This article presents an innovative UHF RFID tag sensor featuring a flexible ring resonator dipole integrated with a fluidic channel. Leveraging the unique characteristics of the resonator dipole, the sensor demonstrates high sensitivity in detecting the dielectric properties of various liquids. The RFID integration facilitates wireless communication and remote monitoring, enabling real-time, continuous measurement of sensor data. The sensor's flexible design allows for easy attachment on the PLA fluid channel, enhancing its practical utility. Experimental results show a strong correlation with reference measurements obtained using traditional laboratory methods using VNA. The sensor achieves effective impedance matching up to 1 GHz, even without the presence of a liquid in the channel. Moreover, confining liquids with high dielectric constants within the channel broadens the operational range across the UHF RFID band, spanning 865 MHz to 928 MHz, and the wireless RFID tag sensor is well suited for applications requiring real-time analysis and continuous monitoring. The proposed flexible ring resonator dipole UHF RFID tag sensor, coupled with fluidic channel-based tuning, offers significant potential for applications such as chemical analysis of liquids. Its unique blend of flexibility, wireless data communication, and accurate dielectric characterization opens new avenues for noninvasive and remote sensing in liquid-based system.

This study presents a compact four-port antenna optimized for sub-6 GHz 5G MIMO systems. The design incorporates a crescent-shaped radiating element paired with a defected ground structure (DGS) to improve both bandwidth and port-to-port isolation. Operating within the 3.2-3.8 GHz frequency band, the antenna maintains a VSWR below 2. The orthogonal arrangement of the radiators effectively suppresses mutual coupling, ensuring that isolation levels exceed -15 dB. Simulated and measured results validate the design, demonstrating a maximum gain of 5 dBi and radiation efficiency reaching up to 80%. Key MIMO performance indicators - such as envelope correlation coefficient (ECC), total active reflection coefficient (TARC), channel capacity loss (CCL), and diversity gain (DG) - confirm the antenna's suitability for robust 5G communication.

In this paper, a novel hybrid-excitation external-rotor switched reluctance motor is presented to solve the problem of low output torque of traditional switched reluctance motors (SRMs). The hybrid-excitation SRM, serving as an effective alternative to electric excitation SRMs, achieves comparable torque output with reduced excitation currents and lower power consumption within a certain range. First, the structural configuration and operational principles of the proposed SRM are presented and investigated. Then, key electromagnetic properties based on three-dimensional finite element analysis are analyzed in detail, such as the distribution of magnetic density, torque, and flux linkage. Furthermore, the validation is subsequently conducted through simulation data and performance comparisons with conventional outer-rotor 6/4 SRMs, conclusively confirming the theoretical framework's practical feasibility. Finally, the direct torque control with variable flux linkage based on the HESRM is executed, and the good control performance is verified under different conditions.

The model predictive control (MPC) for quasi-Z source inverter (QZSI)-based permanent magnet synchronous motor (PMSM) system suffers from the problems of inductor current ripple, large motor stator current pulsation and system susceptibility to load torque disturbance. A QZSI composite voltage vector model predictive current control strategy with a novel sliding mode reaching law (CVVs-NSMRL-MPCC) is proposed. Firstly, a composite voltage vector - including one shoot-through, one zero, and two active voltage vectors - is applied to the QZSI during each sampling period, which can effectively reduce the QZSI inductor current ripple and three-phase current pulsation. And the design work for weighting coefficients in the cost function is simplified by calculating the inductor current at ST duty cycle using dead beat control. Furthermore, a sliding mode controller with a novel reaching law is designed for the motor speed loop. Based on it, the external load disturbances are feed-forward compensated to the output port of the controller by the disturbance observer, which reduces the PMSM speed loop pulsation during load torque disturbances and improves the system transient control performance. Finally, the practicality of the strategy proposed in this paper is verified by experiments.

