This article reports a single layer tri-band bandpass, polarization insensitive Frequency Selective Surface (FSS). The unit cell is designed by considering different square loop elements and cross dipole element to pass Wi-Max and WLAN frequency range with low loss. Three different shapes of loops and one cross dipole are arranged in a way that gives a triple-band-pass characteristic from the proposed structure. These loops and dipole are designed to pass Wi-MAX (2.5-2.7 GHz, 3.4-3.6 GHz) and WLAN (center frequency, 5.5 GHz) bands. The structure performance is independent of incidence angle of wave due to its symmetrical geometry which makes the design polarization insensitive and achieves good angular stability. A 14x14 array of proposed unit cell is realized and measured. The proposed FSS achieves a 3 dB transmission bandwidth of 25% at 2.6 GHz, 65.6% at 3.5 GHz and 65.6% at 5.5 GHz. The advantage of the proposed design is that it has a simple and compact geometry fabricated on a low-cost substrate and achieved tri-band band pass response with a wide angular stability.

To address the problems of large volume, heavy weight, and inconvenient installation of the shield board of a wireless charging coil (WCC) installed on the body of an electric vehicle (EV), a new shielding method is proposed in this paper. From the perspective of engineering practice, according to the principle of passive shielding, and in line with the vertical direction of WCC with ferromagnetic material shielding, this novel shielding method involves only a low permeability metal shielding ring set around the transmitting coil in the horizontal direction. Using the finite element simulation software COMSOL Multiphysics, the EV model, the magnetic coupling resonance (MCR) WCC model, and the pedestrian body model at the observation point are designed. The influence of the metal shielding ring on the self-inductance and mutual inductance of WCC is calculated. The magnetic induction strength (B) and electric field strength (E) of pedestrian body at observation points before and after adding a metal shielding in the horizontal direction are evaluated, and the electromagnetic exposure safety of a pedestrian body in this electromagnetic environment is analyzed. Compared with the shielding method of only adding ferromagnetic material in the vertical direction and after using new shielding, the maximum B of a human trunk is reduced by 43%, the maximum E reduced by 44%, the maximum B of human head reduced by 44%, and the maximum E reduced by 39%. After adding the metal shielding ring, the maximum B and E of human trunk decreased from 8.56 × 10^-1 times and 2.28 × 10^-1 times of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) exposure limit to 4.89 × 10^-1 times and 1.27 × 10^-1 times, respectively, and the maximum B and E of human head decreased from 1.62 × 10^-3 times and 8.58 × 10^-4 times of the ICNIRP exposure limit to 9.18 × 10^-4 and 5.25 × 10^-4 times, respectively. The simulation results show that the new shielding method can significantly reduce the electromagnetic radiation of the pedestrian's trunk and head central nervous system (CNS) at the observation point. The effectiveness of the shielding method is proven, and this work provides a certain guidance for the engineering design of WCCs.

This paper proposes a Yagi-Uda antenna array realized on a Silicon substrate and supported by a substrate integrated waveguide for multi-band operation in the K and Ka bands. The structure of the dipole and the first director of the Yagi-Uda antenna were modified and tuned for multi-band response, making it completely novel in comparison to the existing Yagi-Uda structures supporting multi-band operation. As the feed, a substrate integrated waveguide was designed to assist with multi-band operation and to overcome the challenges presented by the Silicon substrate. An array is implemented to improve the gain. The antenna array's prototype was constructed and tested to back up the claims. The proposed array operates at frequencies of 23.7, 26.3, 27.5-28.3, and 29.4 GHz. The array exhibits good end-fire radiation patterns for the resonant frequencies, with a peak gain of 19.65 dBi and an efficiency of 89.8% at 23.7 GHz. This is the first report of an antenna fed by a substrate integrated waveguide and realized on Silicon with a high gain and applications in the K and Ka bands.

The aim of this paper is to develop a hybrid modeling approach based on direct coupling between the finite element method (FEM) and the partial element equivalent circuits method (PEEC). Through this FEM-PEEC approach, we can efficiently compute the three-dimensional eddy current distribution created by a rectangular coil (exciting coil) in conductive and magnetic structures having heterogeneous dimensions. Magnetic field created by the rectangular coil is given by calculating quasi-static Green's function integrals. In goal to construct rectangular coil, the calculation is made for elementary parallelepipedic conductors oriented respectively in x and y directions. By this manner, three possible configurations are proposed and compared to show errors, especially in corners. By only meshing the active parts of the domain (without air region), we confirm through the issued results that the proposed methodology contributes to accelerate the execution time while maintaining the precision. The obtained results are validated with the numerical ones by 3D FEM (Flux 3D Software).

