Low Sidelobe Research Articles

Hybrid Sparse Array Design Based on Pseudo-Random Algorithm and Convex Optimization with Wide Beam Steering

In this paper, a hybrid optimization method utilizing a pseudo-random algorithm and convex optimization is proposed to avoid grating lobe and achieve lower side lobe level (SLL) of a planar sparse array when the minimum inter-element distance is one wavelength. The pseudo-random algorithm is utilized to distribute the positions of elements. The convex algorithm is utilized to optimize the excitations of elements. The results show that a planar sparse array with no grating lobe and peak side lobe level (PSLL) of −17 dB can be obtained with a minimum inter-element distance of one wavelength, which indicates the effectiveness of the hybrid optimization method. In addition, beam steering can be achieved within an 80∘ field of view range.

Low Sidelobe Level, High-Gain Patch Antennas Operating at Higher-Order Modes

Low Sidelobe Level, High-Gain Patch Antennas Operating at Higher-Order Modes

LPI radar waveform design based on complementary phase and discrete chaotic frequency joint coding

In order to reduce the probability of radar radiation signals being detected by enemy passive detection systems, this paper proposes a phase and frequency joint coding low intercept Radar waveform design method. Based on the linear frequency modulation signal, this method uses complementary binary code and chaotic sequence to phase encode the intra-pulse modulation. Code and frequency coding. The numerical simulation results show that the designed waveform exhibits pseudo-random characteristics in the time-frequency domain, and the low recognition performance is improved; The signal has an extremely low peak sidelobe level after matched filtering, showing excellent low intercept performance; its three-dimensional ambiguity function diagram presents an ideal “graph”. Fishing type”, with good distance, speed resolution and anti-interference characteristics.

Marine predator’s algorithm-based linear and elliptical antenna array design for 5G communication

The highly efficient linear and elliptical antenna array design presented in this article is intended to synthesize far-field radiation patterns for 5G communication. The objective is to achieve the best possible radiation pattern, which includes a lower side lobe level (SLL) and a narrower half-power beam width (HPBW). A low SLL is crucial to minimize intervention in the entire side lobe region, whereas long-distance communication requires a low HPBW. The marine predator’s algorithm (MPA) is used here to determine the optimal feeding currents to each array element to reduce the SLL and HPBW values. Two linear antenna array (LAA) design examples and the three elliptical antenna array (EAA) design examples are discussed in this article which are achieved using the optimal current excitations to each array element. Two well-established evolutionary optimization techniques, namely the genetic algorithm (GA) and the differential evolution (DE) technique, are also employed for comparison to demonstrate the superiority of the MPA optimization-based technique. The results achieved utilizing the MPA show the improvement of SLL contraction compared to the uniform antenna array and the methods affirmed in the recently published article.

Phase gradient metasurface for arbitrary three-dimensional shaped near-field

This paper proposes a methodology for generating arbitrary three-dimensional (3D) shaped near-field using phase gradient metasurface (PGMS) based on phase conjugation (PC) backtracking and shaped diffraction-free Bessel beam array techniques. The PGMS is designed by combining MATLAB and electromagnetic (EM) simulation software (CST). To the knowledge of the authors, for the first time, a 3D-shaped near-field is generated without increasing cost, structural and calculating complexity, and a methodology for generating arbitrarily shaped diffraction-free beam array is developed by MATLAB. To verify the technique, a planar PGMS is designed for dual x-polarized 3D-shaped near-fields: qq image “” in direction (θ1 = 5°, φ1 = 0°) and a flower image “” in direction (θ2 = 10°, φ2 = 180°). The advantages of the 3D-shaped near-fields are as follows: high conversion efficiency 30.5% (measured), wideband 60.5%, and low sidelobe -15 dB. The proposed technique is confirmed by the calculated, simulated, and measured results.

Experimental Study of Omnidirectional Scattering Characteristics of Complex Scale Targets Based on Coded Signals

To investigate the omnidirectional geometric scattering characteristics of an underwater vehicle and the target detection performance of phase coded (BPSK) signals, acoustic scattering tests were carried out in an anechoic chamber using the Suboff scale model. To mitigate the overlapping interference of the direct wave on the scattering wave in the limited test space, physical suppression with an “anechoic cloak” and direct wave cancellation were proposed. Target echo and reflection wave tests at different offset angles were carried out, and the accuracy of the BPSK signal in acquiring highlight features and the feasibility of anechoic chamber tests were verified through comparison with theoretical range profiles. A series of echo and omnidirectional scattering characteristics were obtained through the experiment and simulation, which verified the effectiveness of the low-frequency submarine model detection (there were still strong scattering waves at the dimensionless frequency ka = 1.88). Comparison tests of CW, LFM, and BPSK signals were carried out, and the measured data proved that the BPSK signal had the advantages of low sidelobe, high resolution, and noise resistance in target detection. The acoustic scattering test method designed in this study and the omnidirectional scattering characteristics obtained can be used as a reference for semi-physical target acoustic scattering simulations and practical multistatic detection.

