Conventional Patch Research Articles

Slice-Aided Defect Detection in Ultra High-Resolution Wind Turbine Blade Images

The processing of aerial images taken by drones is a challenging task due to their high resolution and the presence of small objects. The scale of the objects varies diversely depending on the position of the drone, which can result in loss of information or increased difficulty in detecting small objects. To address this issue, images are either randomly cropped or divided into small patches before training and inference. This paper proposes a defect detection framework that harnesses the advantages of slice-aided inference for small and medium-size damage on the surface of wind turbine blades. This framework enables the comparison of different slicing strategies, including a conventional patch division strategy and a more recent slice-aided hyper-inference, on several state-of-the-art deep neural network baselines for the detection of surface defects in wind turbine blade images. Our experiments provide extensive empirical results, highlighting the benefits of using the slice-aided strategy and the significant improvements made by these networks on an ultra high-resolution drone image dataset.

Core-Shell Droplet-Based Angiogenic Patches for the Treatment of Ischemic Diseases: Ultrafast Processability, Physical Tunability, and Controlled Delivery of an Angiogenic Cocktail.

The patch-based delivery system has been a promising therapeutic approach for treating various vascular diseases. However, conventional methods face several challenges, including labor-intensive and time-consuming processes associated with patch fabrication or factor incorporation, inadequate physical properties, and uncontrolled release of factors. These limitations restrict the potential applications in clinical settings. To overcome these issues, we propose a novel core-shell-shaped droplet patch system called an angiogenic patch (AP). Our system offers several distinct advantages over conventional patches. It enables a rapid and straightforward fabrication process utilizing only two biodegradable ingredients [alginate and ε-poly(l-lysine)], ensuring minimal toxicity. Moreover, the AP exhibits excellent physical integrity to match and withstand physiological mechanics and allows for customizable patch dimensions tailored to individual patients' pathological conditions. Notably, the AP enables facile loading of angiogenic cytokines during patch fabrication, allowing sustained release at a controlled rate through tunable network cross-linking. Subsequently, the AP, delivering a precisely formulated cocktail of angiogenic cytokines (VEGF, bFGF, EGF, and IGF), demonstrated significant effects on endothelial cell functions (migration and tubule formation) and survival under pathological conditions simulating ischemic injury. Likewise, in in vivo experiments using a mouse model of hindlimb ischemia, the AP encapsulating the angiogenic cocktail effectively restored blood flow following an ischemic insult, promoting muscle regeneration and preventing limb loss. With its simplicity and rapid processability, user-friendly applicability, physical tunability, and the ability to efficiently load and control the delivery of angiogenic factors, the AP holds great promise as a therapeutic means for treating patients with ischemic diseases.

Characterization of a Split Circle Element for Microstrip Reflectarrays

A split circular element is proposed as a unit cell for reflectarray antennas. The unit cell is derived from a circle divided into four equal sectors. The radius of two oppositely located sectors is then scaled by a certain factor to form the proposed shape. The CST Microwave Studio Suite software simulator was used to investigate the performance of the proposed unit cell, which was evaluated using Floquet port excitation. The designed element's reflection phase range was compared to that of a conventional circular patch. Four scenarios of varied substrate characteristics are investigated for the antenna to establish the best performance parameters. The simulations showed that a basic substrate with a thickness of 0.16 mm and a dielectric constant of 3.2, backed by a 3 mm foam with a dielectric constant of 1.05 and a scaling factor of 0.72 offers a wide phase range of 601.3°. The obtained phase slope is 76.37°/mm or 134°/GHz.

Microstrip Leaky-Wave Antenna With Circular Polarization and Broadside Radiation

In this letter, a novel circularly polarized microstrip leaky-wave antenna is proposed with broadside radiation and high gain. A conventional microstrip patch has been modified to obtain broadside gain along with circular polarization. The modified patch is periodically placed along one side of the 50 Ω delay line to form leaky-wave antenna. The optimized broadside frequency of the antenna is 10.1 GHz. The bandwidth associated with 3-dB axial ratio is 13.3% while the maximum obtained gain is 15.8 dBic. The measured gain variation within 3-dB axial ratio bandwidth is 1.6 dB. Measured results of the fabricated antenna follow the simulations.

