This paper introduces a novel compact, flexible hexagonal loop shaped patch antenna embedded with a novel electromagnetic bandgap (EBG) structure designed for ISM band operation, targeting 2.45 GHz wearable applications in close proximity to the human body. The EBG unit cell is formed using a rectangular patch which has nested U shaped slots with a stretched strip of inverted U shaped slot at bottom. Both hexagonal loop antenna and the 2 × 2 EBG array are simulated using Ansys HFSS (High Frequency Structure Simulator). A key aim of this research is to achieve the specific absorption rate (SAR) reduction. The effectiveness of the EBG array structure in reducing surface waves and dropping down the SAR is demonstrated using a multilayer human tissue equivalent phantom comprising skin, fat, muscle, bone layers, confirming obtained SAR values are within the safety limits set by regulatory authorities. The simulation results are verified and validated by the fabricated antenna experimental measurements. Furthermore, the antenna was experimentally assessed in terms of its performance under bending and in practical on-body conditions.

In this work, we present a single-layer, wideband circularly polarized (CP) metasurface antenna fed by a coplanar waveguide (CPW). The proposed antenna employs a rotated CPW feed structure, which achieves circular polarization without adding dielectric layers, significantly simplifying the antenna structure and improving manufacturability, while incorporating two stubs to adjust impedance matching and broaden the bandwidth. Measurement results indicate a -10 dB impedance bandwidth covering 4.23-6.2 GHz (a fractional bandwidth of 37.7%), and a 3-dB axial ratio bandwidth of 5.26-6.32 GHz (a fractional bandwidth of 18.3%), with a peak measured gain of 9 dBi. The antenna targets Sub-6 GHz with strong 5G integration potential.

The multi-mode dual five-phase hybrid excitation (MM-DFHE) motor, owing to its unique dual-stator configuration, is capable of operating in four distinct modes, offering exceptional operational flexibility. However, this flexibility introduces a control challenge, particularly in Mode IV where the auxiliary stator acts as both an exciter and a torque producer. The additional current variables in this mode lead to suboptimal current distribution, compromising efficiency and dynamic response. To address this, this paper proposes a novel low-loss current optimization control strategy. The key contribution is a Gradient Descent (GD) based online optimization algorithm that dynamically distributes the auxiliary excitation current, specifically tailored for the improved Mode IV operation. This approach resolves the trade-off between loss minimization and dynamic performance prevalent in conventional methods. Simulated and experimental results demonstrate that the proposed strategy reduces total copper loss by up to 13% compared to conventional methods.

This article presents the design and simulation of a small, high-gain circular patch antenna specifically for an implantable biotelemetry application. The antenna is constructed on a Rogers RT/Duroid 6010/6010LM™ substrate, 1.27 mm in thickness, including 0.035 mm circular radiating patches, as well as a ground plane. The antenna is tiny, with a patch radius of 14 mm, and the total volume of the antenna is 825 mm³. The reduced size creates a more efficient radiation pattern, and the substrate material is high in dielectric constant (ε_r = 10.2), allowing for a smaller size without sacrificing performance. Our suggested work introduces a novel solution to the given problems and presents a compact multi-band implantable antenna for implantable medical devices, which are used in the wireless medical telemetry service (WMTS) (1395-1400 MHz), medical body area network (MBAN) (2360-2400 MHz), lower ultra-wide band (UWB-L) (3100-4800 MHz), and upper ultra-wide band (UWB-U) (4800-10600 MHz) frequency bands. The proposed antenna design intends to enhance bandwidth, efficiency, and radiation pattern, all while remaining within strict size limits and biocompatibility requirements of implantable medical devices by carrying out widespread simulation and experimental verification.

