To enhance the electromagnetic transient performance and torque dynamic response quality of permanent magnet synchronous motor vector control systems, this study proposes a novel adaptive sliding mode control strategy based on a state-dependent nonlinear approach law. This method first replaces the sign function in traditional sliding mode control with a sigmoid function, mechanistically achieving continuous construction of quasi-sliding mode dynamics and effectively eliminating high-frequency chattering in control signals. Building upon this foundation, the electromagnetic-mechanical state variables are dynamically incorporated into the approach law design to construct a state-dependent nonlinear approach law. This enables the controller to adaptively adjust based on the motor's operational state, thereby achieving dynamic optimization control of electromagnetic torque and speed without relying on precise models. Furthermore, a global fast terminal sliding surface is introduced to achieve rapid convergence of system states within finite time. For composite disturbances such as load transients, flux fluctuations, and unmodeled dynamics, a fuzzy logic-based gain adaptive mechanism for extended state observers is designed. This dynamically adjusts observer bandwidth to enable real-time, precise observation and feedforward compensation for total disturbances. Experimental results demonstrate that the proposed method exhibits significant advantages in improving torque dynamic response, enhancing steady-state accuracy, and strengthening system disturbance rejection capabilities, providing an effective solution for high-performance permanent magnet synchronous motor drive control.

Radar-based vital sensing methods have received significant attention due to their potential to provide continuous, non-contact measurements for heartbeat and respiration monitoring. Our original two-wave model extracts respiration and heartbeat data by formulating the estimation process as a minimization problem. Although the original method examines temporal changes in respiration and heartbeat signals in a different manner from existing methods, it remains sensitive to the slight body movements that often occur in laboratory experiments. In this study, we propose a modified two-wave model with improved robustness against such movements. Using experimental data collected with a millimeter-wave Multi-Input Multi-Output (MIMO) frequency-modulated continuous-wave (FM-CW) radar system, we demonstrate that the improved model can successfully measure both respiration and heartbeat signals even in cases where the original method fails, thereby improving the capability for non-contact vital signal detection.

This study explores the anisotropic electromagnetic properties of carbon nanotube (CNT)/polylactic acid (PLA) nanocomposites, fabricated in-house and shaped using traditional compression molding and advanced 3D printing techniques. By examining the effects of CNT content (ranging over 1-4 wt.% (weight percent)) and 3D printing path orientation, this research investigates how these factors influence shielding effectiveness (SE) and the corresponding nanocomposite complex dielectric permittivity tensor. Notably, a significant variation in SE was observed between the different printing path orientations, with a difference of over 20 dB at 4 wt.% CNT. Experimental measurements were used to develop an anisotropic model for the complex dielectric permittivity, with the permittivity components for samples at 4 wt.% CNT extracted to be 36.5-j44.5 along the printing direction (ε_||) and 8.3-j3.1 in the perpendicular direction (ε_⊥) over the X-band frequency range (8.2-12.4 GHz). These findings demonstrate that CNT alignment during 3D printing induces highly directional electromagnetic properties. Furthermore, we demonstrate that anisotropic simulation models provide a more accurate prediction of the electromagnetic response of 3D-printed nanocomposite structures than isotropic models. In brief, this study emphasizes the necessity of considering anisotropic properties in the design and simulation of 3D-printed nanocomposites for electromagnetic shielding and other applications.

To improve the position detection accuracy of sensorless control for permanent magnet synchronous motors (PMSM) and address issues such as significant chattering amplitude in traditional Sliding Mode Observers (SMOs), a Novel Adaptive Nonlinear Super-Twisting Sliding Mode Observer (NANSTSMO) combined with a Higher-order Gain Compensation Phase-Locked Loop (HGCPLL) is designed in this study. First, a multimodal nonlinear function is designed to replace the sign switching function, and this multimodal nonlinear function is then integrated with both the NANSTSMO and the HGCPLL. Second, a compensation mechanism is introduced to precisely estimate the rotor position. Finally, simulations are conducted using MATLAB/Simulink, and a motor test platform is constructed. Compared with the traditional sliding mode control and referenced sliding mode control strategies, the proposed method demonstrates superior effectiveness.

