Side Lobe Level Reduction Research Articles

Design Procedure for Compact Dual-Circularly Polarized Slotted Substrate Integrated Waveguide Antenna Arrays

In this paper, a complete design procedure of low-profile dual-circularly polarized slotted substrate integrated waveguide antennas is developed at the Ku-band frequencies. The design method includes a recipe for controlling the beam squint angle, determining the optimum slot aperture distribution, and tapering slots coupling and excitation to increase the gain/efficiency and reduce the array sidelobe levels. The structure is designed in such a way to provide dual circular polarization and improve the radiation characteristics including reduced sidelobe levels using optimized symmetric nonuniform coupling factors and tapering the lengths of the slots. The radiation performance of the fabricated 64×12 slot antenna array has been tested using a planar near-field range measurement. The beam tilt angles in elevation, peak gain, cross polarization component, and sidelobe levels have been measured and compared to previously designed 32 × 13 and 16 × 12 slot arrays.

Amplitude Quantization Techniques of Aperture Distribution in Phased Array Antennas

In phased array antennas, the high side-lobe levels due to the amplitude quantization often need to be reduced to meet some requirements. In order to develop the digitalization of antenna arrays in phased array radars, the amplitude quantization of aperture distribution in array antennas is studied. In this paper, the random technique and a novel appropriate random technique are presented and used to reduce the side-lobe levels, and the side-lobe levels in the amplitude quantized array pattern are calculated. The reduction of side-lobe level due to amplitude quantization are introduced using the improving method and confirmed with computations, where the related parameters are modified and numerous patterns are computed and compared. The quasi-optimum patterns are also obtained and given.

Dual-Layer SIW Multibeam Pillbox Antenna With Reduced Sidelobe Level

In this letter, a dual-layer substrate integrated waveguide (SIW) multibeam pillbox antenna with reduced sidelobe level (SLL) is presented. To avoid the problem of aperture blocking, the feeding network and an antenna array are placed in different layers connected through an SIW parabolic quasi-optical system. Aiming to reduce the SLLs, two extra parabolic reflectors are introduced into the parabolic quasi-optical system placed on both sides of the central parabolic reflector. Moreover, by adding some metal posts in the antenna array section, a further reduction in SLLs can be achieved. The proposed antenna, operating at 28 GHz, has been verified by measurements, showing good performance over a coverage angle of ± 45 ° , and the SLLs of all the beams are lower than −12 dB.

Compact 60 GHz Phased-Array Antennas With Enhanced Radiation Properties in Flip-Chip BGA Packages

Compact phased-array antennas embedded in flip-chip ball grid array (BGA) packages are proposed to operate over the unlicensed 60 GHz frequency band. Radiation properties are enhanced by designing novel corrugated soft-surface structures and implementing them using the low-temperature co-fired ceramic process with no extra cost and fabrication complexity. This is achieved by adjusting via land diameters of periodic grounded vias in top four layers of the package, which in fact create perfect magnetic boundaries between the phased-array antenna elements to modify the electric near-field distributions and consequently improve far-field characteristics including gain, cross polarization, sidelobe level, and beam steering. Low-loss transitions from flip-chip IC to antenna elements are designed with less than 0.1 dB amplitude and 2° phase imbalance over 50–70 GHz. Prototypes with/without soft-surface structures are fabricated to work with flip-chip ICs with/without switches. A USB-interface adapter and a waveguide-interface module with a compact vertical power combiner are proposed for the first time to experimentally evaluate the phased-array antenna while connected to the flip-chip RF IC. Significant miniaturizations and improvements are achieved over the wide frequency range of 56–67 GHz, demonstrating up to 7 dB reduction in sidelobe level, up to 4 dB reduction in cross polarization, and up to 3 dB enhancement in gain at different directions.

Feasibility study of antenna synthesis using hyper beamforming

Wireless communication requires an effective antenna synthesis that characterizes adequate infrastructures to provide the broader bandwidth and reduced interference. Antenna design with minimal signal degradation, optimal gain directive main beam to sustain minimal loss has been a hot issue among many communication engineers for several years. In this paper, the effects of eccentricity of the antenna, element-spacing, number of elliptical rings and number of elements are evaluated. For efficient antenna synthesis, deep Side Lobe Level (SLL) reduction and superior directivity are critical. We have also studied the significance of hyper beamforming in Elliptical Cylindrical Antenna Array (ECAA) in comparison to the geometric configuration of the antenna parameters (eccentricity of the antenna, element-spacing, number of elliptical rings and number of elements). The hyper beam exponent has resulted in flexible pattern synthesis while simultaneously reducing the side lobe of the proposed antenna array, thus decreasing the SLL and increasing directivity that are vital for wideband applications.

