Dynamic wireless power transfer technology has significant advantages in the power supply of mobile loads, achieving electrical isolation between the load and the charging line, and meeting the continuous work demand of the mobile load. The segmented guide dynamic wireless power transfer is the most widely used at present, but the uneven distribution of the magnetic field at the transmitting end of the system leads to power fluctuation during the whole operation cycle, which limits the further development of this technology. Based on this, the distribution characteristics of the dynamic coupling magnetic field of the segmented guide rail are analysed, and an integrated receiving module with a compensation structure is proposed. By compensating the transverse magnetic field component coupled by the receiving coil, the lack of coupling performance of the planar receiving coil in the transition state is made up, and the problem of low receiving power in the transition state is solved. Finally, the experimental platform of the segmented guide rail dynamic wireless power supply system is set up, and the effectiveness of the proposed scheme is verified by comparing the total power received by only planar receiving coil and adding compensation receiving coil.
This paper proposes a method for estimating the excitation of array antennas by backward-transforming phaseless field data into the very near-field. The very near-fields are reconstructed at the antenna aperture using the Tikhonov source current reconstruction method (SRM). Two field amplitudes in different planes recover very near-field data from phaseless fields. The excitation estimation technique relies on the localised nature of very near-field currents around the antenna. Through spatial filtering of the reconstructed equivalent currents, the current distribution of each individual element is isolated. The excitation of each array element is then determined by analysing its current distribution over a separate surface mesh. Excitation estimations of two different array antennas with measurement and simulation results have been carried out to validate the proposed method. The relative amplitude errors of the excitation estimation with simulation data are 7.5% and 3.9% for using equivalent electric and magnetic current, respectively. In the measurement scenario, which includes the errors of manufacturing and testing, the maximum relative amplitude error is about 12% and the maximum phase recovery deviation is about +/- 9 degrees.
In this paper, we propose a phased antenna array with enhanced coupling configuration that integrates ultra-wideband performance, low profile and significantly reduced scattering. The antenna design leverages an innovative arrangement of cross-stacked planar dipole layers and a nonbalanced feed structure, achieving a miniaturised and highly integrated form. To further enhance performance, we incorporate resistive frequency selective surfaces (RFSS), short-circuit columns and optimised dielectric layers to mitigate multifrequency resonance points caused by the ground plane and unbalanced feeding. These innovations enable a broader 9:1 operating bandwidth. Additionally, the integration of a hybrid-functional metasurface is optimised using a synergy of equivalent circuit characterisation and space mapping (SM) technology, improving both design efficiency and functionality. We also extend the phase cancelation technique into the folded metasurface to induce reflection phase differences, resulting in an RCS reduction of more than 5 dB across the entire frequency band. An 8 x 8 antenna array was fabricated and tested, demonstrating exceptional wide bandwidth, wide scanning angles and low scattering characteristics, validating the effectiveness of the proposed design.
Microwave absorbers play a critical role in controlling electromagnetic wave propagation, especially in stealth technology and EMI shielding applications. In this work, we introduce a novel microwave absorber design inspired by the Sakarya chaotic system, which offers broadband and enhanced absorption properties. The proposed absorber structure exhibits distinct fractal geometries that enhance polarisation and angular stability using chaotic attractor-based patterns. The design process entails generating chaotic datasets from the Sakarya attractor, transforming them into fractal patterns via the Julia set, and fabricating the final structure using resistive ink by a screen printing method on an FR-4 substrate. Numerical simulations and experimental measurements verify the high absorption efficiency of the structure over a wide frequency range, demonstrating the potential of chaotic attractor-based designs to enhance electromagnetic absorption performance and offer innovative applications in stealth technology.
In this work, a graphene-based tunable phase shifter is proposed which deploys a semiautomated procedure for graphene deposition leading to a high-quality graphene transfer. The deposited graphene's complex impedance values are extracted from measured transmission coefficient values in the X band. Analysis of different widths of graphene is performed for better understanding of the microwave properties of graphene. It is evident that by decreasing the width of graphene, the impedance of graphene decreases, making it more conductive for lower widths. In order to observe the microwave tunable behaviour of graphene, varying DC biasing voltages are applied and the variation of transmission coefficients are measured. From the extracted values of complex impedance of graphene, it is observed that graphene possesses significant reactance variation, something that is not considered in literature. The reactance variation can be exploited in the variation of the phase of microwave signals. The reactance variation of graphene is further enhanced for increased phase variation by deploying it with an Interdigitated Capacitor (IDC). The IDC graphene phase shifter provides a phase variation of 60 degrees with negligible amplitude variation at 9 GHz.