Monitoring the Effects Brought By a Drug on Myocardial Cells Using Field Effect Transistor (FET) Based Sensing Platform

: Ion channels are the membrane proteins that modulate the active flow of ions between cellular environment. These therapeutic targets are expressed in every active cell and can be used as important targets for cellular changes. The ion channels play an important role in different physiological processes including blood regulation, cell proliferation, nerve relaxation, etc. Various cardiac and neurological diseases have been reported to be related to ion channel regulation. They are brought through by the ion channel mutations. Several techniques are currently deployed for monitoring drug effectiveness of ion channels. Among these techniques, patch clamp technology is considered as a golden standard for monitoring the ion channel function. Unfortunately, the conventional patch clamp technologies are not enough to be employed in the early stages of drug discovery. Similarly, serval fluorescence detection methods and combination technologies have been developed for calcium ion channel detection. These assays are not suitable for large scale detection due to less selectivity and sensitivity.At present, field-effect transistor-based biosensors (BioFETs) have been widely employed in various applications due to their non-invasive detection, and high sensitivity. In this work, we adopted an extended gated EDL-FET platform for rapid drug screening on myocardial cell lines (H9c2). The drug effectiveness was studied by tested nifedipine on myocardial cells which were mounted over an EDL-FET platform. Two different surface conditions were studied using Ca2+ treatment and the capability the of EDL-FET sensor as a drug screening platform was discussed.Surface functionalization and Measurements An extended gate chip was used as the sensor array. Before probe immobilization, the sensor electrode was treated with oxygen plasma. Cell attachment over the sensor platform was facilitated using a glycoprotein- Fibronectin. Traut’s reagent was used to modify fibronectin to initiate the covalent attachment to the sensor surface. Optical images and electrical readings were taken to ensure proper functionalization of the fibronectin-attached surface before the cells were seeded over it. Myocardial cells (H9c2 cells), removed from their culture media, were incubated over the functionalized electrodes for ~2 hours following which, electrical measurements were taken to establish a baseline reading using the BioFET device. Different concentrations of nifedipine [0 to 50 μM] and calcium ions [18 μM to 1.8 mM] were used to make testing solutions, which were used for monitoring various changes occurring on the ion channels of the myocardial cells. Figure 1

Miniaturized Micro Strip Patch Antenna to Achieve Wireless Power Transfer for ISM Applications

This article proposes a miniaturized defective ground structure (DGS)-based microstrip patch that is suitable for usage in a variety of applications, including those in the medical, scientific, and industrial fields. The dimension of a conventional patch antenna at 2.7 GHz on an FR4 substrate consists of 11.01×5.19×0.1575 cm3, where the proposed antenna geometry is set as 5.89×3.06×0.1575 cm3, reducing the overall circuit size by 68.9%. This miniaturized antenna will be easily implementable in wearable devices for healthcare applications. The dimension and shape of the DGS are optimized in such a way as to improve the return loss from -19 dB to -24 dB at the desired frequency. Finally, the transmission coefficient for a conventional and suggested DGS-based antenna has been examined while these antennas are placed in a near-field region.

A Frequency-Reconfigurable Antenna With Filtering Characteristics Using Characteristic Mode Analysis

In this letter, a planar filtering antenna with reconfigurable frequency selectivity is proposed. The basic structure is a linear array of three patches. Unlike the conventional gap-coupled patch antennas, the electric and magnetic coupling between adjacent patches is formed respectively by placing a row of shorting pins on the chosen edge of a patch. As a result, the mixed coupling effect makes the antenna array have filtering characteristics with no extra circuit. With the aid of characteristic mode analysis, intuitive but physical insights are shed upon its working mechanism. Besides, it shows that the resonant frequency and coupling strength are sensitive to the number and the locations of shorting pins. By using diodes to control the shorting state of each pin, the frequency band can be finely tuned from 2.19 GHz to 2.81 GHz while maintaining stable filtering performance within nearly constant bandwidth.

