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.

In this Article, the antenna is designed by using different shapes of patch structures on 8.468×9.741 mm² ground plane. Different shapes like A, H, F, T, and U are simulated by using HFSS Software. For gain enhancement, various techniques on the different shape patches have been applied. The maximum gain achieved in the case of A shape patch with MTM structure and circular reflector with superstates is 14.2 dBi, and the band covered is (36.248-38.764) GHz and (33.384-34.503) GHz. Other shapes like H, F, T, and U are designed by modification in A shape patch, and by applying various techniques like MTM and reflector surface with superstates interesting results have been achieved. The designed antenna is an mm-wave antenna and a novel structure for 5G communications.

In order to further reduce the computational complexity as well as the average switching frequency of the inverter for model predictive torque control (MPTC), an improved MPTC control strategy for a three-vector low switching frequency based permanent magnet synchronous motor is proposed. Firstly, an analysis is conducted on the combined effect of the torque and magnetic chain based on the three voltage vectors, based on which the vector combinations are matched to form an offline optimized switching table, and then the three voltage vector combinations are selected from the offline optimized switching table according to the torque control requirements in order to reduce the amount of system calculations. Then, on this basis, a hysteresis loop technique for direct torque control is introduced to reduce the average switching frequency of the inverter. An improved MPTC control strategy with fuzzy variable hysteresis loop width is further proposed to fuzzy control the dynamic output hysteresis loop width scaling factor according to the motor operating state. Experimental results show that the improved MPTC control strategy with fuzzy variable hysteresis loop width results in optimal combined average switching frequency and current harmonics with reduced computational effort.

In this paper, a miniaturized Ultra-Wideband (UWB) flower-shaped radiator antenna is designed and simulated for 2.9 GHz to 14.8 GHz applications in Wireless Body Area Networks (WBAN). To achieve wideband, two alterations have been incorporated into the proposed design i.e. by adopting a flower-shaped patch to enhance bandwidth and by using the defective ground plane, which reduces capacitive effects, increasing impedance matching within the operating band. This innovative antenna has a footprint of 15 mm x 20 mm x 1.6 mm and uses textile material denim as its substrate, making it compatible with portable UWB devices. Aside from these characteristics, the device also has omnidirectional radiation patterns, a peak gain up to 5 dB, and a fidelity factor over 85%. It is found that the simulation and measurement results are in good agreement. In comparison with existing structures, the antennas obtained show wide operating ranges and compact dimensions.

Modern wireless communication systems require low profile, high gain and wideband antennas. To meet these requirements a low profile Cylindrical Dielectric Resonator Antenna (CDRA) is proposed with wide bandwidth and high gain for ISM and C-Band applications. The CDRA is excited with a 50 ohm microstrip feed line with HEM_12δ, HEM_21δ and HEM_13δ modes being observed at 5.6 GHz, 7.4 GHz and 8.6 GHz resonant frequencies respectively. The perturbation on the basic CDRA leads to the excitation of higher order modes and also decrease the effective permittivity of the CDRA by a factor of 13.4%, thereby reducing the antenna's Q factor, which helps to broaden the antenna's operating frequency range. The proposed structure offers wide impedance bandwidth of 69.4% from 4.8 GHz to 9.9 GHz. A peak gain of 8.9 dBi at 9.4 GHz and 95% radiation efficiency at 5.6 GHz are observed. Additionally, the proposed CDRA has a small footprint of 1.12λ₀ x 1.12λ₀ with a low profile of 0.16λ₀ where λ₀ is the wavelength of the lower cut-off frequency. The proposed antenna is fabricated and measured, and a close agreement is found between the simulated and measured results.

In this paper, a planar passive array antenna is proposed with capability of reradiating the incoming incident wave to predetermined θ and φ reflection angles (2-D). This purpose is achieved by differentiating array elements' phases with the help of inter-connecting transmission lines. Incident and reradiated signal paths are isolated through two orthogonal polarizations used in the array structure. The idea is realized with a 2×2, microstrip, dual linearly polarized antenna arrays in 2 GHz operating frequency on the Ro5880 substrate with 1.2 mm height. Nonlinear nature of the theory behind this idea leads to some limitations in choosing the angles of incident and reflected signals which is thoroughly investigated.

A 2 bit reconfigurable beam-steering antenna array using phase compensation is proposed, which consists of a 1 bit reconfigurable antenna and 90˚ digital phase shifter. The p-i-n diodes are soldered in the 2 bit element to realize 2 bit phase shift. Due to the 2 bit phase quantization error, a fixed compensation phase is added to each array element to reduce sidelobe level. A 2 bit reconfigurable antenna array with 1×8 elements shows that the sidelobe levels of the scanning-beams are less than -6.2 dB. At the same time, simulated results also show that the antenna can steer beam direction from -48˚ to 50˚, and the beam gain fluctuation is less than 2.2 dB. A prototype is fabricated and tested. The proposed antenna can provide a novel idea to design a 2 bit reconfigurable beam-steering antenna array with a better beam-scanning performance in various applications.

An optically transparent and flexible coplanar waveguide (CPW)-fed wideband antenna is proposed and demonstrated experimentally based on sub-micron thick micro-metallic meshes (μ-MMs). Due to the high visible transmittance (83.1%) and low sheet resistance (1.75 Ω/sq) of the silver μ-MM with thickness of only 190 nm, the transparent CPW has very low insertion loss and provides a good feed to the high-performance transparent antenna. The measured S₁₁ spectrum of our antenna matches well with that of the opaque counterpart. The measured fractional bandwidth is 22% from 3.4 to 4.25 GHz. Based on numerical modeling, whose accuracy is experimentally verified, the radiation efficiency and the peak gain of our transparent antenna at 3.45 GHz are calculated to be 89.7% and 3.03 dBi, respectively. Besides the good optical and electromagnetic properties, our transparent antenna is also highly flexible. Despite the sub-micron thick μ-MMs, the transparency, radiation efficiency and mechanical properties of our transparent antenna are obviously superior to those of the transparent antennas reported previously, and the overall size and radiation gain are also comparable. Therefore, our transparent antenna has an excellent comprehensive performance, showing great potential for practical applications as well as the emerging applications in the field of flexible and wearable electronics.