Rectangular Array Research Articles

Directive Multiband Antenna Based on Rectangular Loop Array and Dumbbell-Shaped Slot Radiator.

In this article, a combination of rectangular loop array and slot radiator for multiband applications is presented. The antenna is configured by arranging, concentrically, a set of rectangular loop radiators excited by electromagnetic coupling provided by a dumbbell slot. The size of the loops is calculated to obtain the desired resonant frequencies, which are almost independent of the adjacent rings. The exciting slot is designed to operate in a wideband frequency range to cover the upper desired resonance. In addition, to obtain directive radiation patterns, a reflector shaped like a box is introduced, giving a stable gain, radiation pattern shape, and port matching at the selected frequencies. The configuration presents great results, since to the authors’ knowledge, even a similar configuration given in the open literature presents some disadvantages compared to this one; moreover, not just any structure can be employed as the resonating elements, obtaining multiband behavior at the same time.

Miniaturized flexible metamaterial antenna of circularly polarized high gain‐bandwidth product for radio frequency energy harvesting

SummaryA discussion of using an ultrawide band (UWB) Hilbert‐shaped metamaterial (MTM) antenna structure for RF energy harvesting is exemplified in this article to conduct the use of organic substrates. Therefore, the proposed design is structured as a low profile rectangular MTM array in the context of wearable systems. The antenna is mounted on a prepared indium‐nickel oxide‐based polymerized Palm fiber (INP) substrate and backed with a ground plane of square electromagnetic band gap (EBG) defects. Fifteen samples of INP substrate are prepared for this study. Thus, the prepared INP substrates characterizations are tested using a T‐resonator transmission line technique printed on an FR4 substrate. In this technique, the measured scattering parameters are interpreted from two resonators with two different characteristics impedance to be employed for retrieving the relative permittivity (εr) and permeability (μr). This process is included to ensure the prepared substrate properties controllability for microwave devices manufacturing. After that, the proposed antenna is manufactured from silver nanoparticle (SNP) printout. The performance of the proposed antenna is tested numerically and experimentally. It is found that the proposed antenna shows an UWB response to start from 3 and up to 10 GHz that suits different applications including IoT, 5G, and WiMAX system networks. The measured gain spectrum shows four peaks at 3.5, 4.2, 5.4, and 6 GHz with gain values of 1.1, 2, 3.4, and 3.9 dBi, respectively. Finally, the conversion efficiency of RF harvesting is measured experimentally for the antenna in case of flat profile and bended structure at the frequency bands of interest to reveal insignificant changes.

Effects of array shape and disk ellipticity in dipolar-coupled magnetic metamaterials

Two-dimensional lattices of dipolar-coupled thin film ferromagnetic nanodisks give rise to emergent superferromagnetic (SFM) order when the spacing between dots becomes sufficiently small. In this paper, we define micron-sized arrays of permalloy nanodisks arranged on a hexagonal lattice. The arrays were shaped as hexagons, squares, and rectangles to investigate finite-size effects in the SFM domain structure for such arrays. The resulting domain patterns were examined using x-ray magnetic circular dichroism photoemission electron microscopy. At room temperature, we find these SFM metamaterials to be below their blocking temperature. Distinct differences were found in the magnetic switching characteristics of horizontally and vertically oriented rectangular arrays. The results are corroborated by micromagnetic simulations.

A Frameless 2-Coloring of the Plane Lattice

Summary A picture frame in two dimensions is a rectangular array of symbols, with at least two rows and columns, where the first and last rows are identical, and the first and last columns are identical. If a coloring of the plane lattice has no picture frames, we call it frameless. In this note, we show how to create a simple 2-coloring of the plane lattice that is frameless.

