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This paper aims to study the effect of eliminating some elements from the original planar array (OPA) to generate a useful flat‐top coverage pattern (FTCP) using a genetic algorithm. The study involves dividing the fully planar array (i.e., OPA) into two regions with an unequal number of elements. The first region includes the elements located in the core (center) of the array, and the remaining elements are the second region, and their location is within the boundary (side) of the array. Only the elements of the first region are included in the optimization process, while the elements of the second region are eliminated in the form of a specific geometric composition without affecting the FTCP generation. Comparing the OPA that N×M elements with the first region (active subarray) elements, it is noted that the number of elements has been reduced from N×M to (N − 2x) × (M − 2y) to reduce the complexity of the system as much as possible without affecting the performance in general. Different boundary subarray shapes are presented in this paper with different numbers of elements. The obtained results showed the effectiveness of the proposed method in generating FTCP close to its counterpart in the OPA. [ABSTRACT FROM AUTHOR]

Summary This paper presents the design and performance evaluation of a single‐layer, high‐gain, millimeter‐wave (mm‐wave), corporate–series‐fed, 16‐element circular patch array antenna tailored for the 28 GHz frequency band, pertinent to fifth‐generation (5G) wireless communication systems. The proposed antenna configuration employs a dual‐port feeding technique, where consecutive junction patches are interconnected with two separate feed networks. By simultaneously exciting the two ports with identical amplitude but opposite phases, the antenna achieves high gain directed towards the broadside. The proposed structure is fabricated on a grounded substrate, enabling accurate performance measurement of the prototype. Close agreement between simulated and measured results validates the precision of the designed structure. The measured performance of the proposed antenna configuration demonstrates an impedance bandwidth of 3.79% within the desired frequency band of 27.6‐28.7 GHz for S11 ≤ −10 dB. Experimental measurements demonstrated that the mutual coupling between the two distinct ports is <−30 dB, with a diversity gain exceeding 9.99 dB. Simulated radiation efficiency exceeds 90% at the 28 GHz center frequency, while the measured peak gain approaches 17.7 dBi. Measured stable radiation plots specify that the proposed array exhibits broadside patterns with half‐power beamwidths (HPBWs) of 30.4° and 11.3°, sidelobe levels (SLLs) below −25 and −10 dB, and cross‐polarization levels <−25 dB in both the E and H planes, respectively. The superior performance characteristics of the proposed array antenna make it well‐suited for 28 GHz mm‐wave 5G applications, facilitating efficient and reliable long‐range communication in the mm‐wave spectrum. [ABSTRACT FROM AUTHOR]

The frequency diverse array (FDA) is a very interesting technique in wireless communications. Many research papers are introduced in this field. A lot of them is concerned with linear point sources array. In this paper, a design of a time-modulated planar frequency diverse array architecture is proposed for tracking single or multi-target for the first time. The time-modulation array (TMA) and FDA are combined for detecting single and multi-target. The effectiveness of this combined scheme is demonstrated through simulation results that compared with a point source case to show its superior performance. Authors introduce planar FDA array instead of linear FDA array and realize the planar array using cylindrical dielectric resonator antenna array (CDRA). A planar array consists of 8 × 8 CDRA is used to enable the detection of single target/multi-target. The operating frequency of the antenna is set at 10 GHz, aligning with its applications in the FDA radar. The radiation characteristics of the CDRA antenna element are introduced. High maximum gain of 6 dBi is achieved with a remarkably high efficiency. A set of representative results is reported and analyzed to assess the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

MIMO (Multiple Input Multiple Output) makes a major contribution to 5G communication systems by increasing network capacity and spectrum efficiency. In 5G, MIMO enables the use of multiple antennas at base stations and user devices, allowing simultaneous sending and receiving of data over multiple paths. This significantly increases data throughput and connection reliability, especially in environments with high user density. In addition, MIMO technology supports the implementation of beamforming, which focuses signals on a specific direction, reduces interference, and improves signal coverage and quality, making it one of the keys to achieving faster and more responsive 5G performance. Therefore, antennas with wide bandwidth, high gain and MIMO performance are crucial for supporting 5G communication systems. This paper proposes a high-performance MIMO microstrip antenna based on a series planar array with 8×2 elements operating at a resonant frequency of 3.5 GHz for 5G communication systems. A spiral stub and a feed inset are proposed to control the reflection coefficient and bandwidth of the antenna while the series planar array is proposed to increase the gain. To support the MIMO communication system, the proposed antenna is separated into two different ports with a certain distance. From the measurement results, the proposed antenna has high performance indicated by a wide bandwidth of 680 MHz (3–3.68 GHz) and a high gain of 17.8 dB at a resonant frequency of 3.5 GHz. In addition, the proposed antenna has high mutual coupling and diversity indicated by ECC and DG of 0.001 and 9.99 dB, respectively. This work provides a solution to design a high-performance microstrip antenna and can be implemented as a receiving antenna for 5G communication systems [ABSTRACT FROM AUTHOR]

This paper presents a microstrip planar antenna array designed for near-field focusing operating at 10 GHz. It is a challenge to reach the phase and amplitude distribution of near-field-focused antenna arrays with small focal spots. The antenna elements of this array are arranged radially on the aperture of only 5.6λ0 × 5.6λ0, which reduces the focal spot diameter. We designed an unequal-amplitude unequal-phase power divider to reach phase distribution and binomial taper distribution. The proposed array suppresses the sidelobes on the focal plane. It increases the electric field intensity by 11.46 dB compared with the horn with the same aperture size and increases 9.42 dB compared with the equal-phase array. The focus spot diameter is only 0.33λ0. The simulated and measured results are in good agreement, which verifies the high performance of the array. This miniaturized high-focus array has a good prospect in near-field applications like wireless energy transmission and industrial detection. [ABSTRACT FROM AUTHOR]

