A sensor to accurately predict chemical concentrations has been proposed in this research work. Inspired by Metamaterials, the sensor is composed of Complementary Split-Ring Resonators (CSRRs) and utilizes the Machine Learning technique to accurately predict the concentrations. The sensor is designed to maximize the interaction of the Material Under Test (MUT) with the sensitive regions of the CSRRs. The usage of costly and complex fluidic channels and sample containers is avoided by using filter paper for the liquid MUT placement in between the resonators. The proposed sensor is small (2.3 cm × 2.3 cm), simple, employs a low-cost fabrication technique and offers an alternate sensing mechanism that requires a minimal amount of the MUT. The multiple resonances exhibited by the proposed sensor add to the reliability and accuracy of the sensor.
In this paper, the development and design of angle independent Metamaterial Microwave Absorbers (MMAs) are presented. The unit cell consists of four trapezoids that are linked by consolidated resistors with the coextensive squares. The absorber is built on a dielectric substrate (FR4) with a thickness of 0.256 mm (λ/144) and a dielectric constant of 4.3. The wideband absorption is acquired in the range of 2.21 to 6.61 GHz with a wide band of 4.40 GHz with absorptivity above 90%. In the area of interest, a flat band is obtained, and to examine the current distribution and electric field in the respective region two peaks are considered at a frequency of 2.49 and 5.68 GHz, with maximum absorptivity of 92.50% and 92.14% respectively. The presented absorber is examined under different angles for phi and theta variation. From the phi variation, it is observed that for all the angles absorptivity does not vary which confirms that the absorber acts as an angle independent. The fabricated sheet consists of an array of a unit cell, which is examined inside an anechoic chamber with the help of two horn antennas and VNA. The tested and simulated results are compared, and it was observed that they are in close agreement. At last, the presented and already reported MMAs are compared, and it is observed that the presented one operates for the low frequency with higher bandwidth. The presented absorber can be practically used for defense applications for Radar Cross Sections (RCS) reduction.
This paper presents the design of a frequency reconfigurable monopole microstrip patch antenna for wireless communication applications. The proposed antenna functions in one single-band mode and one dual-band mode, depending on the diode switching configuration. When the diode is in the OFF state, the proposed antenna operates at single band 5.8 GHz (WLAN), and in the ON state, the antenna operates at dual bands 1.8 GHz (GPS/RADAR) and 5.2 GHz (WLAN). To enhance the gain of the proposed reconfigurable antenna, a multilayer frequency selective surface (FSS) reflector is presented. A significant enhancement in gain has been achieved in a low-profile design. The average peak gain of the antenna has been increased from 4 dBi to 6 dBi as a consequence of the use of the FSS reflector. The simulation of the proposed design is carried out using CST (Computer Simulation Technology) based on the FIT (Finite Integration Technique) numerical method. To validate the simulated results, a prototype of the antenna was fabricated and measured using PIN diodes. The simulated and measured results of the proposed antenna exhibit a reasonable agreement.
In this paper, a microstrip millimeter-wave (MMW) array antenna with a Defected Ground Structure (DGS) has been presented for the applications of fifth generation (5G) wireless networks. This novel antenna, which has small dimensions with higher gain, can be used for licensed 5G applications in many countries, like the United States of America, Canada, Australia, Japan, India, and China. It also covers a band that is planned for licensed use in some countries, like Colombia and Mexico. The proposed model has a single element design, and for gain and efficiency enhancement, a two-element array has been designed. Both single and two element models resonate at a frequency of 39.96 GHz. Using a commercial electromagnetic simulator (CST-Studio), the model was designed and optimized with the goal of achieving a return loss rate of less than -10 dB. The proposed antenna is built on a compact Rogers substrate (RT-5880) with dimensions of 6 mm x 6 mm for the substrate of the single element and 9 mm x 13 mm for the two-element array. The substrate has a thickness of 0.508 mm, a dielectric constant εr of 2.2, and a loss tangent tanδ value of 0.0009. This suggested design is small, low profile, and simple to guarantee the dependability, mobility, and high efficiency needed to be used with a variety of 5G wireless applications. The high gain of 11.6 dBi for the two-element array model of the proposed antenna is one of its distinctive features. The suggested single element model has an impedance bandwidth of 2.3 GHz, and 2.1 for the two-element array model, satisfying efficiency of approximately 73.5% for the single element and 85% for the two-element array model, respectively. The proposed structure, compared to other designs found in the literature, has smaller size while maintaining other parameter values of comparable orders.
