One-dimensional Linear Array Research Articles

Formation of the maximum amplitude of the electric field strength using two one-dimensional linear antenna arrays located orthogonal to each other

The paper considers the problem of forming the maximum amplitude of the electric field strength at a required point using two identical one-dimensional linear antenna arrays located orthogonally to each other and focused at one point in space. Relationships have been obtained that allow us to determine the geometric dimensions of all areas. The results of theoretical calculations of the sizes of the zone of increased electric field intensity turned out to be close to the results of simulation. For example, the size of the zone of increased electric field intensity for two orthogonal antenna arrays consisting of 20 elements, the theoretical dimensions of the zone of increased intensity were 310 mm. The simulation results showed the dimensions of this zone to be equal to 325 mm, which is explained by taking into account the influence of radiation from the other antenna array.

A review for design, mechanism, fabrication, and application of magnetically responsive microstructured functional surface

Abstract Magnetically responsive microstructured functional surface (MRMFS), capable of dynamically and reversibly switching the surface topography under magnetic actuation, provides a wireless, noninvasive, and instantaneous way to accurately control the microscale engineered surface. In the last decade, many studies have been conducted to design and optimize MRMFSs for diverse applications, and significant progress has been accomplished. This review comprehensively presents recent advancements and the potential prospects in MRMFSs. We first classify MRMFSs into one-dimensional linear array MRMFSs, two-dimensional planar array MRMFSs, and dynamic self-assembly MRMFSs based on their morphology. Subsequently, an overview of three deformation mechanisms, including magnetically actuated bending deformation, magnetically driven rotational deformation, and magnetically induced self-assembly deformation, are provided. Four main fabrication strategies employed to create MRMFSs are summarized, including replica molding, magnetization-induced self-assembly, laser cutting, and ferrofluid-infused method. Furthermore, the applications of MRMFS in droplet manipulation, solid transport, information encryption, light manipulation, triboelectric nanogenerators, and soft robotics are presented. Finally, the challenges that limit the practical applications of MRMFSs are discussed, and the future development of MRMFSs is proposed.

MVDR Algorithm Based on Loading Factor and Sample Selection Strategy

The MVDR (Minimum Variance Distortionless Response) algorithm is a classic Wiener filtering method used for beamforming in array signal processing. In a one-dimensional linear array high-frequency ground wave radar system, it can be employed to suppress various types of ionospheric clutter. A key step in suppression is the use of maximum likelihood estimation (MLE) to estimate the ionospheric clutter covariance matrix. However, MLE typically assumes that samples are independently and identically distributed (i.i.d.). Traditional MVDR algorithms estimate the clutter covariance matrix using all samples, which may not satisfy the i.i.d. condition. Therefore, this paper proposes a new sample selection strategy that utilizes the Mahalanobis distance method to select samples. Meanwhile, due to the very small numerical values of the ionospheric clutter covariance matrix, even if the matrix is full-rank, numerical instability may occur during inversion. To address this issue, the paper introduces 4 different forms of regularization factors. Empirical data demonstrate that the proposed new method offers better suppression of ionospheric clutter compared to the traditional MVDR algorithm.

Modulation of Surface Plasmon due to the Inhomogeneity of a One-Dimensional Linear Array of Gold Nanoparticles Observed by Optical Second-Harmonic Generation Microscopy

Modulation of Surface Plasmon due to the Inhomogeneity of a One-Dimensional Linear Array of Gold Nanoparticles Observed by Optical Second-Harmonic Generation Microscopy

Photoacoustic imaging of peripheral vessels in extremities by large-scale synthetic matrix array.

Various peripheral vascular diseases (PVD) in extremities, such as arterial atherosclerosis or venous occlusion in arm or legs, are a serious global health threat. Noninvasive vascular imaging is of great value for both diagnosis and assessment of PVD. By scanning a one-dimensional non-focusing linear array, an equivalent large two-dimensional (2D) matrix array with hundreds of thousands or more ultrasound elements is formed, thereby achieving a wide signal reception angle as well as large imaging area for three-dimensional (3D) imaging of peripheral extremities. To provide a feasible bedside and noninvasive imaging method for vascular imaging in extremities. Our system can achieve high-quality photoacoustic (PA) peripheral vessel imaging. The 3D subcutaneous vascular imaging results of the palms and arms of healthy volunteers demonstrate the superior performance of the system. This work proposes a clinically oriented PA 3D subcutaneous vascular imaging system for human extremities. The system employs a synthetic matrix array via scanning a one-dimensional non-focusing linear probe, providing noninvasive, high-resolution, and high-contrast images of human extremities. It has potential application value in the diagnosis and monitoring of vascular diseases.