Reducing the number of phase shifters by grouping antenna elements into subarrays has been extensively studied for decades. The number of phase shifters directly affects the cost, complexity, and power consumption of the system. A novel method for the design of phased planar antenna arrays is presented in this work in order to perform a reduction of up to 70% in the number of phase shifters used by the array, while maintaining the desired radiation characteristics. This method consists of creating fusions of subarrays to generate random sequences that form the best feeding network configuration for planar phased arrays. The obtained solution allows scanning the mainlobe at θ=−40∘ elevation with a range of scanning of [−75∘<ϕ<75∘] in the azimuth plane, while maintaining a side lobe level below −10 dB and achieving a reduction of 62% in the number of phase shifters. It is shown that each solution is created based on search criteria, which influence the morphology of the array in terms of subarray size and orientation. The proposed methodology shows great flexibility for creating new phased antenna array designs that meet the requirements of specific applications in a short period of time.

This paper tries to obtain the maximum estimation accuracy of 2‐dimensional Direction of Arrival (2D‐DOA) from the spatial signal resource in the angle approaching the horizon by using the volume arrays pattern synthesizing. For this purpose, the well‐known Multiple Signal Classification (MUSIC) and the algorithm Root Mean Square Deviation (RMSD) are used to investigate 2D‐DOA estimation accuracy. For accurate design of array structure, the antenna elements' radiation pattern have been considered based on the full‐wave simulations along with the mutual coupling and shadow effects. The results show that the volume array structure presented with 13 radiative elements and the two side angles of 30 and 45 degrees has a much better DOA estimation accuracy in all angles especially in angles close to the horizon, compared to the planar array with the same number of radiative elements. Also, at the angle ±90° from broadside the presented volume aperture provides a maximum gain of up to 15.4 dBi, which is much more than the produced gain of planar aperture under the same conditions. [ABSTRACT FROM AUTHOR]

Controlling the vapor-deposited nanoribbons to grow along a consistent orientation will enable the desired in situ integration of functional devices, representing a major technological advance compared to post-growth processing strategies. In this work, n-type F16CuPc molecules are self-assembled into horizontally-oriented nanoribbons with a consistent growth axis after creating periodic hydrophobic nanogrooves on a sapphire surface. Consequently, electrodes are deposited directly on the growth substrate to enable in situ fabrication of photodetectors. Depending on the deposited electrodes, these horizontally-oriented nanoribbons are connected to form a monolithic photodetector with a large sensing area or an on-chip array of photodetectors with multiple detector units. This in situ integration strategy avoids potential structural damage and contamination from impurities associated with post-growth processing steps. Therefore, the vapor-deposited nanoribbons can retain their high quality during the device manufacturing process, which contributes to performance improvement. As a result, the in-situ integrated F16CuPc photodetectors exhibit a sensitive response in the ultraviolet-visible-near-infrared (UV-vis-NIR) region. The response time is on the order of tens of milliseconds, the fastest record ever for the F16CuPc-based photodetectors. Furthermore, statistics from an array of 6 × 6 photodetectors show little variation in their sensitivity and response time, and hence this in situ fabrication scheme will contribute to the implementation of on-chip integrated photodetectors with consistent performance based on bottom-up nanoribbons. Overall, this self-oriented growth provides a versatile option to achieve desired in-situ integrated functional devices based on bottom-up nanoribbons. [ABSTRACT FROM AUTHOR]

A dual-polarized paralle-plate waveguide slot array antenna operating at 24.5 GHz band is proposed in this paper. The radiating panel using a 5mm-thick expanded dielectric substrate ( $\epsilon _{r}=1.12$ ) consists of two orthogonally oriented $20\times 19$ radiating slot arrays, where the slots are positioned collinearly. The centered longitudinal feeding slots are introduced into the feeding waveguides, which offer improved aperture efficiency and higher cross-polarization discrimination (XPD) compared to the conventional tilted feeding slot approach. The antenna achieves a remarkable simulated radiation efficiency of over 95% within the operation bandwidth. A prototype antenna is fabricated and verified through measurements. The measured results demonstrate an impedance bandwidth of 13%, with reflection below -10 dB. Moreover, the antenna achieves a simulated peak aperture efficiency of 54% and a measured peak antenna efficiency of 40%. The measured XPD of the antenna prototype exceeds 26 dB.

In this paper, we present a method for reducing the quantization lobe in a 1-bit beam steering planar array antenna. The method is inspired by reflectarray feeding in such a way that as we move away from the center of the array, the phase becomes more negative. This type of element phasing disturbs the periodicity of the quantization phase error and therefore suppresses the quantization lobe. Each 1-bit antenna element has two phase states (0 and 180°) that are provided through two symmetrical feeding points and are controlled with two PIN diodes. The planar array is fed by a series microstrip line network. One prototype of the proposed planar array with $8\times 8$ elements was fabricated and tested at 3.4 GHz, which showed a measured scan range between −45° and +45° with a maximum quantization lobe level of −9 dB and a gain variation of 1.5 dB. The proposed 1-bit beam scanning antenna has a much simpler feeding network than other planar array antennas. The overall thickness of the proposed array antenna is only $0.045\lambda _{\text {o}}$ , which has a much lower profile than 1-bit reconfigurable reflectarray and transmitarray antennas with the same specifications. This proposed antenna is a usable and suitable candidate for wireless communication applications.

