This article introduces a novel ship detection method for Synthetic Aperture Radar (SAR) images that leverages the principles of Finsler information geometry. It employs the curvature features of a statistical manifold as a discriminative mechanism to diminish the impact of sea clutter and augment the contrast between a target and its background. The ambiguity of the local microstructure and statistical characteristics is partially resolved by using information theory to select metric definitions and curvature representation of non-European space. This method models sea clutter using the Gamma Distribution Function (GDF), transforming the detection challenge into an anomaly detection framework within the GDF space. This approach establishes a theoretical detection framework rooted in Finsler information geometry by integrating statistical modeling with Finsler geometry. It harnesses the Finsler characteristics of GDF space to extract the curvature feature representations for each GDF. Detection is achieved by applying one-class support vector machines (SVMs) to a matrix of curvature values derived from these representations. The detection algorithm unfolds in two primary phases. Initially, it utilizes a family of probability distributions to capture geometrical information. Subsequently, curved features are employed for target detection. Through rigorous experimentation with real datasets, the method demonstrates enhanced resilience to sea clutter and outperforms existing techniques for analyzing distribution families, validating its effectiveness and robustness.

This paper introduces a compact, circularly polarized exponential slot antenna with a rectangular island. The concept of the proposed antenna is similar to that of fractal antennas as it is based on designing an asymmetric slot shape with an increased electrical length within a small area, thanks to the exponential path. The obtained results are as follows. The reflection-coefficient |S₁₁| of the proposed antenna covers the band from 5.5 GHz to 9 GHz. The proposed antenna is circularly polarized with an axial-ratio (AR) bandwidth that extends from 6.87 GHz to 8.9 GHz. It offers simultaneous dual circular polarizations (RHCP and LHCP). The gain of the proposed antenna varies between 4.2 dBic and 5.4 dBic. The efficiency reaches 94%. The size of the antenna is compact making it suitable for CubeSats with limited surface area. The proposed antenna intended application is X-band Earth-Space satellite communication. The proposed antenna can be employed for both the X-band satellite downlink (from 7.25 GHz to 7.75 GHz) and uplink (from 7.9 GHz to 8.4 GHz) frequency bands. Additionally, the antenna can be utilized in military applications, and RFID tag tracking-equipment. A prototype of the proposed antenna has been fabricated and then measured using Vector-Network-Analyzer (VNA) and inside an anechoic chamber. The measurement results of the proposed antenna are in excellent match with the simulated ones.

This work designs an electromagnetic band gap structure-based quad port rectangular MIMO antenna to operate in the 5G new radio (NR) sub-6 GHz n79 band, with a frequency range of 4.3-5.0 GHz. To achieve optimal radiating element isolation with the least complexity, MIMO antennas' four radiating elements are oriented orthogonally using an A-shaped electromagnetic band gap (EBG) structure. The EBG structure is located between the human phantom model and the MIMO antenna. The MIMO antenna's measurements are 40 × 40 × 1.6 mm³, and it is implemented on an FR-4 substrate with whole ground. Due to EBG structure, the mutual coupling is improved to -26.0 dB. The ECC, DG, and CCL were also calculated. In addition, the SAR (specific absorption rate) value is reduced to 0.22 w/kg. The MIMO antenna is simulated using HFSS software. The vector network analyzer (VNA), model Anritsu MS 2037C is used to measure the various MIMO antenna parameters.

This paper presents a compact double sided Ultra-Wideband (UWB) vivaldi antenna with corrugated structure. The proposed antenna is designed to operate from 5 GHz to 20 GHz frequency band. A comprehensive analysis of the antenna is carried out for its design, optimization, and performance especially for enhanced bandwidth and improved radiation characteristics. The antenna structure consists of vivaldi section which is printed on top and bottom layers of multi-layer printed circuit board (PCB) and fed with microstrip to strip lines transition. The antenna is fabricated and measured its return loss and radiation characteristics. The measured peak gain is 10.25 dBi at 17 GHz and return loss is better than -10 dB over the band 5 GHz to 20 GHz. Symmetrical radiation properties are observed over the band with excellent radiation characteristics especially in lower frequency bands as a result of comprised corrugated structure. Also, the far-field radiation pattern is symmetrical and directive throughout the operating band. The proposed design finds a suitable application in the field of an electronic warfare, precision ranging, microwave imaging.

