In this paper, we propose a method for generating broadband orbital angular momentum (OAM) beams, utilizing the two neighboring ports of the uniform circular array (UCA) excited with a phase difference of (2(π+δ)l)/N. This approach differs from current arrays used to generate an OAM beam with a phase difference of 2πl/N. We establish that the UCA can produce OAM beams covering 83% (7-17 GHz) of the bandwidth. The array antenna consists of three Vivaldi elements with a phase difference between adjacent ports, capable of generating OAM beams of mode 2 when being fed with equal amplitude and phase. In contrast to current OAM antenna arrays that require complex phase-shifting networks for feeding, our proposed antenna array offers simplicity in its feeding mechanism. Furthermore, the UCA-based Vivaldi antenna presents a novel approach for generating wideband OAM beams and holds significant potential for applications in broadband communication.

The development of materials with excellent absorption properties in the C-band through the utilization of the magnetoelectric coupling effect holds great potential within the field of absorption research. However, there are still several challenges. To address these challenges, Fe@Carbon (Fe@C) microspheres were successfully fabricated using spray-drying followed by pyrolysis. The average size of the Fe@C microspheres is 3.6 µm with uniform dispersion, where iron nanoparticles (NPs) are tightly anchored with the carbon matrix to tune the microwave absorption properties. Synthesized Fe@C microspheres exhibit remarkable electromagnetic wave absorption capability within the C-band (4-8 GHz), covering a bandwidth of 2.8 GHz. Also, the Fe@C microsphere exhibits a minimum reflection loss of -48.11 dB at 4.5 mm thickness and 6.88 GHz. Systematic analysis has uncovered that the integration of large-sized magnetic carbon structures, high-density confinement of magnetic units, and robust magnetic coupling are crucial for enhancing the magnetic loss dissipation. This study introduces a novel approach for the preparation of electromagnetic absorbing materials, providing inspiration for further exploration of the mechanism behind low-frequency magnetic loss.

This article deals with the detection of defects of rectangular geometric shape, in a carbon fiber reinforced polymer (CFRP) composite material based on non-destructive testing by eddy current (ECT). For this, a stochastic finite element calculation code is developed in a Matlab environment. The main objective is to evaluate the ECT signal of a fault by determining the impedance variation for the two configurations, in the absence and presence of a fault. Additionally, the impact of the direction of the carbon fibers is exploited to evaluate the reliability of the material. The validation of our work is carried out using experimental data from the work of Takagi et al., provided for reference.

To address the insufficiency of large computation and unfixed switching frequency in permanent magnet synchronous motor (PMSM) of three-vector model predictive current control (TV-MPCC), simplified three-vector selection model predictive current control (STV-MPCC) for PMSM considering fixed switching frequency is proposed. Firstly, a novel voltage vector selection strategy is constructed by calculating the reference voltage in combination with the deadbeat control and re-dividing the sectors, reducing the number of optimizations from 11 to 5. Then, the current error is introduced in the calculation of the duty cycle to simplify the conventional control algorithm, The current ripple is reduced, and the system switching frequency is fixed. Finally, the experimental results indicate that compared with the conventional TV-MPCC, the d-q axis current ripple has been reduced by 13% and 18% respectively, and the torque ripple has been reduced by 6%, THD decreased from 4.70% to 4.25% and the steady-state performance of the motor is improved.

A compact UWB FSS reflector is presented based on an interdigital structure for gain enhancement of a UWB antenna. An equivalent circuit approach is proposed for the analysis of the FSS reflector. The reflector comprises a 6 × 6 array of unit cell dimension 6 mm × 6 mm and is very compact. The reflector gives a linear phase response over UWB. A UWB monopole antenna is designed with a half circular disc structure based on microstrip technology. A maximum of 5 dBi gain enhancement is achieved with this compact FSS reflector when it is placed at a distance below the antenna. The measured results closely follow the simulated ones which proves feasibility of this design.