Addressing the deployment challenges of 5G communication equipment in the complex electromagnetic environment of substations, this paper takes an actual substation as the research object. Through a combined approach of physical modeling and field measurement validation, it systematically investigates the deployment issues of 5G devices in substations. Firstly, a power frequency electromagnetic field model of the substation is established, and its reliability is verified by comparative analysis between simulation results and on-site measured data. Secondly, by establishing a radiation model of 5G communication equipment, the mutual interference between 5G devices and secondary equipment within the substation is investigated. Finally, leveraging the distribution characteristics of the power frequency electromagnetic field in the substation, a tailored deployment scheme for 5G communication equipment is proposed. This study provides both a theoretical foundation and technical support for the practical deployment of 5G in smart substations, thereby advancing the deep integration of power systems and communication systems.

Permanent magnets have a unique ability to generate a permanent magnetic field that has been found in various applications. In this study, to facilitate the design and optimization processes of magnetic devices, fast-computed expressions of the magnetic field created by a magnetised paraboloid are developed. It is demonstrated that the derived models are in good agreement with the conventional Finite Element Analysis (FEA). Moreover, these models are multiple magnitudes faster than the FEA in terms of computational time. Furthermore, analysing the magnetic field distribution generated by this magnet, it is shown that the field is concentrated around its revolute axis. In addition, the field is sharply concentrated and pointy, close to the apex of the paraboloid. The field expressions and their properties are expected to assist in the design and optimization processes of magnetic devices utilizing this magnet, such as in static magnetic field brain stimulation.

Offsets in the coupling mechanism and load fluctuations usually lead to instability in the output voltage of wireless power transfer (WPT) systems. Therefore, accurate and rapid identification of the mutual inductance and load parameters of the system is crucial for achieving stable output control for communication-free WPT systems. In this paper, a method based on the joint real-time identification of both mutual inductance and load parameters is proposed. By measuring the primary inverter current and the current on the shunt compensation capacitor, two current equations about the mutual inductance and load resistance are constructed, in which only the RMS values of the above two currents need to be determined. The traditional equations are too slow to be solved, and the amount of computation is too large; therefore, this paper combines this method with particle swarm algorithm, which transforms the problem of the system parameter identification into a function optimization problem. Through this method, the identification results of mutual inductance and load resistance can be obtained in real time, and then the conduction angle of the inverter can be calculated quickly to realize the constant voltage output control. Finally, a wireless power transmission experimental platform is built, and in the experiment, the recognition accuracy of mutual inductance and load reaches more than 96.7% and 96.4%, respectively, which verifies the feasibility and practicality of the design.

This paper addresses the problem of sizeable cogging torque and torque ripple of conventional consequent pole permanent magnet motor (CPPM) and proposes an asymmetric pole-consequent pole permanent magnet (AP-CPPM) motor as a solution. This paper proposes an asymmetric pole-consequent pole permanent magnet (AP-CPPM) motor. A combined strategy of response surface method and multi-objective genetic algorithm is adopted. Firstly, sensitivity analysis of design variables and stratification were carried out, and subsequently, the mathematical model between the design variables and the optimization objective is obtained by Response Surface Methodology (RSM). Then, the high-sensitivity parameters are optimized using a Multi-Objective Genetic Algorithm (MOGA) to get the optimal solution. Finally, the electromagnetic performances of the motor before and after optimization are compared using Finite Element Analysis (FEA) software. The results indicated that the optimized motor reduced the torque ripple by 39.9% and the peak-to-peak value of cogging torque by 62.41% with only a 3.1% reduction in the output torque, which ensured good output characteristics and verified the feasibility of the optimization scheme.

