This research presents the design of a Chebyshev linear antenna array (CLA) integrated with the dielectric lens. In comparison to a uniform amplitude distribution (UAD), a Chebyshev amplitude distribution (CAD) is used to achieve a low side lobe level (SLL) characteristic and increase the directivity of the antenna array. The proposed CLA is optimized to operate at a high fifth generation (5G) frequency. The proposed CLA achieves a -10 dB wide bandwidth from 25.8 GHz to 42.4 GHz. Dielectric lenses can be employed to modify the phase and amplitude of the antenna array, which increases the realized gain and leads to stable radiation over the operational bandwidth. The main purposes of the dielectric lens are to improve the realized gain, enhance efficiency, and result in stable radiation pattern properties. Also, the research presents a study of two types of dielectric lenses with different shapes and their effects on the efficiency and the realized gain of the antenna. The substrate of the dielectric lens is epoxy resin, which has a relative permittivity (ε_r) of 2.716. The proposed CLA integrated with the proposed Type 2 dielectric lens has a realized gain of 15.2 dB and 11.94 dB at the dual-bands 28 GHz and 38 GHz, respectively. All the suggested designs are simulated using CSTMWS2020 and HFSS. However, to verify the obtained results, the proposed CLA is fabricated using a photolithography process technique, and the proposed Type 2 dielectric lens is fabricated using a 3D printing technique.

An elliptical shape multi-band microstrip patch antenna with narrow semicircle cuts and bulges on two horizontal ends is proposed for Global Positioning System (GPS), Indian Regional Navigation Satellite System (IRNSS), Sub-6 GHz 5G and Wireless Local-Area Network (WLAN) wireless communication applications. The proposed antenna operates at 1.56 GHz, 2.49 GHz, 3.5 GHz, and 5.24 GHz for desired applications, respectively. The proposed antenna, fed by coaxial feeding mounted on Rogers AD255C substrate, has optimized physical dimensions of 80×80×3.175 mm³. The semicircle cuts and bulges on horizontal ends on the elliptical element contribute to exciting higher-order modes and affect the current distribution at the resonant frequencies resulting in producing multi-band operations. The antenna is fabricated and tested. The measured return loss characteristic (S₁₁) below -10 dB is -14.58 dB, -18.80 dB, -22.25 dB, & -27.03 dB, with the radiation efficiency of 58.7%, 94.8%, 93.2%, & 84.9% and peak gain of 3.49 dBi, 6.49 dBi, 4.93 dBi & 4.36 dBi for desired application band, respectively. The proposed antenna also offers impedance bandwidths of 40 MHz (1.55-1.59 GHz), 90 MHz (2.43-2.52 GHz), 100 MHz (3.44-3.54 GHz) & 90 MHz (5.23-5.32 GHz) at resonant frequencies and relatively stable radiation patterns. Simulated and measured results for the proposed antenna exhibit good agreement. The proposed multi-band antenna offers a simple design and improved performance.

This article presents the performance of a hexagonal split-ring resonator (H-SRR) antenna in the 2.4/5.2 GHz bands and evaluation of channel capacity for single-input multiple-output (SIMO) and multiple-input single-output (MISO) systems. The proposed antenna consists of two hexagonal-shaped split-ring resonators for dual-band operation with higher gain and metallic loadings between the rings to achieve a wide impedance bandwidth. Impedance modeling of the proposed antennas confirms the role of conductance and inductance of metallic loading for enhancing the antenna characteristics, and thus, the fabricated H-SRR antenna achieves dual-band features with improved impedance bandwidth of 50%/76% and a gain of 2.32/2.57 dB at 2.4/5.2 GHz frequency bands. The performance of the hexagonal SRR antenna is then investigated for space diversity applications in the 1×3 SIMO and 3×1 MISO systems with circular SRR antennas. In linear and spherical arrangements of the antennas, the channel capacity is found in the range of 2.7 to 4.8 Mbps at the 2.4/5.2 GHz bands, which also confirms its dependency on the number of antennas as well as on the placement of antennas.