This study introduces a groundbreaking circular ring-shaped fractal antenna optimized using particle swarm optimization (PSO) for wireless ultra-wideband (UWB) applications. The proposed fractal antenna design, featuring a central plus sign and an outer circular ring with eight smaller rings, enhances bandwidth for UWB response. The ground plane is modified with an etched curved slit to optimize antenna impedance. Utilizing PSO, we determine the fractal antenna's dimensions with optimization goals of minimizing size while ensuring |S₁₁| < -10 dB. Experimental data demonstrates strong performance across the 2.05 GHz-14.5 GHz frequency range, covering diverse wireless standards like UWB from 3.1 up to 10.6 GHz, X-band from 8 up to 12.5 GHz, and lower band of Ku from 12.5 to 14.5 GHz. Consistent measured and simulated results validate our contribution's applicability. Additionally, a time-domain analysis underscores the antenna's adaptability to UWB applications, offering insights into its response to transient signals.

Biomedical telemetry is, therefore, significant considering it facilitates prompt telecommunication as well as tracking of medical devices between centralized systems and patients. The availability and quality of communication of information are determined by the performance and selection of the telemetry antenna. This article analyzes the current state of BMA technology, aiming to extend the communication range and transmission speed of the data. The research article intends to contribute to the development of wireless technology. A plethora of antenna sizes are tackled from wearable to insertable antennas in addition to the improvements in materials and fabrication methods. The present review paper puts the thesis on only a few of the numerous biomedical telemetry antenna applications in healthcare, and these are the Internet of Medical Things (IoMT) and remote patient monitoring applications. it discusses case studies where better antennas had led to the creation of new therapeutic strategies, and diagnostic capacities, and had overall improved the quality of services. Therefore, the architectural problems of the existing designs are scrutinized, and this gives the other research areas the chance to be explored. A biological telemetry antenna is set to be the mobile edge computing solution that combines artificial intelligence, a 5G network, and edge computing. It also improves capital effectiveness over the transition period. Presentation makes it evident, why antennas are the essential component of the connected healthcare system and how antennas might redefine individualized care and the healthcare ecosystem. In conclusion, this research provides an extensive overview of the developments, uses, and future directions of biomedical telemetry antenna technology. It is an invaluable resource for academics, engineers, and medical professionals who seek to understand more about the evolving nature of this crucial component of modern healthcare systems.

In order to solve the problems of low reliability, low integration, and high cost brought by mechanical sensors in the control system of permanent magnet-assisted bearingless synchronous reluctance motor (PMa-BSynRM), a displacement self-sensing method of the Bback propagation (BP) neural network left-inverse system under the optimization of an improved particle swarm algorithm is proposed. Firstly, the working principle of PMa-BSynRM is introduced, and the mathematical model of PMa-BSynRM is derived. Secondly, the suspension force model is established to prove the left reversibility of the PMa-BSynRM displacement subsystem on the basis of the observation principle of the left reversible system. Thirdly, the weights of BP neural network are optimized by using the improved particle swarm algorithm to avoid local optimum, and the final weights are obtained to complete the construction of the displacement self-detection control system. On this basis, velocity change and anti-interference simulations are conducted to prove the tracking performance of the displacement system. Finally, static suspension, velocity change, and anti-interference experiments are executed which verify the accuracy and feasibility of the proposed displacement self-detection system.

In wireless communication systems, a control signal (CS) plays a vital role in managing the connection between transmitters (Txs) and the user equipment (UEs). This work presents CSs for non-orthogonal multiple access (NOMA)-based on visible light communication (VLC) systems. Moreover, pairing schemes, successive interference cancellation (SIC), and load balancing are considered with the NOMA-VLC technique for enhancing the entire performance. The CSs, which are single tones or can be described as unmodulated signals, are exploited to estimate the channel between Txs and UEs, and to evaluate the amount of interference at each UE. Thus, a controller, which is employed to manage the connections between Txs and UEs, can balance the load between Txs based on the level of interference at each UE. Each Tx is allocated a unique CS, i.e. a single-tone frequency. A power measurement unit (PMU) is utilized at each UE for measuring the power of each CS. Therefore, the controller divides the UEs into small groups based on the feedback signals from the PMU, then each group is connected to one Tx. Besides, CSs are used to find the optimum number of UEs that can be served by each Tx with a particular data rate of 50 Mbps and with an acceptable error probability of 10^-6, by utilizing on-off keying (OOK) modulation scheme.