Object: The varying breast morphologies can lead to enormous differences in microwave backscatter signals, making it difficult to identify weak tumor responses, which adversely affects the performance of microwave detection. Existing deep learning methods for microwave tumor detection struggle to generalize across diverse breast morphologies. The purpose of this study is to develop a deep learning method to overcome the influence of breast morphology on microwave tumor detection. Methods: This paper proposes a domain-adversarial tumor detection network (DATDNet) to improve detection performance. The proposed method employs breast backscatter signals with known tumor information as source domain data for training a convolution neural network. Subsequently, deep adversarial training is conducted on the backscatter signals of breasts with unseen morphologies and unknown tumor information in the trained network, in order to mitigate the adverse effects of variations in breast morphology on detection. In the process of microwave breast image feature extraction, our method introduces channel and spatial attention mechanisms in the convolution modules to pay more attention to tumor information. Results: The feature distribution estimations demonstrate that the microwave data from different breast morphologies are effectively aligned. In two datasets with completely different breast morphologies, the detection accuracy reaches 76.64% and 83.15%, with an improvement of 5.36% and 7.79% compared with baseline CNN. The ablation studies demonstrate that the proposed method effectively enhances the generalization performance and accuracy of microwave breast cancer detection.

Shorter frequency reuse distance in a densified small cell network for fifth generation (5G) could cause more substantial inter-cell interference. Rather than relying on down tilt, it is more necessary to design the azimuth patterns of the antennas to substantially reduce the gain at the sector edges which can reduce the line of sight radiation towards a sector positioned over a reuse distance. The antenna employs a modified ground plane, which utilizes both reflection and diffraction to reduce the gain at the sector edge, and is designed and prototyped from 3.5-4.2 GHz.

Fibre optic coupling is a critical component in optical communication systems, which involves efficiently transmitting optical signals from a light source to an optical fibre and efficiently receiving optical signals from the optical fibre to an optical detector. This process requires minimizing the loss of optical signals during the coupling process to maintain the performance and stability of the communication system. The complex environmental conditions and dynamic changes in optical systems that traditional optimization methods face often make it difficult to handle effectively. Therefore, this study uses deep reinforcement learning and adaptive optics technology to optimize fibre coupling efficiency. The optical fibre transmission performance is analyzed and optimized. Because the 2.6 Gb/s optical transmission system is a highspeed optical communication system capable of transmitting 260 million bits of data per second on a single optical fibre, this study selected the 2.6 Gb/s optical transmission system for single fibre three-way optical components. The optimization results show that the thickness of the isolator has been reduced by 2.356 mm, and the coupling efficiency has reached 79.95%. The optimized coupling steps can effectively optimize the coupling process, and the optimized optical components have high coupling efficiency, yield, and integration. The analysis of multiple sets of experimental data showed that the proposed method could improve the fibre coupling efficiency by an average of 15% to 20% under different environmental conditions. These data also show that the new framework performs well in optical path optimization and demonstrates excellent stability and real-time response capabilities in complex environments.

In this paper, the characteristic basis function method (CBFM) is accelerated to calculate the monostatic and bistatic normalized radar cross sections from one-dimensional highly-conducting sea surfaces in the microwave bands (C and Ku). In the framework of the two-scale asymptotic model, the subsurface length of the block is judiciously derived to contain all the surface curvature components (small scale) and the associated PBFs, assumed to be identical for all blocks, are rapidly calculated from the Kirchhoff approximation. In addition, the reduced matrix calculation is accelerated by neglecting the interactions between far blocks and by introducing a roughness slight approximation (matrix-matrix products can be done from fast Fourier transforms), which also allows us to expedite the resolution of the linear system since the matrix is sparse. Numerical results show the efficiency of CBFM-KA.

