This communication presents the design analysis and development of a compact, dual-band, circularly polarized, multilayer antenna for global positioning system (GPS), wireless local area network (WLAN), and Industrial Scientific, and Medical (ISM) applications. The antenna comprises two etched strip radiator and reflector layers on two Kapton substrates situated at a vertical distance of 18.47 mm. The inverted U-strip results in WLAN/ISM band from 2.30-2.62 GHz whereas the semi-circular arc-strip is responsible for generating the lower band from 1.46 to 1.73 GHz. The bottom surface reflector plane is applied below the main antenna radiator which results in a unidirectional radiation pattern with improved front-to-back ratio (FBR), antenna gain, radiation efficiency, and specific absorption rate (SAR). The reflector contains an inner square ring with a circular center ring. The reflection coefficient below -10 dB fractional bandwidth (FBW) is suitable for GPS/ISM/WLAN/Wi-Fi/Bluetooth etc. operations. The maximum gain of 5.82 dBi is obtained at a frequency of 2.80 GHz. The antenna is designed on a flexible Kapton substrate of a size 28 × 31 mm². The SAR values below 0.01 W/kg and 0.02 W/kg are obtained at two resonance frequencies 1.60 GHz and 2.41 GHz, respectively. Therefore, the designed antenna is most suitable for indoor/outdoor wearable tracking purposes and also for medical applications.

The design of a compact low-loss diplexer based on complementary microstrip spiral resonators is described. The resonant elements are two: one is low-pass (channel A) and the other is passband (channel B). The low-pass element is composed of spirals departing from a circle, whereas the passband element is composed of spirals etched on a circle. The former element is novel and has been extensively analyzed here. These elements are connected using a star nonresonant Y-junction to form a single-layer vialess diplexer. As an example, a diplexer working at 0.87 and 2.0 GHz for satellite communications is manufactured and tested. The measured data show an insertion loss equal to 0.58 dB (0.66 dB) for channel A (B). The return loss exceeds 15 dB for both channels, and the dimensions are 0.129λ × 0.265λ ≈ 0.0343λ².

To address the problem of traditional speed loop controllers being unable to achieve rapid system convergence in the face of complex external operating conditions, this paper designs a new nonsingular fast terminal sliding mode control algorithm (NNFTSMC) for PMSM with a super twisting sliding mode perturbation observer (STSMO). Firstly, the mathematical models of PMSM for ideal case and parametric composite uptake are established. Secondly, a new non-singular fast terminal sliding mode control surface (NNFTSM) is proposed to design the PMSM speed-loop controller, which is also paired with the STSMO to observe the total system perturbation in real time and compensate the perturbation to the speed-loop NNFTSMC controller to form a new composite controller of NNFTSMC+STSMO. Finally, the proposed composite control algorithm of NNFTSMC+STSMO is verified to be effective in improving the control of the PMSM drive system during the parameters and load mutation by comparing simulation and RT-Lab semi-physical experiments.

To improve torque characteristics, this study proposes an upgrade over the standard salient pole stator in a Permanent Magnet Synchronous Motor (PMSM) using a segmented stator. The rotor is externally oriented and has a permanent magnet (PM) incorporated in it. The structure is studied theoretically through flux linkage analysis, torque production, and magnetic circuit model (MCM) analysis. Next, the finite element technique (FEM) is used to model the suggested motor and the salient pole stator, both of which have the same size. Next, a comparison is made between the simulation findings and the static torque, PM demagnetization, flux linkage, magnetic flux density distribution, and average and maximum torque. The proposed design results in a 79.97% increase in average torque, a 90.89% increase in maximum torque, and a 3.02% decrease in cogging torque.