5G wireless communication offers higher channel capacity, high data rate, sufficient bandwidth, enhanced coverage, and reliable link as compared to the previous generation mobile networks. Also, 5G becomes more relevant with the recent launches of low earth orbit satellites by various ventures like starlink, amazon, one web, etc. As these satellites have heights up to the range from 300 km to 1000 km, the free space path loss decreases drastically which in turn improves the signal reliability and efficient communication at dead spots. With these advancements, antenna researchers have the freedom to design compact, easy to manufacture, with adequate gain user equipment terminal antennas which can be easily integrated in the modern passenger car body. This paper will focus on the recent development in the design considerations of the compact antenna design at sub-6 GHz (n78 frequency band) and mm wave (n278 frequency band) according to 3gpp standards. This manuscript also discusses the various design specifications like selection of material for antennas, design complexity, feeding methods, fabrication and measurement challenges and performance parameters which include reflection coefficient, gain, polarization, axial ratio, cross polarization discrimination, radiation efficiency, radiation pattern shape, etc. The proposed antenna design considerations will facilitate the possible integration into the various parts of the car body according to the recent vehicular applications to uninterrupted communication.

The problem of unstable vibration signal and accurate fault feature extraction of motor bearing fault causes the low accuracy of motor bearing fault diagnosis. In order to improve the accuracy of motor bearing fault diagnosis, the variational mode decomposition (VMD) is used to decompose the vibration signal and combine with the convolutional neural network (CNN).The bearing faults are categorized into inner ring wear, outer ring wear and cage fracture; then each category of faults is further subdivided into the degree of loading, which is categorized into 0, 25% and 50%, with a total of 9 cases. In order to select sensitive fault features, the vibration signals of motor bearings in three dimensions are collected, decomposed into multiple endowment modal function (IMF) components by VMD. The energy entropy of each IMF in each dimension is extracted, and the sensitive fault features are selected by feature selection (ReliefF), and then input into CNN for fault diagnosis. At the same time, the fault diagnosis of transverse vibration signal and three-dimensional vibration signal is also carried out respectively. The experimental results show that the accuracy of the method is greatly improved, and the fault diagnosis can be realized.

Constant current (CC) charging and constant voltage (CV) charging are the two main charging stages of lithium-ion batteries in wireless charging systems. The traditional LCC-LCC topology has a high degree of design freedom. The conversion from CC to CV output is usually achieved through composite topology or frequency switching, which results in high control complexity and increases system cost. This paper proposes a wireless power transfer (WPT) system with CC and CV output characteristics based on topology reconstruction. Based on the LCC-LCC topology, by introducing one MOSFET in the rectifier and one AC switch which consists of two MOSFETs connected in reverse series to reconfigure the topology, the conversion from CC to CV mode can be achieved without complicated control methods and additional components. In addition, the proposed system works at a fixed operating frequency point, which can effectively avoid frequency bifurcation phenomenon. Therefore, the proposed system features a simple structure, easy control, low cost, and high robustness. In addition, ZPA operation can be realized in both CC and CV modes, ensuring high transmission efficiency. An experimental prototype with a rated power of 480W is built, and a maximum efficiency can reach 93.5%, which verifies the feasibility of the system.

