon fiber T 700 and the composite wing box of the aircraft were carried out. Samples with monolayers laying 0; 90; –45 were subjected to shock loads, which were applied at their center with a load in the form of a blunt tip weighing 0.53 kg. Loads were dumped from a height of 0,3; 0,5; 1 m per sample. Impact damage with an energy of 15 J was also applied to the upper surface of the carbon fiber wing box. Acoustic emission (AE) signals were recorded from the piezoelectric antenna sensors mounted on the wing samples and box both during the impact of the weight with the object under study and during rebounds. The locations where the shock load were applied were located and the parameters of the AE signals were analyzed. The influence of the type of monolayer laying on the process of cracking in the material of the samples arising at different energy of shock loads was determined.

A Review of Flexible Wearable Antenna Sensors: Design, Fabrication Methods, and Applications.

This review paper summarizes various approaches developed in the literature for antenna sensors with an emphasis on flexible solutions. The survey helps to recognize the limitations and advantages of this technology. Furthermore, it offers an overview of the main points for the development and design of flexible antenna sensors from the selection of the materials to the framing of the antenna including the different scenario applications. With regard to wearable antenna sensors deployment, a review of the textile materials that have been employed is also presented. Several examples related to human body applications of flexible antenna sensors such as the detection of NaCl and sugar solutions, blood and bodily variables such as temperature, strain, and finger postures are also presented. Future investigation directions and research challenges are proposed.

Application of Artificial Neural Networks for Accurate Determination of the Complex Permittivity of Biological Tissue.

Medical devices making use of radio frequency (RF) and microwave (MW) fields have been studied as alternatives to existing diagnostic and therapeutic modalities since they offer several advantages. However, the lack of accurate knowledge of the complex permittivity of different biological tissues continues to hinder progress in of these technologies. The most convenient and popular measurement method used to determine the complex permittivity of biological tissues is the open-ended coaxial line, in combination with a vector network analyser (VNA) to measure the reflection coefficient (S11) which is then converted to the corresponding tissue permittivity using either full-wave analysis or through the use of equivalent circuit models. This paper proposes an innovative method of using artificial neural networks (ANN) to convert measured S11 to tissue permittivity, circumventing the requirement of extending the VNA measurement plane to the coaxial line open end. The conventional three-step calibration technique used with coaxial open-ended probes lacks repeatability, unless applied with extreme care by experienced persons, and is not adaptable to alternative sensor antenna configurations necessitated by many potential diagnostic and monitoring applications. The method being proposed does not require calibration at the tip of the probe, thus simplifying the measurement procedure while allowing arbitrary sensor design, and was experimentally validated using S11 measurements and the corresponding complex permittivity of 60 standard liquid and 42 porcine tissue samples. Following ANN training, validation and testing, we obtained a prediction accuracy of 5% for the complex permittivity.

InSb Based Microstrip Patch Antenna Temperature Sensor for Terahertz Applications

Reconfigurable sensing antennas (RSA) play a significant role in modern internet-of-things (IOT) applications. The RSAs are capable of transmiting and receiving electromagnetic waves besides sensing different enviroment parameters. This paper introduces a reconfigurable sensing microstrip patch antenna desinged to sense high temperature variations in harsh environment. The indium antimonide (InSb) semiconductor material is a temperature sensitive material employed in RSA designs in the Terahertz (THz) frequency band. An investigation of the temperature dependency of the electrical properties of the InSb-material is introduced. The proposed sensing antenna introduces high sensitivity of 1.588 GHz shift in resonance frequency per unit change in temperature (Kelvin). The resonance frequency of the InSb sensor antenna is changed according to the surrounding environment temperature from 264 GHz to 502.2 GHz with a broadband tuning range of 90.2%. The InSb patch sensor have temperature sensing range of 150 K starting from 250 up-to 400 K. At 300 K the InSb sensor antenna proposes a peak gain of 6.4 dBi with impedance matching bandwidth of 9.57%. An equivalent circuit consists of five lumped elements is estimated for the InSb sensor antenna using particle swarm optimization (PSO) technique at different temperatures. At T = 250 K the maximum radiation efficiency is 2.5% and is increased up to 86.3% at T = 400 K.

