In this paper, a polarization-insensitive and dual-band Electromagnetic Induced Transparency-Like (EIT-Like) metamaterial is proposed, which is made of a cross-shaped graphene structure. Due to the mutual coupling between intralayer and interlayer, two high transmission windows can be obtained in different frequency bands. The sensibilities located at the two transmission peaks are calculated as 0.385 THz/RIU and 0.979 THz/RIU respectively. In addition, the maximum group index of 174.5 is obtained. By adjusting the Fermi level of graphene, the transmission and group index could be modulated independently. The characteristics make the proposed metamaterials possess the potential as a tool for biological detection, slow light technology, and filters in THz region.

In this paper, the electromagnetic vibration characteristics of hybrid excitation double-stator Bearingless Switched Reluctance Motor (HEDSBSRM) used in flywheel battery are analyzed when the rotor is eccentric. Firstly, the influence of rotor eccentricity on motor vibration is theoretically analyzed. Then the finite element method is adopted to study the radial electromagnetic force of the motor in the two-dimensional air-gap region. In addition, the three dimensional equivalent vibration model of the motor outerstator is established, and the mode shapes and natural frequencies of the motor stator are obtained by the modal analysis. The vibration characteristics of the outer stator under eccentric motion are analyzed by the coupling calculation of electromagnetic field and mechanical field. Finally, the modal combination principle is used to analyze the vibration characteristics of the motor running at multiple speeds under eccentric condition. The results show that the vibration of HEDSBSRM is closely related to eccentricity, which affects the motor performance and lays the foundation for the optimization design of HEDSBSRM application in flywheel battery.

This manuscript refers to the electromagnetic scattering problem involving plane waves at skew incidence with respect to the edge of a right-angled metallic wedge having one face coated by a double negative metamaterial sheet. Its presence in the propagation scenario is properly accounted at high frequencies by considering the geometrical optics response of the structure and the diffraction contribution arising from the edge of the wedge. In particular, the reflection coefficients related to the coated surface are determined for both the polarizations by using the equivalent transmission line circuit, whereas the diffraction coefficients are obtained by applying the uniform asymptotic physical optics approach. This last is based on electric and magnetic equivalent surface currents under the physical optics approximation and permits to evaluate the diffraction contribution in the context of the uniform geometrical theory of diffraction. The resulting approximate solution is characterized by the same simplicity of use of the heuristic solutions and provides reliable field values as confirmed by the numerical tests carried out by a full-wave commercial software.

A simple balanced bandpass filter is presented. It is constructed mainly by a loop-type resonator with loaded shorted/opened stubs. The resonator is fed by the balanced coupled-line structure. In the loop-type resonator, three approaches can be simultaneously utilized to achieve high common-mode suppression. One is that the loop-type resonator has different differential/common-mode resonant frequencies, which results in a good in-band common-mode suppression. The second is that the loaded short stubs with different lengths will make the input/output port couplings to have different coupling strengths, which will deteriorate the common-mode bandpass response. The third is that loading the grounded resistors can effectively dissipate the common-mode signal. Meanwhile, loading the grounded resistors in the balanced coupled-line structure can effectively dissipate the reflective common-mode signal. A detailed description about its structure, operational mechanism and design method is given. For demonstration, a prototype balanced bandpass filter working at 2.4 GHz is designed, fabricated and measured. A high in-band common-mode suppression of 49 dB is achieved. The measured and simulated results can verify the effectiveness of the proposed balanced bandpass filter and the design method.

Most of the works on sparse array synthesizing via the compressed sensing (CS) approach assume that the active elements exactly lie on the predefined grids. In fact, grid-mismatch error is unavoidable when an array aperture is discretized into grids, and the synthesizing results largely depend on the density of the grids. To overcome this limitation, an innovative off-grid CS approach is proposed for jointly estimating the excitations and positions of array elements. The synthesis problem is specifically formulated using a ridge regression model based on dynamic grids. The candidate positions of elements are treated as variables rather than constants predefined by discretization. Numerical experiments are conducted to validate the effectiveness and flexibility of the proposed method in realizing several maximally sparse arrays meeting the targeted patterns, i.e., the focused and shaped beam patterns of 1-D and 2-D arrays.