W-Band FMCW MIMO System for 3-D Imaging Based on Sparse Array

Multiple-input multiple-output (MIMO) technology is widely used in the field of security imaging. However, existing imaging systems have shortcomings such as numerous array units, high hardware costs, and low imaging resolutions. In this paper, a sparse array-based frequency modulated continuous wave (FMCW) millimeter wave imaging system, operating in the W-band, is presented. In order to reduce the number of transceiver units of the system and lower the hardware cost, a linear sparse array with a periodic structure was designed using the MIMO technique. The system operates at 70~80 GHz, and the high operating frequency band and 10 GHz bandwidth provide good imaging resolution. The system consists of a one-dimensional linear array, a motion control system, and hardware for signal generation and image reconstruction. The channel calibration technique was used to eliminate inherent errors. The system combines mechanical and electrical scanning, and uses FMCW signals to extract distance information. The three-dimensional (3-D) fast imaging algorithm in the wave number domain was utilized to quickly process the detection data. The 3-D imaging of the target in the near-field was obtained, with an imaging resolution of 2 mm. The imaging ability of the system was verified through simulations and experiments.

Формирование максимума напряженности электрического поля в заданной точке пространства сфокусированной линейной антенной решеткой

The possibility of forming a maximum of the electric field strength at a given point in space with the help of a focused one-dimensional linear antenna array is considered. It is shown that the location of the maximum electric field strength does not coincide with the point of in-phase addition of electromagnetic waves emitted by the elements of the antenna array - the focusing point. The dependence of the shift of the maximum electric field strength on the focus point for various focal lengths and sizes of antenna arrays is presented. It has been found that the value of the shift in the focusing coordinates is determined only by the size of the antenna array and does not depend on the number of its elements. The relationship between a decrease in the intensity of an electromagnetic wave and a shift in the maximum amplitude of the electric field strength is described. The paper presents the dependences of the amplitude of the electric field strength for antenna arrays of various linear sizes and the calculation results confirmed the theoretical concepts. A phase portrait for antenna arrays of various sizes is presented showing the in-phase arrival of waves at a given point in space. According to the family of dependencies presented in the paper, it can be concluded that the greater the ratio of the linear dimensions of the antenna array to the focal length, the smaller the shift in the maximum amplitude of the electric field strength.re frequency plane as a result of an iterative process, which makes it possible to determine the values of the required function.

S-QRD-ELM: Scalable QR-Decomposition-Based Extreme Learning Machine Engine Supporting Online Class-Incremental Learning for ECG-Based User Identification

User identification enables secure access to data and machines in smart factories. Compared with other modalities, ECG-based user identification is rising due to its intrinsic liveness proof and invulnerability to spoofing without contact. On the other hand, as new employees are registered at the factory, the ECG-based user identification system needs to be updated based on the new coming data. This scenario can be defined as an online class-incremental learning (O-CIL) problem. By exploiting hardware-software co-design, this work presents a Scalable QR-decomposition-based extreme learning machine (S-QRD-ELM) engine that can effectively and efficiently support O-CIL for ECG-based user identification. At the software level, we apply the concept of “the others” class and inversion-free QR-decomposition (QRD) recursive least squares to the S-QRD-ELM. This makes S-QRD-ELM achieve 79.7% higher accuracy in the O-CIL scenario compared with the neural network trained with back-propagation (BP-NN). At the hardware level, a one-dimensional diagonally-mapped linear array (1D-DMLA) is proposed to efficiently compute the QRD and back-substitution (BS) operations inside the S-QRD-ELM, reducing 98.5% of the silicon area. Moreover, the integrated processing element (PE) design with the unified COordinate Rotation DIgital Computer (u-CORDIC) further reduces 15.3% of the area and 22.4% of the power consumption. This engine is fabricated in 40nm CMOS technology with a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.33\times1.33$</tex-math> </inline-formula> mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula> die area. The chip achieves 0.02 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $</tex-math> </inline-formula> J/sample and 2.47 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $</tex-math> </inline-formula> J/sample inferencing and learning energy efficiency, respectively, which is 6.4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> and 28.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> than the state-of-the-art. To the best of our knowledge, the proposed highly energy-efficient S-QRD-ELM engine is the first chip to meet the requirements of O-CIL for ECG-based user identification.