An efficient compact blazed grating antenna for optical phased arrays

Abstract Phased arrays are vital in communication systems and have received significant interest in the field of optoelectronics and photonics, enabling a wide range of applications such as LiDAR, holography, and wireless communication. In this work, we present a blazed grating antenna that is optimized to have upward radiation efficiency as high as 80% with a compact footprint of 3.5 µm × 2 µm at an operational wavelength of 1.55 µm. Our numerical investigations demonstrate that this antenna in a 64 × 64 phased array configuration is capable of producing desired far-field radiation patterns. Additionally, our antenna possesses a low side lobe level of −9.7 dB and a negligible reflection efficiency of under 1%, making it an attractive candidate for integrated optical phased arrays.

A 94-GHz Dual-Polarized 1-D Series-Fed Phased Array Antenna With Low Sidelobe Level Based on Multilayer Coreless ABF Substrates

A 94-GHz Dual-Polarized 1-D Series-Fed Phased Array Antenna With Low Sidelobe Level Based on Multilayer Coreless ABF Substrates

A Deep Learning Application for Dolph-Tschebyscheff Antenna Array Optimisation

This paper proposes a design for a Dolph-Tschebyscheff-weighted microstrip antenna array using a deep learning application. For this purpose, a multilayer perceptron and a deep learning model, both created using the same data set generated by a genetic algorithm, were compared. The antenna array population is initially generated randomly and then optimised with a genetic algorithm. The data produced by this model becomes a data set used for training in the deep learning application. The dimensions and specifications of the antenna array are obtained from this application, ensuring precision and optimisation in the design process. A new microstrip antenna array structure is employed for the proposed method, taking advantage of this design technique. The Dolph-Tschebyscheff weights are applied to achieve better characteristics for the microstrip antenna array, thus obtaining low side lobe levels, which are crucial for enhancing signal clarity and reducing interference. The results demonstrate that the proposed algorithm significantly improves the specifications of the structure. This improvement highlights the potential for integrating deep learning with traditional optimisation algorithms for advanced antenna design.

Sidelobes and sideband minimization in time-modulated array antenna based on chaotic exchange nonlinear dandelion optimization algorithm

Time-modulated array antenna (TMAA) is a new type of array antenna based on time modulation technology. By introducing "time" as the fourth dimensional design freedom into the design of conventional array antennas in three-dimensional space, the array antenna has time modulation characteristics, which better controls the radiation characteristics of the array antenna and achieves the best far-field radiation pattern synthesis. This paper designs a Time-modulated linear array (TMLA) with low sidelobe level (SLL) and low sideband level (SBL) based on the chaotic exchange nonlinear dandelion optimization (CENDO) algorithm. Three optimization methods are studied: firstly, determining the optimal on-time (τnn) for each array element; The second is to determine the optimal on-time (τnn) and optimal uniform array element spacing (d) for each array element; The third is to determine the optimal opening time (ton), closing time (toff), and optimal uniform array element spacing (d) for each array element. To achieve simultaneous reduction of sidelobe level and suppression of harmonic interference. The same array model contains different harmonic frequency radiation. In this article, we only considered two harmonic frequencies, namely the first sideband frequency and the second sideband frequency. Because the harmonic of other sideband frequencies has a very small impact on the radiation of the fundamental wave, it can be ignored. To demonstrate the stronger ability of the CENDO algorithm in optimizing Time-modulated array antennas, and in line with the principle of fairness and impartiality, this paper also simulates different Time-modulated array models and compares the results of the CENDO algorithm with other published literature. It is concluded that this study shows lower SLL and lower SBL in different models. This provides a more scientific and accurate explanation of the superiority of the CENDO algorithm compared to other algorithms in the field of antenna optimization in electromagnetics. At the same time, this also provides great research value and fundamental support for designing high-performance Time-modulated array antennas in subsequent engineering applications.

Deep Learning based enhanced hybrid beamforming using RSSI signals in MIMO systems

Hybrid beamforming has gained popularity in recent years due to its ability to enhance the performance of massive multiple-input multiple-output (massive MIMO) systems and improve the efficiency of wireless communication. However, designing a hybrid precoder is a challenging task as it requires accurate channel state information (CSI) and needs to solve an optimization problem. This paper introduces an unsupervised hybrid deep learning technique, namely CNN-BiLSTM, for developing hybrid beamforming in massive MIMO systems based on received signal strength indicator (RSSI) without having prior knowledge of CSI. Additionally, incremental principal component analysis (Incremental PCA) is used to reduce the dataset's dimensionality. The results of our proposed model demonstrate a significant improvement in spectral efficiency. This technique reduces the training overhead significantly and is able to quickly serve all the users. The simulation results indicate that proposed model produces low side lobes when providing coverage to areas. As a result, the performance of our model has a noticeable advantage compared to other models. In addition, proposed method achieves 99.21% accuracy and 5.30 bps/Hz sum-rate that is close to optimal performance and outperforms the state-of-the-art method.