Compact wireless devices have been proposed as a result of the introduction of wireless communication systems, allowing more space to be used for other electronic components. A reconfigurable antenna is critical in today's cutting-edge wireless technologies. Reconfigurable antennas can perform a variety of tasks depending on their operating frequency, radiation pattern and polarization. Dynamic tuning can be done by altering mechanical, electrical, physical, or optical switches to run a certain switching mechanism. This can be accomplished using a single reconfigurable antenna that allows the user to customize a range of performance attributes such as resonant frequency, polarization and radiation pattern to meet their specific requirements. This paper looks into different types of reconfigurable antenna switching mechanisms, different types of effective implementation techniques, different types of reconfigurable antennas, and some recently proposed reconfigurable antenna designs for the Fifth Generation (5G) and IoT applications in various wireless communication systems.

Flux reversal machines (FRMs) have a broad application prospect due to its simple structure, high efficiency, and high reliability. However, due to the large magnetic flux leakage between poles, the further improvement of torque density of the FRMsis limited. To reduce magnetic flux leakage and improve torque, a novel consequent pole FRM with asymmetric stator poles is proposed in this paper. The `NS-NS' arrangement order of thepermanent magnets (PMs) of the conventional FRM is changed to the `NSN-S' PMs arrangement order with asymmetric stator poles, and the consequent pole topology is used simultaneously. All the N-poles of PMs are replaced by iron poles. Finally, the topology of the `Fe/S/Fe-S' arrangement order is obtained. A simplified magnetic circuit model is established to explain the principle of reducing magnetic flux leakage. To improve the torque density, the key design parameters are optimized by genetic algorithm, and the optimal parameters of the machine are finally determined. Finally, the finite element model is established. Compared with the conventional FRM, the torque of the proposed machine is increased by 67.18%, and the consumption of PM is reduced by 51.6%. Therefore, the proposed machine has good electromagnetic characteristics and economic benefits.

In this paper, a new plasmonic absorbing metasurface sensor has been proposed to determine glucose concentrations. Surface Plasmon Resonance (SPR) shift has been used as the indicator of glucose concentration. The sensor employs metal-dielectric-metal configuration along with metal nano-cylinders to provide near unity absorption in the near infrared wavelength range (1800-2200 nm). The absorption frequency shifts when the sensor is surrounded by materials of different refractive indices. The structure has been investigated through Finite Difference Time Domain (FDTD) simulations. The results show reflectance and absorbance peaks with different analyte concentrations. The sensor displays a linear response along with sensitivity and Figure of Merit (FOM) equal to almost 500 nm/RIU and 11.82 RIU^-1 respectively. The proposed sensor has potential applications in food and biomedical industries.

We show a new polarization- and angle-insensitive ultrathin metasurface design using four conjugated hexagonal split-ring resonators (CHSRRs). The CHSRRs are made of copper and arranged in a λ/4 cell-size polyimide film substrate with a dielectric constant of 3.5 and thickness of 0.2 mm (λ/400 at 3.75 GHz). Each CHSRR aperture faces one corner of the square unit cell, thus forming a conjugated loop to achieve TE and TM polarization-insensitive behavior in a wide range of incident angles. Results demonstrated a -10 dB impedance bandwidth of 530 MHz (3.44 to 3.97 GHz) under normal incidence, partially covering the n77 band used for 5G applications.

Raman imaging for a sepsis study is reported here for the first time. We propose a confocal resonance Raman microscopic imager (CRRMI)to measure in vivo the redox state of mitochondria over a surface area of a septic rat. The CRRMI has excellent performance with spectral and spatial resolutions of 0.1 nm and 2 um, respectively. It is found for the first time that the Raman signal related to the mitochondrial dysfunction in sepsis is abnormally large only locally at many points with some random spatial distribution. Our CRRMI can detect the mitochondrial redox state through the skin of a naturally living rat even without the removal of hairs, and overcomes some issues that a pointwise measurement method of Raman signalsmay encounter when monitoring mitochondrial dysfunction of a sepsis rat, such as the fluorescence of hairs, hitting the points without mitochondrial redox metabolic disorder, etc.The present Raman imager can be used for giving an early warning for sepsis. It provides a new method for noninvasive monitoring of mitochondrial redox status in sepsis.