An eye bolt shape slotted microstrip patch antenna design utilizing a substrate-integrated waveguide for 5G systems

Antenna design is usually done on FR4 substrates, since they have a dielectric constant of 4.4, and a loss tangent of 0.02. The proposed microstrip patch antenna operates at 28 GHz and incorporates substrate-integrated waveguides (SIW) in a 0.8 mm thick FR4 substrate into the design to increase bandwidth performance so that the 5G network can function reliably. In comparison with conventional patch antennas, substrate-integrated waveguides bear the advantage of being able to shift to a frequency of 29 GHz, therefore resulting in a more effective antenna. A slot of eyebolt shape has been added to the patch to increase antenna gain. The design was simulated with HFSS software, and it was able to attain a maximum bandwidth of 8 GHz (28%), a gain of 5.5 dB, and a minimal return loss of −38 dB. The VSWR of this antenna is 1.02, which indicates good impedance matching, and a high efficiency of 87% has been achieved as a result. This is a low-profile antenna that combines enhanced bandwidth with the ability to be mounted at the edge of a device, making it an ideal choice for the use of 5G technology to enable machine-to-machine communication.

Multi-Beam Luneburg Lens with Reduced Size Patch Antenna

This paper describes the integration of a plate Luneburg lens with a microstrip patch antenna (MPA) with a complementary split ring resonator (CSRR) at 17 GHz frequency. The main advantage of the method is the compact size of the optimized MPA with CSRR such that the radiation pattern of the antennas successfully overlaps at −3 dB. The overlapping is achieved by positioning multiple MPA with CSRR structures around the plate Luneburg lens with 0.408λ distance between the elements. To test the performance of the lens, CST simulations are carried out using a classical WR62 open-ended waveguide to feed the structure, then adding more waveguides rotated at focal points of the lens. After that, the waveguide is substituted with the MPA with CSRR structure. The superiority of the proposed method over the conventional waveguide or regular patch antenna is confirmed by an overlap in radiation pattern at −3 dB with a narrow beamwidth of 10.9°.

Design of folded rectangular microstrip antenna on thinner substrate for wideband response

ABSTRACT Wideband microstrip antenna is realized by adding more than one resonant modes in the patch. In this paper, on electrically thinner substrate, design of modified shape rectangular microstrip antenna by employing folded rectangular patch is presented for linear polarized wideband response. Unlike the conventional rectangular patch, radiation pattern and resonance frequency at the second-order resonant mode are modified and along with the fundamental mode, yield wider bandwidth. On substrate of thickness 0.045λ0, folded patch design yields bandwidth of more than 20% along with the broadside radiation pattern and gain more than 8 dBi. Against the reported wideband designs, proposed design does not employ parasitic patches, resonant slot, modified ground plane structures, but on thinner substrate achieves the bandwidth of more than 20%. Resonant length formulation and subsequent design methodology are presented, which is useful in realizing similar folded antenna as per the specific frequency band. Simulated results have been experimentally verified, which shows close agreement.

Circularly Polarized Polarization Conversion Metasurface-Inspired Antenna Array With Low RCS Over a Wide Band

A circularly polarized (CP) metasurface-inspired antenna array with low radar cross section (RCS) over a wideband based on polarization conversion metasurface (PCM) is proposed. Without increasing the structural complexity, the PCM units serve directly as antenna radiators, which not only maintains good radiation characteristics but also reduces both the in-band and out-of-band RCS of the antenna. Simulations show that the proposed PCM-inspired antenna array has an impedance bandwidth of 37.6% (8.2 to 12 GHz), a 3 dB axial ratio (AR) bandwidth of 32.5% (8.5 to 11.8 GHz), and a 3 dB gain bandwidth of 23.3% (9.5 to 12 GHz). The RCS of the proposed antenna array is greatly reduced for both polarizations in the frequency range of 7.6 to 16.2 GHz (72.3%) compared to conventional microstrip patch antenna array, with a maximum reduction of 20.6 dB. Moreover, the proposed PCM-inspired antenna array has a smaller element size compared to conventional low-RCS metasurface antennas, making it more conducive to the composition of a phased array. Finally, the proposed array is fabricated and measured, and the results confirm the simulations.