To enhance the stability of the spindle drive system in computer numerical control (CNC) machine tools and ensure machining accuracy by reducing non-ideal torque fluctuations caused by current harmonics during high-precision processes, a multi-factor harmonic current suppression algorithm based on an extended state observer (ESO) is proposed. Firstly, a mathematical model of the permanent magnet synchronous motor (PMSM) is established, and the current measurement offset errors (CMOEs) and their effects on the current waveform are analyzed in depth. Subsequently, the zero-point lag phenomenon of the voltage source inverter (VSI) and its resulting harmonic characteristics are discussed in detail. Furthermore, the compensation principles for CMOE and VSI dead-time nonlinear distortion are elucidated, and a corresponding ESO structure is designed through theoretical derivation. The proposed method constructs a unified perturbation model and designs adaptive ESO to achieve cooperative compensation. A comparative analysis of the control strategy's performance before and after optimization validates the significant effectiveness of the proposed method in harmonic suppression. Experimental results show that the proposed strategy reduces the total harmonic distortion (THD) of the phase current to 3.28%, and key harmonics such as the 5th and 7th are suppressed to much lower levels. Torque ripple and speed fluctuation are significantly reduced, effectively improving the operational stability of the motor. The experimental results indicate that the proposed dual compensation scheme for dead-time and DC offset current can effectively reduce harmonic distortion and significantly enhance the operational performance of the PMSM.

Mobile network data rates are increasing with each generation, due to the usage of emerging technologies and advanced architectures. They may consume substantially more power than the present fourth-generation (4G) and fifth-generation (5G) systems. Base stations have been determined as the primary source of energy usage in a mobile network. They are responsible for more than 60% of the energy consumption of mobile networks. Moreover, the recent 5G base stations (BSs), which provide higher bandwidth and data rates and have more transceivers with centralized antennas, raise alarms about their power consumption. With eco-friendly concerns about the amount of carbon dioxide (CO₂) reduction, the intergovernmental panel on climate change (IPCC) sees climate change as a threat to human well-being and planetary health, and ever-increasing energy costs have already created an urgent need for more energy-efficient and low-power consumption BSs in mobile communications. As a result, the energy consumption and carbon emissions of 5G mobile networks are concerning. Information and communication technologies (ICT) have great potential for reducing CO₂ emissions. Therefore, power consumption is one of the central topics for telecom network providers, especially when they are challenged by higher costs. Distributed antenna systems (DAS) could decrease network power usage through smaller cell size or moving closer to users. In this study, we look at the impact of cell size on power consumption in centralized and distributed antenna systems. The distributed antenna system consumes more than 35% less power than the usual centralized structure; thus, swapping a centralized antenna with a distributed antenna may lower total power consumption.

This paper examines the use of extreme value theory (EVT) in modelling and forecasting extreme noise events in Power Line Communication (PLC) networks. PLC noise is characterised by random, high-amplitude noise spikes that significantly degrade PLC performance. As such, EVT, which is a branch of statistics that is concerned with modelling and analysing extreme deviations of random processes, is particularly useful for modelling PLC noise impulsive noise events, which are random since it focuses on the tail behaviour of the noise distribution. In this proposed EVT analysis, the probability of extreme noise events is estimated from the high-amplitude spikes. The heavy-tailed characteristics of PLC noise are estimated by the shape parameter (ξ) to model impulsive noise distributions, and the Block Maxima (BM) approach is employed to handle the worst-case PLC noise events lasting over long periods, consequently estimating the maximum expected noise over time. Lastly, the peaks over threshold (POT) method is proposed to handle the threshold exceedance probability, which can be used for threshold selection for PLC noise suppression.

Logging-While-Drilling (LWD) azimuthal resistivity measurements deliver critical support for geosteering in complex hydrocarbon reservoirs by acquiring real-time azimuthal responses of formation electrical properties around the borehole; the precision and efficiency of its inversion directly govern the reliability of horizontal well trajectory optimization strategies. Currently, the inversion study of azimuthal resistivity logging with drilling mainly focuses on the simplified three-layer stratigraphic model, and this simple layered model and limited stratigraphic parameter settings have been difficult to adapt to the needs of the increasingly complex geological exploitation. However, inversion of complex multilayer formations (≥5 strata) confronts three main challenges: high-dimensional parameterization, attenuated response sensitivity, and noise-impaired accuracy. These constraints compromise field-applicable accuracy thresholds for multilayer stratigraphic inversion. To address the above problems, in this paper, by combining the advantages of traditional inversion methods with machine learning concepts, a new optimized supervised descent inversion method is proposed for azimuthal resistivity LWD in a five-layer formation model. The data-adaptive reconstruction algorithm enhances outer formation response sensitivity. Subsequent integration of multi-matrix fusion with secondary inversion optimization further augments accuracy in field well-log inversion. Numerical simulations and downhole measurements verify the effectiveness of the proposed method, which is a field-deployable real-time inversion algorithm with higher accuracy and stronger noise immunity.

