Conventional model predictive flux control (C-MPFC) generates large steady-state ripples, and the system reference values are heavily dependent on the permanent magnet (PM) flux This paper proposes a discrete space vector modulation model predictive flux control with a reformulated incremental cost function and efficient search strategy (RDSVM-MPFC) for surface-mounted permanent magnet synchronous motors (SPMSMs). First, a unified cost function based on flux increments is reconstructed by redefining the d-axis reference flux. Second, the candidate set is expanded via discrete space vector modulation (DSVM) in the spatial flux increment plane to generate a set of virtual flux increment vectors (VFIVs), thereby significantly suppressing steady-state errors. Furthermore, to manage the heavy computation burden associated with the expanded VFIVs, a three-stage hierarchical optimization strategy is designed. This approach achieves rapid identification of the optimal control vector, which preserves the high steady-state precision while largely reducing the computational complexity of the system. Finally, experimental studies demonstrate that the proposed RDSVM-MPFC strategy eliminates sensitivity to PM flux variations and markedly suppresses steady-state pulsations.

This study focuses on a Short-Primary Single-Sided Linear Induction Motor (SSLIM), which is widely used in the rail transit sector due to its low operating noise and small turning radius. Therefore, designing linear induction motors with better performance is of great significance. This study aims to enhance electromagnetic thrust and reduce fluctuations in electromagnetic force by optimizing the motor's structural design. First, a motor model is established based on its operating principles, and a brief analysis of its electromagnetic characteristics is conducted. Second, two design schemes were selected for both the primary and secondary components. For the primary components, one scheme employs a chamfered structure to suppress fluctuations in electromagnetic force, while the other modifies the tooth tip shape from rectangle to trapezoid to increase thrust. For the secondary components, one scheme involves incorporating a material with higher electrical conductivity into specific areas of the aluminum plate, and the other involves slotting to optimize the magnetic field distribution and increase thrust. Finally, the performance of the optimized model was compared with that of the initial model. The results showed that the average thrust increased by 5.3%, while the fluctuations in thrust and normal force decreased by 13.6% and 30%, respectively, validating the effectiveness of the optimization approach.

In this study, a novel miniaturized multiband flowerpot-shaped patch-based cylindrical dielectric resonator antenna (FPSDRA) is proposed for 5G-enabled GNSS (GPS), UMTS, PCS, Wi-Fi5, WiMAX, and NR 77/78 sub-6 GHz 5G applications. The proposed antenna prototype operates at 1.54 GHz, 2.01 GHz, 3.23 GHz, 3.95 GHz, and 5.54 GHz for the mentioned applications. It employs a novel low-cost flowerpot-shaped radiating patch underneath a cylindrical dielectric resonator (CDR) made of alumina ceramic (Al₂O₃, ∈_DR = 9.8) material and is fed by a combined microstrip-line-tapered trapezoidal feedline. Later, a reduced ground plane is used as a reflector on the rear side of the substrate to reduce antenna size. It is made up of a low cost 1.6 mm FR4 laminate sheet (∈_r = 4.4, tanδ = 0.02) and miniaturized to a physical size of 65 × 45 mm². The parametric analysis was carried out for reflection coefficients (S₁₁-dB) by changing the ground plane width, CDRA radius, and flower petal radius to achieve adequate results. Likewise, this prototype has measured reflection coefficient of < -20 dB for 1.54 GHz (L1-band), < -25 dB for 2.01/3.23 GHz (S-band), < -20 dB for 3.95 GHz (S-band), and 5.54 GHz (C-band), peak gains of 2.01 dBi, 2.05 dBi, 3.02 dBi, 4.85 dBi, and 2.24 dBi for the respective bands along with adequate -10 dB impedance matching bandwidths and stable radiation features in a convincing agreement compared to earlier designs. The proposed prototype is simulated in CST software, assembled, and tested by VNA and an anechoic chamber setup for L1/S/C band applications.