Sparse TFM imaging of different-scale phased array based on the DWSO algorithm

ABSTRACT Using sparse matrix for total focusing method (TFM) imaging can improve computational efficiency in non-destructive testing (NDT). In sparse matrix design, binary particle swarm optimisation (BPSO) and genetic algorithm (GA) often fall into local optimal solution, and the computational efficiency decreases significantly with the expansion of array scale. In this paper, a discrete war strategy optimisation (DWSO) is proposed to realise sparse array ultrasonic imaging. This method uses equidistant scatter mapping to real-number encode the array position and limit the search range. Then, the fitness function is constructed with low side lobe peak and narrow main lobe width to obtain the optimal array element distribution. Experiments on standard test block demonstrate the DWSO algorithm has a narrower main lobe width and lower side lobe peaks than BPSO and GA. The imaging time of the sparse array constructed by this algorithm is reduced by more than 65% compared with the full array. As array scale grows, the running time variation of the proposed method is reduced by 73.2% and 77.3% compared with GA and BPSO, which has good adaptability and provides theoretical support for real-time defect detection.

H-plane gap-RGW horn antenna with very low side lobe level

This paper presents and applies a new concept of gap-RGW to develop a new configuration for RGW H-plane horn antennas. The proposed antenna is fully metallic and can generate a very low side-lobe level along with a flat gain response over a reasonable bandwidth, which is one of the advantages of this antenna. A prototype of the presented structure is designed and fabricated which provides the impedance bandwidth (S11 < − 10 dB) of about 25% with SLL < − 20 dB and 2 dB gain variation over the operating bandwidth.

Low-profile, low sidelobe array antenna with ultrawide beam coverage for UAV communication

This paper presents a design method to implement an antenna array characterized by ultra-wide beam coverage, low profile, and low Sidelobe Level (SLL) for the application of Unmanned Aerial Vehicle (UAV) air-to-ground communication. The array consists of ten broadside-radiating, ultrawide-beamwidth elements that are cascaded by a central-symmetry series-fed network with tapered currents following Dolph-Chebyshev distribution to provide low SLL. First, an innovative design of end-fire Huygens source antenna that is compatible with metal ground is presented. A low-profile, half-mode Microstrip Patch Antenna (MPA) is utilized to serve as the magnetic dipole and a monopole is utilized to serves as the electric dipole, constructing the compact, end-fire, grounded Huygens source antenna. Then, two opposite-oriented end-fire Huygens source antennas are seamlessly integrated into a single antenna element in the form of monopole-loaded MPA to accomplish the ultrawide, broadside-radiating beam. Particular consideration has been applied into the design of series-fed network as well as antenna element to compensate the adverse coupling effects between elements on the radiation performance. Experiment indicates an ultrawide Half-Power Beamwidth (HPBW) of 161° and a low SLL of −25 dB with a high gain of 12 dBi under a single-layer configuration. The concurrent ultrawide beamwidth and low SLL make it particularly attractive for applications of UAV air-to-ground communication.

Synthesis of Non-Uniform Spiral Antenna with Low Peak Sidelobe Level Using Enhanced Harris Hawks Optimization Algorithm

Synthesis of Non-Uniform Spiral Antenna with Low Peak Sidelobe Level Using Enhanced Harris Hawks Optimization Algorithm

Minimum peak sidelobe ratio filter for MIMO radar via convex optimization

Multiple input multiple output (MIMO) radar retains transmitting freedom by transmitting multiple waveforms simultaneously. However, due to the cross-correlation between waveforms, the performance of range sidelobes is degraded. So, low sidelobes techniques are especially demanded in MIMO radar. This article proposes a mismatched filtering method for minimizing MIMO radar’s peak sidelobe level ratio (PSLR). In this method, we formulate the problem as a convex optimization (CO) problem and thus ensure its solution is globally optimal. To apply mismatched filters to MIMO radar, we introduce the traditional strategy and propose a new one. Instead of attempting to minimize all auto-correlations and cross-correlations of all waveforms as in the traditional strategy, our proposed strategy directly optimizes the mismatched filter of the synthesis signal for each considered direction. To verify the effectiveness of our method, numerical simulations are carried out. Firstly, the PSLR effects of those two strategies are compared. The results indicate that our proposed strategy dramatically improves the PSLR performance of MIMO radar compared to the traditional one. Then, the influences of several parameters on the PLSR performance are revealed, which indicates that our method is flexible enough to make trade-offs between PSLR and other parameters.