This article presents a slot-enhanced compact antenna tailored for next-generation millimeter-wave communication systems. The design, implemented on an FR4 substrate with dimensions of 15 × 16 × 1.5 mm³, was optimized using CST Microwave Studio and validated through fabrication and experimental testing. At 9.1 GHz, the antenna exhibits an electrical size of 0.45λ × 0.48λ × 0.045λ, confirming its suitability for integration into modern high-frequency platforms. The measured and simulated results demonstrate an ultra-wide impedance bandwidth of approximately 166%, covering 9.1-100 GHz with a primary resonance observed at 45.45 GHz. Throughout this wide operating spectrum, the antenna maintains stable radiation characteristics, achieving a peak gain of 8.91 dBi and efficiency close to 90%. The slot-based geometry enables excitation of multiple resonant modes, ensuring wideband operation while maintaining compactness. With its robust performance across multiple frequency bands, the proposed antenna is a strong candidate for applications in X-band radar, Ku- and Ka-band satellite communications, K-band sensing, V-band short-range links, W-band automotive radar, and future 6G wireless networks.

A pattern reconfigurable wideband leaky wave corrugated antenna is designed and presented in this paper. The proposed antenna shows a beam steering performance. The proposed antenna is designed using transverse periodic logarithmic slots at the top layer and longitudinal periodic leaky wave slots at the bottom ground layer. The transverse leaky wave antenna radiates in end fire direction at 25.9 GHz and 27.3 GHz. The longitudinal periodic slots on the antenna's bottom metal layer provides broadside radiation at 24.7 GHz. The leaky wave antenna scans beam at 90°, -90°, 159° and -160° by varying the port excitation. The proposed antenna design is suitable for millimeter wave applications.

This paper proposes a novel four-port MIMO antenna specifically designed for millimeter-wave (mm-wave) 5G applications. The antenna features a compact symmetric layout measuring 22 mm × 22 mm, corresponding to approximately 2.7λ × 2.7λ at 37 GHz. The prototype is fabricated on a Rogers RT Duroid 5880 substrate (ε_r = 2.2, tanδ = 0.0009, h = 0.8 mm) to ensure low loss and stable performance at high frequencies. The antenna operates effectively over two targeted frequency bands, 37-41 GHz and 42-43.5 GHz, making it suitable for high-data-rate, short-range communication systems in emerging 5G networks. The structure is evolved through multiple design stages using strategically placed curved parasitic elements to achieve dual-band operation, high isolation, and enhanced gain. Experimental validation using a vector network analyzer and anechoic chamber confirms good agreement between simulated and measured S-parameters, with isolation better than -20 dB. The antenna demonstrates a measured gain between 9.3 and 9.7 dBi, with simulated peaks up to 11 dBi. Far-field pattern measurements exhibit stable bidirectional radiation with low cross-polarization and well-defined main lobes at both 38 GHz and 42 GHz. MIMO performance metrics such as ECC < 0.01, DG ≈ 10 dB, MEG ≈ -3 dB, and CCL < 0.4 bps/Hz confirm efficient multi-port operation. The proposed antenna thus offers a compact, high-isolation, high-gain solution for next-generation mm-wave 5G MIMO systems.

In the dynamic wireless charging system for intelligent rail vehicles, coil misalignment causes mutual inductance fluctuations, resulting in significant output power variations and low transmission efficiency. To address this, a reverse series multilayer interactive coil (RSMIC) structure is proposed. This configuration enhances mutual interaction between coils by incorporating reverse-wound coils, symmetrical DD coils, and magnetic cores, thereby improving the system's misalignment tolerance. First, the structural characteristics of the RSMIC coils are introduced, and their mutual inductance patterns are analyzed. Next, based on a vector magnetic potential mutual inductance calculation method, coil and core parameters are optimized using a mutual inductance fluctuation minimization strategy to achieve quasi-constant mutual inductance and improved transmission efficiency. Ultimately, a wireless charging system was developed according to the optimization outcomes, and its accuracy was validated via both simulation and practical tests. The findings show that even when the ferrite-aided RSMIC coil is misaligned by up to 55% (184.8 mm) of the transmitter coil's external length, the highest variation rate in mutual inductance remains as low as 4.79%, enabling the system to attain a transfer efficiency of 97.35%.

