Search

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]

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]

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]

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]

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]

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 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]

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]

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]

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]

In this article, a densely integrated and unified paralleled amplifier and antenna architecture is proposed and demonstrated for next-generation millimeter-wave (mmW) and terahertz (THz) front-end modules. It makes use of topologically paralleled transistors cohabitated within a compact rectangular patch antenna (CRPA) as a unified cell. This design simultaneously amplifies and radiates power without resorting to any power divider, input and output matching networks, or power combiner whatsoever, therefore, greatly reducing front-end loss, size, and complexity. Then, the unified unit cell is self-consistently distributed to form a unified planar array with active elements between array elements as power feeders. In this demonstration, the input power is sequentially amplified, radiated through each array element, and spatially added up, resulting in low on-board circuit losses and efficient radiation. In this article, we investigate and present challenges and early results of implementing this unification concept of active circuitry and antenna at mmW frequencies. Using a standard 65-nm CMOS process, a set of chips were designed, fabricated, and tested under different amplifier biasing conditions at 146 GHz for experimental demonstration. The realized low-loss, matched, and compact unified prototypes have demonstrated an amplified radiation, with power enhancement of 3.4 dB through single element and 6 dB through $2 \times 2$ layout compared to their respective passive counterparts. Moreover, frequency tuning is observed varying drain bias and self-matching is improved with increasing gate bias. Therefore, the feasibility of a unique feature in the architectural implementation of low-loss, compact, and densely integrated and topologically cohabitated mmW and THz front-end modules is confirmed. [ABSTRACT FROM AUTHOR]

In this article, a $7\times 7$ reconfigurable reflectarray operating at X- band is proposed and experimentally verified. The reflectarray consists of linearly polarized, dual-resonance, tunable unit cells fabricated on a single layer. Reconfigurability is achieved by loading each dual-resonance unit cell with four varactors; the two resonances provide a phase range greater than 360°. The unit cell design utilized in this reflectarray is analyzed using full-wave Floquet simulations. A biasing network supporting individual biasing of each array element is designed, allowing beamsteering in E-, H-, and diagonal planes. The proposed reflectarray is evaluated using both full-wave simulations and measurements. To facilitate measurements, a fused filament deposition 3-D printer is used to fabricate an antenna mounting fixture using micrometer stages to make fine adjustments for the final alignment. A measured gain of 15.03 dBi, 3 dB gain fractional bandwidth of 7.81%, and continuous beam scanning are demonstrated in multiple planes from −50° to +50° at 10.1 GHz. [ABSTRACT FROM AUTHOR]

The tool setting technology by laser diffraction is a method of evaluating the tool setting precision by detecting the distance between the light intensity peak points of the first order diffraction fringes formed on the charge-coupled device (CCD). In order to solve the problem that the planar array CCD has low detection accuracy due to the limitation of sampling density during conventional imaging. The sampling density of the tool setting diffraction image is improved by using the planar array CCD staggered imaging technique in this paper, detailed methods are as follows: The single planar array CCD is integrally shifted by the combination of the nano-lifting platform and the high precision two-dimensional (2-D) translation stage, is used to image the tool setting gap with a certain object distance. And then, four diffraction-strip images with complementary information are obtained, which we can use to stitch the image information according to the translocation relationship between each image, and finally a higher resolution diffraction image is obtained. Through detecting the distance between the light intensity peak points of the first order diffraction fringes of higher resolution diffraction image, the detection precision of the tool setting gap of laser diffraction is improved 50 to 70 µm. The results indicate that the detection precision of tool setting gap can be improved effectively by increasing the image sampling density with the planar CCD staggered imaging technology. [ABSTRACT FROM AUTHOR]

The design of isophoric phased arrays composed of two-sized square-shaped tiles that fully cover rectangular apertures is dealt with. The number and the positions of the tiles within the array aperture are optimized to fit desired specifications on the power pattern features. Toward this end, starting from the derivation of theoretical conditions for the complete tileability of the aperture, an ad hoc coding of the admissible arrangements, which implies a drastic reduction of the cardinality of the solution space, and their compact representation with a graph are exploited to profitably apply an effective optimizer based on an integer-coded genetic algorithm. A set of representative numerical examples, concerned with state-of-the-art benchmark problems, is reported and discussed to give some insights on the effectiveness of both the proposed tiled architectures and the synthesis strategy. [ABSTRACT FROM AUTHOR]