The paper addresses a bioinspired printed antenna in the shape of a `Lotus' which is further loaded with a new type of Frequency Selective Surface (FSS) structure with unit cell dimension as 0.16λ₀×0.16λ₀×0.033λ₀, where λ₀ is the lowest operating wavelength. The two dissimilar layers of FSS, which are separated by an air gap of about 3.2 mm, have been placed below the antenna. The combined structure operates over 3.8 GHz to 14.4 GHz (116.5% measured) with peak realized gain of 7.5 dBi. The introduction of the FSS layer provides gain enhancement of about 5.9 dBi. The standalone FSS geometry provides a wide transmission bandwidth from 5.5 to 12.5 GHz along with good angular stability of about 50º. The Gielissuper formula has been used to develop the petal of the lotus shaped antenna. The time domain analysis of the lotus shaped antenna has also been provided. The proposed structure can be used as an electromagnetic sensor for wide band applications over C, X and partially Ku bands.

A novel subarray layout method is proposed for the problems of high power dispersion and high complexity of the existing layout methods of receiving rectifier antenna arrays. By the traditional RF synthesis and DC synthesis array layout, the number of units used is high, and the received power dispersion is high. Therefore, this paper proposes a uniform non-overlapping triangular subarray partition layout, and the layout takes three discrete parameters of subarray type, subarray position, subarray placement direction as optimization variables. The minimum dispersion of the received power of the subarray is used as the optimization objective to establish the optimization model. We adopt the Taboo Search (TS) algorithm to achieve the global optimum by setting up a taboo table for global neighborhood search and homogenize the received microwave power value from each subarray. The result shows a lower coefficient of variation (CV) with fewer subarrays and a globally symmetric subarray layout, which reduces the engineering complexity and cost of the subsequent rectification circuit, as well as a lower dimensional span between different subarray types in this novel subarray layout model. We conducted a series of numerical simulations to prove that the method can meet the requirement of minimum power dispersion while ensuring that the total reception efficiency will not be greatly reduced, which verifies the effectiveness of this receiving subarray layout method.

This paper presents a terahertz high gain beam steering transmitarray antenna (BSTA) working at 340 GHz. Substrateless double hexagon ring slots unit-cells which present low loss characteristics at THz band are used to constitute the layout of THz BSTA. To improve the beam steering performance, bifocal technique is used to design the layout of BSTA. Because the fabrication risk of the THz BSTA prototype increases a lot as the aperture dimension is enlarged, four inch silicon wafer is chosen after weighting the risk and gain of the BSTA. Micromachining process is used to fabricate the large aperture THz BSTA to ensure the machining accuracy of the unit-cells. The measured results of the prototype show that the THz BSTA could realize -15°~15° range beam scanning with gain > 38.3 dB, scanning loss < 1.2 dB and side lobe level < -17.8 dB, by moving the feed along the focal plane of the BSTA.

An exhaustive numerical analysis is presented on the effects of defect layers and electric and magnetic loss factors on the transmission spectrum of one-dimensional metamaterial photonic crystal. The proposed structure is a symmetrical multilayer configuration consisting of alternating layers of lossy metamaterial and double-positive material, with a defective region in the middle. The study shows that one or more defect transmission modes are generated in photonic band gaps. The optical properties have been numerically analyzed and simulated using the transfer matrix method. Parameters, such as permittivity, thickness and number of the defect layers, influence the band gap width and the tunability of the defect peak frequency. The effects of the electric and magnetic loss factors (or damping frequencies) of the metamaterial on the intensity and on the quality factor of the defect modes are also well observed. The analysis is validated by comparing the results to some available in the literature, and the proposed structure can be exploited in the design of narrowband filters in the microwave domain.