Sidelobe level reduction in ACF of NLFM waveform

In this paper, an iterative method is proposed for nonlinear frequency modulation (NLFM) waveform design based on a constrained optimization problem using Lagrangian method. To date, NLFM waveform design methods have been performed based on the stationary phase concept which we have already used it in a previous work. The proposed method has been implemented for six windows of Raised-Cosine, Taylor, Chebyshev, Gaussian, Poisson, and Kaiser. The results reveals that the peak sidelobe level of autocorrelation function reduces about an average of 5 dB in our proposed method compared with the stationary phase method, and an optimum peak sidelobe level is achieved. The minimum error of the proposed method decreases in each iteration which is demonstrated using mathematical relations and simulation. The trend decrement of minimum error guarantees convergence of the proposed method.

Printed Circular Antenna Array for Reduce SLL and High Directivity Using Cuckoo Search Algorithm

This paper presents the synthesis and optimization of printed circular antenna array using the Cuckoo Search Algorithm (CSA). The CSA is a simple and effective global optimization algorithm which can be used to solve linear and non-linear problems. It has been applied to solve a wide variety of optimization problems. In our case, it is used to find the optimum weights of amplitudes and phases of complex feeding currents of a uniform printed circular antenna array. The goal to be achieved is a directional radiation pattern. To study the effect of these optimizations, a Gaussian centered at 90° is considered in our simulations. The obtained results are promising in terms of reduced Side Lobe Level (SLL) and directional factor array.

Optimization of Sparse Planar Arrays with Minimum Spacing and Geographic Constraints in Smart Ocean Applications.

Sparse arrays can fix array aperture with a reduced number of elements to maintain resolution while reducing cost. However, grating lobe suppression, high peak side-lobe level reduction (PSLL), and constraints on the location of the array elements in the practical deployment of arrays are challenging problems. Based on simulated annealing, the element locations of a sparse planar array in smart ocean applications with minimum spacing and geographic constraints are optimized in this paper by minimizing the sum of PSLL. The robustness of the deployment-optimized spare planar array with mis-calibration is further considered. Numerical simulations show the effectiveness of the proposed solution.

Notice of Retraction: Most Valuable Player Algorithm for Circular Antenna Arrays Optimization to Maximum Sidelobe Levels Reduction

Retracted.

28 GHz Taylor feed network for sidelobe level reduction in 5G phased array antennas

AbstractThis paper presents a design procedure for a phased array feed network. The procedure is validated by designing and fabricating a set of 28 GHz 8‐element beam steerable antennas. Within the feed, a Taylor n‐bar amplitude taper is implemented using unequal power dividers. At boresight, the taper reduced the sidelobe level by 2.84 dB to −15.2 dB. Beam steering from 0° to 48° is achieved using meanders. An empirical formula for the meander widths is proposed, enabling independent control of amplitude and phase. Empirical formulae for the initial parameters of the unequal dividers are also proposed. The wide transmission lines in this feed network are compatible with low‐cost PCB fabrication techniques.

A compact low-side lobes three-layer array antenna for X-band applications

This paper proposes a low-side lobe lightweight array antenna for X-band applications with center frequency of 9.5 GHz. The proposed array antenna, being composed of 144 (12 × 12) single antenna elements, is designed in a three-layer configuration with total size of the 30 cm × 30 cm. Technically speaking, it is composed of two substrates and three conductive layers on the top, bottom, and between the substrate layers. The main part of the feeding network is located on the bottom side of the antenna structure while the radiating patches are printed on the top side. The ground plane is placed in the middle layer between the two substrates. Isolation of the feed network from the radiating patches, which is realized by the embedded ground plane, yields cross-polarization and side lobe levels (SLLs) reduction. Besides, the feeding system excites the top side patches by connecting to them through vias. Moreover, 1–6 power dividers in the feeding system are connected to each other to form the complete 144-element array configuration. Adopting this technique provides easy development of a planar 2n × 2n element array antenna. To achieve low side lobes, the Dolph-Chebyshev amplitude taper coefficients are used in the design process.