In this study, we describe a circular ring slot antenna with three circular holes, which is supplied by a CPW-fed split ring resonator metamaterial. This proposed antenna covers sophisticated satellite communication applications for wireless devices, including 5G, military, and aerial radar, and resonates between 2.4 GHz and 10.4 GHz, with a center frequency of 3.542 GHz and an S₁₁ of -37.7 dB, and a center frequency of 7.5 GHz and an S₁₁ of -30.4 dB, respectively. The produced antenna satisfactorily validates the specified antenna metrics. The suggested antenna is built on an affordable FR4 substrate and has physical dimensions of 38 × 38 × 1.6 mm³. The proposed simulated design antenna is validated by the measured data. The results show a good correlation between the measured data and the simulation. The operational impedance range of the proposed antenna is less than -10 dB. The circular ring slot antenna has proven to be remarkably capable of reaching multiband frequencies of 3.54 GHz and 7.5 GHz. The proposed antenna may have an effect on radiation characteristics and gain, resulting in a good contender. Each component of the circle-shaped ring slot antenna design is essential to achieving the important and encouraging results.

This article presents a miniaturized wideband planar inverted-F antenna (PIFA) for deep biomedical implant applications at 915 MHz. Compactness and wide impedance bandwidth are achieved using a shorting pin, a circular radiating patch, and open-ended slots etched in the ground plane. The antenna occupies an ultra-small volume of 63.5 mm³ and is designed and analyzed inside a four-layer cylindrical human tissue phantom. Simulated and measured results show stable impedance matching over the ISM band, with a measured -10 dB bandwidth of 481 MHz (44.02%) and a peak realized gain of -28 dBi. Specific absorption rate (SAR) analysis confirms compliance with IEEE safety limits. In-vitro measurements using minced pork exhibit close agreement with simulations, validating the antenna's performance and suitability for reliable deep biomedical implant communication systems.

Metamaterials are emerging as a key enabler for 6G wireless communications, attracting growing attention from industry due to their engineered electromagnetic properties that enable control over wave propagation. Metamaterials have shown promise across diverse applications; however, the desire to achieve 1 TBPS data rates in 6G communications is partially constrained by a major fundamental challenge in metamaterials: achieving gigahertz of instantaneous bandwidth (IBW) values. To address the IBW issue, we designed, fabricated, and tested a fundamental component of metamaterial, i.e., a modified split ring resonator (MSRR), achieving 90% of the targeted 1 GHz IBW and an effective permeability (μ_eff) close to 25 within the IBW. In addition, the gain-bandwidth product (GBWP) is over 1.5× greater than that of commercial 5G antennas, while maintaining the same aperture size of 1.59λ_c. We studied and reported the effect of MSRR frequency-dependent μ_eff on the IBW and GBWP and proposed an optimized MSRR design that achieves 3× the bandwidth of a conventional SRR. Finally, we integrated the proposed MSRR atop a wideband patch antenna, enhancing peak realized gain by 6 dBi.

A low sidelobe dual-beam reflectarray antenna is proposed based on the sparse array principle. The reflected dual beams achieve high gain through optimized phase compensation, in which the transmissive elements act as dummy elements to suppress sidelobes. A global search optimization technique based on genetic algorithm (GA) is adopted to improve the arrangement of transmissive and reflection elements. Since all the reflective and transmissive elements operating in the same wide frequency band are non-uniformly distributed on the aperture, both the backward radiation and cross polarization levels are effectively suppressed. The measurement results show that the sidelobe level of the dual-beams is less than -19 dB. The peak gain and peak aperture efficiency of the designed antenna are 26.0 dBi and 38.9%, respectively. The 3-dB gain bandwidth is 13.8%. The front to back ratio at 30 GHz is 27 dB. This dual-beam antenna has the advantages of high gain, low sidelobes, and wide beam radiation range, which make it suitable for millimeter-wave multi-target radar detection systems.

