Antenna Sensor Research Articles

Strain Sensor Based on Rectangular Microstrip Antenna: Numerical Methodologies and Experimental Validation

In this paper, two different computational methodologies are implemented to predict the behavior of a strain sensor based on a microstrip antenna. The first approach attributes changes in resonance frequency only to variations in patch length produced by an applied axial tensile loading. In the second approach, a Multiphysics model has used to couple the mechanical and electromagnetic phenomena. Thus, this model considers the characteristics of the variations in the antenna structure and the dielectric substrate that is used. Additionally, this study describes the fabrication of such a sensor and an experimental validation in which the rectangular microstrip antenna was subjected to tensile forces. The obtained results gave a good convergence between simulation results and measurements, so the proposed models clearly describe the behavior of the strain sensor. Nevertheless, the sensor analyzed here achieves a sensitivity of −2.847 kHz/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mu } {\varepsilon }$ </tex-math></inline-formula> , high repeatability, and its resolution depends on the implemented vector network analyzer. Moreover, the proposed sensor operates in an ISM band and, as a result, it can be integrated with commercial electronic devices. This article aims to lay the foundation for the future use of patch antenna sensors for structural health monitoring by introducing a computational methodology that can predict the behavior of this kind of sensor.

Temperature and Pressure Wireless Ceramic Sensor (Distance = 0.5 Meter) for Extreme Environment Applications.

This paper presents a design for temperature and pressure wireless sensors made of polymer-derived ceramics for extreme environment applications. The wireless sensors were designed and fabricated with conductive carbon paste on an 18.24 mm diameter with 2.4 mm thickness polymer-derived ceramic silicon carbon nitride (PDC-SiCN) disk substrate for the temperature sensor and an 18 × 18 × 2.6 mm silicon carbide ceramic substrate for the pressure sensor. In the experiment, a horn antenna interrogated the patch antenna sensor on a standard muffle furnace and a Shimadzu AGS-J universal test machine (UTM) at a wireless sensing distance of 0.5 m. The monotonic relationship between the dielectric constant of the ceramic substrate and ambient temperature is the fundamental principle for wireless temperature sensing. The temperature measurement has been demonstrated from 600 °C to 900 °C. The result closely matches the thermocouple measurement with a mean absolute difference of 2.63 °C. For the pressure sensor, the patch antenna was designed to resonate at 4.7 GHz at the no-loading case. The sensing mechanism is based on the piezo-dielectric property of the silicon carbon nitride. The developed temperature/pressure sensing system provides a feasible solution for wireless measurement for extreme environment applications.

Antenna Sensor Based on AMC Array for Contactless Detection of Water and Ethanol in Oil

When ethanol and water are mixed into gasoline, the dielectric properties of gasoline will change. Based on this characteristic, we propose an antenna sensor and study its radiation and sensing performance in detection of ethanol gasoline in 6-7GHz band. In order to avoid the corrosion of the oil sample on the antenna, the antenna adopts a multilayer dielectric substrate structure. A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 2$ </tex-math></inline-formula> artificial magnetic conductor (AMC) array is loaded on the bottom of the antenna to increase the gain of the sensor and reduce the return loss. The antenna sensor has good radiation pattern with a peak gain of 4 dB and high quality factor(Q) up to 69. Furthermore, the antenna sensor shows the advantages of high sensitivity and wide detection range on the detection of oil-water mixture and ethanol gasoline concentration. In order to verify the simulated results, the radiation and sensing performance of the antenna were measured, and the measured results were basically consistent with the simulated ones. Therefore, the proposed antenna sensor can be used for real-time wireless detection in ethanol gasoline transportation.