A Weak Reverse Coupling Cascaded Injection-Locked VCO Array for Beam Scanning in Phased Arrays

We propose a novel phase shifter for beam scanning in phased arrays using a cascaded injection-locked voltage-controlled oscillator (VCO) array with weak reverse coupling. We analyze the phase noise performance of a multi-signal injection-locked oscillator and establish a phase output model for the array, studying the effects of forward and reverse injection ratios on phase and phase noise at each stage. By decoupling and cascade locking VCO array elements through controlled injection ratios, we design a 2.45 GHz one-dimensional linear array of four VCOs that achieves a continuous fixed phase difference between adjacent oscillators from −180∘ to 180∘, enabling electronic tuning of phase shift and beam scanning. Finally, the beam scanning of the antenna array is realized by using the VCO array. Our theoretical and experimental results demonstrate the effectiveness of our proposed approach.

Millimeter-Wave Image Deblurring via Cycle-Consistent Adversarial Network

Millimeter-wave (MMW) imaging has a tangible prospect in concealed weapon detection for security checks. Typically, a one-dimensional (1D) linear antenna array with mechanical scanning along a perpendicular direction is employed for MMW imaging. To achieve high-resolution imaging, the target under test needs to keep steady enough during the mechanical scanning process since slight movement can induce large phase variation for MMW systems, which will result in a blurred image. However, in the scenario of imaging of a human body, sometimes it is difficult to meet this requirement, especially for the elderly. Such blurred MMW images would reduce the detection accuracy of the concealed weapons. In this paper, we propose a deblurring method based on cycle-consistent adversarial network (Cycle GAN). Specifically, the Cycle GAN can learn the mapping between the blurred MMW images and the focused ones. To minimize the effect of the shaking blur, we introduce an identity loss. Moreover, a mean squared error loss (MSE loss) is utilized to stabilize the training, so as to obtain more refined deblurred results. The experimental results demonstrate that the proposed method can efficiently suppress the blurring effect in the MMW image.

Comparative Long-Wave Infrared Laser-Induced Breakdown Spectroscopy Employing 1-D and 2-D Focal Plane Array Detectors.

Long-wave infrared (LWIR) emissions of laser-induced plasma on solid potassium chloride and acetaminophen tablet surfaces were studied using both a one-dimensional (1-D) linear array detection system and, for the first time, a two-dimensional (2-D) focal plane array (FPA) detection system. Both atomic and molecular infrared emitters in the vicinity of the plasma were identified by analyzing the detected spectral signatures in the infrared region. Time- and space-resolved long-wave infrared emissions were also studied to assess the temporal and spatial behaviors of atomic and molecular emitters in the plasma. These pioneer temporal and spatial investigations of infrared emissions from laser-induced plasma would be valuable to the modeling of plasma evolutions and the advances of the novel LWIR laser-induced breakdown spectroscopy (LIBS). When integrated both temporally (≥200 µs) and spatially using a 2-D FPA detector, the observed intensities and signal-to-noise-ratio (SNR) of single-shot LWIR LIBS signature emissions from intact molecules were considerably enhanced (e.g., with enhancement factors up to 16 and 3.76, respectively, for a 6.62 µm band of acetaminophen molecules) and, in general, comparable to those from the atomic emitters. Pairing LWIR LIBS with conventional ultraviolet-visible-near infrared (UV/Vis/NIR) LIBS, a simultaneous UV/Vis/NIR + LWIR LIBS detection system promises unprecedented capability of in situ, real-time, and stand-off investigation of both atomic and molecular target compositions to detect and characterize a range of chemistries.