The modular design of planar phased array antennas with hexagonal apertures is addressed by means of innovative diamond-shaped tiling techniques. Both tiling configuration and subarray coefficients are optimized to fit user-defined power-mask constraints on the radiation pattern. Toward this end, suitable surface-tiling mathematical theorems are customized to the problem at hand to guarantee optimal performance in case of low/medium-size arrays, while the computationally hard tiling of large arrays is yielded thanks to an effective integer-coded GA-based exploration of the arising high-cardinality solution spaces. By considering ideal as well as real array models, a set of representative benchmark problems is dealt with to assess the effectiveness of the proposed architectures and tiling strategies. Moreover, comparisons with alternative tiling architectures are also performed to show to the interested readers the advantages and the potentialities of the diamond subarraying of hexagonal apertures. [ABSTRACT FROM AUTHOR]

A novel dual-polarized crossed slot planar array antenna is presented in this communication. The proposed design integrates the antenna array with the feeding networks on a single laminate. The antenna element is developed by using a TE210 and TE120 mode cavity, which is constructed by inserting a number of metalized posts around the crossed region of two perpendicular substrate integrated waveguides (SIWs). The crossed slot is etched over the cavity and is excited from two orthogonal directions to realize dual-polarization. Owing to the orthogonality between the TE210 and TE120 mode, high isolation and low cross-polarization are achieved. A prototype of the designed antenna array operating at 25 GHz is fabricated and measured. The measured results confirm that the presented array antenna has high port isolation (>41 dB), high cross-polarization discrimination (XPD) (>26 dB), and high aperture efficiency (40%). With the advantages of simple configuration, good radiation performance, and easy fabrication, this proposed array antenna is a good candidate for millimeter-wave wireless systems. [ABSTRACT FROM AUTHOR]

Linear arrays along radiating (E-plane) and nonradiating (H-plane) edges are designed for broadside radiation pattern at 5.8 GHz using U-shaped series- and corner-feed configurations, respectively. U-shaped feedlines are used to reduce the interelement spacing and size of the array. A 25-element radiating edge linear array provides 19.9 dBi gain with sidelobe level (SLL) and cross polar (X-pol) level of less than −15.3 and −33.8 dB, respectively. Nonradiating edge linear array is designed up to 31 elements using the corner-feed configuration to achieve 18 dBi gain with SLL and X-pol level of less than −15.2 and −22.5 dB, respectively. Furthermore, a planar array is designed using the series and corner feeds in E- and H-planes. A $15 \times 15$ -element array is designed to achieve 24.4 dBi gain with SLL and X-pol level of less than −14.7 and −18.8 dB, respectively, in both the E- and H-planes. This array eliminates the need of complex-, multilayer-, and lossy-feed network and improves SLL and X-pol level. A planar array of $9 \times 9$ elements is fabricated, and the measured results are in agreement with the simulated results. [ABSTRACT FROM AUTHOR]

We consider the problem of two-dimensional (2D) direction of arrival (DOA) estimation for planar array, and propose a successive propagator method (PM)-based algorithm. The rotational invariance property of the propagator matrix is exploited to obtain the initial angle estimations, while the accurate estimates can be achieved through successive one-dimensional and local spectrum-peak searches. The proposed algorithm can obtain automatically paired 2D-DOA estimations, and it requires no eigenvalue decomposition of the covariance matrix of received data, which remarkably reduces the computational cost compared with traditional 2D-PM algorithm. In addition, the DOA estimation performance of the proposed algorithm is better than estimation of signal parameters via rotational invariance technique (ESPRIT) algorithm and PM algorithm, and is close to 2D-PM algorithm which requires 2D spectrum-peak search. Numerical simulations demonstrate the effectiveness and improvement of the proposed algorithm. [ABSTRACT FROM AUTHOR]

A practical implementation of wideband and wide-scanning cylindrically conformal phased array is presented in this communication. First, the design of a dual-polarized planar array is introduced in advance. Then, as a preliminary performance investigation of a conformal phased array, a single-polarized array element counterpart is developed from the dual-polarized planar array with simple modifications. Finally, a conformal array is implemented using the $8 \times 8$ single-polarized radiating elements that are axially mounted onto a cylindrical surface with a radius of 150 mm. A conformal array prototype is fabricated and measured. The experimental results demonstrate that the array achieves active VSWR less than 3.0 over a bandwidth of 6–18 GHz (3:1), within a wide-scanning range of ±60° in two principal planes. The measured results are in good accordance with the simulations, thus validating the performances of the proposed wideband and wide-scanning cylindrically conformal phased array. [ABSTRACT FROM AUTHOR]