An Electromagnetically Induced Transparency Inspired Antenna Sensor for Crack Monitoring

The simultaneous communication and sensing based on antenna sensors are receiving increasing attention for pervasive monitoring in the internet of things (IoT). The open structure for high radiation limits the antenna’s sensitivity and resolution when it functions as an electromagnetic sensor. In this article, an antenna sensor operated in the ultra-high frequency (UHF) radio frequency identification (RFID) band is reported for structural health monitoring (SHM) applications. A loaded split-ring resonator (SRR) renders a low Q-factor bright mode for communication and two back-sited U-shaped strip resonators are embedded among high dielectric material, confining the near-field and yielding a high Q-factor dark mode for sensing. The two modes are proximity coupled and form an electromagnetically induced transparency (EIT)-like effect to achieve simultaneous communication and sensing in the narrow UHF RFID band. An enhancement around five times in the sensitivity can be observed resulting from the trapped field in the dark mode. The simulated sensitivity and the maximum peak realized gain of the proposed antenna sensor are around 3.0 MHz/mm2 and 3.77 dBi respectively. A prototype antenna sensor in a size of 42.0 mm $\times42.0$ mm $\times9.0$ mm is fabricated and measured. The detectability of surface crack using the proposed antenna sensor is experimentally validated by two case studies. The measured results demonstrate a sensitivity of 2.73 MHz/mm2 for crack depth characterization and a sensitivity of 2.75 MHz/mm2 for crack width characterization.

High-Resolution Dielectric Constant Measurement Using a Sensor Antenna With an Allocated Link for Data Transmission

A dual-band low-profile patch antenna, which operates based on aperture-coupling mechanism, is exploited to measure the permittivity of a sample under test (SUT) in the microwave frequencies and send the measured data simultaneously. The upper resonant frequency, which is considerably affected by changing the permittivity of the SUT, can be utilized for sensing purpose. In contrast, the lower resonant frequency is almost independent of the samples hence can be used as the communication link. The samples are placed on top of the feeding side of the structure. The variation in the sample’s permittivity leads to changes in the input impedance of the sensor antenna. While this change results in having different feedline-dependent resonant frequencies, the cavity-dependent resonant frequency is almost preserved intact for different samples. The sensor antenna is designed using electromagnetic solver and an equivalent circuit is proposed to model its behavior. The effect of varying parameters in the equivalent model is investigated. Moreover, by fabricating the sensor, the measurement results show that by changing the permittivity of samples from 1 to 12.85, the upper band resonant frequency (feedline-dependent) shifts from 12.30 to 11.37 GHz (78 MHz per unit dielectric constant). Nevertheless, the small variation in resonant frequency and radiation characteristics of the antenna in the lower band (cavity-dependent) can provide a stable communication channel with respect to the SUT. This link with a reasonable 2.8% (9.54-9.81 GHz) 10-dB impedance bandwidth can be reserved for sending the measured and pilot data in a wireless sensor system.

Thermally Stable Wireless Patch Antenna Sensor for Strain and Crack Sensing.

Strain and crack are critical indicators of structural safety. As a novel sensing device, a patch antenna sensor can be utilized to wirelessly estimate structural strain and surface crack growth through resonance frequency shift. The main challenges for the sensor are other effects such as temperature fluctuation that can generate unwanted resonance frequency shift and result in large noise in the measurement. Another challenge for existing designs of patch antenna sensor is the limited interrogation distance. In this research, thermally stable patch antenna sensors are investigated for more reliable measurement. Fabricated on a substrate material with a steady dielectric constant, a new passive (battery-free) patch antenna sensor is designed to improve reliability under temperature fluctuations. In addition, another newly designed dual-mode patch antenna sensor is proposed to achieve a longer interrogation distance. Extensive experiments are conducted to characterize the patch antenna sensor performance, including thermal stability, tensile strain sensing, and emulated crack sensing. The two new patch antenna sensors are demonstrated to be effective in wireless strain and crack measurements and have potential applications in structural health monitoring (SHM).