In this study, we present a novel broadband microwave absorber that is both optically transparent and capable of dynamically adjusting its absorptivity. The absorber is composed of a graphene sandwich structure (GSS), a polyvinyl chloride (PVC) layer, an indium tin oxide (ITO) layer, another PVC layer, and an ITO ground plane, arranged in a top-to-bottom configuration. This unique design allows for a working bandwidth of 6.8 GHz to 14.0 GHz, with absorption levels ranging from 95% to 60%, achieved by varying the impedance of the GSS from 1000 Ω/sq to 200 Ω/sq through tuning the bias voltage. By utilizing materials with high optical transmittance, this nonpatterned device maintains exceptional optical transparency. Furthermore, by incorporating additional ITO layers with different impedances at equal intervals, this multilayer design can be extended to create an ultra-broadband absorber covering a range of 5.28-39.52 GHz. This is made possible due to the dispersionless resistance of nonpatterned graphene and ITO sheets in the microwave spectrum. This transparent wideband microwave absorber, with tunable absorptivity, holds great potential for a wide range of applications in broadband and intelligent stealth technology.

The flywheel-type dual-stator permanent magnet starter generator combines engine flywheel and starter generator rotor into a single unit, which has the advantages of high efficiency, high power density, and compact structure. This paper proposes a new type of dual-stator permanent magnet starter generator topology in which the two stators are concentric and share the same permanent magnet rotor. Equivalent magnetic circuit modeling of the inner stator's magnetic field, outer stator's magnetic field, and synthetic magnetic field using the equivalent magnetic circuit method list the system of flux equations and solve the main magnetic flux, leakage flux, and leakage coefficient, and the results show that the equivalent magnetic circuit method has smaller error and higher accuracy than the finite element method. The harmonic electric potential of the starter generator is modeled and analyzed. The permanent magnet rotor and inner and outer stator structures are optimized to obtain the optimal parameters, and the prototype is manufactured and tested. The optimized starter generator no-load induced electromotive force fundamental amplitude is improved. The induced electromotive force harmonic distortion rate is reduced, and the output performance of the whole generator is significantly improved.

A Negative Group Delay (NGD) prototype filter design based on the reciprocal transfer function of a low-pass Butterworth filter of a given order, is presented. The out-of-band gain of the prototype transfer function is capped at a finite constant value via multiplication by a transfer function of a low-pass Butterworth filter with 3 dB bandwidth that is wider than the reciprocal function bandwidth. Such synthesized transfer function exhibits maximal magnitude characteristic flatness within the 3 dB bandwidth (Butterworth-like property), while it also exhibits NGD and satisfies Kramers-Kronig relations (causal transfer function). The prototype design achieves an NGD-bandwidth product that in the upper asymptotic limit as the design order increases, is a linear function of out-of-band gain in decibels. This is an improvement compared with previously reported cascaded first-order and second-order designs, which have NGD-bandwidth functional dependency of out-of-band gain in decibels to the power of 1/2 and 3/4, respectively. It is shown that the transfer function of the corresponding design transformed to a non-zero center frequency can be exactly implemented with a Sallen-Key topology employing parallel resonators, or approximately implemented with an all-passive ladder topology. An in-band magnitude/phase distortion metric is applied to the prototype designs, evaluated for Gaussian and sinc pulse input waveforms, and compared with values obtained for a well-known commonly used medium. It is also shown that when the specified bandwidth corresponds to the entire bandwidth over which the group delay characteristic is negative, the magnitude characteristic variation approximately equals half the out-of-band gain value in decibels. Therefore, for any NGD design with large out-of-band gain (typically higher than 6 dB), using the entire bandwidth where group delay is negative can result in strong levels of distortion and should be checked for applied waveforms.

The magnetic resonance coupling based wireless power transfer (WPT) technology has been of great interest due to its usefulness and persistent characteristics in powering multiple devices simultaneously. However, it is the foremost challenge to make possible easy access and manage the effective power transmission to the multiple gadgets through the WPT technology. In order for the multi-receiver system to run at its most favourable operational area, a prompt access is necessary at this point to identify the appropriate selection of functional parameters. Thus, a circuit model analysis has been put forward, and the influences of functioning parameters such as electric load at the receivers, mutual coupling between the coils, frequency of operation on the system's performance indicators like input power, power at the receiver's load, power transfer efficiency at individual receiver, and moreover the input impedance of the system have been investigated. The perception has been validated through a bench-top experimental setup. The observed experimental result closely matches the theoretical data derived from the circuit model. The outcomes are crucial which may provide the important selection criteria for the effective operation and creation of successful electromagnetic coupling based multi-receiver WPT system.