A Novel High Isolation 4-Port Compact MIMO Antenna with DGS for 5G Applications.

This paper presents the design and realization of a simple and low-profile, four-port multiple-input-multiple-output (MIMO) antenna operating in a mm-wave band supporting 5G communication technologies. As part of the design methodology, the initial stage involved the development of a conventional monopole patch antenna optimized for operation at 26 GHz, which was matched to a 50 Ω stepped feed line. Afterward, a square-shaped defected ground structure (DGS) with semi-circle slots on the edges was placed on the ground to improve the isolation, and the circular and rectangular slots were incorporated as DGSs to optimize the antenna impedance bandwidth. Etching semi-circular-shaped slots on the ground plane achieved more than 34.2 dB isolation in the 26 GHz operating band. In addition, an arrangement of four symmetrical radiating elements was positioned orthogonally to minimize the antenna's physical size and improve the isolation. The proposed MIMO antenna's overall dimension was 25 × 25 mm2, which was printed on a Rogers 5880 substrate at a width of 0.787 mm and εr = 2.2. The proposed antenna covered the 5G mm-wave band with a 10 dB bandwidth ranging from 25.28-28.02 GHz, whereas the maximum gain attained for the proposed structure was 8.72 dBi. Additionally, the implementation of these slots effectively mitigated mutual coupling, resulting in reduced envelope correlation coefficient (ECC) values. Furthermore, other MIMO performance metrics, including channel capacity loss (CCL), mean effective gain (MEG), and diversity gain (DG), were analyzed for the proposed structure. The obtained results indicate its suitability for various usage areas, such as smart devices, mobile phones, and sensors in 5G applications.

DNG Metamaterial-Based Superstrate for Performance Enhancement of Compact Size Wideband Patch Antenna

Recently, electromagnetic metamaterials are of great interest to researchers because of their unusual electromagnetic properties. The proposed work presents a metamaterial as a superstrate for enhancing the performance parameters of a conventional patch antenna. The metamaterial unit cell is examined using classical waveguide theory to confirm its metamaterial properties such as permittivity and permeability at the resonant frequency. The proposed meta-structure comprises of a 5 × 5 array of circular-shaped split ring resonators backed with wire strips and placed above an inset-fed rectangular patch antenna that resonates at 9.96 GHz. The metamaterial superstrate improves the gain, impedance bandwidth, and radiation efficiency by 2.4 dBi, 770 MHz, and 18.4%, respectively and simultaneously reduces reflection coefficient by 5 dB. Several benefits such as compact size, simpler structure, low profile, and low cost have been obtained from this design. EM simulation of the proposed composite structure has been carried out with the help of the HFSS EM simulator and measurement has been done for validation.

A Patch Antenna with Enhanced Gain and Bandwidth for Sub-6 GHz and Sub-7 GHz 5G Wireless Applications