This paper demonstrates a Hybrid Fractal MIMO Antenna (HFMA) integrated with a Complementary Split Ring Resonator (CSRR) for fifth-generation wireless applications. Two radiating elements based on Meander and Minkowski Hybrid fractal geometry are included in the proposed design. The defected ground plane, along with CSRR, has been employed to enhance the isolation, bandwidth, gain, and other performance characteristics of the proposed HFMA. The proposed antenna was constructed using Rogers RT/duroid 5880 material. The designed model offers a maximum isolation of -55.86 dB and a wide bandwidth of 28.72 GHz, spanning the frequency range from 1.28 GHz to 30 GHz. All the diversity parameters of the designed antenna are found within operating limits. The proposed antenna is capable of covering multiple 5G spectrum bands, including LTE band 46 (5.15-5.925 GHz), 5G New Radio and 3.5 GHz frequency bands (3.3-5.0 GHz), the 26 GHz 5G spectrum, the European Union 5G spectrum (5.9-6.4 GHz), and is highly suitable for a range of other advanced applications, including Internet of Things (IoT), satellite communications, and vehicular networks in the frequency range of 1-30 GHz band.

We present a full-physics simulation workflow for modelling the installation and isolation of flush-mounted antenna arrays on rockets, which employs a combination of finite array domain decomposition method (FADDM) and shooting and bouncing rays (SBR) solver. An advanced domain decomposition method is first demonstrated, incorporating `non-identical' unit cells to efficiently solve a 4×4 antenna array residing in a metal cavity and operating in the X-band at 8.5 GHz. The proposed workflow eliminates the need for any computer-aided design (CAD) modifications for constructing conformal geometries of antennas and recesses in the fuselage, enabling seamless flush mounting of the array into an accurate model of a SpaceX Dragon capsule. The SBR simulation in the workflow is enabled with essential methodologies such as automati current conformance, creeping-wave physics, physical theory of diffraction, uniform theory of diffraction and current source reduction technique to obtain a high-fidelity yet computationally economical solution that determines radiation characteristics of installed antenna array and isolation between two flush-mounted antenna arrays.

By utilizing the symmetry of the field distribution of a coplanar waveguide (CPW) SSPP transmission line (TL), a half-mode SSPP (HMSSPP) transmission line (TL) is presented. Through electromagnetic simulations, it is demonstrated that the proposed HMSSPP TL has a lower asymptotic frequency than the CPW SSPP TL, while occupying only half of the size. Through equivalent circuit analysis, the miniaturization mechanism of the half-mode structure is revealed, and the method to further reduce the asymptotic frequency has been developed. The fabricated and measured HMSSPP TLs confirm the effectiveness and benefits of the half-mode transmission line, achieving significant size reduction and maintaining low insertion loss. Such compact transmission lines are particularly advantageous in space-constrained applications such as portable communication devices, radar systems, and compact RF modules for wireless sensing.

This paper introduces a compact dual-band wearable antenna designed for mmWave applications. The antenna is fabricated on a Rogers 3003 semi flexible substrate with dimensions of 15 × 15 × 1.52 mm³ and features a circular radiating patch with a full ground plane. Initially designed to resonate at 28 GHz, the antenna incorporates a square split-ring resonator in the ground plane to achieve an additional resonance at 38 GHz. To improve bandwidth and gain, a round necktie configuration is applied by adding two diagonal rectangular patches to the periphery of the radiating patch. The measured impedance bandwidths are 21.4% at 28 GHz and 23.7% at 38 GHz. The antenna achieves gains of 5.91 dBi and 4.57 dBi, with efficiencies of 90% and 78% at the respective operating bands. Simulated SAR values are 0.57 W/kg and 0.31 W/kg for 1 g and 10 g of human tissue at 28 GHz, and 0.18 W/kg and 0.16 W/kg at 38 GHz. These SAR values comply with FCC and ICNIRP safety standards. Additionally, bending tests illustrate that the antenna's performance was stable under deformation. As a result, the proposed antenna is ideal for fast connectivity 5G and biomedical applications since it efficiently spans fundamental mmWave frequency ranges.