The propagation study of electromagnetic (EM) waves within a human body is becoming essential due to the growing demand for the design and development of implantable sensing nodes in a body area network (BAN). Many researchers are interested in contributing to the development of propagation models in the ultra-wideband (UWB), i.e. 3.1 to 10.6 GHz, for biomedical applications, as well as the license-free Industrial, Scientific, and Medical (ISM) band. This kind of propagation model is essential in order to design and develop UWB transceivers for in-body, on-body, and off-body communications. This paper looks at the possibility of using a stepped slot patch antenna with a copper ground plane as either an off-body or on-body antenna by comparing measurements taken on a liquid human phantom. In addition, we use the empirical data to propose a statistical model.

This paper introduces a complementary split ring resonator (CSRR) patch antenna with elliptical slots on the ground plane for wireless communication, significantly amplified by placing two conducting elements over the substrate. The dimensions of the designed CSRR dual element multiple-input-multiple-output (MIMO) antenna are 16 x 32 mm² (0.66λ x 1.33λ). In this paper, the CSRR dual element MIMO antenna with an elliptical DGS resonates at 11.523 GHz, 12.305 GHz, and 15.178 GHz with reflection coefficients of -22.67 dB, -26.25 dB, and -47.65 dB respectively. It presents an impressive wide impedance bandwidth of 1.462 GHz covering 11.523 GHz and 12.305 GHz resonating frequencies and 1.446 GHz at 15.178 GHz resonance. The proposed design gives a gain of 5.29 dBi, 6.12 dBi, and 5.97 dBi for the resonating frequencies respectively. The results show a minimum envelope correlation coefficient (<0.025) and a significant diversity gain (>9.85) across the entire bandwidth. The measured results are close to the simulated ones, confirming the efficiency of the triple resonating frequencies with wideband, high-gain antenna design used for wireless communications for faster data transmission rates.

To improve the coupling problem between radial degrees of freedom in six-pole axial-radial active magnetic (AR-AMB), a decoupling control method based on an improved linear active disturbance rejection decoupling control strategy optimized by the least square support vector machine (LSSVM-ILADRC) is proposed. Firstly, the structure and working principle of the six-pole AR-AMB are introduced, and the mathematical model of suspension force is derived. Secondly, cascaded linear extended state observers (LESOs) are used to estimate the disturbance in degrees of freedom step by step, with LESO1 providing an initial estimate of the total disturbance, and LESO2 estimating and compensating for the difference between the initial estimate and the actual disturbance. The regression prediction function of LSSVM is employed to enhance the response speed and estimation accuracy of the LESO to the disturbance. Finally, the simulation and experimental research show that the proposed LSSVM-ILADRC decoupling control method has better decoupling performance and anti-interference performance than the ILADRC decoupling control method.

This article introduces a novel ship detection method for Synthetic Aperture Radar (SAR) images that leverages the principles of Finsler information geometry. It employs the curvature features of a statistical manifold as a discriminative mechanism to diminish the impact of sea clutter and augment the contrast between a target and its background. The ambiguity of the local microstructure and statistical characteristics is partially resolved by using information theory to select metric definitions and curvature representation of non-European space. This method models sea clutter using the Gamma Distribution Function (GDF), transforming the detection challenge into an anomaly detection framework within the GDF space. This approach establishes a theoretical detection framework rooted in Finsler information geometry by integrating statistical modeling with Finsler geometry. It harnesses the Finsler characteristics of GDF space to extract the curvature feature representations for each GDF. Detection is achieved by applying one-class support vector machines (SVMs) to a matrix of curvature values derived from these representations. The detection algorithm unfolds in two primary phases. Initially, it utilizes a family of probability distributions to capture geometrical information. Subsequently, curved features are employed for target detection. Through rigorous experimentation with real datasets, the method demonstrates enhanced resilience to sea clutter and outperforms existing techniques for analyzing distribution families, validating its effectiveness and robustness.