The use of Artificial Intelligence (AI) in electronics and electromagnetics is opening many attractive research opportunities related to the smart control of phased arrays. This is particularly challenging especially in some high-mobility contexts, such as drones, 5G, automotive, where the response time is crucial. In this paper a novel method combining AI with mathematical models and firmware for orientation estimation is proposed. The goal is to control two-dimensional phased arrays using an Inertial Measurement Unit (IMU) by exploiting a feed-forward neural network. The neural network takes the IMU-based beam direction as input and returns the related phase shift matrix. To make the method computationally efficient, the network structure is carefully chosen. Specific and discretized cross-section regions of the array factor (AF) main lobe are considered to compute the phase shift matrices, used in turn to train the neural network. This approach achieves a balance between the number of phase-shifting processes and spatial resolution. Without loss of generality, the proposed method has been tested and verified on $4\times 4$ and $6\times 6$ arrays of 2.4 GHz antennas. The obtained results demonstrate that reconfigurability time, easiness of use, and scalability are suitable for a wide range of high-mobility applications.

This work generalizes the iterative fast Fourier transform (FFT) via least‐square active element pattern expansion method to efficiently synthesize two‐dimensional (2D) patterns with accurate sidelobe and mainlobe shape control for planar arrays with radomes. The 2D active element patterns (2D‐AEPs) of a planar array‐radome structure are utilized to include the mutual coupling and radome effect. The 2D‐LSAEPE method is presented to approximate each 2D‐AEP as the pattern by exciting a virtual rectangular subarray with identical element patterns, and the weighting coefficients of the virtual subarray are found by minimizing the least‐square error of the 2D‐AEP approximation. With the help of the 2D‐LSAEPE, the pattern of a planar array with a radome can be efficiently calculated by FFT. To apply the FFT via 2D‐LSAEPE for planar array pattern computation, a blocked accumulating matrix is introduced which relates the virtual and physical excitation vectors. In addition, an interpolation‐based pre‐processing technique is implemented to obtain the virtual element pattern data in uniform grid of the (u, v)‐space so as to meet the requirement of employing the 2D‐FFT. By integrating the FFT with the 2D‐LSAEPE and the interpolation technique, an efficient iterative method is developed to implement accurate pattern synthesis for planar arrays with radomes. Three examples of synthesizing different planar array‐radome systems are conducted. Synthesis results show that the proposed method achieves much more accurate synthesis result than the traditional FFT‐based technique, while taking much less computation time than some other methods. This verifies the effectiveness of the proposed method. Key Points: An efficient and accurate pattern synthesis method for radome‐enclosed planar antenna arrays in radar applications is presentedIterative fast Fourier transform via two‐dimensional least‐square active element pattern expansion is proposedA blocked accumulating matrix is introduced which relates the virtual and physical excitation vectors [ABSTRACT FROM AUTHOR]

Broadcasting, radar, sonar and space telecommunication systems use phased arrays to produce directed signals to be transmitted at the desired angle. This system requires a large number of antenna elements. The presence of faulty element(s) in an array causes asymmetry, which results in a deformed radiation pattern with higher sidelobe levels. Higher sidelobe levels indicate waste of energy by transmitting and receiving signals in unwanted directions. Hence, it is important to develop a method that detects faulty elements and corrects the radiation pattern. To correct the failed radiation pattern, failed elements in an array must be identified first. There have been various studies conducted on linear array failed radiation pattern correction and the finding of faulty elements, but investigation on the planar array is limited. Further, the optimization suggested for linear arrays does not necessarily work for the planar array. In this study, planar array faulty antenna detection was developed with pattern search (PS), simulated annealing (SA), and particle swarm optimization (PSO) methods by reducing the Signal to Noise Ratio (SNR) as the objective function. The analysis was varied for 8 × 8 and 6 × 6 planar arrays with different types of failures. The results were compared to find the best method to identify the faulty element's location in a planar array. The pattern search method produced outstanding results in finding the faulty element's locations by providing 100% accuracy for all types of failure, while other methods failed to do the same. [ABSTRACT FROM AUTHOR]

Millimeter wave (mm-Wave) wireless technology has invaded every aspect of modern life because of its ability to transmit data quickly and securely. This paper presented a square patch antenna at a resonance frequency of 26.2GHz for millimeter wave wireless communication. The proposed antenna consists of single square radiating element. The suggested antenna was designed using CST Microwave Studio’s version 2020 on a Rogers RO 3003 lossy substrate with a relative permittivity of 3 . The result of this paper shows a minimum S11 of 19.34 dB, a gain of 6.97dBi, with bandwidth of 2GHz at the resonant frequency of 26.2GHz. The gain was enhanced to 16dBi and 25.8dBi with a high radiation efficiency by converting the single element patch antenna to a uniform linear array of 8 elements and uniform planar array of 8 × 8 elements respectively. The simulation results show that despite the simple design of the patch (without holes and cracks), which facilitates manufacturing in a small size; However, it achieves higher gain than the more complex designs found in the previous literature to suit mm wave communication requirements. Also, we used CST Microwave Studio for simulation which provides two methods for implementing arrays: the array factor method, which builds virtual arrays (the direct method), or building arrays by repeating the elements depending on the required size of the array, A comparison has been conducted between the numerical analysis of both methods, and the results show that even though the numerical analysis of the second method gives more accurate results that can be close to a manufactured antenna array, it needs high processing ability and time. Creating arrays with array factor may save time and processing ability but the results may not be accurate. Therefore, a relation was driven to show the error that can be added to give precise results.