Traditional side-lobe suppression techniques such as Chebyshev and Taylor tapering provide limited adaptability to hardware constraints and fixed array geometries. Existing Genetic Algorithm applications predominantly focus on planar arrays with variable spacing, leaving linear arrays with fixed element spacing underexplored. This work presents a genetic algorithm-based amplitude tapering framework for optimizing side-lobe levels in 8­element linear phased arrays with fixed 0.48λ spacing. The approach incorporates hardware quantization constraints and validates performance through experimental implementation. Experimental validation uses the Analog Devices CN0566 Phaser kit operating at 10.25 GHz (centre frequency) with 0.5 dB gain resolution and 2.8125˚ phase quantization. Genetic algorithm parameters including population size, mutation rate, and fitness function were held constant while the convergence rate and side-lobe suppression are evaluated. This research work demonstrates practical genetic algorithm implementation for linear phased array optimization under real-world hardware constraints, providing design guidelines for X-­band radar and communication systems.

The traditional microstrip-fed Vivaldi antenna has the disadvantage of a high cross-polarization level owing to the nonparallelism between the electric field and the antenna plane. Based on the balanced E-field distribution property of the grounded coplanar waveguide (GCPW) structure, this paper proposes a planar ultrawideband Vivaldi antenna with low cross-polarization. The measured results confirm that an enhanced impedance bandwidth of 159.54% is achieved in the range of 2.01-17.86 GHz (|S₁₁| < -10 dB) with a 4-6 dB improvement in cross-polarization over traditional Vivaldi antenna. In addition, the proposed antenna has a maximum gain of 9.9 dBi within the size of 88.2 mm × 107.3 mm × 1 mm. Owing to the advantages of ultra-wideband, low cross-polarization ratio, stable radiation patterns and high gain, the proposed method can be widely applied in UWB communication and multifunctional integrated RF systems.

This paper proposes a novel less-rare-earth variable-leakage-flux reverse-salient-pole motor (LRE-VLF-RSPM). The proposed motor achieves the reverse-salient-pole and variable-leakage-flux characteristics by reasonably arranging three layers of arc-shaped flux barriers between adjacent magnetic poles. Furthermore, it incorporates ferrite magnets to reduce the usage of rare-earth permanent magnets by one-third while maintaining torque output, thereby fulfilling the less-rare-earth objective. First, the paper introduces the rotor topology and operational principle. Subsequently, it employs two-dimensional finite element analysis (FEA) to compare the electromagnetic performance - including torque, flux-weakening capability, constant power speed range (CPSR), and high-efficiency region proportion - among a conventional V-type synchronous motor (CTVSM), a variable-leakage-flux reverse-salient-pole motor (VLF-RSPM), and the LRE-VLF-RSPM. The final results demonstrate that the proposed motor reduces rare-earth usage by one-third compared to the benchmark motor and exhibits superior flux-weakening capability, a wide constant power speed range, and a large high-efficiency region. These findings verify the effectiveness and feasibility of the proposed motor.

This paper presents a wide-passband, miniaturized filter based on quarter-mode substrate-integrated waveguide (QMSIW) resonant cavities and microstrip resonators. The filter employs two QMSIW resonant cavities, which effectively reduce its size. Moreover, the higher-order modes TE₁₂₀, TE₂₁₀, and TE₂₂₀ cannot propagate within these cavities. The addition of two microstrip resonators at the coupling iris between the QMSIW cavities enables a fourth-order filter response using only two resonant cavities. High selectivity is achieved through cross-coupling, which introduces two transmission zeros (TZs). The filter was fabricated and measured, showing good agreement with the simulation results. Compared with other substrate-integrated waveguide (SIW) filters, the proposed filter offers advantages in compactness, passband bandwidth, and higher-order mode suppression.