We use a genetic algorithm to minimize the relative sidelobe level (RSLL) of a dual polarized concentric ring array. The optimization variables are the placement of uniformly weight spiral antennas in an aperture with a small area. We optimized a cost function with isotropic sources instated of spiral elements to make the cost function reasonable to evaluate. We developed approaches to calculate a faster cost function and reduce the number of function calls in the optimization. We then calculated the array with an approximation of the element pattern to evaluate its performances. [ABSTRACT FROM AUTHOR]

The requirements for circularly polarized (CP) phased array antennas are growing with the rapid development of electronic systems. To achieve a low-profile, wideband, and large scanning-angle CP, we constructed a novel CP unit cell with a two-layer folded coupling patch and a top-loaded patch. The design of the folded coupling patch was based on the principle of reverse current cancellation. Compared with the single-layer coupling patch, the folded coupling patch suppressed the occurrence of strong in-band resonance and obtained a wider axial ratio (AR) bandwidth. To solve the problem of AR performance deterioration in the D-plane scanning, we introduced the top-loaded patch to replace the thick wide-angle impedance matching layer, which improved the difference in co-polarization components and reduced cross-polarization level. Thus, a large scanning angle of more than 60 ° in the D-plane was obtained. An 8 × 8 planar array based on the proposed CP unit cell was designed. The array achieved a 3.9:1 (3.2–12.5 GHz) AR bandwidth and up to 60 ° scanning angle in the D-plane and 70 ° in the E-/H-plane; an AR smaller than 3 dB was demonstrated over the entire scanning range. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of angle measuring of the target in the presence of jammings with planar arrays. The relationship between the quiescent monopulse ratios and azimuth/elevation is first studied. On this basis, the distortion of the surface of the conventional minimum variance distortionless response monopulse ratio is analyzed. In order to avoid such distortion and approximate the adaptive monopulse ratio surface to the quiescent one, an adaptive monopulse approach with joint linear constraints on both the azimuth and elevation is proposed. Simulation results demonstrate that the proposed approach is capable of attaining a high angle measuring accuracy in the presence of mainlobe jammer. [ABSTRACT FROM AUTHOR]

The theory, design, fabrication, and measurement of a new class of planar ultrawideband modular antenna (PUMA) arrays are presented. The proposed PUMA array class achieves twice the bandwidth (from 3:1 to 6:1) of the conventional shorted via-based PUMA without using an external matching network and while retaining convenient unbalanced feeding, manufacturing, and assembly characteristics. The chief enabling technical innovation hinges upon the reconfiguration of shorting vias into capacitively-loaded vias that simultaneously: 1) mitigate low-frequency bandwidth-limiting loop modes and 2) shift problematic common-mode resonances out-of-band. A simple theoretical model based on ridged waveguides is proposed that qualitatively and quantitatively explains this novel common-mode mitigation. An infinite array operating over 3.53–21.2 GHz (6:1) is designed to achieve active VSWR < {2, 2.5, 3.8} while scanning to {broadside, 45°, 60°}, respectively, without oversampling the aperture. D-plane cross-polarization is around {−15, −10} dB for {45°, 60°} scans with high efficiency, i.e., 0.5 dB co-polarized gain loss on average. A dual-polarized prototype 256-port (128 elements per polarization) array is fabricated and measured having good agreement with full-wave finite array simulations. [ABSTRACT FROM PUBLISHER]

The commands to control the phases shifters in a phased array can be sent through a parallel or serial channel. Parallel commands simultaneously change the phase shifters, allowing the beam to nearly instantaneously hop from one direction to another. If a serial channel is used, then the commands are sequentially sent to the phase shifters. The sequential approach causes the beam to gradually move from one position to another, rather than the quick hop encountered with a parallel channel. This paper shows simulated results of the behavior of the array factor due to serial phase shifting and effects the element sequence has on that behavior and a method to optimize the command sequence. [ABSTRACT FROM AUTHOR]