In this paper, a tunable ultra-wideband antenna based on slot structures is presented and verified using Characteristic Mode Analysis. The antenna is backed with a partial ground plane and covers the 2.8-13.2 GHz frequency band. In this wide frequency range, satisfactory VSWR and gain are achieved. To avoid interference with wireless local area network WLAN (5.2 to 5.8 GHz) and X-Band satellite links (7.9 to 8.4 GHz), two notches are created using U-shaped and elliptical slots. An important feature of this paper is the use of varactor diode in the elliptical slot to achieve tunable frequencies for the second notched band. By applying different bias voltages, the center frequency of the second notched band is continuously tuned. The antenna performance is verified using modal parameters including modal significance and characteristic angle within the working region of the proposed antenna using the theory of characteristic modes analysis. This antenna is implemented on top of a cost-effective FR4 substrate with a 1 mm thickness. The proposed flower-shaped antenna is compact in size and provides ultra-wide bandwidth. The dimension of the optimized design is 25 × 35 × 1 mm³.

When permanent magnet synchronous motors (PMSMs) drive flexible loads, unknown disturbances (such as sudden load torque changes, parameter uncertainties, and unmodeled dynamics), can degrade the control performance of the system and may even cause irreversible physical damage. To deal with this problem, this paper presents an improved non-singular terminal sliding mode control (INTSMC) scheme based on a finite-time extended state observer. First, the acceleration feedback is introduced into the speed loop to establish the dual-inertia model of the PMSM flexible load system. Secondly, the conventional exponential reaching law is improved to obtain a novel reaching law with adaptive adjustment of the convergence speed, and a novel INTSMC controller is designed accordingly to enhance the system response speed. Then, a finite-time extended state observer (FTESO) is designed to estimate the disturbances of the system, and the estimated disturbances are compensated for the INTSMC controller to achieve convergence in finite time and improve the robustness of the system. The finite-time stability theory is used to prove the stability of the designed controller and observer. Finally, the simulations and experiments demonstrate the effectiveness of the proposed control scheme in improving the system’s anti-disturbance capability.

The proposed planar antenna features F and U shaped strips on the patch, along with U shaped slits on the ground plane, catering to WLAN/Bluetooth/WiMAX/HYPERLAN applications. Initially designed for a resonance frequency of 2.4GHz using standard formulae, the rectangular patch antenna boasts dimensions of 38.60 x 46.70 mm², totaling 1803 mm². However, employing the covering electrical length technique, the proposed antenna effectively reduces size for multiband applications. The lengths of the strips determine the resonance frequencies, while the U shaped slits facilitate adjustment of resonance frequencies as required. Following parametric optimization, the rectangular patch antenna becomes suitable for multiband operation, shrinking in size by up to 71.47% compared to its original form. The proposed antenna achieves resonance at 2.45 GHz, 3.55 GHz, and 5.37 GHz, effectively covering WLAN, Bluetooth, Zigbee, WiMAX, and HYPERLAN frequencies. Despite size reduction, the antenna maintains acceptable gain, ensuring its viability for multiband operations. The compact dimensions of the proposed planar antenna measure 39.5 x 13 mm², making it ideal for integration into small portable devices such as mobile handsets, laptop computers, and USB dongles. Following fabrication, various parameters of the antenna are measured using a Vector Network Analyzer (VNA), including reflection coefficient, Voltage Standing Wave Ratio (VSWR), and impedance.

A planar, short-circuited dipole design, constructed from cutting a flat metallic plate, capable of operating in the 2.4/5/6 GHz Wi-Fi 8 bands and also the 6G upper mid-band in the 7125-8400 MHz range is presented. The antenna comprises two folded dipole arms, each of which has a cut-out portion, with one short-circuiting portion connecting them. The plate dipole can operate at its 0.5-, 1.5-, and 2.5-λ resonant modes with two higher-order resonances forming a very wide 10-dB impedance bandwidth of about 5.0-9.4 GHz, easily covering the 5150-8400 MHz band for the 5/6 GHz Wi-Fi bands and the 6G upper mid-band. The design is simple in structure, has a compact size of 10 mm × 30 mm (0.08-λ × 0.24-λ at 2.4 GHz), and also shows good radiation performance. The design concept is elucidated and discussed in this paper with the numerical and experimental results.