A novel adaptive beamforming with reduced side lobe level using GSA

PurposeThe purpose of this paper is to present and solve the problem of adaptive beamforming (ABF) for a uniform linear array (ULA) as an optimization problem. ABF mainly concerns with estimation of weights of antenna array so as to direct the major lobe in the direction of desired user and nulls in the direction of interfering signals with reduced side lobe level (SLL).Design/methodology/approachThe potential of gravitational search algorithm is explored to optimize multi-objective fitness function for ABF using MATLAB software.FindingsThe performance of the algorithm has been compared by considering different number of interference signals at different power levels. The proposed algorithm presents good convergence rate and accurate steering of main lobe and nulls with reduced SLL compared to the well-known ABF technique, namely, minimum variance distortionless response (MVDR) and previously reported results. The simulation results are presented in tabular form.Research limitations/implicationsThe present work is limited to simulation. The researchers are encouraged to solve the problem of ABF using the proposed approach in hardware.Originality/valueThe application of proposed algorithm is to optimize multi-objective function for ABF with reduced SLL in linear antenna arrays.

Utilization of graphene oxide-based microwave absorber for pattern enhancement of patch antenna array

Nanomaterial-based electromagnetic microwave absorber composed from epoxy resin loaded with graphene oxides is proposed for performance enhancement of patch antenna array operational in X and Ku bands (8 to 20 GHz). Nanocomposite graphene offers inherent benefits of structural flexibility and small surface to volume density, which enables implantation of the absorber on same quartz substrate along with the antenna array. The variable positioning of the absorber provides the benefit of controlling the antenna radiation pattern, hence demonstrating significant improvement in the performance of antenna array. Initially, the microwave absorber is designed, and its absorption coefficient and reflective properties are validated by placing the absorber in rectangular waveguide. The realization of two-element patch antenna array loaded with the proposed absorber is then performed on high-frequency structural simulator software. The reflection loss of the absorber is observed to be −81.71 dB at 11 GHz and when applied on array, the beamwidth of major lobe is narrowed by 26 deg with reduction in side lobe levels while maintaining pattern symmetry.

Phase improvement algorithm for NLFM waveform design to reduction of sidelobe level in autocorrelation function

In this paper, a phase improvement algorithm has been developed to design the nonlinear frequency modulated (NLFM) signal for the four windows of Raised-Cosine, Taylor, Chebyshev, and Kaiser. We have already designed NLFM signal by stationary phase method. The simulation results for the peak sidelobe level of the autocorrelation function in the phase improvement algorithm reveal a significant average decrement of about 5 dB with respect to stationary phase method. Moreover, to evaluate the efficiency of the phase improvement algorithm, minimum error value for each iteration is calculated.

Manipulation of focal patterns in acoustic Soret type zone plate lens by using reference radius/phase effect

The manipulation of focal patterns of acoustic underwater Soret Zone Plate lens in far fields, such as manipulation (optimization) of Sidelobe Level and the design of long depth of focus by selecting the simple free parameter called reference radius (phase) has been demonstrated.Two effects have been studied by means of numerical simulations. Regarding the first effect, simulations demonstrate diffraction limited focal spot (0.47 wavelength) and 3 dB reduction of the first Side Lobe Level using Soret ZP with an optimal reference radius and without causing neither main lobe broadening or gain reduction. In the second effect, by using numerical simulations an increasing of depth of focus, more than 2 times, in comparison with classical Soret ZP with high numerical aperture (F/D = 2.5), was observed.

Dynamic Programming Applied to Large Circular Arrays Thinning

In conventional arrays, improving angular resolution requires larger aperture which demands more number of elements. On the other hand, array thinning is an efficient method of achieving narrow beamwidth (high angular resolution) with fewer number of elements. Reducing the number of elements results in reducing weight, cost, hardware complexity, and energy consumption. In this paper, a novel dynamic programming algorithm of array thinning with the objective of reducing sidelobe levels (SLLs), desired for large circular arrays, is proposed. The circular array is partitioned into annular rings, and the objective of the optimization problem is to determine the number of active elements in each ring. Then, active elements of the rings are selected. Although optimal array thinning is an NP-hard problem, converting the problem of selecting active elements into the number of active elements in each ring causes a huge reduction in computational complexity of the proposed algorithm that makes it affordable for large arrays. Moreover, beampatterns with very low SLLs are synthesized.