Copyright of Journal of South China University of Technology (Natural Science Edition) is the property of South China University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An all-metallic multi-layered parallel-plate slot array antenna operated in the 60-GHz band with wide impedance bandwidth and high-gain characteristics is proposed. The $16\,{\times }\,16$ -slot antenna is composed of $2\,{\times }\,2$ -slot subarrays perpendicularly-fed by a hollow waveguide corporate feeding network. The subarray is partitioned into three functional layers including a bottom one for feeding, a mediate one for radiating and a parasitic one atop for bandwidth enhancement. An undesired resonance of a high-order mode introduced with the parasitic layer is eliminated by loading metal grids between the slotted plates. The contribution of the parasitic layer on bandwidth improvement is verified by a measured 19.2% bandwidth of the antenna with reflection below −10 dB. The removal of the dielectric plate loaded in the conventional double-layered counterpart also contributes to the better performance of the array. The all-metallic feature exempts the design from dielectric loss and beneficial for realizing a higher gain. A high aperture efficiency over 90% is realized over a 19.3% bandwidth and an antenna efficiency over 70% is obtained over a 18.5% bandwidth for the fabricated prototype antennas. The measured realized gain is up to 33.2 dB and the antenna efficiency is 87.2% at 62.0 GHz.

In fifth-generation (5G) communication systems, the mm-wave (millimeter-wave) frequency band is a key aspect in overcoming the exponential increase in data traffic of the existing cellular networks, which requires compatible and low-profile antenna arrays. In this case, a microstrip patch antenna (MPA) is a viable option. However, MPA has certain limitations, such as the deterioration of the antenna’s bandwidth and radiation efficiency with its substrate thickness. In addition, its gain and directivity are too low to meet the 5G systems requirements in beamforming techniques of massive MIMO systems. Thus, to ameliorate these limitations, in this paper, a microstrip patch antenna arrays (2x2, 4x4, and 8x8) with semi-elliptical shape slotted patch and etched ground structure for 5G broadband applications is proposed. The radiator element of the antenna is designed using Rogers 5880 substrate with a dielectric constant of 2.2 and thickness of 0.3449 mm. It has been designed to operate at 28 GHz in LMDS (local multipoint block distribution service) band. The performance of the proposed structure was analyzed using the CST-MW simulator. The simulation results reveal that the gain, bandwidth, and total efficiency of the studied 2x2, 4x4, and 8×8 MPA arrays are 13.24 dBi, 16.54 dBi, 21.45 dBi; 1.33 GHz, 1.461 GHz, 1.561 GHz; 97.03 %, 81.72 %, 69 %, respectively. Likewise, the return losses of these structures are −43.321 dB, −40.665 dB, and −22.678 dB, respectively. In general, all of the proposed planar semi-elliptical slotted rectangular MPA arrays offer improved performance compared to existing works and meet the requirements of 5G systems’ antennas.

Unmanned aerial vehicle (UAV)-enabled backscatter communications (BackComm) is deemed to be a vital technique enabling the data transmission over massive battery-less devices for Internet of Things (IoT). However, the UAV-enabled Backcomm suffers from information leakage due to the broadcasting nature of wireless channels. To cope with the security issue, in this paper, a UAV-enabled multi-user secure BackComm system is developed using analog beamforming (ABF) and randomized continuous wave (RCW) techniques, where the multiple users are supported by the multi-carrier RCW over a single low-complexity radio frequency (RF) chain. By exploiting the RCW transmitted towards backscatter, the eavesdropping link can be eroded without any specific jamming signals. The closed-form of the secrecy rate is studied with the approximations, which is then maximized by jointly optimizing the beamforming together with the UAV’s location and the RCW settings. Simulation results are carried out to confirm the accuracy of the proposed approximation, while the convergence behavior of the optimization algorithm is analyzed. As a result, it can be shown that the secrecy rate can be significantly improved compared with the benchmark schemes. [ABSTRACT FROM AUTHOR]

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 prespecified 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. [ABSTRACT FROM AUTHOR]

A cavity antenna array with low-profile and favorable aperture efficiency for Ku-band mobile satellite communication applications (10.9–12.5 GHz) is presented in this letter. Key features are the much reduced loss of the feed network and miniaturized aperture size of the array element, and therefore, the high aperture efficiency of the array. The antenna element operates under an odd mode of a fundamental frequency, miniaturized by about a half compared with the conventional cavity antenna. The waveguide-microstrip (WG-MS) hybrid network is employed for the element feeding. Especially, a corners-shorted patch and stepped-length slot are introduced in the WG-MS transition for better transmission, lowering the loss by about 20% according to simulation. For verification, an antenna array is implemented and tested. The results show aperture efficiency up to 86.1% and a maximum gain of 28.8 dBi in the operation band. Besides, this array achieves a wide bandwidth from 10.5 to 13 GHz (20.8%) based on the standard of voltage standing-wave ratio (VSWR) $< 2$ , entirely covering the desired band of 10.9–12.5 GHz. [ABSTRACT FROM AUTHOR]