Detection of setting time in cement hydration using patch antenna sensor

Detection of setting time in cement hydration using patch antenna sensor

A multi-physics informed antenna sensor model through the deep neural network regression

A passive wireless strain sensing method using antenna sensors has significantly advanced structural health monitoring systems. Since the dimensions of antenna sensors are sensitive to their strain sensing performance and operating frequency, an iterative tuning process is required to achieve a final optimized design. Although multi-physics finite element simulation enables accurate estimation of antenna performance for each turning iteration, the simulation process requires high computational resources. Therefore, antenna tuning processes are recognized as obstacles to delay the final design process. In this study, we explore the potential of multi-physics informed models as an alternative approach for analyzing antenna sensors. Through deep neural networks, as a branch of the machine-learning algorithms, we formulate multi-physics informed models with six input parameters (antenna dimensions) and two outputs (resonance frequency and strain sensitivity). Twenty-two hundred high fidelity data sets are prepared by simulating multi-physics models: 1,600, 400, and 200 data sets are applied to deep neural network regression (DNNR) training, validating, and testing, respectively. From extensive data investigation, an optimized DNNR architecture is obtained to be two layers, with 16 neurons in each layer. Its training, validating, and testing values of mean square errors are 13.01, 44.22, 37.27, respectively. Finally, the proposed multi-physics informed model predicts the resonance frequency and strain sensitivity with errors of 0.1% and 0.07%, respectively. In addition, since the average computation speed for each tuning process is 0.007 seconds, the practical usefulness of the proposed method is also proven.

Partial discharge detection with on-chip spiral inductor as a loop antenna.

In this paper, a pioneer partial discharge (PD) loop antenna sensor is presented and examined. It is made of a 70-turn square planar inductor with a side length of 1.8mm, which is fabricated on top of a silicon substrate in complementary metal oxide semiconductor technology. The microsensor ability to detect corona PD is demonstrated once connected in series with a 60 dB gain amplifier. The behavior is studied at different separation distances from the line through which the PD pulses flow. At 5cm away, a damped sinusoidal induced voltage with an amplitude of about 100 mV has been measured. The output signal spectrum is highly concentrated around a central resonance frequency of ∼5MHz. The microsensor response is compared with those of other industrial sensors from Techimp, i.e., horn antennas and high-frequency current transformer sensors. The presented on-chip sensor can be considered a non-intrusive competing solution compared with other heavy and expensive commercial sensors due to its lightweight, compact size, and low cost. In addition, it shows an acceptable signal to noise ratio compared with other commercial electromagnetic wave-based sensors.

Intelligent Ureteral Stent for Early Detection of Hydronephrosis

AbstractMillions of people around the world currently suffer from kidney stone diseases. While ureteral stenting is an unmistakably effective treatment of these patients, their long‐term adverse effects can result in the build‐up of crystals around the stent. This, in turn, can lead to new ureter blockages that can dangerously increase kidney pressure, a condition known as hydronephrosis, which, if severe and prolonged, can cause irreversible kidney damage. Toward enabling early detection of hydronephrosis, this paper investigates the first intelligent ureteral stent with an integrated radiofrequency antenna and micro pressure sensor for resonance‐based wireless tracking of kidney pressure. Prototyping is conducted using a commercial ureteral stent as the substrate for microfabrication of the device. The packaged device is experimentally assessed for electrical characterizations and wireless pressure sensing using an in vitro test model. Preliminary telemetry testing demonstrates the fundamental ability of the device with its approximately linear responses of up to 1.7 kHz mmHg−1 over a pressure range of up to 120 mmHg in air, water, and artificial urine. These findings verify the efficacy of the device design and the approach to kidney pressure monitoring through indwelling stents, paving the way for the transfer of this technology to today's ureteral stent products.

A Wearable Button Antenna Sensor for Dual-Mode Wireless Information and Power Transfer.