A compact ultra-wideband (UWB) bandpass filter is realized with the combination of dual-split square complementary split ring resonator (DSS-CSRR) and substrate integrated waveguide and is investigated in this paper. Three DSS-CSRRs are carved on the top and bottom layers of SIW to achieve the required passband and enhance the selectivity of the filter. Slots are etched in the ground to improve the return loss characteristics and to lower the insertion loss. The proposed filter offers a fractional bandwidth of 107% (3.1-10.3 GHz) and an insertion loss range of 0.6-1.6 dB in the entire passband. The prototype was fabricated on an FR-4 substrate, with dimensions of 0.3λ_gL × 1.06λ_gW. The group delay variation is almost flat over the entire passband. The prototype was fabricated and validated the measured results.

In the wireless communication industry, achieving gigabit-per-second data rates with low-profile, ultra-wideband (UWB) microstrip patch antennae poses a significant challenge. Conventional optimization algorithms, though effective, are often computationally expensive, particularly for complex antenna geometries with high degrees of freedom. There is an imperative need for new methodologies to address this challenge and revolutionize the antenna optimization process. Successful and timely development of antennas relies on the efficiency and computational speed of optimization algorithms, full-wave electromagnetic (EM) solvers, and the intuition of radio frequency engineers. To mitigate the dependence on complex and time-consuming processes, we propose an efficient machine learning (ML)-based antenna optimization methodology that minimizes optimization time by more than 90%. This paper aims to apply and study the performance of two specific ML models, the radial basis function (RBF) and the least squared regression (LSR) models, in the bandwidth optimization without increasing the aperture area of a hexagon-shaped fractal antenna. The hexagon-shaped fractal antenna was chosen for its UWB characteristics, low profile, and high degrees of freedom (10 adjustable parameters). The reflection coefficient response of a hexagon-shaped fractal antenna is predicted by the trained RBF and LSR models and further optimized by the genetic algorithm (GA). The proposed approach stands out among other notable works in this research domain, especially for ultrawideband (UWB) applications, by prioritizing the optimization of the mean of |S₁₁| across the entire frequency range instead of solely targeting individual frequency points. The GA-based optimization using trained ML models has increased the bandwidth by 30.20% and reduced the computational time by 90% compared to conventional optimization without increasing the physical or electrical size of the antenna. Simulation and measurement results concurred with a maximum difference of 5%, demonstrating the efficacy of the ML approach for antenna optimization.

This work provides the design, analysis, and performance optimization of an artificial magnetic conductor (AMC)-based wideband printed monopole antenna. The proposed antenna structure is constituted with CPW feeding, and an AMC layer has been added beneath the proposed antenna configuration to decrease back lobe radiation. By employing an AMC reflector, composed of periodic copper metallic Minkovski square fractal patches on a circular serrated antenna with an air gap separation of 8\,mm, the proposed antenna has obtained a peak gain of 12.9 dBi, and wideband is also achieved by the antenna for wearable applications. The prototyped model of cotton fabric substrate material based measurement results with antenna measurement setup match the CST-tool simulation results, enabling the applicability in real time communication systems.

In this article, a low-profile high gain stack microstrip antenna (MSA) with low Cross Polarization Level (CPL) using multiple metasurfaces is proposed. MSA on a thick substrate having low dielectric constant enhances the gain and bandwidth (BW). However, as substrate thickness increases, the CPL increases due to increase in coaxial probe length used for feeding MSA. The CPL is reduced by using metasurfaces formed by an array of square metallic patches of dimensions and periodicity < 0.1λ₀. A suspended MSA (SMSA) is designed on a reactive impedance surface (RIS) backed substrate, to reduce the interaction between substrate and ground plane, surface waves and to increase impedance BW and polarization purity. A parasitic patch is fabricated on a superstrate and placed above the SMSA and metallic patches forming the metasurfaces are fabricated around the MSA, PP and on the other side of superstrate. These metasurfaces increase the inductance of the antenna, and to compensate the inductance, the height of SMSA and the spacing between MSA and PP are decreased which results in the decrease in probe feed length and CPL. This novel low-profile high gain wide band stack MSA offers CPL < -20 dB, Side Lobe Level (SLL) < -20 dB, Front to Back lobe ratio (F/B) > 20 dB and S₁₁ ≤ -10 dB over 3.3-3.6 GHz to cover 5G applications. The 0.935λ₀ × 0.99λ₀ × 0.046λ₀ prototype antenna offers peak gain of 8.3 dBi, antenna efficiency >90%, and λ₀ being the free-space wavelength at 3.3 GHz.