Since wireless technology has been developed so quickly, there is a surge in interest in multi-band reconfigurable antennas as devices and satellites continue to advance in the direction of downsizing. Due to physical limitations, current and future wireless technologies as well as the cutting-edge compact satellites need antenna systems that are dependable, effective, and have a large bandwidth. The fifth generation of mobile communication technology promises to deliver fast data rates, low latency, and exceptional spectrum efficiency. One of the most crucial factors that makes this technology possible is the way in which satellite technology is integrated with terrestrial communication systems. Therefore, it is crucially important to develop next-generation antennas that can meet the functional requirements for 5G and CubeSat applications. Additionally, the antenna components need to be small and low-profile for Advanced Driver-Assistance Systems (ADAS) and Vehicle-to-Everything (V2X) to function properly. Reconfigurable antennas can offer a wide range of configurations in terms of operating frequency, radiation pattern, and polarization. This paper aims to investigate pixel antenna arrays for wireless communication and Internet of Things (IoT) systems. Design, analysis, and comparison have been done on both the traditional and proposed pixel design configurations. The proposed pixel patch design area reduction is about 75%, and the full design area reduction is about 90%, compared to conventional patches. The pixel design parameters of these antennas are carefully examined to increase their gain, radiation pattern, and efficiency. For a variety of applications, increased gain and various radiation pattern configurations may be advantageous. As a result, increasing the coverage of 5G, 6G, and small satellites requires antennas with a small size, higher gain, and better radiation patterns.

A low-cost and mechanical reconfigurable substrate integrate waveguide (SIW) equalizer is presented and studied in this work. Different from the previous SIW equalizers using Tantalum Nitride (TaN) or absorbing material as the resistive element, the indium tin oxides (ITO) are introduced into SIW equalizer. The absorbing material will deform under uneven pressure due to the structural softness of material, resulting in instable equalizing values. Compared with the absorbing material, ITO provides more structural stability, excellent high frequency characteristic, and can be easily integrated with traditional printed circuit board (PCB). Furthermore, an equalizer with reconfigurable equalizing values can be realized by adjusting ITO materials with different impedances. A SIW equalizer based on the ITO Conductive Film, operating from 26 to 40 GHz, has been designed, fabricated and experimentally verified. For measurement results, the return losses are better than -17.4 dB with 3, 6, and 10 dB equalizing values respectively over the entire Ka-band, and the insertion losses at the frequency point of 40 GHz are -2.89 dB, -4.80 dB, and -7.37 dB, respectively. The proposed equalizer presents the advantages of mechanical reconfigurable, low cost, and high stability. In addition, ITO Conductive Film is a good candidate for the design of high millimeter-wave band equalizer.

A miniaturized quadruple band reject UWB-MIMO antenna with high degree of isolation is designed and experimentally evaluated in this study. The reported design utilizes dual antenna elements that are organized orthogonally by employing polarization diversity. Notch bands can be acquired by incorporating three U-shape slots and a split ring resonator (SRR) on the antenna element that exhibits band rejection of 3.41-4.07 GHz, 4.41-4.76 GHz, 5.21-5.64 GHz and 6.92-8.63 GHz to reject the potential interference from 5G, INSAT, WLAN and X-band. The UWB-MIMO antenna is resonating in the frequency band from 2.9 to 12 GHz with a good isolation (<-25 dB). The response of the reported antenna has been examined experimentally in terms of notch frequencies, surface current variation, gain, radiation patterns, envelope correlation coefficient, diversity gain, and total active reflection coefficient.