This paper proposes a flexible four-element super-wideband (SWB) multiple-input multiple-output (MIMO) antenna based on characteristic mode analysis (CMA) for wearable wireless communication, broadband sensing, and wireless body area network (WBAN) applications. The antenna employs a spiral mesh radiator combined with a defected ground plane incorporating triangular and T-shaped slots to form a multi-slot-coupled current path, enabling the cooperative excitation of multiple characteristic modes. The proposed antenna achieves an impedance bandwidth of 3.23-44.68 GHz, satisfying the SWB criterion. A four-port MIMO configuration is adopted to enhance diversity and isolation performance. Measured results agree well with simulations, with port isolation better than 20 dB across the operating band. In addition, the envelope correlation coefficient (ECC) is below 0.0015; the diversity gain (DG) is close to 10 dB; the total active reflection coefficient (TARC) is below -10 dB; and the channel capacity loss (CCL) is less than 0.12 bit/s/Hz. The antenna also maintains stable SWB impedance matching and radiation performance under bending conditions, making it suitable for flexible SWB wearable and WBAN systems.

An improved scattering (S-)parameters extraction method, based on the forward and backward propagating waves under oblique incidence on metamaterials (MMs), is proposed to accurately extract electromagnetic parameters for asymmetric uniaxial MMs in a broad frequency range. The proposed approach equivalently models asymmetric MMs as two isotropic media (distinct from the 3 × 3 matrix-form anisotropic medium). To validate the effectiveness of the proposed method, a low-thickness asymmetric absorptive frequency-selective surface (AFSS) and a high-thickness 7-layer absorber were designed, simulated, and analyzed.

This paper presents a compact dual-band reconfigurable MIMO antenna array that simultaneously addresses the challenges of frequency agility and strong inter-element coupling in densely integrated antennas. The proposed antenna element employs a slit-loaded microstrip patch combined with a varactor diode to achieve continuous tuning of the high-frequency band while maintaining a stable low-frequency resonance. To suppress the severe mutual coupling typically induced by reconfigurable structures, an optimized etched ground-plane topology featuring branched Π-shaped slots is introduced. This isolation structure effectively alters surface-wave propagation paths and attenuates coupling fields, resulting in a significant improvement in port-to-port isolation across both operating bands. Comprehensive parametric studies validate the effectiveness of the slot configuration in enhancing decoupling performance under various tuning states. A 1×4 MIMO array prototype was fabricated and experimentally evaluated, showing good agreement with simulations. Measurements demonstrate wide-range high-band tuning from 3.6 to 4.2 GHz, stable low-band operation near 2.3 GHz, improved radiation efficiency, and low envelope correlation coefficients, confirming strong diversity performance. Owing to its compact structure, stable dual-band characteristics, and robust reconfigurability, the proposed design offers a promising solution for adaptive and space-constrained modern wireless communication systems.

The Plasmonic nanoantennas operating in the optical frequency range often experience reduced radiation efficiency due to substrate-induced nonradiative losses and insufficient electromagnetic field confinement. This work aims to systematically examine the influence of substrate material properties on plasmonic resonance behavior, surface current distribution, and radiation efficiency of a gold nanostrip patch antenna. A fixed-geometry plasmonic nanoantenna is designed and numerically investigated on five substrates, namely SiO₂, GaN, GaAs, AlAs, and AlGaAs. Full-wave electromagnetic simulations are performed using frequency-dependent material dispersion modelled through established Drude-Lorentz formulations. The antenna implemented on the Au-SiO₂ combination provides the most favourable plasmonic performance, yielding the best impedance matching (-51.27 dB), maximum radiation efficiency of 83%, wide impedance bandwidth (118 THz), and highly stable radiation patterns. GaN also exhibits strong performance with a high radiation efficiency (71%) and wide bandwidth (97 THz), making it a viable choice for high-power optical systems. GaAs, AlAs, and AlGaAs substrates show reduced efficiency due to higher dielectric losses and weaker plasmonic confinement. The study confirms that substrate permittivity and loss characteristics play a crucial role in determining plasmonic nanoantenna performance.

Accurate modeling of millimeter-wave (mmWave) and terahertz (THz) electromagnetic wave propagation is crucial for analyzing and designing emerging high-frequency wireless systems at an early stage. Conventional parabolic equation (PE)-based models offer high computational efficiency but suffer from reduced accuracy at mmWave/THz frequencies owing to material losses, fine-scale scattering, and complex non-line-of-sight (NLOS) interactions. Although purely data-driven approaches are flexible, they often lack physical consistency and generalization capability. This study proposes an AI-enhanced parabolic equation (AI-PE) framework that integrates a wide-angle PE solver with a neural-network-based residual correction model. The AI component learns systematic PE prediction errors associated with frequency-dependent attenuation, diffraction, and scattering while preserving the underlying physical structure of the wave model. Validation was performed against full-wave and ray-tracing reference solutions in representative indoor corridor and urban microcell scenarios. The numerical results at 28, 60, and 140 GHz demonstrate a 25-40% reduction in the path-loss prediction error, improved statistical agreement of the RMS delay-spread estimates, and over 50% reduction in the computational cost compared with deterministic ray tracing. The energy conservation and phase continuity of the corrected fields were explicitly verified. The framework was primarily validated for interpolation within the trained frequency range and demonstrated robust performance across structured propagation environments.