This paper, using the distributed parameter line model, presents an accurate fault location method based on fundamental frequency positive sequence fault components for EHV transmission line. The method based on positive sequence fault components Extra-High Voltage (EHV) electric transmission line. The method based on the positive sequence fault component is robust to the operating state of the prefault system and fault path resistance. The technique proposed in the paper does not require the fault type, fault phase, and the zero-sequence parameter to be obtained in advance. In addition, due to the use of fault component protection theory, the algorithm itself is not aected by the previous operating state of the system. The method uses a distributed parameter model, which is more accurate in positioning and smaller in error than a lumped parameter model by a large number of simulations. Accurate fault location is important for shortening the fault time and reducing the loss of the fault, so the positioning method proposed can improve the power supply quality and safety. This paper describes the characteristics of the proposed technique and assesses its performance by using Power Systems Computer Aided Design/Electromagnetic Transients including DC (PSCAD/EMTDC).

Integrated time delays are important for self-forced oscillation techniques in opto-electronic oscillators (OEO). Add-drop filters (ADFs) resonators using optical waveguide coupled to micro-ring resonators (MRR) are suitable for integrated optical time delays but suffer from a limited expected delay. 2-dimensional (2-D) photonic crystals (PhCs) with line defect are employed as confined optical waveguide to realize ADF resonators where longer optical delays than standard homogenous resonators are achieved by leveraging the slow-light effect. Moreover, achieving time delay up to microseconds (μs) is envisioned by cascading multiple identical ADF based on dispersive 2-D PhC micro-resonators. The focus of this paper is to devise a hybrid modeling procedure for accurate calculations of achieved time delays in various complex structures, while a combined electromagnetic modeling and analytical calculation technique overcomes a substantial computational resources and long computation times for a brute forced full-wave design and modeling. This innovative hybrid modeling for time delay estimation of cascaded ADFs is proposed for the first time to optimize physical design within short time period. First, transfer function performance of a homogenous ADF resonator is simulated using finite-difference-time-domain (FDTD) for both the full structure and structures with bi-fold symmetry and compared against proven analytical solutions to demonstrate accuracy of bi-fold symmetry while the computational resources are economized. The same modeling procedure is then extended to predicting performance of 2-D PhC based ADF resonator by quantifying key physical parameters of coupling factor, complex optical propagation constant, and optical transfer function for ADF resonator for the ring radius of curvature about 1.5 μm with various coupling gaps between feed waveguide and resonator guide. These parameters and the effective group index calculated by OptiFDTD software are applied to the analytical expressions to estimate single 2-D PhC ADF and attain a simulated time delay of 200 ps. The estimated time delay of 70 cascaded 2-D PhC based ADF resonators with R of 100 μm is estimated to be about 925 ns for the on-resonance frequency of 1534 nm.

Due to the optical diffraction limit, the resolution of a wide-field (WF) microscope cannot easily go below a few hundred nanometers. Super-resolution microscopy has the disadvantages of high cost, complex optical equipment, and high experimental environment requirements. Deep-learning-based super-resolution (DLSR) has the advantages of simple operation and low cost, and has attracted much attention recently. Here we propose a novel DLSR model named Modified Hybrid Task Cascade U-Net (MHTCUN) for image super-resolution in optical microscopy using the public biological image dataset BioSR. The MHTCUN has three stages, and we introduce a novel module named Feature Refinement Module (FRM) to extract deeper features in each stage. In each FRM, a U-Net is introduced to refine the features, and the Fourier Channel Attention Block (FCAB) is introduced in the U-Net to learn the high-level representation of the high-frequency information of different feature maps. Compared with six state-of-the-art DLSR models used for single-image super-resolution (SISR), our MHTCUN achieves the highest signal-to-noise ratio (PSNR) of 26.87 and structural similarity (SSIM) of 0.746, demonstrating that our MHTCUN has achieved the state-of-the-art in DLSR. Compared with the DLSR model DFCAN used for image super-resolution in optical microscopy specially, MHTCUN has a significant improvement in PSNR and a slight improvement in SSIM on BioSR. Finally, we fine-tune the trained MHTCUN on the other biological images. MHTCUN also shows good performance on denoising, contrast enhancement, and resolution enhancement.