This research proposal includes the design of a unique coplanar waveguide (CPW) fed ultra-wideband (UWB) antenna prototype with dual notch band characteristics. The microstrip line fed antenna features a configuration of geometric slots, including a rectangle, a semi-circle slots, and a pentagonal stub, along with a microstrip feedline. The antenna measures 35.4 mm × 28.82 mm. Two notches are introduced at 5 to 5.8 GHz (14.8% bandwidth) and 7.2 to 7.8 GHz (8% bandwidth) by incorporating split ring resonators (SRRs) on the bottom surface. Aside from the dual stop bands for the WLAN band (5 to 5.8 GHz) and the SHF satellite communication band (7.2 to 7.8 GHz), the designed antenna operates over an impedance bandwidth from 3 to 11.2 GHz with a voltage standing wave ratio (VSWR) below 2. The proposed antennas have been developed, prototyped, and successfully verified. Simulation data and measurement results are thoroughly examined and analyzed. To confirm the suitability of the designed antenna for pulsed communication systems, the correlation between the input signal of the transmission antenna and the output signal of the reception antenna in the time domain is estimated. This confirms that the antenna prototype is well suited for wireless communication applications in military radar systems, medical imaging, consumer electronics, and more.

In today's era of wireless communication, interaction of electromagnetic energy and living biological systems is unavoidable - both in far field and in near field of the radiating antenna. Consequent basic safety limits on radiation levels are enforced through Specific Absorption Rate (SAR) limits. Practical measurement and validation of these SAR values require the deployment of phantom models containing tissue equivalent dielectric liquids - these liquids are conventionally single layer and homogeneous in nature. However, structured basis to formulate these custom made homogeneous phantom liquids representing arbitrary combinations of stacked tissue layers has not been properly reported in literature. To address the issue, this paper develops and illustrates a novel structured technique to define equivalent permittivity and loss tangent of homogeneous phantom liquid representing arbitrary combinations of stacked tissue layers - both in far field and in near field exposure scenarios. Electric field distribution and later on point SAR distribution inside different tissue layers have been attempted to replicate as closely as possible using equivalent homogeneous phantom liquid with properly tuned permittivity and loss tangent values. The fitting procedure involves minimization of the absolute/normalized maximum difference (of electric field and point SAR) between the original multilayer tissue and the modelled single layer homogeneous equivalent. This generalized technique is applied to two distinct multilayer (four layers are considered) biological models at 2.45 GHz where one is composed of four layers of equal thicknesses while the other one has four layers with unequal thicknesses. Moreover, the proposed technique has been tested and validated in the two abovementioned multilayer biological models for both far field (plane wave irradiation) and near field (in close proximity to antenna) exposure scenarios. This technique is quite successful in achieving equivalent dielectric liquids in which original point SAR data and its overall distribution across different layers can be realistically replicated while attempting point wise matching at several spatial points. In some cases, the original electric field/point SAR values are achieved with reduced precision near layer interfaces with significant dielectric contrast. Thus, the proposed technique can significantly contribute to accurately measure, validate and reflect the true spatial SAR distributions in original multilayer biological models using the derived homogeneous tissue equivalent phantom liquids.

In this paper, a proposed design features a single-fed broadband circularly polarized antenna based on a rotating metasurface. The antenna is positioned between a rotating 4 × 4 periodic patch and the ground plane. The antenna comprises a driving patch and a parasitic patch. It utilizes the two modes of the driving patch, which exhibit different polarizations along the two directions. When the metasurface is placed on it, the truncation angle of the metasurface cells causes the excitation of the two modes with left-rotating circular polarization (CP) and right-rotating CP, respectively. To weaken the right-handed CP relative to the left-handed CP, effectively enhancing the latter, another angle is truncated on the metasurface cell, and the metasurface is rotated by an angle. The final antenna was fabricated and tested with an overall size of 32 × 32 × 3 mm³. Measurements indicate that the |S₁₁| < -10 dB bandwidth ranges from 4.72 to 7.67 GHz (47.9%), and the 3 dB axial ratio (AR) bandwidth ranges from 4.97 to 6.48 GHz (26.3%). Additionally, it achieves a peak gain of 7.75 dBi.

The performance and response characteristics of simulated optical biosensor have been greatly enhanced in this work. The results were obtained by evaluating three different structures, each varying in the number of holes surrounding the cavity. The guide-cavity coupling's structural and dimensional characteristics were varied for an effective comparative study. The high sensitivity quality of this optical biosensor was achieved using large transmission rate. The results showed sensitivity around 800 nm/RIU in the first version, 800 nm/RIU in the second version and 700 nm/RIU in the last version. Furthermore, the design parameters were optimized by finite difference time domain (FDTD) method.