A dual-band serrated microstrip MIMO antenna is proposed for 5th generation wireless applications in this article. The simulated -10 dB impedance bandwidth of 160 MHz (3.340-3.50 GHz) and 220 MHz (5.50-5.72 GHz) can cover 3.40-3.60 GHz and 5-5.7 GHz fifth generation bands. Here the designed MIMO antenna is a serrated basic microstrip patch antenna. A full ground copper layer has been utilized in the design to attain a better isolation, whereas the fabricated antenna's isolation among the antenna elements is measured to be greater than -20 dB. In addition, the measured ECCs are less than 0.0025 and 0.001 at the two resonant frequency bands and for the two MIMO antennas. The antenna diversity parameters covering ECC and DG were analyzed. The average gain for the single-element, dual-port and quad-port MIMO antennas is 3 dBi. These parameters make the serrated microstrip MIMO antenna also suitable for intelligent IOT devices operating in sub-6 GHz band.

In this paper, we study one-dimensional (1D) integrated photonic systems composed of waveguides connected to resonators. We explain and discuss the appearance of two unique resonance phenomena: Fano transparency and electromagnetically induced transparency (EIT). These resonances play a crucial role in optimizing signal filtering in photonic devices. Our study focuses on two geometrical configurations: a cross-shaped arrangement with collocated lateral resonators at the same site, and a U-shaped configuration with resonators positioned at different sites. We use Transfer Matrix Method (TMM) to analyze these configurations, improving existing theoretical models for photonic waveguide systems. Using this method, we can manipulate the geometrical parameters of resonators to fine-tune the transmission properties associated with the Fano and EIT resonances. Our results indicate that symmetrical resonators eliminate Fano resonance in cross-shaped structures, while the introduction of asymmetrical resonators induces their emergence. For U-shaped structures, we demonstrate the presence of Fano and EIT resonances, and show that their manifestation depends on the geometric parameters of the resonators. Our research has two major implications: Firstly, it advances the theoretical knowledge of resonance phenomena in photonic waveguides. Secondly, it provides a methodology for the design of photonic structures with adapted transmission characteristics, opening the way to applications in advanced signal processing technologies.

The vibration and noise of a low-speed high-torque permanent magnet motor with a dovetail magnetic isolation device (DMID) structure is analyzed. The motor structure and the main structural parameters of the DMID are introduced, and the radial electromagnetic force wave of the motor is investigated. The notch width, radius, and position of the inner circle of the DMID are selected as design variables, and the constraint conditions are given. The influence of a single parameter on the radial electromagnetic force wave is discussed. The multi-objective optimization of the particle swarm optimization (PSO) algorithm is used to obtain the Pareto relatively optimal solution set that simultaneously satisfies the requirements of low noise, ample output torque, and small torque ripple, and the optimal design scheme is selected. Besides, the harmonic amplitudes of the radial electromagnetic force, motor vibration acceleration, electromagnetic noise, losses, and efficiency are compared and analyzed before and after optimization. Finally, the electromagnetic vibration experiment of a permanent magnet synchronous motor is carried out, and the data shows the feasibility of the above analysis. The results show that the optimal design scheme of the structure parameters of DMID can increase the average output torque, reduce the torque ripple, and effectively reduce the electromagnetic vibration and noise of the motor.

In this paper, the propagation of electromagnetic rays in a tropospheric waveguide and spatial processing using digital antenna arrays are studied. The beam traveling through the layers of the atmosphere depends on the refractive index and its vertical change. In this regard, conditions may arise when radio rays propagate in a waveguide manner at low altitudes. In this case, attenuation takes place, and the effect of multipath fading may also occur, when several rays reflected from different layers of the troposphere and with various spatial coordinates in elevation arrive at the receiver. It is proposed to apply digital antenna arrays to increase the range and reliability of radio communication through the tropospheric waveguide. Parabolic equations are utilized to estimate the path loses of radio waves of the centimeter wavelength. A ray-tracing algorithm via a tropospheric waveguide is used to estimate the mutual phases in the aperture of the receiving array. Bit error rate curves were obtained depending on the geometry of the antenna arrays after the signal passed through the tropospheric waveguide.