In order to satisfy the requirements of 2G/3G/4G wireless communication, two kinds of base station antennas with wideband, dual-polarized and three-modes are proposed in this paper. Firstly, a pair of diamond dipoles is placed in an orthogonal way to realize dual-polarizations, then a pair of Y-shaped branches is added to generate a new mode. The Y-type coupling feeding can increase the impedance bandwidth without increasing the size of antenna. The antenna achieves an impedance bandwidth of 51.75% (1.69-2.87 GHz) with a return loss lower than -14 dB. The antenna also has a stable radiation performance. The gain is greater than 8.6 dBi, and the port isolation is less than -27 dB over the entire frequency band. Then based on above antenna, a C-type slot notched antenna is added to improve anti-interference ability. Finally, band stop characteristics are obtained by etching a C-type slot line resonator on two dipoles. The results show that the bandwidth is 1.7-2.69 GHz, and the sharp notched band is 1.8-1.95 GHz. The C-type slot line here can be regarded as a quarter wavelength resonator in series. Moreover, the isolation of the port is less than -28 dB, and the 3 dB beamwidth in the bandwidth is 66±5˚. Both antennas are fabricated and have dual polarizations, simple structure, and good radiation performance, which can be used in the next generation of wireless communication.

Transverse electromagnetic (TEM) cell is usually used to evaluate the electromagnetic immunity and electromagnetic radiation disturbance of the equipment under test (EUT) and integrated circuit (IC). Affected by the structure of the TEM cell, high-order modes and reflection will be generated in the high frequency range, which will limit the higher frequency applications of the TEM cell. In this paper, the TEM cell specified in IEC61967-2 standard is improved by adopting several methods, including segmented impedance matching, slitting outer conductor, slotting inner conductor, adding absorbing materials and adding an external shielding box. The results show that the improved TEM cell voltage standing wave ratio (VSWR) is less than 1.2 in 0-3.4 GHz, less than 1.3 in 0-3.75 GHz, and less than 1.5 in 0-4.06 GHz; at the same time, the S-parameter characteristics are better.

This paper presents the design and measurements of a dual-band Triple H-Defected Ground Structure (Triple H-DGS) antenna. DGS has proven to be successful in the design of multiband antennas; however because of the lack of a standard approach, the determination of the exact position of the Triple H-DGS requires rigorous and lengthy numerical computations. The aim of the current work is to present a state-of-the-art innovative, efficient, and accurate solution based on Machine Learning (ML) techniques. The design is based on Substrate Integrated Waveguide (SIW) technology which provides low cost, small size, and convenient integration with planar circuits. The antenna is fabricated on a Roger 5880 substrate with a thickness of 1.6 mm, relative dielectric constant of 2.2, and tangent loss of 0.0009. The proposed antenna was developed using a hybrid solution based on CST Microwave Studio assisted by ML, and the fabricated prototype was measured using both ROHDE & SCHWARZ ZVB20 network analyser and an anechoic chamber setting. The measurement results show good agreement with the simulation. The antenna demonstrates a dual-band performance at centre frequencies of 12.67 GHz and 14.56 GHz, for which the respective antenna gains are 7.03 dBi and 7.38 dBi, and antenna directivities of 7.77 dB and 8.13 dB, respectively. The antenna total efficiencies are 95.25% and 95.60%, at the corresponding centre frequencies. The developed ML based technique shows good accuracies of about 98% in the determination of the DGS position and saves more than 99% of the computational time. The developed antenna is compact, simple in structure, and can be used for different applications in the Ku band.

The time-harmonic scattering problem from an isotropic multilayer coated 3-D object is considered. The coating is modeled by an impedance boundary condition (IBC) prescribed on the outer surface of the coating. The standard Leontovich IBC is local and constitutes a poor approximation for low index materials. A possible remedy is to employ high order IBCs (HOIBCs) involving tangential differential operators multiplied by coefficients. A generic HOIBC formulation (termed here IBC3) with five coefficients is considered here. Sufficient uniqueness conditions (SUCs) are derived for the corresponding Maxwell's problem (i.e. Maxwell's equations in free-space, radiation condition at infinity and IBC3 on the surface). The IBC3 coefficients are obtained by minimizing, with the SUCs as constraints, the error between either the exact and IBC3 impedances (local planar approximation) or the exact and IBC3 Mie series coefficients (local spherical approximation). Finally, the IBC3 is numerically implemented in a well-posed EFIE+MFIE formulation. Numerical results obtained on 3D objects demonstrate the high accuracy achieved with the constrained IBC3.