This paper addresses the issue of sidelobe imbalance due to spurious coupling in quasi-elliptic filters designed in groove gap waveguide (GGW) technology using TE₁₀₂ overmoded cavity based resonator to realize the cross coupling in the cascaded quadruplet topology. The filter is designed at 38 GHz with 750 MHz bandwidth (1.97% fractional bandwidth) to demonstrate its potential as a narrow-band, high-power output filter at mm-wave frequencies in next-generation high throughput satellites. The filter is designed for production yield avoiding any complex structures to realize the negative cross coupling and using an all-capacitive iris structure. Systematic studies have been performed to identify and mitigate the sidelobe imbalance issue, and a final design has been proposed with a very low (<1 dB) sidelobe imbalance. The measured results of the realized hardware closely match simulated ones. The proposed design configuration is an ideal filter option for next generation SATCOM applications as it provides benefits of narrowband symmetrical frequency response with low insertion loss, sharp near band rejection, and high-power handling capability along with the benefits of gap waveguide technology in terms of ease of fabrication, low passive intermodulation (PIM) level, and low sensitivity towards surface imperfections and misalignment issues.

Wireless power transfer (WPT) for electric vehicles (EV) is a promising technology that can help with e-mobility because of its convenience and ability to reduce range anxiety issues. The safety concerns of such systems have received a lot of attention recently. Magnetic coupler is the most important component of WPT systems in terms of thermal safety as its temperature rises because of power outages during the charging process, which could cause damage to the surroundings and other components associated with the system. This article proposes a new thermal and magnetic coupler design by utilizing a Silicon-Cobalt wafer using the Spin Seebeck effect (SSE) phenomenon fabricated through the sputtering technique which can enhance the efficiency of the transmission coil as well as act as a heat exchanger to remove the heat from the coil as well as reduce temperature with the design model.

The current paper describes a compact, long-reading-range tag antenna for radio frequency identification (RFID) applications in the UHF (ultra-high frequency) band, operating at 915 MHz. The antenna's miniaturized design is achieved through the utilization of the meandering line technique. A T-matching structure matches the chip impedance to that of the antenna. Polytetrafluoroethylene, or PTFE, is used as the substrate for fabrication. The UHF tag's physical dimensions are 44.4 × 14.4 × 0.8 mm³. This antenna was first designed, simulated and then optimized by software CST-MWS (Computer Simulation Technology-Microwave Studio) before being fabri-cated. The Measured reflection coefficient at 915.5 MHz is approximately -24 dB, exhibiting a bandwidth of 7,9 MHz (911.5 MHz-919.4 MHz). The proposed tag is shown to have gain of 1.56 dB and radiation efficiency of 90% at the resonant frequency of 915 MHz. Its long-reading-range at 915 MHz is roughly 18.41 m, for an EIRP of 4 W. The measured results closely align with the simulated ones.

Aiming at the current distributed array subarray optimization design and DOA estimation problem, a robust and effective distributed array subarray optimization method is proposed, and a discrete quantum electromagnetic field optimization algorithm is designed to quickly solve the resulting objective function to obtain the optimal subarray structure. Then, based on this array structure, the infinite-norm exponential kernel maximum likelihood method is utilized for direction of arrival (DOA) estimation. The simulation results show that the proposed method can still be effective in the case of impulsive noise, small snapshots and low signal-to-noise ratio, which further verifies that the proposed method can obtain a better subarray layout and superior DOA estimates.