Synthetic sparse planar array design for two-dimensional DOA estimation

Array motion can efficiently enhance the achievable number of degrees-of-freedom (DOFs) by the virtue of filling the holes in the difference co-array. In this paper, the concept of synthetic array based on array motion is extended to two dimensional cases. A new structured sparse planar array on a moving platform named as Synthetic Augmented Cross Array (SACA) is proposed. The proposed array yields a co-array with much larger virtual uniform rectangular array in it. Closed-form expressions of DOFs with different moving trails are also delineated. Then by further improving the DOFs of SACA, a series of generalized configurations named as Improved Synthetic Augmented Cross Array (ISACA) are proposed. With the same number of sensors, it can achieve larger DOFs than SACA. Numerical results are provided for performance comparison and validations of analysis.

Novel strategy to design a metasurface with integrated radiation and a broadband low radar cross section

In this paper, a novel design strategy that integrates good radiation and broadband low radar cross section (RCS) characteristics based on the concept of metasurface is proposed. The metasurface element adopts an etched cross patch and it directly behaves as a radiating structure. After that, a metasurface-based thinned array antenna A1 and a checkerboard metasurface antenna A2 are designed. The -10 dB operating bandwidth of these two antennas is 13.08–14.92 GHz (13.1%). Compared with the conventional rectangular grid array, A1 and A2 have similar radiation performance along with in-band and out-of-band RCS reduction (RCSR) in any polarized normal incidence. Reasons and merits of different arrangements are analyzed. Simulated and measured results verify the effectiveness of the design strategy.

Synthesis of a Sparse Planar Phased Array Antenna with Reduced Side-Lobe Level and Beam-Width using Particle Swarm Optimization

Computer aided synthesis of sparse array is a popular area of research worldwide for the application in radar and wireless communication. The trend is observing new heights with the launch of 5G millimeter wave wireless communication. A sparse array has a fewer number of elements than a conventional antenna array. In this work, a sparse array is synthesized from a 16×16 uniform rectangular array (URA). The synthesis includes an artificial neural network (ANN) model for estimation of the excitation weights of the URA for a given scan-angle. The weights of the sparse array are computed by the Hadamard product of the weight matrix of the URA with a binary matrix that is obtained using particle swarm optimization (PSO). The objective function of the optimization problem is formulated to ensure that the PSLL is minimized for multiple scan-angles. It is shown from experimental analysis that apart from minimizing the PSLL, the proposed approach yields a narrower beam-width than the original URA

Antenna 5.8 GHz dengan Output Perbedaan Fasa 90 Derajat Ganda Menggunakan Jaringan Matriks Butler Feeding

A complex design of electromagnetic feeding network circuit components is needed for a wireless communication network system, and expensive materials, especially for electromagnetic components at a high frequency of 5.8 GHz with dual 90-degree phase difference output using butler matrix Feeding Network for wireless communication network systems. It is novel in form and has a frequency-free, frequency-free, non-complex configuration of microstrip electromagnetic circuits, and uses inexpensive materials at a frequency of 5.8 GHz. This system is a package consisting of a 5.8 GHz microstrip antenna with a rectangular microstrip antenna array and a Butler matrix of four inputs and outputs to achieve a double 90-degree phase difference. The antenna uses a via hole for the transmission line to the network feeding system, has one band and shallow bandwidth with four ports, and has one working frequency, namely 5.58 GHz under the S criterion -10dB, and uses a via hole for the transmission line to the network feeding system, the radiation pattern is forward, the gain level is 6.83dB, and the feeding impedance is 50 Ohm. S11 -26.19 dB for the 90-degree hybrid coupler, S21 31.65 dB, S51 -26.18 dB, and S61 32.52 dB which means these are all working well, and the overall size of this structure is 80mm x 65mm with FR4 of 4.4 dielectric constant having 50 ohms.