Resistive random access memory (RRAM) devices are promising candidates for next generation high capacity data storagedue to their superior properties such ascost-effective fabrication, high operating speed, low power consumption, and long data retention. Particularly, the two dimensional (2D)-materials-based RRAM has attracted researchers' attention because of its unique physical and chemical properties without the constraint of lattice matching. In this review, the switching mechanisms and modeling of RRAM devices based on the 2D materials such as hexagonal-boron nitride (h-BN) and graphene are discussed. Firstly, the monolayer and multilayer h-BNRRAMs are introduced, and their mechanisms and compact model are further described. Then, the mechanisms of graphene electrode-based RRAM (GE-RRAM) for different applications are also introduced and compared. Furthermore, the electrical conductivity, multi-physic and compact models of GE-RRAM are introduced. This review paper provides the guidance for the design and optimization of the 2D-materials-based RRAM in the next generation memories.

A dual-element miniaturized multiple-input-multiple-output (MIMO) antenna with a defected ground plane and a tapered microstrip feed line is introduced in this article. It achieves a bandwidth (BW) of 10.8 GHz (7.2-18 GHz), frequency ratio (FR) of 2.5, and average isolation of 15 dB over the entire operating band. The proposed antenna is right hand circularly polarized (RHCP) and achieves an axial ratio of < 3 dB in the frequency band ranging from 7.2 to 8.9 GHz. The performance characteristics of the proposed antenna are analyzed in terms of the envelope correlation coefficient (ECC), mean effective gain (MEG), total active reflection coefficient (TARC), isolation between the ports, and channel capacity loss (CCL), and the values obtained are 0.1607, 9.99 dB, ±3 dB, -11 dB, -7 dB, 0.20 bits/sec/Hz respectively. The proposed MIMO antenna is fabricated on an FR-4 dielectric substrate of dimension 10.6×10.3×1.6 mm³ and has good agreement between simulated and experimental results. The proposed antenna can be used for C, X, and Ku band applications.

In the present day scenario, the need for 5G technology is increasing daily, so we design a reconfigurable antenna working in the millimeter-wave range (25 GHz-30 GHz). The antenna is designed using HFSS software, and the antenna is loaded with compact planar metamaterial. This design includes 9 unit cells arranged in a 3 x 3 array, and each unit cell is made up of a hexagonal patch surrounded by a split ring resonator. Apart from this two-unit cells are connected using pin diodes. By operating these two pin diodes in different modes we get four different characteristics. The designed antenna radiates at 27 GHz with a gain of 3.75 dB to 4 dB. The designed antenna is compact and easy to fabricate with dimensions of 30 mm x 23 mm.

Controlled mutual attraction or repulsion, by the aid of light beam, between two or more particles, is regarded as the reversal of optical binding force. It has emerged as an important tool in the area of optical manipulation, facilitating clustering or aggregating between homodimer and heterodimer arrangements of particles. Despite a vast array of works being done in this area, dielectric-plasmonic hybrid dimer pair has not received any attention yet. To the best of our knowledge, in this letter, we have provided the very first proposal of a generic way to attain the controlled broadband reversal of optical binding force between dielectric and plasmonic hybrid dimer pair. A simple optical setup consisting of a plasmonic substrate placed underneath the hybrid dimer pair has been proposed, where the reversal of optical binding force can be attained by the incidence of a non-structured laser beam in both near- and far-field regions. Furthermore, we have demonstrated that the magnitude of this binding force can be enhanced, simply by altering the angle of incidence of the source of illumination. The force reversal has been attained based on two physical phenomena - mutual attraction and repulsion between the charges formed within the hybrid pair and the reversal of current density in the plasmonic object.