In this paper, an elliptical monopole antenna is operated in fundamental mode by reducing the electromagnetic coupling (EMC) between higher-order modes. The electromagnetic coupling is decreased by decreasing the width of the radiating element and ground-plane dimensions, and increasing the gap between the radiating element and ground plane. The ellipse is sliced from the top, as there is little surface current on the top portion of a monopole. The symmetrical portion of this sliced elliptical monopole is selectively etched with little effect on impedance variation. Dual-band characteristics are obtained over 2.3-2.7 GHz (Wi-Fi and Bluetooth bands) and 5.4-5.9 GHz (WLAN band), as well as over 2.3-2.7 GHz (Wi-Fi and Bluetooth bands) and 5.13-5.71 GHz (WLAN band), depending on the etching amount. A rectangular strip is added to the etched monopole to operate over 2.3-2.7 GHz (Wi-Fi, Bluetooth bands) and 3.3-3.9 GHz (5G band). To enhance the gain of a compact dual-band antenna, a reflecting metamaterial surface consisting of an array of square patches is designed and placed below the structure. A high-gain dual-band MIMO antenna is designed by placing four elements orthogonally above the centre of four edges of the metamaterial surface. S₁₁ < -10 dB, isolation > 18 dB and 22 dB, and antenna gain of 7.5 dBi and 7.4 dBi are obtained over 2.35-2.7 GHz and 3.3-3.6 GHz, respectively. The structure is fabricated. The measurement results validate the simulation ones.

To address the randomness and nonlinearity of photovoltaic (PV) power caused by meteorological factors, this paper proposes an ICEEMDAN-WOA-CNN-BiLSTM prediction model integrated with fuzzy entropy clustering and a self-attention mechanism. First, the original PV power sequence is decomposed into multiple multi-scale intrinsic mode function (IMF) components and residuals via the Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (ICEEMDAN). Subsequently, components with similar complexity are merged using fuzzy entropy clustering to simplify the calculations. Then, the Whale Optimization Algorithm (WOA) is adopted to optimize the hyperparameters of the CNN-BiLSTM model, and the self-attention mechanism is integrated into the model to enhance the weights of key features. Comparative experiments demonstrate that the proposed model significantly outperforms single and traditional hybrid models in terms of Mean Absolute Error (MAE), Root Mean Square Error (RMSE), and Coefficient of Determination (R2). This can effectively improve the accuracy of short-term PV power prediction and provide support for power station dispatching and power grid stability.

This paper presents a miniaturized quad-port ultrawideband (UWB) MIMO antenna that integrates band-notch functionality and exhibits high isolation. The design employed four circular monopole radiators positioned on a modified defected ground structure (DGS), and periodic electromagnetic bandgap (EBG). These EBG components are an advanced variation of traditional mushroom-type structures that incorporate grid-shaped top patches, a metallic ground plane, and multiple vias connecting both layers. Located at the center of the substrate, the EBG network effectively reduces the electromagnetic coupling between adjacent radiating elements. To achieve multi-band rejection, five inverted U-shaped slots are etched into each monopole, enabling selective suppression of unwanted frequencies at 3.36-3.56 GHz, 3.72-3.92 GHz, 4.11-4.32 GHz, 4.59-4.83 GHz, and 5.22-5.50 GHz, corresponding to WiMAX, C-band, Wi-Fi, INSAT, and WLAN systems. Experimental validation confirms that the antenna attains -10 dB impedance bandwidth extending from 3.0 to 14.0 GHz, with inter-element isolation above -22.5 dB, gain of 6.2 dB, and radiation efficiency reaching 79.2%.

To address the aperture fill time problem in broadband arrays, this paper proposes an efficient delay compensation algorithm based on a variable fractional delay (VFD) filter with high numerical stability. A low-complexity Newton structure is introduced into the VFD Lagrange interpolation algorithm; in addition, the numerical stability is significantly enhanced by centrally offsetting the element delay parameters and avoiding the explicit inversion of the transformation matrix. Subsequently, the robust Newton-VFD is applied to the implementation of the broadband array aperture fill time correction algorithm. The algorithm utilizes a cascaded architecture consisting of coarse integer-delay compensation and fine fractional-delay correction via the Newton-VFD. Simulation results demonstrate that the proposed low-complexity Newton-VFD significantly reduces hardware complexity while maintaining excellent magnitude-frequency characteristics, which enables efficient and high-precision correction of broadband array aperture fill time.