Microstrip patch antennas are becoming increasingly relevant because of their advantages such as light weight, low costs, and ease of fabrication. To enhance the performance of an antenna, graphene was included into the fabrication of the microstrip patch antenna. Because of its numerous excellent characteristics, graphene has gained attention in recent years as a leading material. In this research, a microstrip patch antenna based on graphene was fabricated and tested at 5 GHz. The fabrication started with the production of graphene paste and was screen printed onto RT duroid 5880 substrates. To verify the binding between the graphene paste and the substrate, an adhesion test was performed on the finished graphene-based patch antenna using the Scotch tape method. The performance of fabricated antenna was measured using vector network analyzer (VNA) which includes return loss and bandwidth. The findings of the measurements were compared with the simulation results that were generated by the High Frequency Structure Simulator (HFSS). The return loss of the graphene-based antenna was measured to be -17.6314 dB, which is a little bit lower than the simulated value of -18.0597 dB that was generated by the HFSS software. The calculated bandwidth for simulated and fabricated graphene-based patch antenna were found at 156 MHz and 297.4 MHz, respectively. Based on the findings, it can be concluded that the return loss result indicates that the fabricated graphene-based patch antenna agrees well with the simulated patch antenna, although the fabricated patch antenna has a greater bandwidth than the simulated antenna.

This paper presents a design of a compact wide slot circularly polarized antenna which is being fed by a microstrip feed line. The designed antenna covers an area of size 25 mmx25 mm with a substrate thickness of 1.6 mm. The 3 dB axial ratio (AR) band can be produced by projecting a circular stub in the ground plane and feeding the slot through an asymmetry-fed microstrip feedline. The AR bandwidth of the antenna is further improved by adding truncation in the ground plane. Measured results show that the graph attains an impedance matching bandwidth of 124.3% centered at 7.4 GHz (2.8-12 GHz) and a 3 dB AR bandwidth of is 52.42% centered at 5.15 GHz (3.8-6.5 GHz). The proposed antenna is suitable for the use in C-band application.

A network optimization approach based on Neural Architecture Search (NAS) and network pruning is suggested to solve the issue of poor recognition performance of missile-borne radar active jamming under the condition of short sample sizes. The approach realized the ideal network design under severely constrained technical indications by combining the benefits of several methods, including NAS, convolutional light-weighting, and network pruning. The recognition network's convolution kernel size parameters were first optimized using NAS. The number of model parameters were then decreased via convolutional substitution. Finally, the structured pruning algorithm further screened the redundant network based on the technical indicators. The WideResNet28_2 wide residual network's recognition accuracy is only 84.38% when there are only 1000 training samples for each type of signal, according to the simulation results. After optimization, the number of new model parameters was increased 2.55M, 2.26M, and 1.78M, respectively, and their respective recognition accuracy was increased to 85.7%, 85.61%, and 85.37%. According to the simulation results, the technique offers a wide range of possible applications in the optimized design of radar active jamming identification networks for small sample sizes.

In this study, an adjustable reflectionless diplexer is designed and fabricated for the L-band based on microstrip transmission lines. The proposed diplexer can separate and combine different frequencies within the L-band frequency range. The equations and theoretical process of the structure can be proved from coupling matrix and even/odd mode circuit analysis. In this design, our aim is that the proposed diplexer not only has low insertion loss and proper return loss in the channels' stopband but also can change the channels' frequency. The physical specifications are calculated proportionally to the central frequency based on the coupling coefficients and diagram. Also, frequency adjustability is achieved by connecting the varactor diode to the structure's resonator. The proposed structure can be used in the frequency range of 1.6-2.2 GHz. Furthermore, the measured return losses in the stopband and passband are 8 dB and 13 dB, respectively. In this paper, all simulations are performed by ADS software.