Detraction the Clutter for the Best Binary Phase Codes that Begot By Genetic Algorithm Using Wiener Filter

This work illustrates the performance of detraction of clutter (unwanted echo signals, which mask the desired target signal and make difficult to detect the target) as a result of binary codes generating by genetic algorithm with length up to 105 bits, with use the minimum peak sidelobes as criteria for generation codes. Then, for further reduction of sidelobes, the mismatched optimum integrated sidelobe level filter (Wiener filter) is used with and without White Gaussian Noise. When the mismatched filter is used without noise, then the reduction of sidelobe level has the improvement of peak sidelobe level value on the average (4-15) dB, and for integrated sidelobe level value on the average (5-17) dB, which depends on the code length while it is accompanied by, signal to noise ratio loss level in range (0.2-1.4) dB. On other hand, when the mismatched filter is used with noise, the signal to noise ratio loss level is in range (0.2-1.4) dB.

Cosine Least Mean Square Algorithm for Adaptive Beamforming

Beamforming and multiple-input multiple-output (MIMO) antenna configurations have received worldwide interest during the recent time. Various beamforming algorithm has been proposed and employed in different applications. The Least Mean Square (LMS) algorithm has become one of the most widespread adaptive beamforming techniques because of its simplicity and robustness. This paper presents a new variant of LMS algorithm named as Cosine Least Mean Square (Cos-LMS) which uses the efficient computation of array factor for linear antenna array.This algorithm gives improved performance in beam width reduction, side lobe level reduction, null depth, and stability as compared to standard LMS and other variants of LMS algorithm. The performance improvement by Cos-LMS algorithm is accomplished without increasing the computationalcomplexity of standard LMS algorithm.

Sidelobe reduction for plane wave compounding with a limited frame number

BackgroundIn ultrasound plane wave imaging (PWI), image details are often blurred by the off-axis artefacts resulting from high sidelobe. Recently plane wave compounding (PWC) is proposed as a promising technique for the sidelobe suppression in the PWI. However, its high demand for the frame number results in an obvious frame rate loss, which is intolerable in the ultrafast imaging modality. To reduce the number of frames required for compounding, coherence in the compounding frames should be exploited.MethodsIn this paper, we propose a global effective distance-based sidelobe suppressing method for the PWC with a limited frame number, where the global effective distance is introduced to measure the inter-frame coherence. Specifically, the effective distance is firstly computed by using a sparse representation-based algorithm. Then, the sidelobe localization is carried out on the basis of the effective distance. Finally, the target-dependent weighting factor is adopted to suppress the sidelobe.ResultsTo assert the superiority of our proposed method, we compare the performances of different sidelobe reduction methods on both simulated and experimental PWC data. In case of 5 steering angles, our method shows a 19 dB reduction in the peak sidelobe level compared to the normal PWC in the point spread function test, and the contrast ratio is enhanced by more than 10% in both the simulation and phantom studies.ConclusionsConsequently, the proposed method is convinced to be a promising approach in enhancing the PWC image quality.

Developing a graphical package for sensor arrays design, optimization and maintenance

The sensor arrays are now an essential part of any communication, medical and remote sensing system. These arrays should be designed with utmost performance to ensure the maximum link efficiency. The available commercial sensor arrays design packages are expensive, complicated and cannot be easily modified to accommodate the users’ needs. This work suggests a solution that is to design an open source specialized application to serve the ever-changing needs of the users. This package is called Sensor Array Design and Optimization (SADO) and it is developed to allow the unexperienced users and the researchers to design, test and optimize their sensor arrays using effi-cient optimization algorithms. The optimization is trying to reduce the sidelobe levels to reduce the interference. The application is simple and friendly to use, with professional graphical results. The predesigned arrays configurations supplied with this package are uniform and random arrays. The built in optimization algorithms are: Artificial Bee Colony (ABC), Biogeography-Based Optimization (BBO) and Teaching Learning Based Optimization (TLBO). The results for various designs and optimization results are also given and compared to indicate the best settings for the user. Some optimization ratios might reach about 50% that represent -3dB reduction in sidelobe level.