A super wideband coplanar waveguide-fed antenna is proposed for Microwave Imaging (MI) applications. The antenna comprising a slotted patch and a defected ground structure (DGS) loaded with a stub has been prototyped on a 1.6 mm thick glass-reinforced FR4 material with an εr of 4.4. The antenna has a size of 0.12λ0×0.12λ0 at the lowest operating frequency of 1.21 GHz. The slotted patch coupled well with the stub-loaded DGS in the ground plane and led the proposed antenna to obtain a range of operational bandwidth from 1.21 GHz to 24.66 GHz. Initially, with a rectangular patch, a super wideband antenna with five notch bands is achieved. To eliminate four notch bands and realize the super wideband two rectangular slots are etched in the patch. The last notch band is eliminated by loading the ground with a stub. To make the proposed antenna a compact space-saving one, the patch is fitted in a hexagonal slot etched in the ground. The experimental result reveals a super wideband performance of 181% (1.21 GHz-24.66 GHz) with a consistent radiation pattern and peak gain of 9.4 dB in a compact area of 30 mm2.
When a planar microstrip patch antenna is conformed to any non-planar surface (e.g., aircraft, missiles etc.), the curvature of the host surface affects its design parameters, which in turn affects its radiation performance. Therefore, achieving a target radiation performance with a planar antenna on a non planar host surface is always a big challenge for an antenna designer. To address this issue, a report on an electromagnetic simulation-based method to optimize a planar-shaped microstrip antenna array conformed to a cylindrical surface is presented here. HFSS was used to investigate the role of different design parameters of the antenna array in the planar and cylindrical planes (for different radius of curvature). Finally, using these simulation observations, the dimensions of the planar antenna conformed to a cylindrical surface (with a radius of curvature of 110 mm) were optimized to achieve a target output performance (in terms of gain, return loss, and VSWR) while retaining its radiation pattern geometry as well as polarization characteristics. A planar 2×2 circularly polarized antenna array with a conical beam pattern from the published literature was used to carry out the current work. After rigorous optimization, return loss < -19 dB, VSWR of 1.807, and as much as 8.135 dBi gain at 2.45 GHz have been achieved. This report should be a useful guide for mounting any planar antenna array on a non-planar host surface. And it will also be helpful to design conformal microstrip antennas for different practical applications.
A smart antenna synthesis approach is described as automatically choosing the optimum antenna type and providing the best geometric characteristics under the demands of antenna performance. Different antenna performance characteristics are examined, and using decision tree classifier, the optimal antenna is suggested using an intelligent antenna selection model. Finally, the geometric characteristics of the antenna are given before the fuzzy inference system is developed by merging five primary learners to fully exploit the benefits of each type of learner. Rectangular patch antenna, pyramidal horn antenna, and helical antenna are the three types of antennas that are classified by a decision tree classifier, and the optimal antenna size parameters are determined using a fuzzy inference method. The performance of decision tree classifier measured using accuracy and FIS is measured using Mean Square Error (MSE) and MAPE. The system demonstrates excellent capability in parameter prediction with antenna categorization with a MAPE of less than 5.8% and accuracy over 99%achieved in our proposed method. The recommended methodology might be widely applied in actual smart antenna design.
We propose a miniaturized triple band printed monopole antenna for 5G, WLAN, WiMAX and X-band applications. Slots are etched in a printed rectangular monopole to design the antenna. A slot etched in a rectangular monopole increases the capacitance and therefore, decreases the resonant frequency or miniaturizes the antenna. Slots in a rectangular monopole antenna also create different current path lengths which resonates at different frequencies. Three slots are etched, and parameters are optimized to achieve triple bands to operate over 5G (3.3 to 3.6 GHz), WiMAX (3.4 to 3.6 GHz), WLAN (5.725-5.875 GHz), WLAN 5.9 GHz band (5.850-5.925 GHz) and X-band (7.3-7.9). The lower 45 MHz (5.850-5.925 GHz), and upper 30 MHz (5.895-5.925 GHz) of WLAN band also find applications for automobile safety in Cellular Vehicle-to-Everything (C-V2X) technology. The radiation patterns are nearly omnidirectional. The antenna is fabricated on a 0.154λ0×0.143λ0 board area, where λ0 is the free-space wavelength at 3.3 GHz. The measured results are in close agreement with the simulation ones.
This article presents a coplanar waveguide (CPW)-fed super wideband (SWB) elliptical slot monopole (ESM) antenna for wireless applications. The SWB impedance bandwidth (IBW) is achieved by symmetrical excitation of defective ground plane with a dodecagon-shaped annular ring (DSAR) radiator. The dimension of a prototype proposed antenna is 0.239λl × 0.253λl × 0.004λl mm3 (λl corresponding to the wavelength for the lowest operational frequency). A high bandwidth ratio of approximately 16.34:1 is produced by the combined radiation, with observed -10 dB IBW from 1.613 to 26.357 GHz (176.93%). Despite the cross-polarization levels being significantly suppressed in the H-plane, the basic concepts of an SWB antenna design have been successfully presented. Additionally, compared to other antennas mentioned in the literature, the proposed ESM antenna has a wider IBW. Successful fabrication, implementation, and comparison of the prototype with the experimental results are presented in this article.