A novel wearable button antenna sensor is proposed for the concept of simultaneous wireless information and power transfer (SWIPT). This integrates two working modes for the transfer of power and information, respectively, and optimizes transfer efficiency. An omni-directional radiation pattern is achieved in the 3.5 GHz World Interoperability for Microwave Access (WiMAX) band to support on-body wireless communications, while a circularly polarized broadside radiation pattern is obtained in the 5 GHz wireless local area networks (WLAN) band to harvest power. The measured −10 dB return loss bandwidths are 4.0% (3.47–3.61 GHz) in the lower band, and 25.0% (4.51–5.80 GHz) in the higher band, respectively. An artificial magnetic conductor (AMC) structure with wideband characteristics is applied to obtain a low-profile design and to increase the stability of the antenna sensor. A high radiation efficiency of over 80% in the whole working band is observed. The specific absorption rate (SAR) of the proposed antenna sensor is below 0.509 W/kg at 3.55 GHz, and below 0.0532 W/kg at 5.5 GHz, respectively, which is much lower than the European standard threshold of 2 W/kg. All these characteristics make the designed antenna sensor suitable for on-body information transmission and off-body energy harvesting. The antenna sensor has been prototyped. Simulations and measurements agree well, proving the validity of the new concept.

Partial discharge type detection and identification based on its sources

Partial discharge (PD) is a symptom of initial damage to high voltage equipment insulators which if left for a long period will cause total damage to high voltage equipment. This study aims to detect and identify the type of PD based on the source of its discharge so that it can be useful in terms of monitoring and maintenance of high voltage equipment. In this research, the Hilbert fractal antenna sensor is used in the detection process of surface, cavity, and corona PD with different input voltage variables that successfully produce a total of 600 PD signal data on the oscilloscope. To reduce noise on the PD signal, the denoising process is done by utilizing the sym4 wavelet feature found in the MATLAB software. The denoising process generates new data so that the research data becomes 600 original PD signal data and 600 denoising PD signal data. With a statistical approach, all PD signal data is extracted successfully into the mean, skewness, kurtosis, and standard deviation parameters which are useful as input for the PD type identification process. From each of the PD signal statistical data, 450 data are used in the training data process and 150 data are used in the data testing process. The PD type identification process is performed using a back propagation neural network with a mean square error (MSE) level of 0.01. The identification results show that back propagation neural networks are able to identify PD types based on statistical input accurately. In addition, the denoising process also affects the accuracy of the identification results of the PD type that is 95.33% for the original discharge signal to 97.33% for the denoising signal.

Mechanical Design and Manufacturing of Signal Interception Antenna in Composite Material for Naval Application

This work shows the mechanical design and the FE analyses performed for an innovative naval Antenna Unit for signal interception application: more than twenty electromagnetic sensors operating from HF up to Ka band and microwave modules are integrated in a unique structure designed for a top mast installation (i.e. for naval platform). The number of constraints in terms of weight and electromagnetic transparency calls for the employment of composite materials such as glass, aramidic and carbon epoxy prepregs. Primary structures was modelled by using FE codes: both orthotropic and isotropic models have been implemented as well as non-linear contacts and bolted joints. The mast-mounted installation requires high mechanical stiffness and strength but the exposure to saline environment needs many manufacturing issues to be respected. In particular, the selection process of suitable materials and the sealing manufacturing procedures to protect them from the external agents was reported. Another key feature of the presented design concerns the electromagnetic compatibility requirement: to avoid electromagnetic emissions (EMC) generated by antenna’s internal units and to protect antenna sensors by external platform’s emitters, an appropriate stacking sequence was chosen for composite laminates with a prepreg copper mesh.

Smart Superhydrophobic Textiles Utilizing a Long-Range Antenna Sensor for Hazardous Aqueous Droplet Detection plus Prevention.