The object of this paper is a permanent magnet synchronous linear motor (PMLSM), whose control method is based on a model-referenced adaptive system (MRAS), and it analyses the speed identification of a permanent magnet synchronous linear motor without position sensors. The article proposes a new model-referenced adaptive method, which utilises a sliding-mode variable structure control method (SMC), to replace the PI control algorithm utilised in conventional model-referenced adaptive algorithm. The control system of the PMLSM is therefore designed and studied based on the change of the adaptive law in model-referenced adaption. the mathematical model of the PMLSM itself is chosen as the reference model, and the feedback magnetic chain model of the motor output is chosen as the adjustable model, replacing the conventional current model and simplifying the control algorithm. The sliding mode surface of the sliding mode variable structure control algorithm is constructed using the reference model and the output error of the adjustable model. Through theoretical analysis and simulation models built by MATLAB/Simulink simulation software, the simulation results show that the designed PMLSM speed induction-free control system MRAS speed observer based on the sliding mode variable structure has strong robustness and excellent dynamic static performance. The advantages verified by the new algorithm achieve the experimental purpose of the expected assumptions.

In this paper, the bandwidth of a bowtie antenna is improved to meet the requirements of Ground Penetrating Radar (GPR) applications that need a fractional bandwidth greater than 100% and are able to operate at low frequencies. This was done using several modification steps, which were the use of Antipodal technique for its advantages in reducing the complexity of the feeder network to achieve good matching with a standard 50-Ω SMA connector, bending the four corners of the arms and adding a triangular slot in each arm. The simulation was carried out using CST Microwave Studio to study the effect of each modification step on improving the bandwidth. The simulation results of the new antenna achieved a fractional bandwidth of 138% within the frequency range (1-5.45) GHz at the values of return loss (S11≤-10 dB). The new antenna was also fabricated, and the return loss was measured and showed a good agreement with the simulation results.

Utilizing spread spectrum time domain reflectometry (SSTDR) to detect, locate, and characterize faults in photovoltaic (PV) systems is examined in this paper. We present a method to obtain the model parameters that are needed to produce digital twin SSTDR responses for PV systems. The digital twin SSTDR responses could be used to predict faults within the PV systems. The model parameters are the reflection and transmission coefficients at each impedance discontinuity in the PV system along with the propagation coefficients across each PV cable segment. We obtain model parameter by applying inverse modeling techniques to experimental SSTDR data associated with PV systems. Our model parameters can be used in any digital twin simulation method for modeling reflectometry in frequency-dependent and complex loads. For validation, we used the model parameters in a graph network simulation engine and adapted it to be used for SSTDR digital twin simulations in PV systems. We produced simulations for 0 to 10 PV modules connected in series. We also simulated SSTDR responses for open circuit disconnections in a PV setup containing 10 PV modules in series. Results show that all but one simulated disconnect locations match experimental disconnection locations of the same setup with an error of less than 5%.

This proposal presents a novel design of a reconfigurable antenna with frequency, polarization, and pattern diversities for wireless body area networks. The design makes use of a 3.2 mm thick FR4 substrate of 39X36 mm² dimensions with a square patch and partial ground structure. The antenna operates in sixteen different modes and resonates at various frequencies ranging from 2.456 to 14.384 GHz. The proposed model has the capability to exhibit elliptical as well as linear polarization with different radiation patterns. For suitability of the proposed design in healthcare applications its SAR analysis has been performed along with other antenna characteristics like reflection coefficient, gain, radiation pattern, and axial ratio. Four PIN diodes have been used to switch the antenna operational modes.

Pneumothorax can cause chest tightness, chest pain, and respiratory failure, which can be life-threatening in severe cases. Therefore, early diagnosis and treatment of pneumothorax are crucial. Magneto-Acousto-Electrical Tomography (MAET)is an imaging technique in which ultrasound and electromagnetism are mutually coupled. It has the advantages of high spatial resolution and high image contrast. In this paper, we use MAET to study porous and air-containing lung tissue. We first simulate the characteristics of the MAET signal as the degree of pneumothorax increases. The relationship between the size of the ultrasonic probe and the size of the pneumothorax was discussed. The simulation results show that the reflection and attenuation values of the MAET voltage signals increase as the pneumothorax size gradually increases, regardless of whether the ultrasound transducer size is larger or smaller than the pneumothorax size. Finally, the MAET experimental platform was built to validate the simulation results of MAET signals. The results of the experiment and simulation are consistent with each other. The research of this paper has a certain reference value for the detection of pneumothorax using MAET.