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.

Electromagnetic energy is being utilized over multiple frequency bands to sustain high speed wireless communication systems around the globe. As a consequence, living bodies such as humans, animals, plants, and fruits continuously get exposed to electromagnetic radiation. To safeguard human health, a number of diversified international and national electromagnetic regulatory standards have been prescribed across geographical boundaries for limiting electromagnetic radiation - specific absorption rate and reference power density limits have been prescribed by the international organizations to protect humans from immediate thermal effects. However, reference power density limits differ by ten to hundred times across geographical boundaries depending upon the electromagnetic standards in effect. Moreover, prescribed reference power density limit also varies with frequency of irradiation. On the other hand, plants and fruits possess reasonably high permittivity and electrical conductivity that contribute to considerable electromagnetic energy absorption rates inside typical plant and fruit models. In addition, plants and fruits are primarily asymmetric in nature, and therefore direction of arrival and polarization of incident electromagnetic field are two additional factors that significantly influence the amplitude and spatial distribution of specific absorption rate. Therefore, prescribing only the maximum permissible power density limit in far field seems inadequate. To address these issues, specific absorption rates inside a typical multilayer mango fruits model have been estimated at five different frequencies in accordance with four different international and national electromagnetic regulatory standards (with contrasting reference power density limits) - the magnitudes and spatial distributions of specific absorption rates have been quantified and reported at different frequencies as well as for distinct averaging techniques. Moreover, the impact of direction of arrival and polarization of incident electromagnetic field on the magnitude and spatial distribution of specific absorption rate has also been investigated. A total of one hundred and twenty rigorous simulations has been performed, and as a consequence, four hundred and eighty specific absorption rate data points have been analyzed. Wide disagreement in specific absorption rate data is observed due to variations in four factors mentioned above, i.e. reference power density, frequency, direction of arrival, and polarization of incident electromagnetic field. Moreover keeping all the other factors unaltered, specific absorption rate cannot be directly correlated with the reference power density limit primarily due to non-identical and asymmetric structures of bunch of fruits and plants in most practical scenarios. Thus, observations indicate the necessity of adopting globally harmonized electromagnetic regulatory standards and direct adoption of specific absorption rate limit for plants and fruits instead of only the reference power density limits in far field exposure scenario.

In this study, a novel vehicle-mounted flywheel battery system is proposed, which can effectively balance the load capacity with margin, strong anti-interference, uncoupled magnetic circuit and low energy consumption. The proposed new flywheel battery adopts multiple magnetic circuits, reducing the number of permanent magnets and the complexity of the magnetic circuit. It is worth mentioning that the proposed ``side branch'' radial/tilting shared magnetic circuit can realize the main bearing function of the flywheel weight, and the axial biased magnetic field is used to suspend the near ``zero weight'' flywheel, so that the flywheel can withstand a certain interference margin in the axial direction, and then improve the active disturbance rejection and effectively reduce the control loss. After optimization, the unique overall structure of the flywheel battery can significantly improve the overall performance of the flywheel battery. Finally, the stiffness, decoupling, and anti-interference experiments are carried out, and the experimental results show that the proposed flywheel battery has good performance.

A broadband artificial magnetic conductor (AMC) metasurface for radar cross section reduction is proposed. Modified Jerusalem cross unit and quasi-circular unit can achieve effective reflection phase difference of 180˚ (±37˚) within a wide frequency range from 8.95-17.3 GHz. The broadband metasurface consists of chessboard-arranged 3 × 3 block arrays, and each block arrays is composed of 4 × 4 AMC units. The proposed AMC metasurface is applied to a microstrip antenna for reducing RCS. The measurement results show that the low RCS antenna can obtain 10 dB RCS reduction from 7.93-17.5 GHz. The relative bandwidth is 75.2%, and the maximum reduction value is 30.2 dB. Also, radiation performance of the antenna is well maintained.

Permanent magnet assisted synchronous reluctance motor (PMaSynRM) has been widely concerned, but the research on the vibration and noise of this kind of motor is relatively limited. In addressing the problem of significant vibration noise caused by radial electromagnetic force waves in PMaSynRM. The research explores a motor vibration and noise suppression solution involving stator slotting and rotor magnetic isolation hole opening. The study analyzed the impact of different slotting parameters on the radial electromagnetic force and air gap magnetic flux density of the motor and compared it with the solution involving slotting of the stator teeth only and magnetic isolation hole opening of the rotor only. Finally, the modal, vibration response and noise response of the motor after slotting are analyzed and verified. The results show that the amplitude of radial electromagnetic force and the total harmonic distortion rate of the air gap magnetic flux density of the motor are significantly reduced by opening the stator auxiliary slot and the rotor magnetic isolation hole. The maximum vibration acceleration of the motor is reduced by 33.44 mm/s², and the peak A-weighted sound pressure level of the motor decreases by 5.49 dBA.

The measurement and decoupling of currents in multi-core power cables is a significant concern for power operators and holds immense potential for optimizing the monitoring and control of urban distribution networks. This paper aims to provide a widely applicable method for reconstructing current measurements. The YJLV22-3 * 300 power cable is taken as an example, specifically focusing on the effect of steel armor on the measurement of the magnetic field generated by the current. Sample tests and field experiments are conducted to verify the spatial distribution of the magnetic flux density. Then the inverse problem of calculating current from the magnetic field is discussed. The defects of the existing methods are shown, and a new method for the inverse problem with the measured waveform of the tangential component of the magnetic flux density is proposed. The feasibility of the new method has been verified. The least-squares method is introduced to obtain the generalized inverse of the position coefficient matrix by maximum rank decomposition to extrapolate the conductor current matrix. A query method is proven to efficiently generate this matrix. Finally, the inverse problem is modeled as a stochastic search problem to compare the efficiency and stability of different algorithms, and CAM-ES performs best. The future research direction is oward developing and testing hardware measurement systems.

Dispersion error analysis can help to assess the performance of finite-element discretizations of the wave equation. Although less general than the convergence estimates offered by standard finite-element error analysis, it can provide more detailed insight as well as practical guidelines in terms of the number of elements per wavelength needed for acceptable results. We present eigenvalue and eigenvector error estimates for cubic Hermite elements on an equidistant 1-D mesh and on a regular structured 2-D triangular mesh consisting of squares cut in half. The results show that in 1D, the spectrum consists of 2 modes. If these are unwrapped, the spectrum is effectively doubled. The eigenvalue or dispersion error stays below 7% across the entire spectrum. The error in the corresponding eigenvectors, however, increases rapidly once the number of elements per wavelength decreases to one. In terms of element size, the dispersion error is of order 6 and the eigenvector error of order 4. The latter is consistent with the classic finite-element error estimate. In 2D, we provide eigenvalue and eigenvector errors as a series expansion in the element size and obtain the same orders. 2-D numerical tests in the timeand frequency-domain are included.

In this paper, the design and validation of an implantable antenna which is applicable to biotelemetry services is presented. This proposed antenna operates in the wireless medical telemetry service (WMTS) frequency band of 1.39-1.4 GHz. As compared to other contemporary antennas, this design provides better gain of -31 dB and reflection coefficient of -20.2 dB with better safe limit of specific absorption rate (SAR). At the resonating frequency of 1.4 GHz, the intended antenna provides good radiation and gain characteristics. The VSWR parameter for this designed antenna has been obtained as 1.25 which promises for proper impedance match. The designed antenna has been fabricated and validated with tissue mimic liquid-phantom to make sure the suitability for implantation. The simulated measurements have a close agreement with the experimentally measured results.