This paper demonstrates the feasibility of a long-range antenna sensor embedded underneath a liquid repellent fabric to be employed as a wearable sensor in personal protective fabrics. The sensor detects and monitors hazardous aqueous liquids on the outer layer of fabrics, to add an additional layer of safety for professionals working in hazardous environments. A modified patch antenna was designed to include a meandering-shaped resonant structure, which was embedded underneath the fabric. Superhydrophobic fabrics were prepared using silica nanoparticles and a low-surface-energy fluorosilane. 4 to 20 μL droplets representing hazardous aqueous solutions were drop-cast on the fabrics to investigate the performance of the embedded antenna sensor. Long-range (S21) measurements at a distance of 2-3 m were performed using the antenna sensor with treated and untreated fabrics. The antenna sensor successfully detected the liquid for both types of fabrics. The resonant frequency sensitivity of the antenna sensor underneath the treated fabric exhibiting superhydrophobicity was measured as 370 kHz/μL, and 1 MHz/μL for the untreated fabric. The results demonstrate that the antenna sensor is a good candidate for wearable hazardous aqueous droplet detection on fabrics.

Reconfigurable Antenna Array Direction Finding System Based on a Fast Search Algorithm.

In a traditional antenna array direction finding system, all the antenna sensors need to work or shut down at the same time, which often leads to signal crosstalk, signal distortion, and other electromagnetic compatibility problems. In addition, the direction-finding algorithm in a traditional system needs a tremendous spectral search, which consumes considerable time. To compensate for these deficiencies, a reconfigurable antenna array direction finding system is established in this paper. This system can dynamically load part or all of the antennas through microwave switches (such as a PIN diode) and conduct a fast direction of arrival (DOA) search. First, the hardware structure of the reconfigurable antenna is constructed. Then, based on the conventional spatial domain search algorithm, an improved transform domain (TD) search algorithm is proposed. The effectiveness of the system has been proven by real experiments, and the advantage of the system has been verified by detailed simulations.

Textile UHF-RFID antenna sensor for measurements of sucrose solutions in different levels of concentration

With the trend of textile antennas development, ultra high frequency (UHF, 865–868 MHz) radio frequency identification (RFID) devices using textile materials are expected to be developed in many areas for replacing or simplifying some complex RFID devices on a PCB. In this paper, we present a textile UHF-RFID tag with two sensing positions (‘radiation parts’ and ‘loop part’) for exploring the feasibility of sucrose solutions measurements and the relationship between variables of the proposed design and the sucrose solutions. The simulated and measured resonance curves of the designs both match well (−20 dB in the simulation and −15.8 dB in the measurement at 868 MHz) and the read range measured by the RFID reader (M6e kit) is 1.71 m in air. Before the tests by the solutions on the proposed designs, a test board is developed as a preparation work for confirming the relative dielectric constants of the sensing substrate area in the real measurements. Compare the results of the simulation and the real tests, the proposed design shows good feasibility by comparing the simulated and measured results in confirmed relative dielectric constants. Moreover, its two sensing positions have different sensing features. The sensing ‘radiation parts’ position shows a stable frequency operation performance but sensing range is from 1.71 m (dry) to 2.3 m, while the sensing ‘loop part’ position has a wide sensing range from 0.4 m to 1.71 m (dry) but a lower frequency operation performance.

An Implantable Antenna Sensor for Medical Applications

Pathological changes of human tissues, such as tumors, can cause changes in the dielectric properties of the tissues. Based on this characteristic, we propose an implantable antenna sensor and study its radiation and sensing performance in breast tumor recurrence diagnosis in the 2.45 GHz Industrial, Scientific, and Medical (ISM) band. The antenna sensor shows the advantage of miniaturization with a volume of 13.2mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> by employing an S-shape monopole antenna and a closed loop. The simulated results show that the antenna sensor has a good radiation pattern with peak gain values of -8.4 and -17.9dBi in normal and malignant breast tissue, respectively. Furthermore, the antenna sensor exhibits good sensitivity to the dielectric properties of breast tissue. When the permittivity increases by 10, the resonance frequency decreases between 9-18MHz. To verify the simulated results, the sensing properties and the radiation patterns of the implantable antenna sensor were measured in the pork and tissue-mimicking liquid. The measured results are consistent with the simulated ones. Hence, the proposed antenna can be used as a wireless sensor to monitor pathological changes of human tissues, such as breast tumors.