This paper presents a novel microstrip patch antenna design using slots and parasitic strips to operate at the n77 (3.3–4.2 GHz)/n78 (3.3–3.8 GHz) band of sub-6 GHz and n96 (5.9–7.1 GHz) band of sub-7 GHz under 5G New Radio. The proposed antenna is simulated and fabricated using an FR-4 substrate with a relative permittivity of 4.3 and copper of 0.035 mm thickness for the ground and radiating planes. A conventional patch antenna with a slot is also designed and fabricated for comparison. A comprehensive analysis of both designs is carried out to prove the superiority of the proposed antenna over conventional dual-band patch antennas. The proposed antenna achieves a wider bandwidth of 160 MHz at 3.45 GHz and 220 MHz at 5.9 GHz, with gains of 3.83 dBi and 0.576 dBi, respectively, compared to the conventional patch antenna with gains of 2.83 dBi and 0.1 dBi at the two frequencies. Parametric studies are conducted to investigate the effect of the parasitic strip’s width and length on antenna performance. The results of this study have significant implications for the deployment of high-gain compact patch antennas for sub-6 GHz and sub-7 GHz 5G wireless communications and demonstrate the potential of the proposed design to enhance performance and efficiency in these frequency bands.

An Ultraminiature Circularly Polarized Microstrip Patch Antenna With MIM Capacitors

In this letter, an ultraminiature circularly polarized micostrip patch antenna is designed by four metal-insulator-metal (MIM) capacitors. First, four lumped capacitors are added to edge of the conventional microstrip patch antenna to conduct the simulation of the theoretical model for brevity. It is found that the micostrip patch antenna achieves electrically small ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ka</i> <1) when the capacitors are selected carefully. In addition, the axial ratio and the resonance of the antenna can be optimized by the capacitors, which derives an effective method to design a compact circularly polarized antenna. Thus, four MIM capacitors are applied to replace the lumped capacitors to make the antenna physically realizable. A circularly polarized (CP) electrically small mictostrip patch antenna is designed, fabricated and measured to justify the effectiveness of the proposed method. The axial ratio bandwidth and the peak gain of the CP ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ka</i> = 0.495) prototype achieves 0.88% and 4.25 dBiC, respectively. The size of the proposed antenna is only 0.104 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.104 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> .

Mutual Coupling Suppression Between Two Closely Placed Patch Antennas Using Higher-Order Modes

This paper presents a novel method for decoupling two patch antennas. Instead of using the TM10 mode of a conventional patch, TM20 mode is utilized as the operation mode of the antenna. By loading stubs at the radiating edge of the patch, the resonance frequency of the TM20 mode is moved down to the same band as the original TM10 mode. Then the mutual coupling between two such patch antennas is suppressed simply by physical placement, even when they are placed extremely close to each other. Without using any extra decoupling elements, isolation is improved by up to 20 dB using this method. Furthermore, this method can also be applied to multi-element multi-input-multi-output (MIMO) array and dual-antenna system with different operating bands. The proposed method is verified with three different application scenarios, including a 2-element MIMO array, a 2-antenna system with adjacent operating bands, and a 4-element MIMO array. Reasonable agreements between simulated and measured results can be observed, showing the advantages of simple structure, low cost, high isolation, and good radiation performance.

Testing of chlorine dosage in drinking water using microstrip patch sensor

A new method using microstrip patch sensor is designed, simulated, and measured to detect the dosage of added chlorine to the drinking water using the relation between permittivity and matching impedance. The simulation is done using computer simulation technology-microwave studio software. The proposed sensor is designed on a single FR-4 layer with a low profile, 0.499 GHz bandwidth, center frequency of 2.94 GHz, gain of 6.55 dBi, and a good front to back ratio of 17.84 dB. In this work, the antenna design is started from a conventional patch antenna equation. Then, an optimization process is performed to achieve good parameter values for obtaining the desired objective. The objective is to utilize the microwave frequency to measure the chlorine dosage in water. The measurement results proved that the matching impedance can be used to find out the dosage of chlorine in drinkable water. The proposed method overcomes the open-ended coaxial probe method in terms of experimental time and contactless testing and shows high matching with the latter actual data. Moreover, the proposed method overcomes the conventional methods in terms of continuity and large scale of testing, non-contacting with the samples of water, and no additive chemical materials, which make the water samples not drinkable.

Results of Fibrin Glue Applied Over the Corneal Surface Immediately After Pterygium Surgery: A Novel Pain Relief Technique.