An ultrawideband antenna array using a right-angled isosceles triangular microstrip antenna as a basic element is presented using inset feed for applications in the Internet of things. A Koch fractal antenna array with defected ground plane is used to generate multiband applications. Further, meander lines are added to increase the equivalent inductance that reduces the size of the antenna and increases the bandwidth and gain. Antenna arrays have been constructed and experimentally studied. The measured results show good agreement with the numerical prediction and wideband operation. [ABSTRACT FROM AUTHOR]

The sensor selection is a technique to reduce the cost, energy consumption, and complexity of a system by discarding redundant or less useful sensors. In this technique, one attempts to select a subset of sensors within a larger set so as to optimise a performance criterion. In this work, the authors consider the detection of sources in the 3D space when the source space could be sparsely represented. The application of compressive sensing (CS) methods in this setting has been extensively studied. Their aim in this work is to carry out the task of sensor selection in a planar array without sacrificing the detection performance. Their approach is to adopt the equivalent CS model and reduce the mutual coherence of the associated sensing matrix. This minimisation task is non‐convex, for which they propose a convex relaxation. Numerical simulations demonstrate that the gap between their relaxed solution and its optimal counterpart is negligible. The proposed sensor selection method is also shown to outperform the uniform approach in terms of source detection. [ABSTRACT FROM AUTHOR]

A $6 \times 6$ wideband antenna array with ±45° dual polarizations is proposed. To achieve good radiation efficiency, cavity antenna is used in this work as the basic element. Feeding probes and strip line feeding networks are printed on general PCB substrate. The feeding circuits for exciting different polarizations are stacked and multilayer substrate step structure is used. Here, strip line to downward SMA connector transitions is also designed, which aids in integrating the proposed array with T/R modules located below and extending it to larger phased array. The antenna array is fabricated and measured. Simulated and measured impedance and radiation performances are also given and compared. The proposed antenna arrays show wide bandwidth of 30% from 10.9 to 14.8 GHz, and isolation of higher than 33 dB is also exhibited across the bandwidth. Furthermore, symmetrical patterns and cross-polarizations of below −25 dB are also demonstrated. [ABSTRACT FROM PUBLISHER]

This paper presents a planar circularly polarized (CP) antenna array with a high-gain and wideband operation. The array is based on a sequentially rotated feeding network for a set of 2 × 2 CP metasurface-based antennas. The single element is a microstrip-line-fed slot antenna, which is coupled to a metasurface having 4 × 4 truncated corner square patches, to produce the CP radiation. The wideband characteristic of the design is obtained by a proper combination between the feeding network and the CP metasurface-based antennas. The proposed array, with an overall size of 50 × 50 × 2.032 mm3(~1.60 × 1.60 × 0.065λ0at 9.6 GHz), has been fabricated and tested. The measurements resulted in an |S11| < –10 dB bandwidth of 7.88–12.0 GHz (41.45%) and a CP radiation bandwidth of 8.4–10.6 GHz (23.16%). In addition, the antenna yielded a broadside left-hand CP radiation with a peak gain of 13.5 dBic, a 3-dB gain bandwidth of 8.6–10.8 GHz (22.68%), and a radiation efficiency of >84%. [ABSTRACT FROM AUTHOR]

A wideband full-metal planar antenna array with full-corporate feed-network is proposed. Cavity and slot are used as the basic radiation element and T-shaped walls are employed in the cavity to achieve wide bandwidth. E-plane waveguide feed-network configuration is utilized so as to suppress wave leakage between adjacent layers when the antenna is fabricated by a conventional machining technique. An 8 \times 8 antenna array prototype with optimized parameters is tested. Experimental results show that the bandwidth of \textVSWR < 2.0 is up to 36.9% (10.24-14.87\;\textGHz). More than 60% aperture efficiency and higher than 23.4 dBi gain are achieved over the operational bandwidth. [ABSTRACT FROM PUBLISHER]

ABSTRACT In this letter, an equilateral triangular antenna with two sides metallic vias resembling perfect electric conductor walls have been proposed. The antenna is designed and fabricated at 5.49 GHz with gain of 5.7 dBi and radiation efficiency of 98%. With the array element, linear (1 × 2 and 1 × 4) and planar (2 × 2) arrays have been proposed and fabricated. Both the linear arrays operate at the centre frequency of 5.43 GHz. The 1 × 2 array produces a gain of 7.5 dBi offering 49 MHz impedance bandwidth while 1 × 4 array offers 52 MHz impedance bandwidth with 10.7 dBi gain. The 2 × 2 planar array, on the other hand, gives 48 MHz impedance bandwidth with 9.6 dBi gain at the operating frequency of 5.45 GHz. The prototypes are fabricated and various antenna parameters are measured. A close agreement between simulated and measured results is observed. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:675-679, 2016 [ABSTRACT FROM AUTHOR]

