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 (εr) 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.
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.
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 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 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 (CCLTotal < 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.
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.
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.
The problem of electromagnetic waves diffraction by a system of pass-through resonators in a rectangular waveguide coupling by diaphragms with resonant slots was solved by the generalized method of induced magnetomotive forces (MMFs). A distinctive feature of the solution is characterized by using approximating functions defining magnetic currents in the slots obtained from solutions of current integral equations by the asymptotic averaging method. Multi-parameter studies of electrodynamic characteristics of such structures have been carried out. The comparison of numerical results with experimental data is presented.
The development of computational electromagnetics methods using potential-based formulations in the Lorenz gauge have been gaining interest as a way to overcome the persistent challenge of low-frequency breakdowns in traditional field-based formulations. Lorenz gauge potential-based finite element methods (FEM) have begun to be explored, but to date have only considered very simple excitations and boundary conditions. In this work, we present a theoretical and numerical study of how the widely used wave port boundary condition can be incorporated into these Lorenz gauge potential-based FEM solvers. In the course of this, we propose a new potential-based FEM approach for analyzing inhomogeneous waveguides that is in the same gauge as the 3D potential-based methods of interest to aid in verifying theoretical claims. We find that this approach has certain null spaces that are unique to the 2D setting it is formulated within that prevent it from overcoming low-frequency breakdown effects in practical applications. However, this method still is valuable for presenting numerical validation of other theoretical predictions made in this work; particularly, that any wave port boundary condition previously developed for field-based methods can be utilized within a 3D Lorenz gauge potential-based FEM solver.
Implementing appropriate absorbing boundary conditions (ABCs) in finite-difference time-domain (FDTD) simulations is essential. Optimal ABCs can help minimize or even eliminate spurious reflections in simulations involving waves impinging on the edges of simulation grid boundaries. In this work, 2D FDTD code facilitating ABCs were implemented and incorporated under plug-and-play conditions. Using this FDTD code, two different types of ABCs were evaluated: a differential ABC and a perfectly matched layer (PML) for the anisotropic medium of the ionosphere. Furthermore, numerical experiments were conducted to examine the efficiencies of both these ABCs; a total of n = 2000 iterations were adopted, under grid conditions of 120 in the y-direction, 600 in the x-direction of spatial step, and Δx = 1000 km. Additionally, n was set as a time-equivalent variable in these simulations. For the interval Δx=1 km between any two adjacent grid points, active conditions for the grid simulation were determined within 120 km in the y-direction (vertical) and 600 km in the x-direction (horizontal). Furthermore, numerical experiments revealed that the PML platform yielded excellent efficiency, as compared with the differential ABC.
Wireless devices that can operate under harsh environments are of great interest for military, space, and commercial applications such as antennas and radomes for fighter jets, wireless sensor networks for oil drilling and aircraft propulsion, and safety devices for first responders. Since antennas are key components of Radio Frequency (RF) Systems, it is crucial to have the antenna be able to withstand the same environmental hardships for a reliable and efficient communication. Various substrates have been utilized to implement antennas to withstand harsh environments and particularly high temperatures. Existing solutions such as silicon carbide (SiC), alumina, and polymer derived ceramics require complex deposition and patterning techniques, which make them unsuitable for low-cost RF and microwave applications. The main objective of this study is to explore microstrip patch antenna fabrication technology utilizing Zirconia Ribbon Ceramic (ZRC) materials and assess ZRC as a potential dielectric substrate for harsh environment applications. To do so, first, a wideband coplanar waveguide (CPW) fed monopole antenna is presented on ZRC substrate operating within the S band. The proposed design has been manufactured using two separate methods including a clean room sputtering process and inkjet printing. A good agreement has been obtained between the measured results of the inkjet-printed prototype and simulations. Impedance matching and radiation patterns are investigated. The inkjet printing process has been shown to be a viable and cost-effective solution for fabricating ZRC-based patch antennas.
This article proposes a four-port multiple input multiple output (MIMO) ultra-wideband (UWB) antenna that operates across 3 to 13 GHz. Four identical fractal patches are placed orthogonally to each other. The uniqueness of the proposed design is that it does not need to incorporate any dedicated/specific design/component to realize notches within the UWB range. The elimination of notches, enhancement of bandwidth, and improvement of isolation have been achieved by integrating a resistance-loaded stub with the ground plane. The isolation between the elements was measured to be below -20 dB across the entire operating band. The fabricated prototype exhibits better diversity parameters like envelop correlation coefficient (ECC) < 0.003, diversity gain (DG) > 9.99, channel capacity loss (CCL) < 0.4 bps/Hz, and mean effective gain (MEG) < 2 dB. The proposed MIMO antenna shows omnidirectional radiation patterns with a peak gain of 5.4 dBi and radiation efficiency > 66% with required compactness having interelement (edge to edge) distance of 5.4 mm. After application of decoupling method radiation efficiency varies from 66% to 82% with gain ranging between 1.8 and 5.54 dBi. The diverse performance of the fabricated MIMO proves it to be a good candidate for UBW imaging, LTE applications, and S, C, and X band applications.