Comparison of Partial Discharge Characteristics Detected by RC Detector and Rectangular Antenna

This study discusses the method of measuring and detecting Partial Discharge (PD) in high voltage electrical equipment that has the characteristics of being veiled with metal. This research uses the UHF (Ultra High Frequency) method based on IEC 60270 and RC Detector to detect and measure PD. This method uses electromagnetic wave energy emitted by PD sources from the metal box. Use this method to get detection and measure without having to activate the test object. Then the sensors used in testing in this study are rectangular spiral antennas and RC detectors. In addition, various stresses will be tested. The measurement results then compare when evaluating the PD between the Rectangular Spiral antenna and the RC Detector to determine the sensitivity level of the rectangular spiral antenna. The test results show the measurement of partial release of rectangular spiral antenna is greater than outside the metal box and measurement using RC Detector is more sensitive than using a rectangular spiral antenna sensor.

Antenna Sensors Prepared by Laser Direct Writing Based on Graphene Hybrid Materials

Antenna Sensors Prepared by Laser Direct Writing Based on Graphene Hybrid Materials

Robust Modified MVDR Scheme Using Chirp Signal for Direction of Arrival Estimation

This research is about an effort to increase the robustness of the Minimum Variance Distortionless Response (MVDR) algorithm to noise by using a chirp signal for direction of arrival estimation (DoA). DoA is a part of radar capability to estimate the angle of arrival on the object under observation. The conventional MVDR as proposed by J. Capon, was designed to work with the monochromatic sinusoidal signal. Even though the conventional MVDR work on low SNR up to 0 dB, however, the conventional method does not work well if chirp signal is used instead of monochromatic sinusoidal signal. The usage of MVDR chirp signal is essential in the case of a very low SNR environment such as in long distance object detection, which is typically more than 10 km. The problem to be solved in this research is how to modify the MVDR algorithm so that it can work well on chirp signal. In this research we offer a modified MVDR algorithm by adding the matched filter and the phase detector components before the MVDR algorithm is applied. Matched filter is responsible for the timing of the chirp signal detection, and the phase detector is to estimate the time delay estimation of each chirp signal from each antenna with a reference signal, which correspond to the phases. Based on the phase estimation, sinusoidal signal is generated and fed to the MVDR algorithm. On the technical aspect, the chirp signal is sent intermittently with a duration of 100 ?s and repeated in time interval of 1 ms. The antenna sensor using an array of Uniform Linear Array (ULA) which consist of N-elements. Computer simulation shows that the modified MVDR using the chirp signal improve the robustness of the algorithm up to -30 dB, while on the other hand the classical MVDR works only up to 0 dB SNR. -30 dB of SNR is the minimum requirement of 3D Radar existing.

Experimental Investigation of the Breast Phantom for Tumor Detection Using Ultra-Wide Band–MIMO Antenna Sensor (UMAS) Probe

In this work, a novel Ultra-wideband-Multi-Input-Multi-Output Antenna Sensor (UMAS) probe is designed for the detection of the malignant cells in the breast. The Sensor probe has four radiating elements and it is operated within the 2.8 GHz to 20 GHz ultra-wide band range. Isolation between the radiating element is more than 20 dB. Further, three kinds of the breast phantoms (i.e. normal phantom, phantom with single and multiple tumors) are fabricated using tissue mimicking material. The electrical characteristics of the malignant cells are different from non-malignant cells of the breast. The S-parameter and Specific Absorption Rate (SAR) analysis are best approaches to detect the malignant cells in the breast. The UMAS sensing probe is embedded on the phantoms and S-parameters of the probe are recorded from the Vector Network Analyzer (VNA). Measured S-parameters of the probe for normal and malignant phantoms are differ from each other. The statistical machine learning concept of Principal Component Analysis (PCA) is also applied on the measured S-Parameters. Which exhibits clear detection of normal and malignant breast phantoms. Further verification is done by using Simulation based specific absorption rate (SAR) study of the phantom models for tumor detection. The obtained maximum SAR results are well differentiating the normal phantom.