In this paper, a coplanar waveguide-to-rectangular waveguide TE₂₀ mode transition using an antisymmetric tapered probe is proposed. The transmission coefficient of the TE₂₀ mode is nearly 0 dB, and the reflection coefficient of the coplanar waveguide mode is smaller than -10 dB from 13.48 GHz to 14.7 GHz. In this frequency range, the transmission coefficient of the TE₁₀ mode is smaller than -20 dB while the reflection coefficient of the coupled slotline mode is smaller than -19 dB. Besides, a microstrip line-to-rectangular waveguide TE₂₀ mode transition using an antisymmetric fork is proposed. The transmission coefficient of the TE₂₀ mode is nearly 0 dB, and the reflection coefficient of the microstrip line mode is smaller than -10 dB from 13.34 GHz to 15 GHz. In this frequency range, the transmission coefficient of the TE₁₀ mode is smaller than -20 dB. To verify the simulation results, the coplanar waveguide-to-rectangular waveguide TE₂₀ transition and the microstrip line-to-rectangular waveguide TE₂₀ mode transition are back-to-back fabricated and measured, with the measurement results agreeing well with the simulation ones.

Temporal metasurfaces offer a promising platform for new-architecture wireless communications by enabling fast modulation of both electromagnetic waves and digital information. Optical control of these metasurfaces is particularly attractive as it establishes a direct physical bridge between optical and microwave signals, forming the foundation for optoelectronic hybrid communication systems. However, existing schemes are confined to static pre-alignment of the laser beam with the metasurface, lacking real-time spatial alignment capability essential for real-world mobile applications. Here, we propose and realize a mobile hybrid wireless communication system based on the designed laser-tracking-modulated microwave temporal metasurface. This communication system is constructed by integrating a photodiode-based microwave temporal metasurface, a vision-assisted laser-tracking transmitter, and a microwave receiver, enabling direct laser-to-microwave signal conversion sustained by dynamic alignment. Experimental results demonstrate that the system maintains successfully a stable hybrid communication link while the laser transmitter is in motion. This work provides a viable strategy for establishing stable hybrid wireless links for moving platforms and drones in high-mobility scenarios.

Conventional permanent magnet synchronous motors (PMSMs) suffer from limitations in speed regulation range, poor fault tolerance, and restricted torque output in electric vehicle drive applications. To address these limitations, this paper proposes a six-phase, 12-slot/10-pole hybrid-excited reverse-salient fault-tolerant motor (FT-HE-RSPM). To achieve reverse-salient characteristics and regulate the air-gap magnetic field, the rotor adopts segmented permanent magnets and a q-axis magnetic barrier. This design increases the d-axis inductance while reducing the q-axis inductance, achieving the reverse-salient characteristic L_d > L_q under rated conditions. Additionally, both the stator and rotor adopt segmented structures, forming axial magnetic paths via magnetic bridges. The excitation windings are embedded in the stator using non-magnetic materials, and the air-gap magnetic field is regulated by controlling the excitation current. The motor's magnetic field regulation mechanism was analyzed using the equivalent magnetic circuit method. Combined with three-dimensional finite element analysis (3D-FEA), the motor's electromagnetic performance and fault-tolerant characteristics were investigated, leading to the design of a current reconstruction fault-tolerant control strategy for single-phase open-circuit faults. Results demonstrate that this motor exhibits high torque output capability, excellent flux regulation characteristics, high efficiency, and outstanding fault tolerance, meeting the demands of complex operating conditions in electric vehicles.

This study proposes an extended design methodology for sequential load-modulated balanced amplifiers (SLMBAs), centered on regulating the impedance characteristics of balanced amplifiers (BAs) through continuous F^-1 class control amplifiers (CA). By expanding the load operating range of CAs at the second harmonic, the flexibility of high-efficiency designs is effectively enhanced. Theoretical analysis demonstrates that this load modulation mechanism overcomes the structural limitations of conventional LMBA, enabling high-efficiency power amplification across a wide frequency range and under conditions of large output power back-off (OPBO). Based on this architecture, an SLMBA prototype operating from 2.0 to 3.7 GHz was developed. Test results indicate that in saturated and 8 dB OPBO conditions, the drain efficiency (DE) reached 55.2%-68.7% and 46.8%-59.0%, respectively. When fed with an LTE signal featuring a 100 MHz bandwidth and 8 dB PAPR, the average DE across the entire bandwidth ranged from 49.2% to 58.3%, with an adjacent channel leakage power ratio (ACPR) exceeding -35 dBc.