A wideband high-efficiency compact all-metal folded transmitarray antenna (CAMFTA) with integrated planar feed is proposed in this paper. It consists of a transmission metasurface (TMS) with the function of reflecting y-polarised wave, as well as transmitting x-polarised wave and twisting its polarisation by 90 degrees, a linear polarisation conversion reflection metasurface (RMS), and a planar slotted patch as the feed. All these components are made of metal, making the entire structure relatively cheap to manufacture and resistant to stringent environments. Particularly, in addition to the low-profile nature of the folded structure, the metal-only planar feed is co-designed and integrated with RMS, resulting in a further reduced profile and a compact configuration. In order to validate the superiority of the design, a CAMFTA is simulated, implemented and measured at X-band. The results of experiments demonstrate a high degree of correlation with simulations, with peak aperture efficiency of 29% and 3 dB gain bandwidth of 13%, respectively. To the best of the authors' knowledge, this is the first CAMFTA reported in the literature, and it offers a number of advantages, making it very suitable for high-gain applications where a compact, low-cost, low-profile configuration with steady performance is required.
This paper proposes a polarisation-insensitive absorptive metamaterial unit cell that achieves a perfect absorption of circularly polarised (CP) incident waves. To overcome the miniaturisation limitations inherent in conventional metamaterial designs, an innovative approach employing a sandwiched configuration with cladding layers is introduced. This approach approximates perfect electric conductor (PEC) boundary conditions, enabling the truncation of the bulky periodic structure into a one-dimensional wall-type absorptive metamaterial (WAM). To mitigate mutual coupling under stringent aperture constraints, four WAM screens are integrated concentrically around the central element of a compact five-element array antenna featuring sub-wavelength element spacing (0.4 lambda) at the GPS L1 frequency. Both simulations and experimental results demonstrate inter-element mutual coupling suppression of less than -23 dB between the central and peripheral elements, alongside a peak realised gain improvement exceeding 3 dB for the central element. The WAM-enhanced adaptive five-element array achieves a maximum improvement of 4 dB in anti-jamming capability.
This article presents a coplanar stripline (CPS) reflectionless filter that integrates out-of-band absorption, exploring a novel configuration that promotes applications of reflectionless filters. By taking advantage of the CPS structure, the CPS absorptive resonator is initially proposed and studied to keep lossless transmission at its resonance and produce sufficient absorption at complementary frequencies. Next, a wide passband is achieved when introducing broadside coupling between two back-to-back CPS absorptive resonators. To guide the design, a transmission-line model representing the wideband CPS reflectionless filter is developed so that the wideband synthesis can be used to obtain all the circuit parameters for the specified transfer function. Subsequently, a 4th-order prototype is implemented. Simulated results reveal the filter achieves good impedance matching across the entire band with significantly reduced out-of-band reflection. Finally, the prototype is fabricated with transitions at its external ports. The de-embedded results in measurement are found in good agreement with the simulated ones, validating its compact size, wide reflectionless range, and efficient design process.
An innovative deep-learning driven convolutional perfectly matched layer (CPML) integrated into the hybrid implicit-explicit finite-difference time-domain (HIE-FDTD) method is proposed to improve the efficiency of open-region electromagnetic simulations. The Autoformer neural network is introduced to replace the conventional multi-layer CPML structure. Both the computational domain size and algorithmic complexity are reduced since only a single-layer boundary layer is involved in the new model. Benefiting from the time series decomposition and sparse attention mechanism, the wave absorption efficacy of the proposed model is significantly improved without backward cumulative errors. Through a column-stacked data acquisition approach, the Autoformer-based CPML is compatible with both the FDTD and HIE-FDTD frameworks. The time step size of this proposed method is only determined by the coarse grid size, thereby extending the applicability of intelligent absorption boundaries beyond traditional FDTD limits. Numerical examples demonstrate that this method markedly improves computational efficiency while maintaining excellent wave absorption performance. Additionally, results confirm the method's robustness in complex scenarios, including multi-material, multi-source and multi-scale environments.
This paper presents a novel method for designing a wideband dual-polarised multibeam transmitarray antenna. First, a dual-polarised element is implemented through a polarisation-separating, orthogonal-interleaved three-dimensional frequency-selective surface (3-D FSS). Subsequently, a wideband dual-polarised unit cell is developed by integrating true-time-delay (TTD) technology, allowing full 360 degrees linear phase shifting for distinct polarisations. A superposition method is then employed to efficiently and stably determine the phase distribution of the array, facilitating multibeam radiation. Finally, measurements of the fabricated transmitarray antenna validate its excellent quad-beam radiation performance at 5 GHz for both vertical and horizontal polarisation, with each beam exhibiting precise spatial separation and maintaining sidelobe levels below -12 dB and cross-polarisation suppression ratios better than -20 dB. The 3 dB gain bandwidths are measured to be 16.31% for vertical polarisation and 16.96% for horizontal polarisation, with corresponding peak aperture efficiencies of 37.27% and 35.63%, respectively.