Patch antenna sensor for wireless ice and frost detection

A patch antenna sensor with T-shaped slots operating at 2.378 GHz was developed and investigated for wireless ice and frost detection applications. Detection was performed by monitoring the resonant amplitude and resonant frequency of the transmission coefficient between the antenna sensor and a wide band receiver. This sensor was capable of distinguishing between frost, ice, and water with total shifts in resonant frequency of 32 MHz and 36 MHz in the presence of frost and ice, respectively, when compared to the bare sensor. Additionally, the antenna was sensitive to both ice thickness and the surface area covered in ice displaying resonant frequency shifts of 2 MHz and 8 MHz respectively between 80 and 160 μL of ice. By fitting an exponential function to the recorded data, the freezing rate was also extracted. The analysis within this work distinguishes the antenna sensor as a highly accurate and robust method for wireless ice accretion detection and monitoring. This technology has applications in a variety of industries including the energy sector for detection of ice on wind turbines and power lines.

Wearable antenna pressure sensor with electromagnetic bandgap for elderly fall monitoring

In this paper, a wearable antenna pressure sensor with electromagnetic bandgap (EBG) is proposed, which can be used to monitor the walking and fall states of the elderly. When the elderly walks and falls suddenly, the knee or elbow wearing the antenna sensor will touch the ground and put a lot of pressure on the antenna sensor, resulting in the resonance frequency shifts. The proposed antenna sensor is fabricated on flexible silicone substrate and works in the 2.45 GHz industrial, scientific and medical (ISM) band. A 3 × 3 EBG array is designed to reduce the specific absorption rate (SAR) of the antenna to the human body and increase the forward peak gain of the antenna from 1.63dBi to 4.36dBi. Furthermore, the antenna sensor exhibits high sensitivity of about 11 MHz/N to the pressure. To verify the simulated results, the sensing properties of the wearable antenna sensor were measured. The measured results have been found to be consistent with the simulated ones. Moreover, the bending performance study and SAR analysis reveal that the proposed antenna sensor is a good candidate for wearable devices.

Absolute value wireless sensing based on nonlinear harmonic analysis assisted with frequency-hopping spread spectrum

We herein introduce a wireless dielectric sensing platform that enables long-range interrogation of compact and fully-passive chipless sensors in complex environments filled with clutters and self-jamming. This telemetry technique requires postprocessing the harmonic received signal strength indicator (RSSI) in the frequency-hopping spread spectrum (FHSS), for which a harmonic transponder sensor (or harmonic sensor) has a narrow-band antenna sensor operating at frequency f 0 and a wideband antenna covering the spectrum centered at 2f 0. As a representative example, we have demonstrated that the information of the microfluids-reconfigured antenna sensor can be successfully encoded in the peak frequency of the harmonic RSSI pattern. Importantly, different from traditional passive backscatter sensors and radio-frequency identification tags, which are vulnerable to the background electromagnetic noises, this FHSS-assisted harmonic-based telemetry method allows robust far-field interrogation of sensors in realistic fully-scattered channels such as indoor environments. We envision that the lightweight battery-free harmonic sensor and system may be beneficial for widespread applications in internet-of-things, industry 4.0, smart cities, and healthcare applications such as rapid contactless point-of-care tests and telemedicine.

First LWD Co-Located Antenna Sensors for Real-Time Anisotropy and Dip Angle Determination, Yielding Better Look-Ahead Detection