Photovoltaic (PV) power sequences are highly susceptible to high-frequency stochastic noise under complex micro-meteorological conditions. Furthermore, existing forecasting models struggle with isolated multi-scale physical features and insufficient nonlinear mapping capabilities. To address these limitations, this paper proposes an improved TimeMixer-based PV power forecasting method. First, the macroscopic trend and microscopic seasonal components are extracted via a past-decomposable-mixing architecture. Second, an adaptive gated feature fusion mechanism is introduced as a physically motivated feature-level filter to attenuate high-frequency noise channels through dynamic attention masks, effectively blocking the cross-scale propagation of invalid meteorological interference. Finally, a cross-scale joint nonlinear network is constructed to capture nonlinear interactions among multi-band components through state matrix aggregation and activation operators. Case studies utilizing operational data from a 50 MW PV power plant, in Xinjiang, China, demonstrate that the proposed architecture effectively overcomes smoothing degradation and phase lag under complex scenarios, such as abrupt cloud cover. Compared with the original baseline, the proposed method reduces the forecasting mean squared error by 10.80%, significantly enhancing both global fitting accuracy and dynamic extreme-value tracking capability.

This study details the design and analysis of a tri-arm-shaped microstrip patch antenna with a partial ground plane, intended for wearable applications. The proposed antenna is designed on a flexible jeans substrate and operates within the Industrial, Scientific, and Medical (ISM) band (2.40-2.48 GHz). It features a low-profile structure with overall dimensions of 40×20×1.2 mm³, impedance bandwidth of 580 MHz, and radiation efficiency of 82%. Impedance matching and miniaturization were achieved in the design through the use of the stub loading technique. Furthermore, on-body measurements, such as bending and crumpling analyses, demonstrated its robust performance with good return loss values. The Specific Absorption Rate complies with the safety limits, and the proposed conformal antenna is reliable for wearable applications.

This paper presents a wideband four-port microstrip antenna operating from 2.75 GHz to 6.75 GHz with frequency reconfigurability and controllable notch characteristics. The antenna employs an asymmetric radiating structure to realize circular polarization around 5.5 GHz, while multilayer graphene(MLG) pads are introduced to enable bias-controlled frequency tuning and adjustable band rejection. The four-port configuration, implemented on an RT/Duroid 5880 substrate (ε_r = 2.2, thickness = 1.6 mm), achieves inter-element isolation better than 20 dB without additional decoupling structures. The proposed design also exhibits strong diversity performance with an envelope correlation coefficient below 0.02 and diversity gain above 9.97 dB. The results demonstrate that the proposed antenna provides a compact and low-complexity solution for wideband and reconfigurable sub-6 GHz wireless communication applications.

An innovative analysis of a negative group delay (NGD) circuit exhibiting a dual bandpass (BP) characteristic is presented. The passive BP-NGD topology consists, essentially, of parallel RLC resonant networks. The BP-NGD topology is characterized by the NGD value, the NGD center frequency, and the attenuation, as functions of the constituent RLC resonant networks. The dual BP-NGD topology is designed using series impedances, which are composed of two distinct parallel RLC networks. After considering the reduced-order model of the passive cell within the NGD frequency range, which enables the determination of component values for the dual BP-NGD circuit, the circuit is formulated as a function of the desired NGD values and center frequencies. The feasibility of the design theory is verified through a proof-of-concept (PoC), designed to operate with the following specifications (1 MHz, -20 μs, -8 dB) and (2 MHz, -20 μs, -8 dB). First, a frequency-domain analysis of the PoC demonstrates the dual BP-NGD behavior, exhibiting an attenuation of approximately 8 dB. Subsequently, time-domain analyses were conducted using input signals with amplitude modulation on sinusoidal carriers at frequencies of 1 MHz, 1.5 MHz, and 2 MHz. The obtained results highlight the possibility of generating output signal envelopes that exhibit a temporal advancement relative to the input ones, provided that the input signal spectrum falls within the NGD bandwidth. However, the output envelope exhibits a positive delay when the input signal spectrum lies outside the NGD frequency band. A potential application principle for the dual BP-NGD circuit is discussed, specifically for the compensation of delay dispersion in electronic and communication systems.