In adaptive beamforming by compact arrays, the excitation amplitude and phase of each array element require dynamic optimization for controlling the radiation pattern at different angular sectors. If the objective function of adaptive beamformer is defined by some properties other than the deterministic properties of arrays such as directivity or signal-to-noise ratio, evolutionary optimization is advantageously implemented to minimize the objective function. Nevertheless, the convergence time of most of the evolutionary optimization methods exponentially increases by the number of array elements $N$. For large $N$ , the above convergence issue slows down the beamforming agility. To improve the above inefficiency, we first express the array factor by a Schelkunoff polynomial of order $N - 1$. Second, a discrete optimization method like genetic algorithm optimally factorizes the polynomial into two polynomials of orders $N - 1 - P$ and $P$ , where $N - 1 - P \ge P$. Third, the locations of zeros of these polynomials are optimized across the visible region by a continuous optimization method like particle swarm optimization to attain the desired objective function. When these two polynomials are multiplied, the resultant polynomial of order $N - 1$ demonstrates improved features with respect to the original polynomial of order $N - 1$ in sensitivity, sidelobe level, and convergence. Representative examples include airborne radars. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Broadcasting, radar, sonar and space telecommunication systems use phased arrays to produce directed signals to be transmitted at the desired angle. This system requires a large number of antenna elements. The presence of faulty element(s) in an array causes asymmetry, which results in a deformed radiation pattern with higher sidelobe levels. Higher sidelobe levels indicate waste of energy by transmitting and receiving signals in unwanted directions. Hence, it is important to develop a method that detects faulty elements and corrects the radiation pattern. To correct the failed radiation pattern, failed elements in an array must be identified first. There have been various studies conducted on linear array failed radiation pattern correction and the finding of faulty elements, but investigation on the planar array is limited. Further, the optimization suggested for linear arrays does not necessarily work for the planar array. In this study, planar array faulty antenna detection was developed with pattern search (PS), simulated annealing (SA), and particle swarm optimization (PSO) methods by reducing the Signal to Noise Ratio (SNR) as the objective function. The analysis was varied for 8 × 8 and 6 × 6 planar arrays with different types of failures. The results were compared to find the best method to identify the faulty element’s location in a planar array. The pattern search method produced outstanding results in finding the faulty element’s locations by providing 100% accuracy for all types of failure, while other methods failed to do the same.

The modular design of planar phased arrays (PAs) arranged on orthogonal polygon-shaped apertures is addressed and a new method is proposed to synthesize domino-tiled arrays fitting multiple, generally conflicting, requirements. Starting from an analytic procedure to check the domino-tileability of the aperture, two multi-objective optimization techniques are derived to efficiently and effectively deal with small and medium/large arrays depending on the values of the bounds for the cardinality of the solution space of the admissible clustered solutions. A set of representative numerical examples is reported to assess the effectiveness of the proposed synthesis approach also through full-wave simulations when considering nonideal models for the radiating elements of the array. [ABSTRACT FROM AUTHOR]

Direction finding in bistatic multiple-input multiple-output (MIMO) radar system is an important issue in target localization. Existing works focus on linear array which can only find 1-D angle information. In this paper, we focus on bistatic MIMO radar where both the transmitter and receiver are equipped with uniform planar arrays (UPAs) which can find full angle information of targets. To overcome the gridding effect, we use atomic norm minimization (ANM) to formulate a gridless model which is equivalent to a semidefinite programming (SDP). By solving the SDP we can obtain the angle estimates without discretizing the 4-D angle space. An alternating direction method of multipliers (ADMM) based implementation is also derived to reduce the computational complexity of the proposed method. Simulation results show that our proposed method can break through the gridding limitation to achieve a high estimation accuracy while enjoying low computational complexity. [ABSTRACT FROM AUTHOR]

In this article, a novel beam shaping technique is developed to synthesize the array factor (AF) radiation pattern of linear and planar antenna arrays. The proposed method is established based on the expanding of AF using Legendre transform in conjunction with an integrand operator. A system of linear equations is derived and its solution is obtained using least-square method (LSM) for the required pattern. In addition, an iterative procedure is introduced to reduce the number of elements of the primary designed array for a specified mean square error (mse). Then, the proposed method is applied to synthesize the AF of planar and ring antenna arrays. To verify the performance of the proposed method, a few comprehensive well-known linear, planar, and ring arrays are examined. The obtained results show that the introduced method can be used to design the AF pattern of many types of practical arrays with good accuracy. [ABSTRACT FROM AUTHOR]

Summary: A novel synthesis method to reduce the maximum side lobe in the entire azimuth plane and for achieving a desired value of directivity of a concentric elliptical array antenna is addressed in this paper. Three well‐performing meta‐heuristic optimization algorithms, teaching learning‐based optimization (TLBO), symbiotic organism search (SOS), and quantum particle swarm optimization (QPSO), are employed to optimize the cost function and to obtain the desired radiation pattern. Different simulation‐based experiments are performed to obtain the best possible set of angular positions and the distribution of isotropic antennas across the ellipses by rigorously maintaining non‐overlapping constraints. The major benefit of the proposed design is the deprecation of interference in all phi planes. The statistical analysis of the simulation results demonstrate perceptible improvement compared with that of a uniformly spaced concentric elliptical array and hence show the efficiency of the proposed algorithms. In both simulation studies, the results obtained using TLBO, SOS, and QPSO are compared. Analysis of the results exhibits that for the stated objective, the TLBO‐ and SOS‐based side lobe reduction approach performs superior to QPSO method. Proposed multi‐objective research work could lead to reduce payload and can simultaneously achieve isoflux coverage in entire azimuth plane on the earth surface which can essentially be utilized in (Low Earth Orbit) LEO and (Geostationary Earth Orbit) GEO satellites applications. [ABSTRACT FROM AUTHOR]