On the PZT/Si unimorph cantilever design for the signal-to-noise ratio enhancement of piezoelectric MEMS microphone

This study presents the design, fabrication, and testing of a novel piezoelectric micro-electro-mechanical-systems microphone with the partially removed lead zirconate titanate (PZT) unimorph structure for signal-to-noise ratio (SNR) enhancement. To demonstrate the feasibility of the presented concept, the unimorph cantilever array with the patterned (triangular shape) PZT film on top of a rectangular Si layer is simulated, fabricated, and tested. In comparison, the rectangular and triangular unimorph cantilever arrays with fully covered PZT film are also investigated. The proposed and reference cantilever arrays have the same foot print for fair comparison. Simulations show the proposed design has the highest output electrical energy which indicates the proposed design could successfully enhance the SNR. Moreover, acoustic measurements in the standard anechoic box show the proposed Si cantilever with patterned PZT film design could significantlyimprove the SNR. As compared to the reference microphone with triangular PZT/Si unimorph cantilever, the proposed design shows a 9.8 dB enhancement in SNR. Finally, the influences of initial structure deflections (due to the thin film residual stresses) on the low frequency responses for proposed and reference microphone designs are also investigated.

Statistical Analysis of 5G Channel Propagation using MIMO and Massive MIMO Technologies

Multiple Input Multiple Output (MIMO) and massive MIMO technologies play a significant role in mitigating five generation (5G) channel propagation impairments. These impairments increase as frequency increases, and they become worse at millimeter-waves (mmWaves). They include difficulties of material penetration, Line-of-Sight (LoS) inflexibility, small cell coverage, weather circumstances, etc. This paper simulates the 5G channel at the E-band frequency using the Monte Carlo approach-based NYUSIM tool. The urban microcell (UMi) is the communication environment of this simulation. Both MIMO and massive MIMO use uniformly spaced rectangular antenna arrays (URA). This study investigates the effects of MIMO and massive MIMO on LOS and Non-LOS (NLOS) environments. The simulations considered directional and omnidirectional antennas, the Power Delay Profile (PDP), Root Mean Square (RMS) delay spread, and small-scale PDP for both LOS and NLOS environments. As expected, the wide variety of the results showed that the massive MIMO antenna outperforms the MIMO antenna, especially in terms of the signal power received at the end-user and for longer path lengths.

The Role of Correlation in the Performance of Massive MIMO Systems

Massive multiple-input multiple-output (m-MIMO) is considered as an essential technique to meet the high data rate requirements of future sixth generation (6G) wireless communications networks. The vast majority of m-MIMO research has assumed that the channels are uncorrelated. However, this assumption seems highly idealistic. Therefore, this study investigates the m-MIMO performance when the channels are correlated and the base station employs different antenna array topologies, namely the uniform linear array (ULA) and uniform rectangular array (URA). In addition, this study develops analyses of the mean square error (MSE) and the regularized zero-forcing (RZF) precoder under imperfect channel state information (CSI) and a realistic physical channel model. To this end, the MSE minimization and the spectral efficiency (SE) maximization are investigated. The results show that the SE is significantly degraded using the URA topology even when the RZF precoder is used. This is because the level of interference is significantly increased in the highly correlated channels even though the MSE is considerably minimized. This implies that using a URA topology with relatively high channel correlations would not be beneficial to the SE unless an interference management scheme is exploited.

Synthesis of a Sparse 2D-Scanning Array using Particle Swarm Optimization for Side-Lobe Reduction

Synthesis of sparse arrays is a promising area of research for a wide range of applications including radar and millimeter-wave wireless communication. The design goal of array thinning problems is to reduce the number of elements of an array without significantly affecting its performance. This work presents a technique for synthesizing a sparse phased-array antenna from a 16×16 uniform rectangular array (URA). The proposed approach reduces the number of elements by 50% without any significant increase in the peak sidelobe level (PSLL) for all possible scan angles in the azimuthal and elevation plans within a finite range of scan angles. The synthesis includes an artificial neural network (ANN) model for estimation of the excitation weights of the URA for a given scan-angle. The weights of the sparse array are computed by the Hadamard product of the weight matrix of the URA with a binary matrix that is obtained using particle swarm optimization (PSO) to minimize the PSLL.