In plain areas, the majority of the ultra-high voltage(UHV) transmission corridors are located in farmland. The induced voltage is generated on the metal casing of the machinery when agricultural machines are working on the ground near the transmission line. If the human body touches, transient electric shock(TES) may occur, causing displeasure and alarm to workers. Therefore, it is crucial to study the induced electrical characteristics in such scenarios. In this article, the finite element method (FEM) was employed to establish a model integrating a 1000 kV transmission line, tractor, and human body, and the induced voltage of the tractor and human body under the transmission line was calculated. Subsequently, a TES model was developed to calculate the current when an electric shock occurs. Finally, an experimental system was constructed in the area beneath the 1000 kV UHV AC line to measure the current characteristics of the human body during the TES. The results demonstrate that the induced voltage is contingent upon the position of research object and whether it is insulated from the ground. Additionally, ground conditions significantly influence the TES current induced by the voltage. Due to the electromagnetic shielding effect of the tractor's metal casing, the TES current experienced by the driver inside the machine is minimized. For ground staff, when the human body is insulated from the ground, the transient electric shock current they bear is smaller than that of the human body grounded.

In this paper, an improved hybrid regularized grounded network imaging algorithm (ITR-Lp) combining Tikhonov regularization and Lp regularization is proposed; through the improvement of the filtering function, the correction of small magnitude for large singular values and increasing magnitude of correction with decreasing singular values for small singular values is implemented for the improvement of the convergence of the solution. The proposed algorithm constructs a regularization matrix to achieve selective correction of singular values and improve the convergence of the solution, while Lp regularization is used to enhance the sparsity of the solution and improve the boundary contrast. the effect of node distribution on convergence is investigated, and finally the ITR-Lp algorithm is validated by simulation and experiment. The results show that the ITR-Lp algorithm proposed in this paper achieves the lowest resistivity relative errors of 0.1695 and 0.1089 for resistive networks with 1 corrosion and 2 corrosions, respectively. The method has good convergence and boundary contrast, which effectively improves the pathology of the inverse problem of imaging the electrical impedance tomography of grounding grid.

We proposed a wireless power transfer system for cardiac pacemakers utilizing a multi-coil series magnetic integrated inductor-capacitor-capacitor/none (LCC-N) circuit topology operating at 50 kHz to reduce the volume of wireless power transfer systems for implanted pacemakers. Firstly, we established a mathematical model of LCC-N compensation topology and analyzed the relationship between the mutual inductance of the compensation and receiving coil and the system's transmission efficiency. The conclusion that the anti-offset performance of the system can be improved by using the change of the mutual inductance value was obtained. Secondly, the optimal coil structure was obtained via parameterized scanning, and a wireless power transfer system model for LCC-N was established for finite element simulation. The comparison of magnetic field strength was made between integrated and traditional non-integrated structures under aligned and offset conditions. Finally, the finite element simulation software ANSYS was adopted to establish a human body model, analyze the electromagnetic interference of the system to the human body, and evaluate the system's safety. Experimental results validated that the transmission efficiency of the system can reach 68.37%, and the output power was 1.47 W under multi-coil series magnetic integrated structure when the transmission distance was 8 mm. The transmission efficiency remained 57.87% even with a horizontal offset of 8 mm, which is 13% higher than the traditional non-integrated structure.

In this paper, the Hybrid Grey Wolf and Improved Bat Optimization Algorithm (HWIBO) is proposed to reduce the peak sidelobe level (PSLL) of linear symmetric array synthesis with aperture and element spacing constraints. The HWIBO utilizes both the Grey Wolf Optimization (GWO) and Improved Bat algorithms (IBA) simultaneously to optimize PSLL. Each iteration generates two sets of results, and the optimal result is chosen for the next loop. Compared to other algorithms used in simulation of antenna sidelobe suppression, the HWIBO not only inherits the fast convergence advantage of the IBA which enhances population diversity but also possesses the strong global search capability of the GWO. This helps the IBA escape local optima and strengthens the global search capability during the later stages of algorithm iterations. Finally, the simulation results demonstrate the successful reduction of PSLL under various constraints, confirming the effectiveness of the hybrid algorithm.