This paper introduces the design of an aperiodic beam steerable planar array antenna using a novel strip-projection (SP) method, offering the reduced array elements with improved peak SLL with beam scan. The SP method generates the aperiodic lattice by projecting a section of the 3D body-centric tetragonal lattice onto the aperture and rotating it using Rodrigue's formula. The optimized lattice parameters are obtained using Jaya algorithm. The proposed SP method requires only three optimization parameters for any aperture dimensions and 21.9% less elements as compared to the rectangular lattice. For comparison, pinwheel-based aperiodic planar array antenna has been designed and analyzed. The peak SLL is maintained <−11.63 dB and <−12.70 dB for 0°-30° beam scan by proposed array and pinwheel-based array respectively. Both types of aperiodic lattice have been populated with S-band dielectric resonator antenna and simulated. Position standard deviation has also been introduced and computed to quantify the aperiodic distribution. [ABSTRACT FROM AUTHOR]

This paper presents the capabilities of an $8\mathrm {\times }8$ Rectangular Dielectric Resonator Antenna (RDRA) planar array with broad bandwidth and high gain. To improve shielding of a multi-stage feeding network, the proposed array is designed using a stripline feeding network with two different substrates. To enhance impedance matching while keeping a sufficient F/B ratio of 20 dB, the lower ground of the stripline has a smaller dimension than the upper ground plane. The proposed array covers the frequency band from 3.79 to 6.29 GHz with 50% fractional bandwidth. The peak realized gain ranges from 18 to 22 dBi, with 85% of radiation efficiency throughout the frequency of interest. The overall size and weight of the array is $215\mathrm {\times } 215 \mathrm {\times }14.5$ mm3 and 650 g, respectively. Furthermore, the radiation patterns appear as low as 15 dB of peak-to-side lobe level with 25 dB cross polarization level, which makes the proposed array suitable for UAS (Unmanned Aerial System) radar applications. The measurements and simulations agree considerably.

This article presents an innovative design technique for feeding phase antenna arrays using coherently radiating periodic structure (CORPS) technology for reducing the number of phase shifters (PSs) in limited-scan applications with low sidelobe level (SLL). The proposed configuration is implemented taking advantage of the phase interpolation property of a CORPS network of one layer. This configuration is built by interconnecting $2\times 3$ CORPS networks in a strategic way in order to provide a reduction in the number of PSs while maintaining the scanning capability. Experimental results and full-wave simulations based on CST Microwave Studio reveal that the proposed design technique reduces the recombination losses and generates a better phase slope with respect to the basic CORPS network providing a reduction in the number of PSs. As a novel contribution, this article provides the full antenna system design in order to analyze and study the PSs reduction performance and scanning capabilities of the proposed technique to feed linear antenna arrays. The proposed design technique provides a reduction in the number of PSs for a scanning range of ±25° in linear arrays. The array design model includes the application of the raised cosine amplitude distribution to generate a radiation pattern with minimum SLL. The linear array system was validated by experimental measurements of the full system prototype and full-wave simulations results are provided to verify the accuracy of the array model and to take mutual coupling into account. The proposed case provides a good design compromise with respect to other cases in the state of the art. [ABSTRACT FROM AUTHOR]

In fifth-generation (5G) communication systems, the mm-wave (millimeter-wave) frequency band is a key aspect in overcoming the exponential increase in data traffic of the existing cellular networks, which requires compatible and lowprofile antenna arrays. In this case, a microstrip patch antenna (MPA) is a viable option. However, MPA has certain limitations, such as the deterioration of the antenna’s bandwidth and radiation efficiency with its substrate thickness. In addition, its gain and directivity are too low to meet the 5G systems requirements in beamforming techniques of massive MIMO systems. Thus, to ameliorate these limitations, in this paper, a microstrip patch antenna arrays (2x2, 4x4, and 8x8) with semi-elliptical shape slotted patch and etched ground structure for 5G broadband applications is proposed. The radiator element of the antenna is designed using Rogers 5880 substrate with a dielectric constant of 2.2 and thickness of 0.3449 mm. It has been designed to operate at 28 GHz in LMDS (local multipoint block distribution service) band. The performance of the proposed structure was analyzed using the CST-MW simulator. The simulation results reveal that the gain, bandwidth, and total efficiency of the studied 2x2, 4x4, and 8×8 MPA arrays are 13.24 dBi, 16.54 dBi, 21.45 dBi; 1.33 GHz, 1.461 GHz, 1.561 GHz; 97.03 %, 81.72 %, 69 %, respectively. Likewise, the return losses of these structures are −43.321 dB, −40.665 dB, and −22.678 dB, respectively. In general, all of the proposed planar semi-elliptical slotted rectangular MPA arrays offer improved performance compared to existing works and meet the requirements of 5G systems’ antennas. [ABSTRACT FROM AUTHOR]

This paper addresses a mathematical formulation to determine the radiation performance of an acoustic beamforming array, which is valid for both near-field and far-field regions. The developed beamforming analysis is generic for application to any array configuration, with the array elements having a radiating aperture of canonical contours. The beamforming analysis presented in this paper for the acoustic transducer array is obtained by the process of vector summation of radiated fields from the elements of the acoustic transducer array with an array factor and beam steering phase factor. The initial validity of the beamforming analysis is examined by considering the far-field region as a particular case of the near-field region with the relevant distance criterion. The numerous simulation studies presented in this paper show that the proposed method produces excellent results with the distinct structure of sidelobes at a distance RNF ≥ 0.5D²/λ from the acoustic aperture of (7 x 1) linear and (7 x 7) planar array of acoustic transducers. If the distance between the transducer array and the point of observation is very low (RNF < 0.5D²/λ), simulation results indicate a less directive main beam. The two-dimensional near field beam steering method proposed in this paper finds the significant utility in many practical applications such as Underwater Acoustic Imaging (UAI) systems and Underwater Acoustic Communication (UAC). [ABSTRACT FROM AUTHOR]