In this paper, we propose a Double Pulse-based Dual Coprime Frequency Diverse Array Multiple Input Multiple Output (DCFDA-MIMO) radar for enhanced target parameter estimation, including range, angle, and Doppler. The proposed model employs an unstructured approach for parameter estimation using the recently developed DCFDA-MIMO radar, which has garnered significant attention due to its superior target resolution compared to traditional Frequency Diverse Array MIMO (FDA-MIMO) radar. Because most conventional designs rely on a structured approach using a single pulse, conventional FDA-MIMO radar suffers from increased computational complexity due to multiple signal classification (MUSIC) and strong coupling between range and angle parameters. To address these challenges, we introduce an efficient, low-complexity method that effectively reduces range-angle coupling and improves target parameter estimation. Unlike existing techniques, the proposed approach uses the Double Pulse method, transmitting the first pulse without frequency increments to estimate the angle. In contrast, the second pulse incorporates suitable frequency increments to estimate range and Doppler separately by incorporating the estimated angle information. Monte Carlo simulations validate that the proposed DCFDA-MIMO-based Double Pulse method significantly improves target parameter estimation in terms of signal-to-noise ratio (SNR), signal-to-interference-and-noise ratio (SINR), and Cram & eacute;r-Rao lower bound (CRLB) compared to existing array structures.
In this paper, a compact broadband flexible wearable antenna with an improved high-order mode radiation pattern is designed and analysed using the characteristic mode analysis (CMA) method. Through loading nonuniform stacked patches on traditional metasurface (MS) unit cells, the radiation properties of high-order mode are enhanced, thereby widening the operating bandwidth of the antenna. The antenna achieves broadband impedance matching by simultaneously exciting the slot radiation mode and two metasurface modes via a coupling feed. The antenna is fabricated using membrane circuits on felt substrates. It is demonstrated that the antenna achieves a -10 dB bandwidth of 4.42-7.66 GHz (53.6%) and a 3 dB gain bandwidth of 4.55-7.54 GHz (49.5%). The peak gain is measured at 9.6 dBi while maintaining a compact size of 0.62 x 0.62 lambda(2)(0). In addition, the robustness and specific absorption rate (SAR) properties of the proposed antenna are evaluated.
This work introduces the biconical cavity as a high-performance resonator for multimode wideband bandpass filters. Unlike conventional cylindrical cavities, its tapered geometry enhances mode separation and extends the rejection band compared to an equal-order cylindrical cavity of the same configuration without additional tuning elements, while maintaining compact size. To verify this advantage, quadruple- and quintuple-mode bandpass filters using biconical cavities are directly compared with equivalent cylindrical implementations. Both quadruple- and quintuple-mode filters using biconical cavities are designed, fabricated and measured. The quadruple-mode filter operates at 3.82 GHz with 46.8% fractional bandwidth and three transmission zeros, whereas the quintuple-mode filter achieves 67.2% bandwidth at 3.52 GHz with four transmission zeros. Close agreement between measured and simulated results confirms improved stopband suppression and stable passband matching, establishing the biconical cavity as a compact and practical alternative for next-generation wideband communication systems.
A compact leaky-wave antenna (LWA) with innovative phase-shift asymmetric coupling for continuous beam scanning is presented. The antenna utilises a slow-wave half-mode substrate integrated waveguide with spoof surface plasmon polaritons (SW-HMSIW-SSPP) transmission line structure to achieve ultra-compact dimensions in both longitudinal and lateral directions. The radiation characteristic is achieved using sinusoidal modulation on the SSPP structure. To enable continuous beam scanning through broadside, a novel and simple phase-shift asymmetric coupling method is developed by placing sinusoidally modulated patches with pi/2 phase shift on the metallised blind via-hole arrays. This approach effectively suppresses the open stopband (OSB) and enables continuous beam scanning from backward to forward directions without radiation degradation at broadside. A prototype of the proposed LWA is fabricated and characterised. The measured results demonstrate that the antenna with 12 unit-cells operates over a wide frequency range from 14.3 to 20.5 GHz with continuous beam scanning from -40 degrees to +30 degrees, while maintaining an ultra-compact aperture of only 6.67 lambda(0) x 0.27 lambda(0).