This paper presents a compact, low-profile, single-layer filtering antenna. The antenna features a simple structure, consisting of a substrate, two pairs of U-shaped defected ground structures, a symmetric dumbbell-shaped radiating patch, and a microstrip cross-feed line with asymmetric branches. The symmetric dumbbell-shaped patch and the asymmetric branch feedline collaboratively introduce additional high-frequency resonances, thereby broadening the impedance bandwidth. Furthermore, two pairs of U-shaped slots are etched into the bottom layer to introduce two radiation nulls on both sides of the passband, enhancing the frequency selectivity at the band edges and optimizing the antenna's radiation and filtering performance. To validate the proposed design, a prototype of the antenna was fabricated and measured. The measured and simulated results are in good agreement. The design achieves a wide impedance bandwidth of 48.6% from 3.7 to 6.18 GHz (centered at 5 GHz), a peak realized gain of 4.5 dBi, and a compact overall size of 35 mm × 29 mm × 0.8 mm. Moreover, the antenna structure is simple and easy to fabricate. Benefiting from its superior radiation performance and filtering characteristics, the proposed antenna is well-suited for wireless communication applications in the 5G Sub-6 GHz and WiFi-6E bands.

To address the shortcomings of conventional permanent magnet synchronous motors (CPMSMs), such as the inability to adjust the permanent magnet field and a narrow speed control range, this paper proposes a variable leakage flux permanent magnet synchronous motor (HPM-VLFM) based on a hybrid series-parallel permanent magnet configuration. This motor achieves a variable leakage flux permanent magnet motor (VLFM) by designing a magnetic barrier on the q-axis, and further realizes the HPM-VLFM by designing ferrite permanent magnets with a series-parallel magnetic circuit. First, this paper introduces a rotor topology of the proposed motor and establishes its equivalent magnetic circuit to elucidate its operating principle. Second, sensitivity analysis and response surface analysis are employed to investigate the relationship between parameters and response variables, and an optimal solution is obtained based on the given constraints. Finally, based on two-dimensional finite element analysis (FEA), the electromagnetic characteristics of the proposed motor were analyzed in detail, including variable flux leakage characteristics, no-load characteristics, inductance characteristics, and torque efficiency characteristics. The results indicate that the HPM-VLFM has a wider speed control range and higher efficiency.

We have developed a carbon nanotube organic silicone rubber (CNT-OSR) composite medium, composed of methyl trifluoropropyl silicone rubber as the matrix, with different mass fractions of carbon nanotubes added and formed through vulcanization using a bis (cyclopentadiene) vulcanizing agent. The CNT-OSR composite media with carbon nanotube contents of 2wt%, 5wt%, and 8wt% were tested, and the maximum absorption and shielding efficiencies of the media for terahertz waves in the 0.5-1.0 THz frequency range were found to be 69.77 dB, 76.28 dB, and 63.69 dB, respectively. Through impedance matching theory analysis, the absorption and shielding effectiveness of the medium for terahertz waves were confirmed. Additionally, the composite medium exhibits excellent hydrophobic properties. It provides a simple and feasible approach for developing lightweight, efficient, and multifunctional terahertz wave absorbing and shielding materials for the next generation of terahertz wireless communication.

Eddy current effects in underwater wireless power transfer (UWPT) systems introduced additional losses and shifted circuit parameters, severely undermining precision of conventional primary-side identification. To address this issue, this study investigated the mechanism of eddy current loss and established an improved mutual inductance model by introducing an equivalent eddy current resistance. Based on this, a primary-side sensing identification method was proposed to achieve the decoupled identification of mutual inductance, load resistance, and eddy current resistance by measuring the input impedance Z_in at multiple frequencies. Experimental results confirmed that at a resonant frequency of 85 kHz, the identification errors for eddy current resistance, mutual inductance, and load resistance were within 4%, 3%, and 5%, respectively. Furthermore, the average error remained below 3.5% across various salinities, lateral misalignments, and load conditions. This study provided a reliable technical foundation for optimizing the performance and ensuring stable operation of UWPT systems in complex underwater environments.