Obtaining Feasible Minimum Side Lobe Level for Narrow Beam Width Using Convex Optimization in Linear, Planar, and Random Antenna Arrays

In many applications, the radiating elements of the used antenna may be configured in the form of a one-dimensional linear array, or two-dimensional planar array or even random array. In such applications, a simple optimization algorithm is highly needed to optimally determine the excitation amplitudes and phases of the array elements to maximize the system’s performance. This paper uses a convex optimization instead of other complex global stochastic optimizations to synthesize a linear, planar, and random array patterns under pre-specified constraint conditions. These constraints could be either fixed beam width with the lowest possible sidelobe levels or fixed sidelobe level with narrower possible beam width. Two approaches for array pattern optimization have been considered. The first one deals with the problem of obtaining a feasible minimum sidelobe level for a given beam width, while the second one tries to obtain a feasible minimum beam width pattern for a given sidelobe level. Both optimization approaches were applied to the linear, planar, and random arrays. Simulation results verified the effectiveness of both optimization approaches and for all considered array configurations.

Circular Optical Phased Array with Large Steering Range and High Resolution.

Light detection and ranging systems based on optical phased arrays and integrated silicon photonics have sparked a surge of applications over the recent years. This includes applications in sensing, free-space communications, or autonomous vehicles, to name a few. Herein, we report a design of two-dimensional optical phased arrays, which are arranged in a grid of concentric rings. We numerically investigate two designs composed of 110 and 820 elements, respectively. Both single-wavelength (1550 nm) and broadband multi-wavelength (1535 nm to 1565 nm) operations are studied. The proposed phased arrays enable free-space beam steering, offering improved performance with narrow beam divergences of only 0.5° and 0.22° for the 110-element and 820-element arrays, respectively, with a main-to-sidelobe suppression ratio higher than 10 dB. The circular array topology also allows large element spacing far beyond the sub-wavelength-scaled limits that are present in one-dimensional linear or two-dimensional rectangular arrays. Under a single-wavelength operation, a solid-angle steering between 0.21π sr and 0.51π sr is obtained for 110- and 820-element arrays, respectively, while the beam steering spans the range of 0.24π sr and 0.57π sr for a multi-wavelength operation. This work opens new opportunities for future optical phased arrays in on-chip photonic applications, in which fast, high-resolution, and broadband beam steering is necessary.

Additively manufactured circularly polarized open‐ended waveguide antenna array based on a linearly tapered double‐ridge polarizer

This article presents a novel circularly polarized (CP) open-ended waveguide antenna array based on additive manufacturing technology. It is a one-dimensional four-element linear array and has a single piece configuration. Its main body is made of dielectric material and partial surfaces are coated by copper films through electroplating to form necessary metal components. Regarding to each element, it is based on a circular waveguide and employs an inbuilt linearly tapered double-ridge structure to act as a polarizer. To design such a polarizer, different shaped ridges are analyzed and a design evolution is presented and discussed. Compared to the conventional designs, the proposed element and array can avoid structure partitioning during the processing, and effectively reduce the fabrication difficulty and complexity, meanwhile, attain light weights. To validate the design idea, two prototypes corresponding to the element and the array are fabricated and tested. Experimental results indicate that their axial ratio bandwidth (ARBW) are 22% (8.9–11.1 GHz) and 11.8% (9.6–10.8 GHz), and the gain are 6.6 ± 1.1 and 10.6 ± 0.6 dBic, respectively. The proposed element and array could be potentially applied for satellite and other CP communication systems.

Transformable Ultrasonic Array Transducer for Multiscale Imaging and Beamforming

Conventional ultrasound probes have inherent limitations in some application scenarios. Because of their fixed shapes and sizes, they can hardly pass through small orifices to examine the target closely. With the recent development of microelectromechanical systems and flexible electronic technologies, collapsible and self-assembling devices are being considered as a potential approach to address this problem. This article presents an innovative transformable ultrasonic transducer (TUT), which can transform between a one-dimensional (1-D) linear array and a 2-D planar array with the ability of switching between different functions including 2-D&#x002F;3-D imaging and high-intensity focused ultrasound beamforming. The transforming process is accomplished with a specially designed flexible printed circuit board inspired by a paper-folding mechanism. The electrical and acoustic properties of the developed transducer along with the acoustic field distribution in its different forms have been characterized. The 2-D&#x002F;3-D imaging performances of the TUT have been also evaluated under 1-D and 2-D configurations, respectively. In addition, the performance of a focused concave transforming mode has been also discussed. The evaluation results suggest that TUT can maintain its performance under different structures with precise transforming control. The TUT device has the potential to considerably expand the applications of industrial and clinical ultrasound.