This work is focused on the array thinning problem in shaped beam far-field synthesis. The orthogonal matching pursuit algorithm, which allows finding sparse solutions in linear systems, is combined with a fast full-wave analysis method for antenna arrays based on a spherical wave expansion, thereby taking mutual coupling between real antennas into account in the thinning process. To this aim, the original iterative algorithm is modified so that the current residual is obtained for the selected real coupled antennas in each step of the algorithm. In this way, the remaining nonselected elements are effectively removed instead of turned off. Results for arrays made up of microstrip patch antennas and dielectric resonator antennas arranged in triangular and rectangular lattices are presented. [ABSTRACT FROM PUBLISHER]

A dual-port, corporate-series fed, planar 8 × 2 rectangular patch compact antenna array with a very high gain is introduced for 28 GHz millimeter wave (mm-wave) communication in 5G Internet of Things (IoT) systems. In the proposed design, successive radiating elements are excited with the same amplitude but opposite phase through two separate feed networks associated with two different ports. To ensure the reliability of the proposed design, a prototype is fabricated and tested. Testing indicates that the measured results closely follow the simulated results, which proves the accuracy of the proposed design. The measured performance specifies that the dual-port antenna array provides impedance bandwidth of 4.3% operating from 27.6–28.8 GHz for | S 11 | ≤ −10 dB, the radiation efficiency of 78%, and gain of 18.2 dB. Measured radiation characteristics verified that the proposed array directs maximum power towards broadside with half-power beam widths (HPBWs) of 24.6°and 9.6°, side lobe levels (SLLs) < −18.3 dB and < −10 dB, as well as cross-polarization levels < −41.16 dB and < −42.51 dB in E plane and H plane, respectively. Due to the very high gain, directional radiation pattern, and low SLLs, the proposed array antenna can be used for mm-wave powered communication in IoT 5G devices. [ABSTRACT FROM AUTHOR]

A dual-polarized aperture array for 6–18 GHz applications is presented in this paper. Wide aperture is used as the array element owing to its simple structure, low-profile and broadband operation. The array elements are combined in a 2 × 2 arrangement to improve the pattern consistency in both polarizations. A metallic stub is placed at 45° between the orthogonal feeding structures to improve the port-to-port isolation, which improves the radiation efficiency in the low frequency band significantly. A corrugated reflector is proposed to replace traditional plane reflector for suppressing the parallel-plate mode, which improve the radiation patterns in the high frequency range. A prototype array with a compact size of 120 mm × 120 mm × 8.25 mm is fabricated. Simulated and measured reflection coefficients are mostly below −10 dB in the frequency range of 6–18 GHz. The radiation patterns are also well behaved with a realized gain ranging from 6.5 dBi to 15.4 dBi. This array is potentially useful for spectrum monitor, data transmission, and electronic warfare on compact airborne platforms. [ABSTRACT FROM AUTHOR]

We propose a wideband and dual polarization open-ended waveguide that makes it easy to construct array antennas. The proposed device stacks feeding circuits for both polarizations on different substrates. In order to equalize the distances from the excitation probe of each polarization to the electrical ground, we propose to place metal slits on the antenna ground. This offsets the characteristic difference between polarizations. Additionally, since multiple elements are fed by using the branched strip lines on the feeding circuits, array antennas are easily formed. We have designed the antenna element, and fabricated a prototype for validation. The calculated and measured results agree well; both polarizations exhibit low reflection levels and similar gains. [ABSTRACT FROM PUBLISHER]