In next-generation mobile networks, hundreds of diverse devices aim to be interconnected, posing huge challenges in capacity, coverage, efficiency, reliability, and connectivity. These and other challenges are addressed at Radio Frequency (RF) parts such as several radiating unit antennas, with very fine beamforming capabilities along with the requirements of high gains and minimized size. This work presents an 8×8 Aperture Coupled Microstrip Patch Antenna (AC-MPA) in the form of a planar array modeled for the 28GHz frequency band with high gain and compact size, making it suitable for 5G networks. The antenna is designed using a substrate with overall dimensions of 74.6×85.648×0.107mm³ and relative permittivity of ε0 = 4.3. [ABSTRACT FROM AUTHOR]

This letter presents a planar endfire Yagi-Uda antenna phased array fed by a corporate network. The phase of each radiating element is controlled by a loaded line phase shifter based on liquid crystal technology. The phase shifters are meandered to minimize the dimension of the array and are measured to provide maximum differential phase shift of 400 ${^\circ }$ with a figure-of-merit of ${54}{{^\circ }\rm {dB}^{-1}}$ at 28.4 GHz. Each phase shifter is tuned individually by applying bias voltage through high impedance chromium line together with dc blocks. The array is designed for full-range scanning in E-plane with $>\!{360}{^\circ }$ phase shifters. Measurements show that it can be steered from −40 ${^\circ }$ to 40 ${^\circ }$ by applying dc bias in the range of 0–5 V and from −50 ${^\circ }$ to 60 ${^\circ }$ with degraded patterns. The maximum gain of the phased array antennas is measured to be 4.5 dBi. The array beam is able to be fast steered within approximately 1 s. [ABSTRACT FROM AUTHOR]

Phased arrays are widely used in different fields, such as broadcasting, radar, optics, and space communications. The principle of phased arrays is to generate a directed signal from a large number of antennas to be steered at any desired angle. This, however, increases the probability of defective elements in an array. Faulty elements in an array cause asymmetry and result in increased sidelobe levels which rigorously distort the radiation pattern. Increased sidelobe radiation wastes energy and can cause interference by radiating and receiving signals in unintended directions. Therefore, it is necessary to find a method that can provide accuracy in the radiation pattern transmitted or received in the presence of failed element(s) in an array. This paper compares the few available optimization methods, namely, simulated annealing (SA), Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and Pattern Search (PS) methods. For each method, various types of failures were examined, and the most suitable techniques to recover the far-field radiation are recommended. The optimization is then carried out by selecting the optimal weights of the remaining working elements in the planar array. The optimized radiation pattern's efficiency was evaluated by comparing the Signal to Noise Ratio (SNR) value of the optimized radiation with reference and failed radiation patterns. The PSO method showed a better performance compared to all the other methods in reducing the failed radiation pattern's SNR value. In various types of failure tests, this method reduced the failed radiation pattern's SNR from 1 to 10 dB. This method also successfully produced a radiation pattern that closely matches the reference pattern before any failed element(s) are presented in the array. The life cycle of a planar array system with faulty elements can be increased by optimizing the remaining active elements in the array with the PSO method. It also reduces the cost of restoring and replacing the failed elements in an array regularly. This approach also prevents near-field measurement that requires complicated processes using costly equipment. [ABSTRACT FROM AUTHOR]

A fully integrated 28 GHz, 5G mmWave microstrip phased array antenna on a multilayer substrate is presented. The proposed 8 × 8 array provides independently steerable, simultaneous multiple beams in any arbitrary azimuth, elevation angles with equal or unequal peak gains. A computation method is proposed to calculate the weights required to generate multiple beams. Multiple beams (up to six) over various arbitrary angles are generated using the proposed method and the results are presented. The inherent amplitude and phase variations due to the hardware impairments are independently captured through simulation and measurements, and their impact on the performance of the phased array is analyzed. Measured results are compared with simulations for single, dual, and multiple beams over arbitrary angles. The phased array performance is measured and presented over ± 35 ∘ and ± 25 ∘ scan angles in azimuth and elevation planes respectively over 400 MHz bandwidth for both single and dual beam deployment. The proposed multibeam computation method is validated with measurements at 28 GHz for a dual beam case, ( θ = 25 ∘ , ϕ = 0 ∘ ) and ( θ = 25 ∘ , ϕ = 180 ∘ ) in azimuth plane for equal and unequal power beams with a side lobe level of better than 17 dB. [ABSTRACT FROM AUTHOR]

A scalable planar 2-D active array antenna configuration that can realize amplified radiation through co-existing active devices is proposed, studied, and demonstrated in this work. The input and output of these amplifying active devices are directly integrated with the feed network and array elements, respectively, thereby eliminating the matching networks typically required in an amplifier circuit. A comprehensive analysis of the rectangular patch antenna (RPA) performance with different feeding techniques is initially analyzed and the choice of nonradiating edge feed RPA as array elements is justified for not only realizing the maximum radiation efficiency but also facilitating the direct active device integration. Subsequently, a physical arrangement of these array elements is devised to reduce cross-polarization. The design of $4\times {2}$ active array antenna unit cell operating at 5.8 GHz is then discussed through extensive analysis of active devices, optimization procedure, potential excitation signal control, and influence of faulty transistors. From simulations, this active array scheme has realized a higher matching bandwidth and exhibited an amplifier gain of around 13.6 dB, compared with its passive counterpart. Eventually, these unit cells are integrated through an equal power hybrid feed network for realizing an $8\times {8}$ active array antenna configuration that is fabricated and measured. The measured results of the experimental prototype match reasonably well with the simulation results, thereby confirming the proposed integration technique. The resulting paralleled configuration promises efficient handling of greater powers, making them suitable for high-power applications. [ABSTRACT FROM AUTHOR]

