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.

Frequency selective rasorbers (FSRs), especially those with ultra-wideband and hybrid characteristics, are of great significance in modern stealth technology and applications. However, currently available FSRs have issues with limited transmission bandwidth and single operating characteristics. Here, a novel strategy is proposed to design multi-characteristic integrated FSRs with ultra-wide and high-efficiency passband via spoof surface plasmon polariton (SSPP). The designed FSR exhibits the characteristics of absorption-transmission (AT), transmission-absorption (TA), and absorption-transmission-absorption (ATA), which consists of AT resistive sheets, TA SSPP slow-wave structures, and ultra-wideband bandpass frequency selective surface (FSS). The top lumped-resistor-loaded resistive sheet and the bottom multi-layer cascaded FSS form an AT FSR which is demonstrated by equivalent circuit model (ECM). Middle dispersion gradient SSPP structure that generates SSPP on the periodic array is an independent TA FSR while the working principle is based on k-dispersion control and energy distribution. Thus, the transition band between the transmissive and absorptive bands is narrowed while the crosstalk between absorber and transmission is avoided. For verification, a prototype is fabricated and experimentally demonstrated. Measured results manifest the validity and feasibility of the FSR with an ultra-wide -1 dB transmission band from 8.9 to 16.4 GHz (59.3%) and two 85% absorption bands covering 2.2-6.4 GHz (97.7%) and 17.6-26 GHz (38.5%). Our work provides a novel method for the design of ultra-wideband multi-characteristic FSR and stimulates its application in broadband electromagnetic stealth, shielding and compatible devices.

The mutual inductance between the transmitting and receiving coils is one of the critical parameters of the wireless power transfer system, and an accurate mutual inductance calculation method can provide a reliable theoretical basis for the optimization of the coil structure of the wireless power transfer system. The addition of magnetic medium materials on both sides of the rectangular coil can effectively increase the mutual inductance, but there is no study on the mutual inductance calculation method for a rectangular coil with a bilateral bounded single-hole type magnetic medium. In this paper, the space vector domain synthesis method is proposed to solve the analytical value of mutual inductance, which solves Poisson's and Laplace's equations by separating the variables to obtain the magnetic vector potential in each region, and combines with the magnetic field boundary conditions to obtain the mutual inductance calculation formula by utilizing different dimensional vector syntheses. An experimental set of wireless power transfer systems with bilateral bounded single-hole type magnetic medium rectangular coils is also constructed, and the maximum error of the mutual inductance calculation value, experimental value, and simulation value is 5.82%, which verifies the effectiveness of the method proposed in this paper. The model proposed in this paper saves 5.86% of the material compared with the rectangular magnetic medium structure under the same parameters, and the mutual inductance is up to 99% of the rectangular magnetic medium structure.

To accelerate the solution of electromagnetic scattering problems, compressive sensing (CS) has been introduced into the method of moments (MoM), Consequently, a computational model based on underdetermined equations has been proposed, which effectively reduces the computational complexity compared with the traditional MoM. However, while solving surface-integral formulations for three-dimensional targets by MoM, due to the severe oscillation of current signals, commonly used sparse bases become inapplicable, which renders the application of the underdetermined equation model quite challenging. To address this issue, this paper puts forward a scheme that employs Krylov subspace, which is constructed with low complexity by meticulously designing a group of non-orthogonal basis vectors, to replace the sparse transforms in the algorithmic framework. The principle of the method is elaborated in detail, and its effectiveness is validated through numerical experiments.

This research suggests a compact, wideband Multiple Input Multiple Output (MIMO) antenna designed for S-band applications, emphasizing high isolation between closely positioned antenna elements. Achieving this isolation is accomplished through the implementation of a Defected Ground Structure (DGS) technique. The DGS is realized by etching two elliptical patterns on an economical FR-4 substrate with inherent loss properties. Three rectangular slots and two L-shaped stubs are introduced to improve isolation and minimize the size of antenna increment by lowering surface wave propagation. To validate the proposed layout, a physical prototype was constructed for a direct comparison of its performance with the simulated parameters. The results demonstrated highly favorable outcomes, including Diversity Gain (DG) exceeding 9.97 dB, Envelope Correlation Coefficient (ECC) registering below 0.05, Mean Effective Gain (MEG) lower than -3 dB, Total Active Reflection Coefficient (TARC) below 0.4, and Channel Capacity Loss (CCL) less than 0.3. Furthermore, the current distribution and radiation pattern were found to be highly suitable for applications in the S-band and the lower part of the C-band, encompassing technologies like Bluetooth, WiFi, WiMAX, 4G, and 5G.

A compact planar self-quadruplexing antenna backed with the SIW technology with high isolation between the input ports is designed and demonstrated for the simultaneous quad-band operation of the antenna. The SIW cavity is integrated with a Swastik shaped slot and two metallic vias to generate four distinct frequency bands with high gain and low cross polarization. Utilizing four distinct orthogonal patches with different lengths, each independently connected to a 50-Ω microstrip feed line, makes the antenna operate at four frequency bands of 4.8, 5.5, 6.6, and 7.6 GHz. The minimum value of Front-To-Back-Ratio (FTBR) is 18 dB, and the minimum isolation between the input ports is 28.4 dB. The measured values of peak gains in the frequency bands 4.8, 5.5, 6.6 and 7.6 GHz are 5.05, 6.20, 6.45 and 6.32 dBi, respectively. Hence, a single antenna consists of four signals transmitting or receiving simultaneously from four individual input ports without interfering with each other and with high isolation between the input ports confirms the self-quadruplexing property of the antenna. This antenna configuration enables the independent tuning of each resonant frequency according to specific application needs by manipulating a single parameter, that is the length of the patch and without disturbing other performance parameters of the antenna. To validate the simulation results, the antenna is fabricated and tested. The measurement findings match the simulation results closely, which confirms the quad-band operation of the antenna design. Simple configuration, compact size, high gain, and low cross polarization of the antenna make the proposed planar antenna suitable for practical multiband applications and for handheld transceivers with high isolation between the input ports.