Reconfigurable 2×1 CPW-Fed Rectangular Slot Antenna Array (RSAA) Based on Graphene for Wireless Communications

This article presents a 2×1 CPW ultra wideband rectangular slot antenna array (UWB-RSAA) with a modified circular slot shape to support a high data rate for wireless communications applications. The proposed antenna array dimensions are 0.7λ×0.8λo×0.064λo at the resonant frequency 1.8 GHz. It is fabricated on Rogers RO4003 substrate and fed by using a coplanar waveguide (CPW). A graphene layer is added on one side of the substrate to realize frequency reconfigurability and improve the array gain. The proposed array acquires -10 dB impedance bandwidth of the RSAA that extends from 1.7 GHz to 2.6 GHz, from 3.2 to 3.8 GHz, and from 5.2 GHz to 7 GHz. The proposed array achieved a realized peak gain of 7.5 dBi at 6.5 GHz at 0 Volt bias with an average gain of 4.5 dBi over the operating band. When the graphene bias is increased to 20 Volt, the antenna bandwidth extends from 1 GHz to 4 GHz and from 5 to 7 GHz with a peak gain of 14 dBi at 3.5 GHz and an average gain of 7.5 dBi. The linearly polarized operation of the proposed array over the operating bands makes it suitable for short-range wireless communications .

Broad Coverage Precoder Design for Synchronization in Satellite Massive MIMO Systems

In this paper, we investigate the massive multi-input multi-output (MIMO) transmission for the satellite communication systems equipped with a uniform rectangular array (URA) and aim to design the precoder with broad coverage radiation power pattern to improve the performance of time and frequency synchronizations. The modified Cramér-Rao vector bounds (MCRVB) are chosen as the benchmark of symbol timing offset and frequency offset estimation problem, which can be viewed as the time and frequency synchronization performance metric for the broad coverage precoder design. By considering the minimax MCRVB criterion and the per-antenna equal power constraint, the precoder design approach is formulated as the non-convex constrained minimax problem over the discrete radiation power pattern. This optimization problem is solved by the smoothing techniques combined with the manifold optimization method. To reduce the calculation complexity, the nonmonotone conjugate gradient method is applied. Simulation results show that the average and the minimum received powers in the coverage area of the proposed scheme are higher than those of the scheme based on fairness criterion. Compared with the existing omnidirectional and broad coverage schemes, the proposed scheme has the best synchronization performance among all the contrast solutions.

Spacetime Frequency-Multiplexed Digital-RF Array Receivers With Reduced ADC Count

Wireless systems operating at mm-wave frequencies require dense antenna arrays to achieve directional gain for overcoming high path loss. Digital mm-wave arrays retain spatial degrees of freedom, but require a dedicated analog to data converter (ADC) per spatial channel, leading to undesirably high receiver complexity, large ADC count, and power consumption. This brief exploits directional sparsity to reduce the number of receivers and ADCs with minimal loss in performance. A multidimensional (MD) linear transformation using transmission lines and a K : 1 combiner is used to reduce the number of ADCs by a factor K. Simulations verify that the proposed method can lead to better than 50% ADC complexity reductions (for K ≥ 2) for linear arrays and more than 75% ADC complexity reduction (for K ≥ 4) for rectangular arrays when sparsity conditions are met. Unlike in analog-digital hybrid beamforming, where a phased-array combines K channels to a single ADC, the proposed method does not lead to loss of spatial degrees of freedom.

Row‐column factorial designs with multiple levels

AbstractAn row‐column factorial design is an arrangement of the elements of a factorial design into a rectangular array. Such an array is used in experimental design, where the rows and columns can act as blocking factors. Formally, for any integer , let . The (full) factorial design with replication is the multiset consisting of occurrences of each element of ; we denote this by . A regular row‐column factorial design is an arrangement of the elements of into an array (which we say is of type ) such that for each row (column) and fixed vector position , each element of occurs times (respectively, times). Let . We show that an array of type exists if and only if (a) and ; (b) ; (c) , and (d) if then 4 divides . Godolphin showed the above is true for the case when and are powers of 2. In the case , the above implies necessary and sufficient conditions for the existence of a pair of mutually orthogonal frequency rectangles (or ‐rectangles) whenever each symbol occurs the same number of times in a given row or column.

Fast Beam Training Technique for Millimeter-Wave Cellular Systems with an Intelligent Reflective Surface.