This article presents an 8 × 8 Multiple-Input Multiple-Output (MIMO) antenna system that operates in two frequency bands: 3.4-3.8 GHz and 10.5-14.0 GHz. The core element of this antenna system is a rectangular patch with a line slot. To assess the diversity performance of this MIMO antenna, various parameters like S-Parameters, Envelope Correlation Coefficient (ECC), Mean Effective Gain (MEG), Channel Capacity Loss (CCL), Total Active Reflection Coefficient (TARC), and Channel Capacity (CC) were used. The study demonstrates a strong alignment between measurement and simulation results. The article thoroughly analyzes the simulated and measured performances of the lower band (LB) (3.4-3.8 GHz) and upper band (UB) (10.5-14.0 GHz). In the LB, the measured values for parameters such as reflection coefficient, mutual coupling coefficient, TARC, total efficiency, ECC, MEGi-MEGj, CCL, and CC all surpass or equal specific benchmarks. Specifically, these values are better than -6 dB, 10 dB, -11 dB, 56%, 0.15, 0.83 dB, 0.275 bps/Hz, and 38 bps/Hz, respectively. For the UB, the values are also quite favorable, exceeding or closely matching key criteria: -6 dB, 10 dB, -5 dB, 40%, 0.2, 1.6 dB, 0.55 bps/Hz, and 33.6 bps/Hz. These findings suggest that the intended MIMO antenna meets the necessary conditions for both the LB and UB regions. As a result, it appears to be a promising choice for applications in 5G mobile networks and satellite communications, including Direct Broadcast Satellite (DBS) and Fixed Satellite Services (FSS).

In order to achieve the optimization objectives of low torque ripple, high torque and high efficiency, this paper proposes a multi-objective optimization strategy based on genetic algorithms optimization BP neural network (GA-BP) combined with non-dominated sorting genetic algorithm (NSGA-II) and applies it to the multi-objective optimization design of an external rotor ferrite-assisted synchronous reluctance motor (ERFa-SynRM). Firstly, the preliminary design and selection of ERFa-SynRM structure are carried out. Secondly, a comprehensive sensitivity analysis is presented on the extent to which the design variables affect the optimization objectives. Following this, a high-precision prediction model is constructed by GA-BP neural network, and NSGA-II is applied to global optimization of the prediction model. Finally, the electromagnetic performances of the motor before and after the optimization are compared by the finite element analysis (FEA) software. Compared with the initial motor, the average torque and efficiency of the optimized motor are improved, and the torque ripple is reduced by 54.9%, which verifies the effectiveness of the multi-objective optimization design method.

This paper focuses on optimizing the radiation pattern of sparse array antennas using reinforcement learning, with many algorithms. The paper aims to leverage Proximal Policy Optimization's (PPO's) advantages in optimization and its effectiveness in handling stochastic transitions and rewards to achieve a reduced number of elements while maintaining desired signal performance and minimizing unnecessary side lobe signals. By removing a few of the antennas using reinforcement learning and PPO optimization, the same results as a complete array have been obtained. The anticipated outcomes of this research hold the promise of significantly enhancing the effectiveness and utility of sparse array antennas in communication systems.

This paper details the design and realization of a high-isolation multiple-input-multiple-output (MIMO) antenna tailored for fifth-generation (5G) wireless applications. The antenna consists of a 2-element array, with each unit being a patch antenna loaded with six uniformly sized complementary split-ring resonators (CSRRs). These CSRRs are strategically etched to minimize the antenna's overall size. In addition, the fragment-type split ring resonators (SRRs) are horizontally positioned between the antenna units to further improve isolation. The placement and structure of these fragment-type SRRs are optimized through a combined use of High-Frequency Structure Simulator (HFSS) and genetic algorithm (GA) techniques, which enables significant isolation levels exceeding -40 dB between antenna units. The proposed MIMO antenna operates within the 5G C-band with a -10 dB bandwidth ranging from 4.84 to 5.00 GHz, while the isolation at 4.9 GHz improves from 14.73 dB to 42.88 dB. Moreover, the maximum Envelope Correlation Coefficient is 0.002, and the antenna dimensions are 50 mm × 44 mm × 1.6 mm. Antenna samples are fabricated using wet etching on an FR4 substrate. The measured and simulated values are found to be in good agreement. Compared to the traditional antenna design method, which relies on parameters sweeping, the algorithmic approach used in this paper significantly enhances both the design's effectiveness and efficiency.