A novel planar slot array antenna with omnidirectional radiation pattern in the horizontal plane is proposed. The antenna has a simple structure based on a stripline. Its fabrication employs a low-cost and accurate planar printed technique. A series of rectangular-shaped loop slots are etched on two parallel ground planes, and act as radiators. The basic principle of operation of the antenna is discussed in this study. An antenna with eight back-to-back slots is designed by employing the genetic algorithm (GA) implemented on a cluster system to achieve good omnidirectional radiation characteristics. A prototype antenna is fabricated and measured. The measurement results agree with the simulation data and show that this antenna possesses encouraging features. For example, at the working frequency of 5.8 GHz, it has a well-formed omnidirectional pattern with maximum gain variation less than 0.5 dB in the horizontal plane, a high gain level of 10 dBi, side lobes 10 dB below the main lobe and no beam squint. Meanwhile, this antenna achieves an impedance bandwidth of 4.6% of the center frequency (5.68–5.95 GHz) for S11 < -10 dB and exhibits stable omnidirectional performance over the impedance bandwidth. [ABSTRACT FROM AUTHOR]

Abstract: Recent advances in miniaturization of analytical systems and newly emerging technologies offer platforms with greater automation and multiplexing capabilities than traditional biological binding assays. Multiplexed bioanalytical techniques provide control agencies and food industries with new possibilities for improved, more efficient monitoring of food and environmental contaminants. This review deals with recent developments in planar-array and suspension-array technologies, and their applications in detecting pathogens, food allergens and adulterants, toxins, antibiotics and environmental contaminants. [Copyright &y& Elsevier]

An analytical method to synthesize shaped-beam patterns with planar arrays, based on the handling of spherical waves, is proposed. Translational Addition Theorems will be used here for two different purposes: 1) relating the spherical modes produced by each element in the array to calculate the mutual coupling effects, and 2) expressing the field radiated by each element in terms of spherical modes corresponding to the whole array, to carry out a spherical-wave synthesis procedure based on the orthogonal properties of spherical modes. This field synthesis method is based on the fact that any antenna radiated field can be expressed as a discrete series of weighted spherical vector wave functions and it only requires the a priori knowledge of the Generalized Scattering Matrix of each array element considered as isolated from the rest of the array elements. [ABSTRACT FROM AUTHOR]

The synthesis of sparse antenna arrays has many practical applications in situations where the weight, size and cost of antennas are limited. In this communication the antenna array synthesis problem, with minimum number of elements, is studied from the new perspective of sparseness constrained optimization. The number of antenna elements in the array can be efficiently reduced by casting the array synthesis problem into the framework of sparseness constrained optimization and solving with the Bayesian compressive sensing (BCS) inversion algorithm. Numerical examples of both linear and planar arrays are presented to show the high efficiency of achieving the desired radiation pattern with a minimum number of antenna elements. [ABSTRACT FROM AUTHOR]

Numerical and experimental study of the effect of the ground plane size on radiation pattern of microstrip antenna on thick substrate is presented in the article. First the results of simulations and measurements of reference microstrip antenna are shown. Next the ground plane sizes were reduced in both x and y directions and the side lobes and backward lobe levels were calculated and measured. It was shown how far we can reduce the size of ground plane without important deterioration of the antenna pattern. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2679-2682, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25568 [ABSTRACT FROM AUTHOR]

Abstract: The application of the genetic algorithms to the optimization of planar array weights will be investigated with −30 dB attenuators weight precision. The aim is to adjust the weight coefficients of the array attenuators in −30 dB precision to achieve a minimum sidelobe level (SLL) with narrower beam width. The peak sidelobe level (PSL) of the synthesized beam pattern has been successfully lowered. The results are compared with synthesized pattern using precision like weights such as Gaussian, Kaiser, Hamming, Blackman and Chebyshev weight coefficients and give a significant improvement for a peak sidelobe level (PSL). The minimum achieved peak sidelobe level (PSL) is −32 dB for beam width of 16° and −22.82 dB for beam width of 12°. [Copyright &y& Elsevier]

Abstract: With few exceptions, high resolution direction of arrival (DOA) estimation algorithms suffer a lot from the mutual coupling between different array elements. In order to compensate this effect, two autocalibration methods are proposed for the 2-D DOA estimation on a planar array. Both of them can estimate the DOAs without any iterative process or calibration sources. We prove that the effect of mutual coupling can be automatically eliminated by the inherent mechanism of the proposed methods. Moreover, they can also achieve an obvious performance improvement even when there is a coupling model mismatch. After getting the DOA estimations, two methods are proposed to estimate the mutual coupling coefficients. Moreover, these coefficient estimates can be used to further improve the accuracy of DOA estimations. The Cramer–Rao lower bound (CRB) for the parameter estimations are also presented as the benchmark. Simulation results demonstrate the effectiveness of the proposed algorithms. [Copyright &y& Elsevier]