A millimetre-wave (mm-wave) microstrip patch antenna with a stable wide beamwidth is proposed for a wide-angle scanning phased array. The proposed antenna element is achieved by loading four semi-open parasitic elements around the stacked patch. The four semi-open parasitic elements can generate two pairs of stable antiphase current radiation sources to achieve a stable rotated '8'-shaped pattern, which can obtain wide-beamwidth radiation patterns when it is synthesised with the broadside radiation pattern produced by the stacked patch. Further, the coupling between the parasitic elements and the driven patch producing the lower reflection zero is weaker than that between the parasitic patch producing the upper reflection zero. Therefore, the proposed antenna can achieve a stable wide beamwidth over wide frequency ranges. The generation of the rotated '8'-shaped pattern is theoretically analysed. An eight-element E-plane scanning linear antenna array based on the proposed antenna element is demonstrated for the potential application in a wide-angle scanning phased array. The simulated and measured results show that the main beam can scan from -75 degrees to 75 degrees with a gain fluctuation < 3 dB under a 10-dB fractional bandwidth of 16.7%.
This study investigates the application of microwave-assisted drilling systems as an alternative to conventional mechanical drilling for marble processing. By utilising microwave energy at a frequency of 2.45 GHz, this research demonstrates how microwave radiation can effectively soften marble surfaces, reduce required drilling force, and improve surface quality. Two specialised microwave probes, Reflector Microwave Drilling Design (R-MDD) and Microwave Drilling Design-Empty Center (MDD-EC), were designed and tested to optimise the energy transfer and thermal impact on different marble types, specifically Burdur Beige and Keciborlu Angel White. Through a combination of simulation (CST Studio Suite) and experimental analysis, electric field intensity, temperature distribution, and drilling depth have been evaluated. Results indicate that microwave-assisted drilling significantly decreases burr formation and enhances drilling efficiency by generating focused thermal zones within the marble. Additionally, the MDD-EC probe's hollow conductor design allows integration with supplementary devices such as vacuum motors to manage waste discharge during drilling. This work concludes that microwave-assisted systems offer a promising cost-effective solution for hard dielectric materials in the marble industry, with potential applications extending to other high-melting-point materials.
A reflectionless filter is designed based on the dual-circuit theory. Two types of reflection-less filters are presented for this methodology. The proposed configuration consists of two dual branches. Two dual-bandpass filters are used in two branches of the structure, which are connected using Wilkinson-like power dividers. Out-of-phase reflected signals from each of the two branches are delivered to a resistor, resulting in a reflectionless port. A coupled line bandpass filter is fabricated and measured to verify the presented configuration and design equations. There is a good agreement between theory and measurement.
A method of batch generation of frequency selective surface structure is proposed in this paper. The method of random image generation and random diode insertion position is used to generate a database through a large number of automatic calculations to replace manual design by screening high-performance cells. This method can achieve most of the possible indicators of FSS, significantly reduce the manual workload and shorten the design cycle.
A double-layer wideband circularly polarised (CP) metasurface (MTS) antenna is proposed. The MTS consists of a 4 x 4 L-shaped patch array. The modal behaviours of the proposed MTS are investigated using the characteristic mode theory. Two characteristic modes with orthogonal current distributions are selected as the operational modes. Furthermore, an aperture-coupled feeding structure is employed to excite the two orthogonal modes with a 90 degrees phase difference, enabling CP radiation. It can also excite the MTS to generate multiple resonances and axial ratio (AR) minimum points, which collectively yield an acceptable bandwidth for both impedance and AR. Finally, an antenna prototype is designed to validate the simulated results. The measured results show that the MTS antenna offers a -10 dB impedance bandwidth (IBW) of 34.9% (4.25-6.05 GHz), a 3 dB AR bandwidth (ARBW) of 13.2% (5.3-6.05 GHz) and a maximum gain of 7.3 dBic.
In order to verify the feasibility of atmospheric duct inversion method using automatic identification system signal in the actual sea area, a sea experiment was carried out. The signal acquisition system of portable high sensitivity civil automatic identification system is developed, and the receiving and processing process of automatic identification system signal is analysed. The sea experiment scheme and main experiment equipment are given, and the collected experiment data are processed and analysed. Finally, the method of atmospheric duct inversion using automatic identification system signal is verified by the measured data. Atmospheric duct inversion is an inverse problem, which requires the use of various optimisation algorithms to optimise the duct parameters in order to obtain the characteristic parameter information of the duct. In this paper, the L & eacute;vy flight quantum-behaved particle swarm optimisation algorithm and the deep learning algorithm are respectively used to invert the atmospheric duct parameters. The results show that there is little difference between the inverted duct parameters and the true duct parameters, which verifies the feasibility of using the automatic identification system signal to invert the atmospheric duct.