Due to the restriction of the low-resolution systems and the interference of background clutter and environmental noise in the exploration process, the traditional classification and recognition algorithms of conventional radar for aircraft targets have low accuracy and poor feature stability. To solve the above problems, this paper proposes to apply high-order cumulant spectrum and deep convolutional neural network (CNN) to feature the extraction and classification of aircraft target radar echoes. Firstly, analyze the high-order statistical characteristics of aircraft echoes, calculate their bispectra, and then enhance the generated bispectrum dataset. Finally, use the augmented dataset to train and test the deep CNN, and obtain the final classification and recognition results. Experimental results show that the proposed method can accurately classify and identify multiple aircraft targets in the dataset, indicating that the bispectral features can better reflect the target characteristics, and the classification method combined with the deep learning model has good classification and identification performance and noise robustness.
This work introduces a novel compact 4-element MIMO antenna in the form of a q for use in the X-band. The proposed antenna has a footprint of 25 × 25 mm2 and can be easily produced using a FR-4 epoxy substrate. The antenna consists of a 50-ohm microstrip line connected to ground and four q-shaped radiators. The antenna's impedance matching characteristics were analysed by performing a parametric study on its several parameters. The antenna has excellent impedance matching capabilities and operates between 7.2 GHz and 12.6 GHz. By utilising the connected ground technique and placing radiating elements in an orthogonal orientation, we can achieve isolation of greater than 15 dB. The measured and simulated results demonstrate the antenna's high peak gain of > 4 dBi and high radiation efficiency of > 90%, as well as its good impedance bandwidth (S11 ≤ 10 dB) and isolation (S21/S31/S41 of ≥ 15 dB). The presented antenna is a good option for X-band applications because its envelope correlation coefficient (ECC) is less than 0.00001, total active reflection coefficient (TARC) less than -10 dB, channel capacity loss (CCL) less than 0.03 bits/sec/Hz, and mean effective gain (MEG) less than -3 dB.
To utilise maximum amount of available optical energy it is necessary to design a solar cell with minimum reflectance from its surface. Broadband anti-reflection coatings are essential elements for improving the photo current generation of photovoltaic modules. The vast majority of antireflection coatings are required for matching an optical element into air. In this work, we choose the substrate of the structure that has an index sufficiently higher than the available thin film materials to enable the design of high performance antireflection coatings. This high index substrate is silicon (Si) of refractive index 3.54 at design wavelength 500 nm. Quarter wavelength optical thicknesses (QWOTs) of films of various dielectrics are coated with refractive indices calculated by ``Root-Principle''. The reflection spectra of visible radiation in normal and oblique incidence with antireflection coatings up to six layers will be analysed to achieve nearly zero reflectance.
This paper proposes a single feed circularly polarised patch antenna with reactive impedance surface (RIS) and metamaterial superstrate (MS) to improve bandwidth and gain for Wi-Fi and Wi-Max applications that demand high gain, wide band, and directional antennas. In this paper, we demonstrate the performance of several antenna designs, including a slot-loaded patch on a single substrate, an antenna on a dual layer substrate with RIS, and an antenna with RIS and MS. The cavity formed by the superstrate and antenna ground plane functions as a Fabry-Perot resonator (FPR) that enhances bandwidth and gain simultaneously. The final optimised antenna has a significantly wider impedance bandwidth (IBW) of 17.32% (5.01 GHz - 5.96 GHz) and an axial ratio bandwidth (ARBW) of 6.29% (5.23 GHz-5.57 GHz) than the conventional slot loaded patch antenna. The proposed antenna gain is 11.73 dB, which is around 9 dB increase over the gain of a standard antenna.
A compact planar edge ultra-wideband (UWB) antenna is designed to operate at a frequency range of 3.5 GHz to 10.4 GHz for water quality detection. The design was constructed on an FR4 substrate with an overall dimension of 30 × 35× 1.6 mm3. The presented design is used to detect the presence of salt in the water in terms of reflection coefficient (S11). The proposed antenna's performance was examined by increasing the salinity of the three water samples: distilled water, reverse osmosis (RO), and raw water. The results showed the decrease of the S11 with the increment of salt in the water samples. In addition, the antenna showed good sensitivity as the resonance frequency of the antenna shifted to a lower frequency as the dielectric constant of water increased. Hence, the proposed UWB antenna can be prominently suitable for monitoring water quality and sensors.