The concept of an intelligent reflecting surface (IRS) has recently emerged as a promising solution for improving the coverage and energy/spectral efficiency of future wireless communication systems. However, as the number of reflecting elements in an IRS increase, the beam training protocol in IRS-assisted millimeter-wave (mmWave) cellular systems requires a large beam training time because it needs to find the best beam pairs for the link between the base station (BS) and the IRS, as well as the link between the IRS and the mobile station (MS). In this paper, a fast beam training technique for IRS-assisted mmWave cellular systems with a uniform rectangular array is proposed for detecting the best beam pairs of BS-IRS and IRS-MS links simultaneously. Two different types of beam training signals (BTSs) are proposed to distinguish simultaneously transmitted beams from the BSs in multi-cell multi-beam environments: the Zadoff–Chu sequence based BTS (ZC-BTS) and m-sequence based BTS (m-BTS). The correlation properties of ZC-BTSs and m-BTSs are analyzed in multi-cell multi-beam environments. In addition, the effect of symbol time offset on the ZC-BTS and m-BTS is analyzed. Finally, simulation results reveal that the proposed technique can significantly reduce the beam training time for IRS-assisted mmWave cellular systems.

Fast Synthesis Method for Large Aperture Array Pattern in the Presence of Array Errors

In this paper, an improved array synthesis method with array errors is proposed for large aperture arrays. Because of the array errors such as amplitude-phase errors and positions errors, the performance of the array synthesis is reduced seriously. Firstly, the ideal fast low sidelobe synthesis method is obtained based on the discrete Fourier transform (DFT) method. Then, by using Taylor expansion to remove the coupling relationship between the position of the element and the scanning angle, the compensation matrix for the pattern function and the array weighted vector with amplitude phase and position errors are derived. At last, the conversion relationship between the array with errors and the array weight vector is corrected in the iterative process. The theoretical simulation experiments verify the effectiveness and robustness of the proposed method for the linear array and rectangular array pattern synthesis. Then, the influence of Taylor expansion order on the pattern synthesis results is analysed.

Compact Full Ka-Band Waveguide Directional Coupler Based on Rectangular Aperture Array with Stairs.

This article presents a compact 3 dB waveguide directional coupler with full waveguide bandwidth. It consists of a pair of rectangular waveguides with stairs structures in the coupling region. The waveguides are placed parallel to each other along their broad wall, which has a rectangular aperture array. The compact size, broad bandwidth, good in-band coupling flatness, and good return loss are achieved by using the proposed structure. For verification purposes, a prototype of the proposed coupler was designed, manufactured, and measured. The experimental results show that over the full waveguide bandwidth a return loss of input port better than 17.46 dB, coupling strength varying between −2.74 dB and −3.80 dB, power-split unbalance within 0.76 dB, and an isolation better than 20.82 dB were obtained. The length of the coupling region was only 15.82 mm.

Double negative bend headed I-shaped metamaterial based Terahertz optical power splitter

Terahertz (THz) technology has piqued the interest of many researchers due to the fascinating characteristics of THz waves. Two new metamaterial array architectures are proposed in this paper to investigate power splitting via backward wave propagation. The first array pattern is a rectangular array arrangement, which is defined analytically and suggested as a power splitter in the TE (transverse electric) mode. From the proposed rectangular metamaterial array pattern, another cavity array structure was proposed which successfully increased DNG (double negative) response inside the metamaterial device and produced better splitting performance in the DNG condition. The unit cell and array patterns had almost identical effective parameter results, but some of them changed because the air-dielectric-metal combination was increased. The power splitter is demonstrated at the 0.91 THz frequency range where it shows the effective permittivity is −6, permeability is −6, and the refractive index is −6. At 0.94 THz, the DNG backward wave divider has negative effective parameters with an effective permittivity of −5.8, permeability of −5.8, and refractive index of −5.8.Both of the analytical structure patterns are proposed for optical power splitter and divider applications, which are used in various microwave circuits, such as mixers, balanced amplifiers, and antenna arrays.