Evaluation of the lightning coupling on the buried signaling cable nearby when the through-ground wire is used as the discharge channel of lightning current requires accurate models for the calculation of the underground lightning electromagnetic field and the induced current of this field on the signaling cable conductor. To accomplish this, a full-wave approach based on the finite-element method (FEM) is used, which incorporates the frequency dependence of soil conductivity and relative permittivity into in the model. The numerical results show that for soils characterized by relatively low resistivity values (less than 4000 Ω.m), the frequency dependence of the electrical properties of the soil has a negligible influence on the horizontal component of the electric field and the vertical component of the magnetic field. However, the distribution of the lightning electromagnetic field is markedly affected by the distance between the air-soil interface and the buried signaling cable. We also find that the coupling strength of the lightning electromagnetic field to the buried signaling cable is strongly dependent on the wave shape of the lightning current, soil resistivity, the distance between the cable and the air-soil interface, and the distance between the cable and the lightning strike point. Finally, the common grounding methods of the cable shielding layer in cable protection are compared. Results show that single-layer double-terminal grounding is the most effective anti-interference measure for the electromagnetic field coupling between the through-ground wire and the buried signal cable near the lightning point of the high-speed railway. The desired shielding effect properties with the frequency from dc to 1 MHz can be achieved using this method.

An analytical multi-rays path loss model with low complexity and high accuracy is proposed to realize the ubiquitous communication links with solid stability and full coverage. The closed-form formulas are derived to describe the path loss above 6 GHz under regularly-structured indoor environments, ensuring a clear propagation mechanism and low computational complexity. In this model, the construction and destruction of the dominant rays, i.e., the direct, reflected, diffracted, diffracted reflected, and reflected-reflected rays, on the path loss, are considered according to variation of the transmitting antenna position and propagation condition. The proposed model contains information on the sizes, structures, and materials of the environments and eliminates the influences of small scale fading by averaging the path loss over a circle with radius of ten wavelengths. Based on the measurements under the ``L-shaped'' corridor and office environments at 8 GHz band, the accuracy and extensibility of the proposed path model are verified. This work can help analyze the propagation mechanisms and construct the solver for calculating the attenuation of electromagnetic waves under indoor environments. It can also provide vital information for the link budget and node deployment for future wireless communication systems above 6 GHz.

In this paper, a new method is introduced to design a simple-profile hybrid coupler in two arbitrary frequency bands. The structure is achieved by means of dual-band quarter-wavelength transformers as the arms of a traditional branch line coupler. A prototype of the coupler operating at 0.9 GHz and 2.45 GHz is designed and fabricated to validate the robustness of the method. Comparing simulated with measured results, a good agreement is observed. Moreover, the performance of the coupler in terms of impedance bandwidth and isolation level between the input ports is compared with existing works. Further, the suggested coupler has the simplest profile resulting from the most flexible design process.

This study describes the development of a low-profile, omnidirectional, CPW fed Ultra-Wide Band (UWB) MIMO antenna. The antenna is designed on a flexible FR4 substrate with thickness 0.07 mm, making it suitable for wearable applications. The fractional bandwidth obtained is more than 100% (3.1-9.3 GHz) which spans the wireless communication bands such as ISM (5.15-5.35 GHz), ISM (5.725-5.825 GHz), Wi-Fi (5 GHz), Wi-Max (3.4-3.6 GHz), Sub 6 GHz 5G (3.3-4.2 GHz), and WLAN (5.15-5.825 GHz). The antenna also provides safe SAR value, low envelope correlation coefficient, good antenna gain, acceptable radiation efficiency, optimum Total Active Reflection Coefficient (TARC) value, low Channel Capacity Loss (CCL), good gain, and acceptable radiation efficiency across the frequency ranges. Simulated and measured performances of the antenna in the entire band are presented.

How will the electrostatic interaction between two point charges change if they are shielded from the other by a dielectrical slab? While the physical setting of this electromagnetic problem is relatively simple, it is easy to be wronged, and the correct solution is surprisingly complicated. Here we will show a general answer using the method of images, in which the electrical field is not found by solving the Poisson's equation but by superposing an infinite number of image charges to recurrently satisfy all interfaces' boundary conditions. We also obtain analytical and algebraic results in some special cases.

A novel polynomial-chaos (PC) techni_nullque is implemented based on anisotropic index sets. The proposed scheme takes advantage of the effect of each random variable on the output parameter of interest and adaptively constructs the PC expansion. Particularly, the algorithm starts by generating bases via low and high reliability heuristics and builds a PC representation, until an error criterion is satisfied or until the maximum desired polynomial order is reached. Our method is tested on a variety of uncertainty problems, where the statistical moments of the outputs of interest are estimated. Numerical results prove the efficiency of the proposed approach, since accurate outcomes are obtained in lower computational times than other techniques.