Detection of metallic andnonmetallicconcealed targets based on millimeter‐wave inverse scattering approach

A millimeter-wave radar based on active invers scattering approach for two dimensional screening of metallic and nonmetallic concealed targets is presented. The perceived challenges of detecting a nonmetallic target exhibiting poor dynamic range for measurement systems are analyzed and discussed by comparing the performance of three different antenna sensors. A short time duration pulse with frequency sweep covering 27 to 33 GHz band is used to feed the antenna sensors. In our experimental test, we buried a concealed target consists of metallic or dielectric strips under a dielectric layer that simulates the human body model. Waveguide and printed antipodal Vivaldi antennas are considered to study the target detectability and the quality of the measured millimeter-wave images. The use of proposed AVA resulted in a better-quality image with lower noise effect for both metallic and nonmetallic cases.

Microfluidic Flexible Substrate Integrated Microstrip Antenna Sensor for Sensing of Moisture Content in Lubricating Oil

In this paper, a flexible microstrip patch antenna sensor is proposed for monitoring of the moisture content of lubricating oil. The sensor identifies liquids having different effective dielectric constants by detecting changes in the resonance frequency. The proposed antenna comprises a radiation patch, a metal ground plane, and a PDMS substrate with microchannels. The microchannels are etched on the PDMS substrate. When the relative permittivity of the microfluidic channel is 1.8∼12.5, the operating frequency of the proposed antenna changes from 2.230 to 2.116 GHz, and the amplitude of the reflection coefficient is greater than −26.3 dB. The simulation and measurement results show that the proposed sensor can monitor the lubricating oil with different moisture contents, which can cause frequency separation of at least 20 MHz and achieve a good linear response. Therefore, the proposed sensor has the feasibility of monitoring the quality of lubricating oil.

Beamforming Optimization in Internet of Things Applications Using Robust Swarm Algorithm in Conjunction with Connectable and Collaborative Sensors.

The integration of the Internet of Things (IoT) with Wireless Sensor Networks (WSNs) typically involves multihop relaying combined with sophisticated signal processing to serve as an information provider for several applications such as smart grids, industrial, and search-and-rescue operations. These applications entail deploying many sensors in environments that are often random which motivated the study of beamforming using random geometric topologies. This paper introduces a new algorithm for the synthesis of several geometries of Collaborative Beamforming (CB) of virtual sensor antenna arrays with maximum mainlobe and minimum sidelobe levels (SLL) as well as null control using Canonical Swarm Optimization (CPSO) algorithm. The optimal beampattern is achieved by optimizing the current excitation weights for uniform and non-uniform interelement spacings based on the network connectivity of the virtual antenna arrays using a node selection scheme. As compared to conventional beamforming, convex optimization, Genetic Algorithm (GA), and Particle Swarm Optimization (PSO), the proposed CPSO achieves significant reduction in SLL, control of nulls, and increased gain in mainlobe directed towards the desired base station when the node selection technique is implemented with CB.

Hybrid Sensing of Internal and Surface Partial Discharges in Air-Insulated Medium Voltage Switchgear

Partial discharge (PD) measurements have proved their reliability for health monitoring of insulation systems in power system components including synchronous generators, power transformers, switchgear and cables etc. Online condition monitoring and pro-active detection of PD faults have been highly demanded over the last two decades. This paper provides results from a research project to develop advanced non-intrusive sensing technologies that are cost effective, reliable and efficient for early detection of PD faults in medium voltage (MV) and high voltage (HV) air-insulated switchgear. Three sensors (high frequency E-field (D-dot) sensor, Rogowski coil and loop antenna) have been developed and tested under various PD faults and their performance were evaluated in comparison with high frequency current transformer (HFCT) which is being used commercially for PD testing and measurement. Among these three sensors, it is shown that D-dot sensor and Rogowski coil are more dependable when it comes to the PD measurements due to their high signal to noise ratio and hence high accuracy. These sensors can be customized according to a specific application and can be connected together with one data acquisition device while developing an online condition monitoring system.