In the dynamic wireless charging system of electric vehicles, the misalignment between transmitting and receiving coils will cause drastic changes in the coupling coefficient, which will lead to system instability. A dynamic and static wireless power transfer system superimposed dislocation coil (SDC) structure is proposed in this paper. This structure ensures a constant coupling coefficient between the transmitting and receiving coils of the dynamic and static wireless power transfer system for electric vehicles. Firstly, the variation law of the coupling coefficient of the SDC structure is analyzed. Secondly, a quasi-constant coupling coefficient optimization method is proposed based on the SDC structure to obtain the coil parameters that meet the requirements. Finally, according to the optimization results, an experimental platform for wireless power transfer based on the SDC structure is built. The experimental results show that the maximum fluctuation rate of the inter-coil coupling coefficient is only 3.12% when the misalignment between the transmitting coil and the receiving coil is within half of the outer length of the transmitting coil. Thus, the correctness and effectiveness of the proposed structure and method are verified.

In this paper, a compact reconfigurable bandstop filter suitable for multistandard and multiband mobile terminals is reported. The proposed dual bandstop filter consists of a microstrip line coupled to two switchable Capacitively Loaded Loops (CLLs). We achieve tuning of individual notched frequency bands by using open circuits as switches and incorporated in each CLL element. The performance characteristics in terms of S-parameters and surface currents distribution show that the proposed filter is able to adjust two stopbands independently in a wide tuning range. A corresponding prototype of tunable dual-stopband filter is manufactured, and practical measurement agree well with the simulation results.

In this work, we propose a compact CoPlanar Waveguide (CPW) fed two-port multiple-input multiple-output (MIMO) antenna with high isolation for Ultra-Wideband (UWB) applications. The proposed antenna consisting of two symmetrical radiators placed side-by-side on an FR-4 substrate with a size of 0,48λ × 0,48λ × 0,01λ mm³ at 3,1 GHz (where λ = guided wavelength at the lowest frequency of operation). The isolation between the antenna elements is more than 16,5 dB in the entire UWB, which is achieved by introducing in the ground plane a vertical T-shaped neutralization line. The simulation results of the antenna system are in good agreement with the measured one. The proposed antenna covers the entire UWB with an impedance bandwidth 8,6 GHz (from 3,1 to 11,7 GHz), considering the -10 dB standard. The designed UWB MIMO antenna has a low envelope correlation coefficient (less than 0,057), a good efficiency (more than 50%), a low total channel capacity loss (CCL_Total < 0,25 bit/s/Hz) and stable total active reflection coefficient (TARC) attributes, thus meeting the standards applicable to various wireless MIMO applications.

In model predictive current control (MPCC), in order to reduce the switching frequency, the number of switching changes is introduced into the cost function. But it will lead to the complexity of weight coefficient adjustment. To solve the problem, a dual cost function model predictive control (DCF-MPC) strategy for permanent magnet synchronous motor (PMSM) is proposed. First, the dual cost function is established, and the cost function g₁ first screens out the combination of two or three voltage vectors which minimizes the current steady-state error. Then, the cost function g₂ selects the voltage vector combination that minimizes the number of switching changes from the selected voltage vector combinations in g₁ as the optimal voltage vector combination. Finally, the experiment shows that compared with the traditional single cost function, the proposed method eliminates the weight coefficient of MPCC, simplifies the system structure and reduces the amount of calculation. Moreover, it suppresses the stator current ripple, reduces the harmonic content of three-phase current, and has better steady-state and dynamic performance under different working conditions.

A high-sensitivity photonic crystal fiber (PCF) Temperature sensor based on surface plasmon resonance (SPR) with a high figure of merit (FOM) is proposed. Compared with most optical fiber inner air holes coated with metal or placed with metal nanowires, owing to the plasma material directly contacting the analyte, the annular channel outside the cladding is convenient for analyte detection, and the sensor is easier to manufacture. The temperature-sensitive liquid is a mixed solution of ethanol and chloroform with a volume ratio of 1:1. The results indicate that the highest sensitivity of this sensor can reach 15.4 nm/˚C, and the maximum FOM is 0.2829/˚C between -10˚C and 60˚C. Furthermore, the influence of photonic crystal fiber air hole size, gold film thickness, and other parameters on the performance of the sensor is analyzed.