This paper presents the design methodology, simulation, and affordable implementation of a mobile digital satellite broadcasting receiver with 64 elements. The speed and range of electronic beamforming are also obtained. The proposed methodology including techniques and architecture are defined by concerning cost, commercial off-the-shelf and components, and avoidance of high-frequency circuit designs by Delay-line-PLL for phase shifting, instead of expensive RF phase shifters with complicated control buses. Choosing this architecture results in using available elements and home receivers for antenna implementation. The design results in 6-bit resolution phase shifters and ±16 degrees 2D half power electronic beam scanning range. For practical implementation feasibility, a prototype of the array is fabricated and tested, successfully. Obtaining the phase shifters' resolution and sampling of the array output power are also described. A simple and effective algorithm is proposed for grating lobes elimination, and SNR maximizing which performs the tracking task under the platform movement conditions.
The present paper describes a substrate integrated waveguide (SIW) band pass filter with a T-shape slot on the upper layer, which exhibits a wide-band frequency response. The parameters of the filter are optimized by using Multi-Layer Perceptron artificial neural network (MLP-ANN) that uses Levenberg-Marquardt (LM) algorithm. A comparison is made between ANN optimized results and simulated results, and they result in minimum mean square error (MSE). A physical prototype is fabricated using printed circuit board (PCB) process, and measurements are conducted using the network analyzer. The measured results obtained agree well with the estimated ones. The filter shows a wide-band response with a transmission bandwidth of 8.96 GHz, ranging from 6.10 to 15.06 GHz with a fractional bandwidth of 81.4%. Furthermore, the insertion loss of the filter in the entire passband is varied from -0.4 dB to -0.2 dB, and the return loss is more than -10 dB.
A concept to minimize the volume of the classic bifocal elliptical lens antenna is proposed. By applying the image theory, a reflective ground plane is placed along the short axis of a bifocal elliptical lens. An antenna-on-chip (AoC), as the lens's feed source, is placed at the upper focus and packaged by the lens body. The AoC radiates toward the ground plane instead of the free space. The geometric optics (GO) ray tracing analysis shows that the optical path of the miniaturized monofocal integrated lens antenna (ILA) is equal to that of the classic bifocal ILAs, so the gain is almost unaffected on the basis of the lens' volume reduction. For the quantitative evaluation of the gain loss caused by feed occlusion, a set of analytical equations is given. To verify the design concept, a 26 GHz miniaturized self-packaged monofocal elliptical ILA is designed and fabricated by 3D printing technology. The ILA achieves a 26.5 dBi gain and a size reduction rate of 38% compared with the classic bifocal elliptical lens. Moreover, the ILA also functions as the package for the AoC's die. The proposed design concept can not only reduce the volume of the classic bifocal elliptical lens dramatically but can also save the effort and cost to package the AoC's die in a highly integrated system, which is believed to have great potential to create large profit margins for the fifth-generation (5G) mobile network applications.
This paper presents the design and fabrication of a wideband circularly polarized CPW-fed compact diamond-shaped antenna. To enhance the wideband response and axial ratio in the desired frequency band, the geometry of the proposed antenna is modified. The modified antenna consists of one radiating element that includes two slits and one horizontal rectangular stub and an improved ground plane. The suggested wide-band antenna has overall measurements of 25 mm x 28 mm x 1.6 mm. The V-shaped slit generates two orthogonal modes in the proposed antenna to excite circular polarization. The rectangular stub improves the wideband response in 2.35-4.62 GHz. The fabricated prototype antenna demonstrates good consistency between simulation and measured results. The suggested antenna resonates over a 2700 MHz transmission bandwidth between 2.35 and 4.62 GHz, making it a good choice for WLAN and WiMAX applications. The average gain in the wideband is 3.1 dBi. It is shown that our suggested approach is a great choice for developing any wideband microstrip antenna for usage in a variety of wireless communication systems.
In this paper, a novel compact 4-port Vivaldi Multiple Input Multiple Output (MIMO) antenna is proposed for 5G wireless devices. The presented antenna has dimensions 40x40x1.6 mm3. The suggested antenna is fabricated on RT/Duroid dielectric material with dielectric constant of 2.2. The orthogonal arrangement of antenna elements and embedding slits between them result in enhanced isolation. The gain observed for the proposed antenna is 2.405 dB. The diversity performance of MIMO structure in terms of Envelop Correlation Coefficient (ECC < 0.02), Total Active Reflection Coefficient (TARC < -10 dB), Diversity Gain (DG > 9.998), Channel capacity Loss (CCL < 0.4) and Mean Effective Gain (MEG < 1 dB) is studied and analyzed. The simulated and measured results are in good agreement.
The next generation 4T4R Multiple Input Multiple Output (MIMO) antenna solution is gradually accepted by operators in many countries as a mainstream expansion to long term evolution (LTE) networks. Using limited spectrum and high capacity, operators have successfully adopted multi-sector 4T4R MIMO deployment and achieved a 70% increase in capacity without increasing spectrum, thus paving way for state of art next generation wireless networking environment requiring antennae that are robust, small size, lighter, preferably with circular polarization. MIMO antennae provide optimality by arresting multipath fade effect and ensuring data link that is reliable. MIMO realizes efficiency in mobility with increase in capacity of links and several sub-bandwidths using polarization diversity providing better cybersecurity. This work therefore is an investigation on a small size 4T4R MIMO antenna for the use in a sub-6 GHz new radio (NR) band in a fading environment with good inter element as well as radiation isolation compared with earlier research. A rectangular patch with loaded slots is designed to obtain small size. Stubs and parasitic elements are introduced between the elements for better mutual coupling performance. Performance of the antenna is stable, with the test results agreeing. The parametrics follow the coefficient of transmission isolation technique to obtain an optimal envelope correlation coefficient.