A design approach using a harmonic-tuned network (HTN) and terminated coupled-line structures (TCLSs) for high-efficiency filtering power amplifiers (FPA) is proposed in this paper, effectively addressing the efficiency degradation caused by the integration of filtering structures in conventional FPA designs. The proposed approach enables compact circuitry while providing bandpass filtering characteristics. Bandpass filtering is realized through the cascaded TCLSs, while the incorporation of open-circuit and short-circuit branches introduces additional transmission zeros and poles, significantly improving frequency selectivity. In addition, HTN enables precise control of the harmonic impedance, effectively improving the efficiency of the power amplifier (PA). Based on this approach, an FPA operating in the 2.3-2.6 GHz band is designed and implemented. Experimental results show that the FPA achieves a output power (Pout) of 40.8-41.3 dBm, a drain efficiency (DE) of 67.2-72.2%, a gain of 12.8-13.3 dB, and stopband suppression greater than 39 dB on both sides of the passband. These results verify the effectiveness of the proposed design in enhancing PA efficiency and enabling circuit miniaturization, while also providing a feasible design approach for FPA development.

A compact spiral antenna is investigated by integrating a modified feed structure with a reflector backing. A significant reduction in antenna height is achieved without affecting performance over the desired frequency band. Experimental results demonstrate a negligible impact on radiation loss, impedance continuity, polarization purity, and bandwidth. The implementation preserves stable impedance matching and maintains circular polarization characteristics across the 2-18 GHz frequency range. The findings validate the practical feasibility of incorporating sharp bends in a tapered balun for spiral antennas. This height reduction facilitates low-profile integration in space-constrained applications without compromising antenna efficiency or radiation quality. The compactness and low-profile configuration make the antenna highly suitable for electronic countermeasure (ECM) applications, including radar warning receivers, missile systems, and EW pods, where size and integration are critical.

This work introduces a compact, low-profile, wideband multiple-input multiple-output (MIMO) antenna module designed for integration into 5G-enabled mobile terminals. The MIMO system comprises four patches with I-slots, each connected to one feed port. For the single patch, the slot controls and merges the TM₁₀ mode with TM₀₁ mode, enabling dual-mode operation. Subsequently, shared-radiator technique is used, utilizing the coupling between the patches. When one patch is activated, it causes adjacent patches to become excited as well, resulting in a multi-patch operational mode that improves impedance matching. To ensure isolation, metallized vias are used to control coupling between elements, achieving an isolation level over 15 dB. The design measures a compact size of 28 mm × 28 mm × 1.5 mm. The prototype exhibits an impedance bandwidth of 4.34-5.06 GHz, confirming its practical usability in N79 band. It achieves over 40% efficiency and low envelope correlation coefficients (ECC). The design's compact size, good isolation, and ease of integration render it a suitable candidate for mobile terminals.

2-D Fast Fourier transform (FFT) is the most time-consuming step for modeling of time-varying sea surface using high-order small slope approximation (SSA). In this paper, a parallel block splitting method is proposed to accelerate 2D FFT calculation. The whole 2-D FFT matrix is divided into m × n blocks, and the traditional 2-D FFT is applied to each block in parallel. Finally, the complete FFT result can be obtained by using the message passing interface (MPI) for data communication and superimposing phase factors. This method can effectively reduce the communication overhead by combining symmetric domain decomposition and is more suitable than traditional parallel libraries. Accordingly, both generations of sea surface and computation of scattering using SSA can be accelerated. Numerical experiments demonstrate that the proposed method exhibits strong scalability. Under a four-node configuration, the parallel efficiency of sea surface generation reaches 61.2%, while the second-order SSA parallel efficiency achieves 80.7%. This effectively resolves low-efficiency issues in large-scale sea surface generation and serial SSA computations.