In this article, a low-profile microstrip patch antenna using an FR-4 substrate with relative permittivity of 4.4 and thickness of 1.6 mm is designed. On the top of a substrate, it consists of one metallic hexagonal patch and a metallic-fed hexagonal ringtone, and the ground part of the structure is covered with orthogonal rectangular slots. The designed structure operates in the ISM band of 434 MHz, and the overall size of the antenna is 124x124x1.6 mm³. The antenna provides a valid SAR input profile.

An enhanced linear active disturbance rejection control (E-LADRC) method with dynamically adjust is proposed to improve the observer gain and observation effect in the convenient linear active disturbance rejection control (C-LADRC), reduce the sensitivity of the observer to interference, and find the appropriate observer gain coefficient. Firstly, the mathematical model of bearingless permanent magnet synchronous motor (BPMSM) and the C-LADRC algorithm are described and analyzed. Secondly, the E-LADRC algorithm is designed to overcome the shortcomings of the C-LADRC. Thirdly, the back propagation neural network (BPNN) algorithm with strong self-learning and adaptive ability is used to dynamically adjust the parameters of the E-LADRC, so as to improve the performance of the control system. Finally, the whole control system is analyzed, and the effectiveness of the proposed algorithm is verified on the experimental platform. The experimental results show that the proposed control algorithm can effectively reduce the jitter amplitude of speed and displacement.

This work aims to evaluate the contribution of cascaded optical amplifiers in improving the performance of optical communication systems in optical access networks. This study is thus carried out by a system simulation software which presents results concerning the characteristic parameters of two optical amplifiers, EYDWA (Erbium Ytterbium Doped Waveguide Amplifier) and SOA (Semiconductor Optical Amplifier) used in cascade, namely their gains, the length of the guide and the concentration of ions.

A flat lens made of a negative index (NI) metamaterial (MTM) focuses the diverging light waves with sub-wavelength resolution. However, to achieve tight 3-D focusing, one needs to realize a 3-D MTM with azimuthal and elevation focusing. In this work, a polarization-insensitive, wide-incident angle 3-D MTM showing an NI band of 0.34 THz (37%) centered at 0.92 THz is realized. A flat lens designed out of the proposed 3-D NI MTM shows sub-wavelength spot sizes of 0.48λ₁ and 0.39λ₂ for cylindrical electromagnetic (EM) waves emanating out of an electric dipole source, at 0.9 THz and 0.95 THz respectively. Also, the sub-wavelength focusing features of the NI flat slab are verified along non-symmetric planes by tilting the dipole source for different angles. It is also found that the finite flat slab configurations efficiently transfer EM beams for long conveyance lengths at NI frequencies. Thus, the realized flat slab configurations are useful for 3-D focusing requirements in optical trapping and imaging, and they are also useful for reducing the transmission losses associated with beam divergences.

The Internet of Things (IoT) has become a vital part of life, with an increasing number of connected devices; its small size, and high rate of data transmission have attracted the attention of many researchers. Antenna plays a major role in providing wireless signal connectivity. With the intention to provide wider bandwidth to improve the rate of data transmission with the smaller size of the antenna, in this work, a third-level iterated diagonally symmetric fractal antenna has been proposed. A partial ground plane with a notch has been experimented to adjust the antenna impedance over a wider bandwidth parametrically. The antenna has been optimized to eliminate the stopband based on surface current distribution. Following optimization, a modal shift separated two overlapping modes and produced a new resonance close to the stopband. The proposed antenna covers all IoT applications between 2 GHz and 7 GHz. The design has been simulated in mentor graphics and CST studio, and it is verified on a vector network analyser and in an anechoic chamber. The measured S₁₁ and gain are in good agreement with the simulated results. The overall antenna size is 40 mm in length, 40 mm in width, and 1.6 mm in height, and it is fabricated on an FR-4 substrate with a dielectric constant of 4.4.