Electromagnetic (EM) resistivity tools measure the electrical properties of downhole formations that are critical in determining the hydrocarbon saturation of a reservoir. In complex and heterogeneous reservoirs, both horizontal and vertical formation resistivities are required to obtain an accurate hydrocarbon saturation. For decades, wireline multicomponent induction type measurements have provided reliable determination of formation anisotropy, structural dip, and dip azimuth in wells with any orientation relative to the bedding planes. Logging-while-drilling (LWD) multi-array propagation resistivity tools have also demonstrated similar capability in deviated wells where the relative dip angle is between 45° and 90°. However, measuring anisotropy and dip in wells with a low relative dip angle still poses difficulties for LWD propagation resistivity systems because of the antenna structures employed. This paper describes the development of a new LWD EM sensor equipped with an innovative, co-located, tilted antenna structure. The tool, along with a unique processing scheme, enables the determination of horizontal and vertical resistivity as well as the dip angle and the azimuth of the formation based on an assumption of transversely isotropic (TI) formation models (Graciet and Shen, 1998) while drilling in real time. The co-located sensor design is capable of acquiring multicomponent signals that are sensitive to formation anisotropy and structural dip in wells at any orientation. Modeling studies and several field trials have proven that the design concept can detect these formation properties at any arbitrary wellbore deviation. This paper presents test results from the new technology, together with reference measurements from azimuthally compensated LWD and fully triaxial wireline resistivity measurements. A good comparison is observed in these trials, providing an independent verification of the tool performance. The azimuthal measurements of the new sensors allow for determining formation anisotropy and dip at any wellbore deviation (Bittar et al., 2011b; Bittar et al., 2012), as well as providing 360° azimuthal resistivity and geosignals and allowing a three-dimensional (3D) resistivity mapping technique for real-time decisions. Integrating the co-located antennas with deep-reading antennas in a near-bit collar further provides both anisotropy measurements and ultradeep signals very close to the bit and enhances look-ahead detection ranges for LWD applications.

A Passive Location Method Based on Virtual Time Reversal of Cross Antenna Sensor Array and Tikhonov Regularized TLS

The multi-station direction finding and cross positioning method is often used in three-dimensional passive detection system when the measurement information only has DOA estimation value. However, the essence of this algorithm is to linearize the nonlinear problem, which is very vulnerable to the influence of direction finding error. In order to solve the above problem, the anti-interference virtual time reversal (VTR) algorithm combined with Tikhonov regularization total least squares (TLS) are for passive location. A multi-station passive location model is built and the cross antenna sensor array is used to receive signals. According to the established array model, the coordinate transformation formula of the observation station is derived and the coordinate formula of each array element is obtained by the transformation matrix, then the signal receiving model is established. The coordinates of virtual points are transformed for DOA estimation which accomplished by VTR, then the direction lines obtained. The results of the VTR direction finding are transformed into new space angles and the observation equations of the space angles are constructed. In order to overcome the influence of noise on the positioning solution, Tikhonov regularized TLS method is used to solve the equations for obtaining target position. The simulation results show that the algorithm can achieve high-resolution DOA estimation of the target at low SNR and the positioning errors under different number of observation stations are analyzed. The positioning accuracy has better performance compared with the unimproved least square method.

Frequency Scanning Conformal Sensor Based on SIW Metamaterial Antenna

A conformal transverse slotted substrate integrated waveguide (SIW) metamaterial leaky-wave antenna sensor with uniform slots is investigated and analyzed for mmWave sensing applications. Firstly, its planar version is introduced. Then, its performance is compared with the curved SIW antenna. The metamaterial characteristics of the antennas are investigated. The transverse slots on the array forms a composite right/left-handed (CRLH) metamaterial structure that controls the radiation direction as the function of frequency. It behaves like a left handed metamaterial and radiates backward in the lower frequencies of the band (28-45GHz), whereas it behaves like a right handed metamaterial that scans forward direction at the higher frequencies (45-62GHz). Approximately 80° beam scanning is obtained in curved version with acceptable side lobe levels, whereas 110° beam steering is achieved with the planar version. Theoretical analysis and the simulation results are confirmed successfully by the experimental results in the 28-40 GHz band. Besides, a practical example of conformal SIW metamaterial antenna on military helmet made of a ballistic material is illustrated. The calculated spatial peak power density values of the proposed curved SIW metamaterial antenna on the outer surface of a head phantom are demonstrated.