A CPW-fed flexible fractal shape circular ring patch (FSCRP) antenna is presented in this paper and operates at ISM band for biomedical applications. The proposed antenna operates at 2.46 GHz both in free space and on a human hand. This antenna functions within a 10 dB impedance bandwidth of 390 MHz (2.38 GHz to 2.77 GHz) in free space and 800 MHz (2.04 GHz to 2.84 GHz) on human hand structure with a reflection coefficient of -33.9 dB and -36.97 dB respectively. The circular shape fractal structure operates the antenna with circular polarization, and a 3 dB axial ratio of 170 MHz (2.4 GHz to 2.57 GHz) has been observed. The proposed antenna can be used in Implantable Medical Devices (IMDs) for biotelemetry applications. The simulated and measured results for the proposed FSCRP antenna are also presented in this paper.

Radio frequency energy harvesting (RF-EH), which uses an ultra-wideband (UWB) antenna, is the best substitute for traditional batteries for continuously powering sensor networks. The UWB antenna helps to receive the ambient radio frequency energy that radiates from communication applications for harvesting purposes to power devices or recharge batteries. A novel aspect of this design is the use of dual antenna ports with four ``A" shaped in radiating patches and ground plane, which permits the harvester to completely utilize all accessible frequency bands. The design analysis of a compact dual-port (2 × 1) ultra-wideband multiple-input multiple-output (UWB-MIMO) antenna based on four ``A" shaped and shared ground plane for RF energy harvesting in the band of 2.3-21.7 GHz is presented. The proposed antenna has been implemented on a Rogers RT 5880 substrate with a size of 39 mm × 30 mm, a thickness of 0.8 mm, and a dielectric constant of 2.2. It achieves S₁₁ ≤ -10 dB at (2.3-21.7) GHz and a maximum peak gain of 10.29 dB at 20.53 GHz. The proposed antenna is designed and simulated with ANSYS HFSS and fabricated. The results of simulation and measurement of the proposed antenna are in good agreement, and the antenna achieves bandwidth of 2.3–20 GHz that supports radio frequency energy harvesting in addition to UWB applications across satellite, Wi-Fi, Wi-Max, and mobile applications.

In order to solve the issues of large computation and control performance affected by motor parameters in the conventional model predictive torque control (MPTC) of permanent magnet synchronous motors (PMSMs), a robust model predictive torque control strategy with online parameter identification based on an improved differential evolution extended Kalman filter (IDEEKF-RMPTC) is proposed To begin with, and a steady-state voltage vector at the next time is obtained through a low-pass filter and used as the reference voltage vector to select the alternative voltage vector. The parameter robustness of the PMSM system is enhanced, and the computational effort is reduced. In addition, an improved differential evacuation algorithm for the extended Kalman filter (EKF) is designed, and the system noise matrix Q and the measurement noise matrix R of the EKF are optimized. The estimation error is reduced; the stability of the system is enhanced; and the accuracy of the identification of the motor parameters is improved. Finally, the computational effort of the system is effectively reduced by the proposed IDEEKF-RMPTC strategy, and the parameter robustness of the PMSM drive system under parameter mismatch conditions is enhanced which are proved by the experimental results.

This article presents a miniaturized dual layer angularly stable quadband frequency selective surface (FSS) for shielding applications. The shield consists of four metallic square rings on a thin FR4 substrate of relative permittivity 4.4 and thickness 0.5 mm with two rings on top layer and other two rings in the bottom layer. The dimension of the shielding unit cell is 0.2λ × 0.2λ, for the lowest frequency. These shields have been analyzed in both planar and conformal configurations. The equivalent circuit models as well as analytical model are determined. The shield exhibits quad band band stop characteristics with transmission zeros at 5 GHz (4.3-5.8 GHz), 6.6 GHz (6.3-6.8 GHz), 8.3 GHz (7-8.8 GHz) and 15 GHz (11-17 GHz). These bands find their application in shielding upper WLAN band, sub 6 GHz 5G band C/Ku band for satellite communication. The proposed FSS prototype is fabricated and tested for shield effectiveness in an anechoic chamber. The proposed FSS design offers stable angular response up to 60˚ for planar and geometry. Simulated and measured transmission coefficients are in good agreement and hence well suited for shielding applications. As the structure is fourfold symmetric, it exhibits polarization insensitive and angular stability in all four bands.