The aim of this study was to compare the use of fibrin glue on the corneal epitheliectomy site at the end of pterygium surgery versus conventional eye patch regarding pain levels, need for oral analgesic medications, number of days feeling pain, and awakening due to pain after surgery. Forty-eight eyes of 24 patients with bilateral primary pterygium were included in this prospective, randomized, double-masked controlled trial. Each eye of the same patient was randomized to the intervention or control group. The intervention group received 2 drops of fibrin glue in the epitheliectomy site at the end of surgery and an eye patch, whereas the control group was only received an eye patch. Patients returned on the first and seventh days after surgery. Pain intensity (measured using the visual pain analog scale), need for oral analgesics, the number of days the pain lasted, and quality of sleep were assessed during follow-up visits and compared between groups. Comparison analysis accounted for sex, age, pterygium grading, and comorbidities. Visual analog pain scale after surgery was significantly lower in eyes receiving fibrin glue (-1.58; 95% confidence interval: -2.84 to -0.32; P = 0.014). In addition, the intervention group presented a 73% lower chance of using oral analgesics (OR: 0.27; 95% confidence interval: 0.07-0.95; P = 0.041). No difference in the awakenings at night was noted (P = 0.240) nor the mean days of ocular pain in the first week after surgery (P = 0.474). Fibrin glue at the end of pterygium surgery effectively reduces pain and the need for oral analgesics compared with conventional eye patching. This study is the first to describe the results of this strategy.

Wideband Single-Fed Circularly Polarized Stacked Patch Antenna With L-Shaped Stub

A wideband single-fed circularly polarized (CP) stacked patch antenna with an L-shaped stub is presented. The CP antenna is made up of the bottom gradient microstrip transmission line, middle driven patch and top square radiation patch. The driven patch with an L-shaped stub and opening slot can achieve a wideband CP radiation which is different from a conventional patch. The presented CP stacked patch antenna maintains good directional radiation, while featuring wideband CP radiation. The final tested results indicate that the presented CP antenna has significant performance with a −10 -dB impedance bandwidth of 42.1% (4.26-6.53 GHz), a 3-dB AR bandwidth of 26.0% (4.36-5.66 GHz) and broadside peak gain of 8.6 dBic. Moreover, the fifth-generation (5G) N79 band (4.4-5.0 GHz) and 5G wireless local area network (WLAN) band (5.15-5.35 GHz) can be covered by the operating bandwidth of the presented CPantenna.

Circularly polarized stub-loaded annular ring patch antenna for 2×2 MIMO satellite application

In this article, a stub loaded circularly polarized annular ring patch antenna which operates at 3–5 GHz band for 2×2 MIMO Satellite application is proposed. The evolution of antenna begins with a conventional annular ring patch antenna, addition of diagonal slots and integrated with λ/2 hair pin stub loaded annular ring patch to improve isolation and circular polarization. The antenna isolation is a critical parameter and important requirement of MIMO system. In satellite communications, circular polarization is used to improve the quality and reliability of the communication link between the satellite and the ground station. The antenna achieves circular polarization and mutual coupling through diagonal slots and stub-loaded design without any additional decoupling techniques. The overall size of the proposed MIMO antenna is 63 × 63 × 1.52 mm3 which is fabricated over Rogers RO3003 substrate. The proposed antenna design is simulated, fabricated, tested and analyzed for various parameters such as Reflection coefficient,Isolation Gain, radiation pattern, Axial ratio (AR), Envelope correlation coefficient (ECC), Diversity gain (DG), Channel capacity (CC) and total efficiency. The isolation of <−22 dB, gain of 7.1 dB, axial ratio<3 dB, diversity gain of 9.9 dB, ECC<0.002,CC of 11.23bps/Hz and efficiency>95% are obtained. The measured 10 dB impedance bandwidth of 270MHz and 3 dB AR bandwidth of 250MHz in the desired band are achieved. The simulated and measured antenna parameters are agreeable with each other. The results are found to be promising and having high potential in the 5G and Satellite MIMO.