Serendipity has long shaped transformative scientific discoveries, from penicillin and microwave oven to cosmic microwave background. These advances were not accidents but arose when prepared minds encountered unexpected phenomena in environments that enabled recognition and follow-up. In today's research climate, which often emphasizes narrowly defined goals and short-term deliverables, the role of serendipity is undervalued and frequently left to chance. This review introduces the concept of serendipity engineering: the intentional design of technologies, analytical frameworks, and research cultures that enhance the probability of meaningful chance discoveries. We outline four core principles - (i) expanding the observable space with advanced measurement tools, (ii) preserving anomalies through unbiased data stewardship, (iii) applying analytical methods that surface rare or emergent patterns, and (iv) fostering openness to unexpected results. Emphasis is placed on applications in biology and medicine empowered by advanced photonics and electromagnetism, where system complexity and disease heterogeneity make serendipitous findings particularly impactful. We propose a roadmap for embedding serendipity as a strategic component of 21st-century science, transforming it from a passive hope into an active driver of discovery.

Photonic crystals (PhCs) play a crucial role in describing the quantized collective behavior of wave functions. However, the existing investigations into their eigenstates primarily rely on classical computational methods. Variational quantum algorithm (VQA) represents a promising quantum computing technology that can be implemented on noisy intermediate-scale quantum (NISQ) devices, potentially surpassing the classical computational capabilities. Here, we propose a method to analyze the band and eigenstate properties of PhCs based on variational quantum eigensolver (VQE). We firstly reformulate the Maxwell's equations into a Hermitian generalized eigenvalue problem. By appropriately selecting a loss function and employing the proposed quantum eigenvalue solver, we successfully obtain the generalized eigenvalues using a quantum gradient descent algorithm. To validate our approach, we perform simulations on two prototypical PhCs in square and hexagonal lattices. The results demonstrate that a complex Ansatz can effectively capture the optimal solution, successfully yielding the generalized eigenvalues, but a simpler Ansatz exhibits significant limitations. Our findings provide new insights into the application of VQAs in PhCs and other quantum topological systems.

This paper proposes a Hybrid Multi-Strategy Enhanced Enzyme Action Optimizer (HSEAO) for designing multilayer broadband microwave absorbers under vertical irradiation conditions. The optimization objective is to minimize the absorber's reflection coefficient within a specified frequency range by selecting suitable material layers from a literature database. The performance of the Enzyme Action Optimizer (EAO) has been improved by introducing three enhancement strategies including Quasi-Opposition Based Learning (QOBL), adaptive coefficient, and leader follower. The effectiveness of these enhancement strategies is validated through simulation examples of five-layer and seven-layer microwave absorbers, achieving maximum reflection losses of -25.7975 dB and -18.1965 dB, respectively. Results demonstrate that HSEAO outperforms other heuristic algorithms in minimizing reflection coefficients for microwave absorber design. CST simulations further demonstrate that microwave absorbers designed by HSEAO achieve lower reflection losses.

With the advancement of wireless communication, Radio Frequency (RF) energy harvesting has gained significant attention over the past decade. RF energy harvesting is emerging as a sustainable alternative to conventional batteries, enabling self-powered operation in wireless sensor networks and Internet-of-Things (IoT) devices. This work presents a single band fractal based rectenna (Antenna with Rectifier) system for efficient RF energy harvesting. Here a single-diode shunt rectifier converts RF signals into usable DC power which will be usable to many self-powered wireless devices applications. The results show that the proposed antenna (41.03×37.24×1.6 mm³) features a bandwidth of 45.64% ranging from 2.08 GHz to 3.31 GHz and reflection coefficient of -60 dB at 2.45 GHz. The proposed antenna obtained maximum gain of 6.02 dBi with maximum radiation efficiency of 71.4% at 2.45 GHz. A diode rectifier with single stub matching network is used in which a HSMS2860 Schottky diode is connected in shunt for the rectification. The proposed rectifier obtains PCE of 70.07% and DC output voltage of 1.664 V at 5 dBm input power (P_in).