The existing research on axial magnetic field (AMF) contacts in vacuum interrupters mostly focuses on power frequency or low current conditions and lacks in-depth optimization of magnetic field characteristics and contact structure parameters under short-circuit current impact. Therefore, the AMF characteristics of the vacuum interrupter under short-circuit current excitation are studied, and the contact structure parameters are optimized. Firstly, a three-dimensional transient electromagnetic field model of the vacuum interrupter, excited by the measured short-circuit current, is constructed, and the effects of four key geometric parameters - contact slotting angle, cup finger angle, slotting length, and slotting width - on the peak AMF are quantified. Secondly, the orthogonal test method is used to screen significant factors, and it is concluded that cup finger angle is the most critical parameter among the four. Finally, a quadratic regression model is constructed by combining the response surface model (RSM) to explore parameter interactions. The theoretical optimum is obtained and further refined through boundary verification to yield the actual optimal parameter combination. This study guides the design of AMF contacts in vacuum circuit breakers under short-circuit conditions.

This paper presents a design methodology for a concurrent dual-band integrated filtering high-efficiency power amplifier (PA) through the coordinated use of a dual-band harmonic control network (DB-HCN) realized with an adjustable-transmission-zero dualband filtering matching network (ATZ-DB-FMN). To improve the efficiency under dual-band operation, the proposed DB-HCN enables simultaneous impedance control up to the third harmonic at both operating frequencies. To realize a compact integrated structure, the proposed ATZ-DB-FMN provides dual-band impedance matching,and introduces transmission zeros (TZs) on both sides of the passbands and in the inter-band region. In particular, the inter-band TZ is adjustable and can be used to suppress interference at a desired frequency between the two passbands. To validate the proposed method, a prototype operating at 2.4 and 3.6 GHz was designed and fabricated, with the adjustable TZ set at 3.1 GHz. The measured results show drain efficiencies of 78.6% and 75.3% and output powers of 40.05 dBm and 40.2 dBm at 2.4 and 3.6 GHz, respectively. The effective tuning range of the TZ is 2.6-3.4 GHz, and the measured power gain at 3.1 GHz is -26.5 dB, confirming effective inter-band suppression. These results demonstrate that the proposed design method can simultaneously achieve dual-band high efficiency, integrated filtering, and adjustable inter-band suppression.

The dielectric constant, which is the real part of the complex permittivity, of composite materials at microwave frequencies was investigated in this study. Ceramics of titanium dioxide, calcium titanate, and strontium titanate with high dielectric constants of 100, 170, and 300, respectively, were selected. Ceramic powders were spread in the polyethylene matrix to form composite samples. The dielectric constants of the composite samples were measured to determine their matching conditions with the mathematical curves of five well-known mixture equations. These five mixture rules were then applied to estimate the dielectric constants of the three selected ceramics from the measured dielectric properties of the composite samples with various volume percentages of ceramic fillers. The mathematical equations of the potential theory errors of the five mixture rules for the dielectric constant estimation were derived and discussed. One of the five rules was selected and modified to obtain a new empirical mixture equation. This proposed empirical equation can significantly improve the accuracy of dielectric constant measurements for the selected ceramic materials. An empirical mathematical relation of the new mixing rule with the dielectric constant of the ceramic is then concluded.

The design of large-scale coding metasurfaces poses significant computational challenges, often limited by the prohibitive time required for full-wave simulations necessary for optimization. This paper proposes an efficient design strategy based on a Hybrid Genetic Algorithm, validated through the design, fabrication, and characterization of an X-band metasurface for Radar Cross Section reduction. The proposed design strategy relies on a two-stage optimization process: a fast pre-optimization phase, based on the analytical Huygens-Fresnel principle, generates a preliminary solution which is subsequently refined by a second optimization stage utilizing full-wave simulations. Specifically, the optimization targets a 1-bit coding scheme, where meta-atoms switch between two distinct states with a phase difference of 180 ± 37°. This hybrid approach demonstrates optimal convergence, reducing computational time by 25% compared to traditional full-wave-only techniques. Furthermore, a novel ``spiralling cross'' unit cell topology is introduced. Owing to its delay-line geometry, this structure provides additional degrees of freedom for spectral tuning and supports intermediate phase shifts, thus enabling encoding schemes beyond traditional 1-bit configurations. Experimental results confirm the validity of the proposed approach, demonstrating how the combination of versatile geometry and hybrid optimization effectively overcomes the trade-offs between numerical accuracy and computational efficiency.