Three-dimensional evaluation of microvascular networks using contrast-enhanced ultrasound and microbubble tracking.

Evaluating tumor microvascular networks with use of contrast-enhanced ultrasound (CEUS) imaging and one-dimensional (1D) linear array transducers have inherit limitations as tumors exist in volume space. The use of a mechanical sweep allows users to overcome this limitation. To that end, we have developed a new method by which a 1D linear array transducer can be mechanically scanned over a region-of-interest to capture a volume of data allowing for the evaluation of microvasculature structures in 3D space. After intravascular injection of a microbubble (MB) contrast agent into a developing chicken embryo, a sequence of CEUS images were acquired using a Vevo 3100 scanner (VisualSonics Inc) and taken at multiple tissue cross-sections. The CEUS images were processed with a singular value filter (SVF) to help remove any clutter signal. MB localization was performed, and frame-to-frame MB movement was analyzed to produce spatial maps depicting blood flow and velocity at each tissue cross-section. Reconstruction of all images allowed visualization of microvascular networks and blood velocity distribution in volume space.

Three Median Relations of Target Azimuth in one Dimensional Equidistant Double Array

Before this paper, the authors have obtained the tangent median relation by using the trigonometric function equation. In this paper, on the basis of the linear positioning solution of one-dimensional equidistant double-base linear array, by proper approximate treatment of the strict solution, and by using the direction finding solution of single base path difference, the sinusoidal median relation of azimuth angle at three stations of the linear array is obtained. By using the sinusoidal median relation, the arithmetic mean solution of azimuth angle at three stations is obtained. All these results reveal the intrinsic correlation between the azimuth angles of one-dimensional linear array.

A New Closed-Form Algorithm for Spatial Three-Dimensional Localization with Multiple One-Dimensional Uniform Linear Arrays

A New Closed-Form Algorithm for Spatial Three-Dimensional Localization with Multiple One-Dimensional Uniform Linear Arrays

Optimized Least Square DOA Estimation Algorithm Based on Phase Interferometer Array

Aiming at the complex process of phase interferometer ambiguity resolution and the strict requirement of baseline comparison, an optimized least square ambiguity resolution algorithm for multi-baseline phase interferometer is proposed. This algorithm is a backward-forward derivation method. First, phase matrix is generated by off-line calculation. Then verify the uniqueness condition of correctly ambiguity resolution, and the angle of arrival (AOA) is solved by criterion function. The algorithm uses the mean square operation instead of the time-consuming cosine function calculation. The algorithm can be applied to the complex array of interferometers and makes the test of the uniqueness condition simpler. Simulation experiments are carried out under the condition of one-dimensional linear array. The result show that the algorithm is effective and has high anti-noise performance.

Generalized L-Shaped Array Based on the Difference and Sum Coarray Concept

L-shaped array (LA) is traditionally used as two one-dimensional uniform linear arrays (ULAs) for two-dimensional direction of arrival (DOA) estimations. With elevation and azimuth angles estimated separately, the detectable source number is strictly limited by the number of elements in the ULAs. To increase the detection ability, in this paper, we propose to exploit the diff-sum co-array (DSCA) concept on the L-shaped array. As such, a virtual element in the quadrants of DSCA can be generated by only one pair of sensors in the LA. Therefore, it can acquire much higher number of degrees of freedom for DOA estimation. To further reduce the redundancy of elements on the horizontal and vertical axes of DSCA, an element moving strategy is proposed. It is proved that the DSCA can remain intact with any one or more physical sensors relocated to the centrosymmetric positions. Based on this strategy, a generalized L-shape array concept and a new configuration referred to as generalized L-shaped array with odd-even locations (GLA-OEL) are developed. For GLA-OEL, the number of sensor pairs with small spacing is as small as one, which dramatically reduces the mutual coupling of adjacent elements. Besides, with the same number of sensors, the GLA-OEL can generate much larger virtual uniform rectangular array in the DSCA. Simulations verify the superiorities of the proposed array in terms of detection performance and estimation accuracy.