Photonic crystal fiber sensors could be used for a variety of purposes including food preservation, manufacturing, biomedicine, and environmental monitoring. These sensors work based on the novel and adaptable photonic crystal fiber (PCF) structures, and controlled light propagation for the measurement of amplitude, phase, polarization, the wavelength of the spectrum, and PCF incorporated interferometry techniques. A new design of PCF was presented in this paper, and a hexagonal microstructured fiber structure was designed. The proposed PCF can successfully compensate for the chromatic dispersion by the influence of the pressure. As a result, a PCF pressure sensor was then successfully developed. The pressure sensitivity of this PCF was measured. We developed a simulation to understand the relationship between pressure and dispersion. In this work, all simulations are discussed, and the pressure sensitivity was numerically calculated for three wavelengths 1.1 µm, 1.4 µm and 1.7 µm to be respectively -0.01 (ps/nm/km)/bar, -0.0207737 (ps/nm/km)/bar and -0.0236908 (ps/nm/km)/bar.
A sensorless control method based on active disturbance rejection control (ADRC) and left inverse of fuzzy neural network is proposed to realize the sensorless control of permanent magnet synchronous motor (PMSM) for machine tools. Firstly, on the basis of analyzing the mathematical model of PMSM and the theory of left inverse system, a left inverse system observer is constructed. Secondly, after verifying the left reversibility of the PMSM control system, the fuzzy neural network is used to construct the left inverse system, and the left inverse system is connected with the PMSM control system in series to realize the sensorless control of the PMSM. Thirdly, according to the mathematical model of PMSM and the sensorless speed observation results, an ADRC method to improve the sensorless control effect is proposed. Finally, the experimental platform of the sensorless control method based on ADRC fuzzy neural network left inverse is built. The experimental results show that the method can estimate the speed and position well.
Two novel ultra compact flexible tri-band antennas with coplanar waveguide (CPW) feed and asymmetric coplanar strip (ACS) feed arrangements are presented in this paper. These antennas are fabricated on an extremely thin substrate with dielectric constant (εr) 3.5 and loss tangent (tanδ) 0.027. The folded geometry of the antennas contributes to the size reduction. While the CPW fed tri-band antenna (19 mm × 19 mm) exhibits bandwidth of 130 MHz, 600 MHz, and 1550 MHz in the lower, middle and upper frequency bands, the ACS fed tri-band antenna (19.5 mm × 15 mm) exhibits 80 MHz, 600 MHz, and 2220 MHz bandwidth respectively. Design equations are developed, and an appropriate circuit model is recommended. The performance of the antenna is investigated for various bending conditions. Simple geometry, compactness, flexibility, and stability under bending conditions over multiband make these incredibly thin antennas quite appealing for ISM 2.4/5.2 GHz, Wi-Fi 2.4/5 GHz, WLAN 2.4/5.2/5.8 GHz and WiMAX 3.5/5.5 GHz applications.
In this paper, an electronic textile (E-textile) antenna design using machine learning (ML) algorithms such as polynomial regression, k-nearest neighbor (kNN), random forest regression, and deep neural network (DNN) is proposed for achieving the optimized solution. These ML techniques, including DNN, have been implemented on a python framework and support in selecting efficient optimum design parameters for a co-planar waveguide fed textile antenna to attain the maximum impedance bandwidth performance in 3-24 GHz band, respectively. Moreover, the accuracy of the predicted response values obtained by these ML methods has also been validated by verifying with the CST simulation software tool.
An eddy current damper for an optimized rotation magnetized direction (RMD) permanent magnet thrust bearing (PMTB) was analyzed in this paper. Initially, optimization of critical design variables was performed for a particular bearing volume for maximum force as well as stiffness. Then, generalized curve fit equations were established to obtain a correlation between different geometrical parameters concerning the outer diameter and airgap. Furthermore, the axial force of the optimized RMD configuration calculated using mathematical model was validated using the results of FEA in ANSYS. Finally, finite element simulation was performed to evaluate the damping forces generated by an eddy current damper (ECD) for an optimized thrust bearing. Analysis has shown that eddy current dampers can improve system damping.
Wideband designs of a U-slot cut square microstrip antenna using bow-tie and H-shape ground plane profiles are proposed on an electrically thinner substrate. The modified ground plane optimizes the input impedance at patch resonant modes on the thinner substrate, which yields wider bandwidth. Against the conventional ground plane design on substrate thickness > 0.06λg, the bow-tie shape ground plane offers 0.03λg reduction in total substrate thickness, 10% increment in the bandwidth with a peak broadside gain of 6.1 dBi. The design methodology to realize a similar configuration as per a specific frequency spectrum is presented, which yields similar response.
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