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The analysis of scanning range for both planar and circular array antenna in 5G application is presented in this research paper. Radiation pattern and scanning angle range of these antenna arrays and enhanced for RF receiver front-end application. A single array consists of various subarrays which represents vertical and horizontal linear arrays of radiators. These radiating elements have prescribed magnitude and phase distribution. They determined the range and shape of radiation pattern in both vertical and horizontal directions. Analysis of directive properties and range of scanning angle of those arrays shows that for small base stations, adaptive arrays with 5 subarrays, the circular configuration is more preferred as compared to planar array, because planar configuration has limitation with scanning angle 120°. Due to different geometry with some degree of curvature, circular configuration allows the beam steering in wider angular range up to 150°. It has wider beam and less directivity as compared to planar array. [ABSTRACT FROM AUTHOR]

Nowadays, the biomolecular assay platforms built-up based on bead counting technologies have emerged to be powerful tools for the sensitive and high-throughput detection of disease biomarkers. In this mini-review, we classified the bead counting technologies into statistical counting platforms and digital counting platforms. The design principles, the readout strategies, as well as the pros and cons of these platforms are introduced in detail. Finally, we point out that the digital bead counting technologies will lead the future trend for the absolute quantification of critical biomarkers, and the integration of new signal amplification approaches and routine optical/clinical instruments may provide new opportunities in building-up easily accessible digital assay platforms.

A cascaded neural network approach has been presented in this paper to estimate the excitation for the desired field distribution using a radial basis function neural network (RBFNN). The article has employed an electromagnetic design example consisting of 5 × 5 and 6 × 6 planar antenna array of isotropic sources with inter element‐distance of 0.5λ to show the adaptation of the neural network model in estimating the desired output. A neural network is trained using a dataset of suitable excitation voltages and its corresponding radiation patterns, which proves to be efficient in predicting the excitation voltages required to generate the desired pattern. A set of techniques based on a cascaded neural network is adopted for pattern synthesis using magnitude and phase, magnitude only, and template‐based input data. The robustness of the method has also been tested by considering noise with different SNR levels. The results found in each case have a close fit with the desired pattern. [ABSTRACT FROM AUTHOR]

A novel 2×2-element corporate-feed horn sub-array antenna for the 77-GHz band is proposed in this paper. The stair-stepping horn is employed instead of a traditional pyramid horn to reduce the profile of the array. A set of composite structure composed of waveguide divider and cavity is designed and fabricated integrally with a computer numerical control milling technique to simplify the feed-network. Most of all, a metallic cross bar with the wall is innovatively loaded to reduce the mutual coupling and suppress the side lobe level of the sub-array. Measured results show that the proposed antenna achieves a -10 dB |S11| with a bandwidth of 72-85 GHz which is corresponding to 16.6%. Moreover, the average gain of the antenna is about 19 dB, and the side lobe level of the antenna is less than -9.3 dB within the working band.

This article presents a fully planar ultrawideband wide-angle scanning tightly coupled array. A tightly coupled element, which has a low input resistance, is used as the basic array element. The element can be fed by a simple microstrip-to-coaxial transition, obviating the need for an additional impedance transform structure. To improve the scan performance of the array in both the E- and H-planes, a polarization-sensitive frequency-selective surface (FSS) structure, whose effective dielectric constant for the TM mode incidence wave and TE mode incidence wave can be changed, respectively, by different structural parameters, is designed to serve as the wide-angle impedance matching (WAIM) layer. The FSS structure is printed on the superstrate dielectric directly without an additional dielectric layer, resulting in a low-cost array. The proposed array can work in 3.7:1 bandwidth with voltage standing wave ratio (VSWR) < 3 for E-plane scanning up to 75° and H-plane scanning up to 60°. Based on the designed unit cell, an $11\times11$ prototype is fabricated and measured. The measured results of the fabricated array show good agreement with simulations, proving the feasibility of the design. [ABSTRACT FROM AUTHOR]

A series-fed millimeter-wave (mm-wave) microstrip linear array with single-layer structure and wide operating bandwidth is proposed and investigated. The antenna array simply consists of a microstrip line and a series of short stubs that are periodically introduced on one edge of the microstrip line, at an interval of about one guide wavelength. Owing to the perturbation of the additional stubs, the original symmetrical E-field distributions on the two opposite edges of the microstrip line become asymmetrical, and the intensities of the equivalent magnetic currents are unequal and unable to cancel each other out as in a pure microstrip line. As a result, the stub-loaded microstrip line can radiate effectively, producing broadside radiation patterns. The introduction of stubs can also generate an extra resonant mode, which combines with the resonant mode of the microstrip line, yielding a wide bandwidth of over 20%. In addition, the microstrip array is simply fed by a coaxial probe, without involving any complex feeding network. Therefore, the array configuration is very simple and compact. For demonstration, a $1 \times 4\,\,1$ -D microstrip linear array operating at 27 GHz is fabricated and tested. The measured results show that the array has an impedance bandwidth of 21.40%, an average realized gain of 12.18 dBi, and a first sidelobe level (FSLL) of about −13 dB. Moreover, the FSLL can be decreased to −28.4 dB by tapering the width of the microstrip line. Finally, the design is extended to realize a $4 \times 4\,\,2$ -D microstrip planar array. This planar array can achieve an impedance bandwidth of 19.15% and an enhanced gain of 18.30 dBi. [ABSTRACT FROM AUTHOR]