This paper introduces a compact, circularly polarized exponential slot antenna with a rectangular island. The concept of the proposed antenna is similar to that of fractal antennas as it is based on designing an asymmetric slot shape with an increased electrical length within a small area, thanks to the exponential path. The obtained results are as follows. The reflection-coefficient |S₁₁| of the proposed antenna covers the band from 5.5 GHz to 9 GHz. The proposed antenna is circularly polarized with an axial-ratio (AR) bandwidth that extends from 6.87 GHz to 8.9 GHz. It offers simultaneous dual circular polarizations (RHCP and LHCP). The gain of the proposed antenna varies between 4.2 dBic and 5.4 dBic. The efficiency reaches 94%. The size of the antenna is compact making it suitable for CubeSats with limited surface area. The proposed antenna intended application is X-band Earth-Space satellite communication. The proposed antenna can be employed for both the X-band satellite downlink (from 7.25 GHz to 7.75 GHz) and uplink (from 7.9 GHz to 8.4 GHz) frequency bands. Additionally, the antenna can be utilized in military applications, and RFID tag tracking-equipment. A prototype of the proposed antenna has been fabricated and then measured using Vector-Network-Analyzer (VNA) and inside an anechoic chamber. The measurement results of the proposed antenna are in excellent match with the simulated ones.

This work designs an electromagnetic band gap structure-based quad port rectangular MIMO antenna to operate in the 5G new radio (NR) sub-6 GHz n79 band, with a frequency range of 4.3-5.0 GHz. To achieve optimal radiating element isolation with the least complexity, MIMO antennas' four radiating elements are oriented orthogonally using an A-shaped electromagnetic band gap (EBG) structure. The EBG structure is located between the human phantom model and the MIMO antenna. The MIMO antenna's measurements are 40 × 40 × 1.6 mm³, and it is implemented on an FR-4 substrate with whole ground. Due to EBG structure, the mutual coupling is improved to -26.0 dB. The ECC, DG, and CCL were also calculated. In addition, the SAR (specific absorption rate) value is reduced to 0.22 w/kg. The MIMO antenna is simulated using HFSS software. The vector network analyzer (VNA), model Anritsu MS 2037C is used to measure the various MIMO antenna parameters.

This paper presents a compact double sided Ultra-Wideband (UWB) vivaldi antenna with corrugated structure. The proposed antenna is designed to operate from 5 GHz to 20 GHz frequency band. A comprehensive analysis of the antenna is carried out for its design, optimization, and performance especially for enhanced bandwidth and improved radiation characteristics. The antenna structure consists of vivaldi section which is printed on top and bottom layers of multi-layer printed circuit board (PCB) and fed with microstrip to strip lines transition. The antenna is fabricated and measured its return loss and radiation characteristics. The measured peak gain is 10.25 dBi at 17 GHz and return loss is better than -10 dB over the band 5 GHz to 20 GHz. Symmetrical radiation properties are observed over the band with excellent radiation characteristics especially in lower frequency bands as a result of comprised corrugated structure. Also, the far-field radiation pattern is symmetrical and directive throughout the operating band. The proposed design finds a suitable application in the field of an electronic warfare, precision ranging, microwave imaging.

In this study, we present a novel broadband microwave absorber that is both optically transparent and capable of dynamically adjusting its absorptivity. The absorber is composed of a graphene sandwich structure (GSS), a polyvinyl chloride (PVC) layer, an indium tin oxide (ITO) layer, another PVC layer, and an ITO ground plane, arranged in a top-to-bottom configuration. This unique design allows for a working bandwidth of 6.8 GHz to 14.0 GHz, with absorption levels ranging from 95% to 60%, achieved by varying the impedance of the GSS from 1000 Ω/sq to 200 Ω/sq through tuning the bias voltage. By utilizing materials with high optical transmittance, this nonpatterned device maintains exceptional optical transparency. Furthermore, by incorporating additional ITO layers with different impedances at equal intervals, this multilayer design can be extended to create an ultra-broadband absorber covering a range of 5.28-39.52 GHz. This is made possible due to the dispersionless resistance of nonpatterned graphene and ITO sheets in the microwave spectrum. This transparent wideband microwave absorber, with tunable absorptivity, holds great potential for a wide range of applications in broadband and intelligent stealth technology.