Fast Generation of Low PAPR and Low Sidelobe Noise Waveform

Noise radar waveform, as an important waveform in the field of low-probability-of-intercept radars, has been widely studied. However, the general noise waveform has a high peak average power ratio (PAPR), which leads to a reduction of signal-to-noise ratio. Thus, it is necessary to control the noise waveform PAPR to a suitable range. In this paper, the PAPR value reduction problem of low sidelobe noise waveform is studied. First, the proposed new algorithm is given a general overview. Then, the Combined Spectral Shaping and Peak-to-Average Power Ratio Reduction (COSPAR) algorithm is adjusted according to the alternate projection method and phase retrieval algorithm, and an improved COSPAR (ICOSPAR) algorithm with a faster execution speed and higher waveform generation efficiency is derived. The specific method performs waveform projection between the spectral constraint domain and the PAPR constraint domain and then evaluates the computational load of the ICOSPAR algorithm. Simulation results show that the ICOSPAR algorithm is reliable and efficient in generating low PAPRs and low sidelobe noise waveforms.

Concentric Elliptical Antenna Array Synthesis using Sine Cosine Algorithm for Reducing the Sidelobe level

This paper employs the Sine Cosine Algorithm, a recent meta-heuristic method, to enhance the radiation properties of concentric elliptical antenna arrays in far-field applications, such as smart grid wireless communication and the Internet of Things. It focuses on minimizing the Sidelobe Level, a key parameter in antenna radiation, to mitigate unwanted signals and interference. The proposed method, known for its global optimization effectiveness, tackles the challenge of designing sparse multiple concentric elliptical arrays. By using the Sine Cosine Algorithm, the inter-element spacing and optimal determination of amplitude coefficients are achieved, resulting in a radiation pattern with reduced sidelobe level. To showcase the adaptability and superior performance of our proposed algorithm, we systematically evaluated its effectiveness across four distinct sets of concentric elliptical antenna arrays. These arrays comprise varying numbers of elements: (6, 12, 18 elements, 6, 12, 18, 24 elements, 6, 12, 18, 24, 30 elements and 6, 12, 18, 24, 30, 36 elements) with and without a central element. Using the sine cosine algorithm, we synthesize arrays and compare their sidelobe level and First Null Beam Width values with those from recent methods. Our findings consistently shows that the proposed algorithm consistently outperforms alternatives, yielding significantly lower sidelobe level values in all comparisons.

Slotted meandered waveguide antenna for X-band radar applications

ABSTRACT This work presents a unique one-dimensional (1D) FSA powered by rectangular meander waveguide which finds usage in bird monitoring and detection in wind farms. Large scan volume, high frequency sensitivity, lower side lobe level and excellent directivity are few of the varied advantages of the suggested approach. The suggested travelling-wave FSA operates in the X-band uses a periodically loaded standard WR90 waveguide and is vertically polarised. The propagation properties and fundamental ideas of the meander-line unit are thoroughly studied for frequency-scanning based applications. The scanning performance over frequency range is enhanced by using the proposed meandering feeding mechanism. Dumbbell-shaped radiating slots are utilised in the waveguide. The beam width in the elevation plane is narrowed by embedding an E-plane horn antenna over it. Using CST microwave studio, the proposed FSA with 10 radiating elements is simulated in order to predict the scanning performance over the frequency range of 9.425 to 10.025 GHz. The results demonstrate a gain above 21 dBi and a high 55-degree scanning coverage performance. The lower SLL is observed around 13 dB. Aluminium is used in the fabrication of the suggested approach. When the FSA is evaluated after manufacture, measurements and simulations accord quite well.

Phase response constrained symbol‐level waveform design for dual‐functional radar‐communication systems

AbstractIn this letter, a novel algorithm is proposed to design symbol‐level waveform for dual‐functional radar‐communication (DFRC) systems with low range sidelobe. Different from current schemes design waveform at the block level, a phase response constraint is introduced at the symbol level to provide an additional degree of freedom to decrease the range sidelobe in the pulse compression procedure, which is highly desired in radar systems. In particular, the phase response at the target direction is constrained to be similar to the given reference phase, and the matching error between the designed beampattern and the desired one is minimized subject to the constant modulus constraint. Furthermore, to guarantee the quality of service for communication, constructive interference is exploited at the symbol level for each communication user. An alternating direction method of multipliers algorithm is also proposed to solve the resulting nonconvex optimization problem with tractable subproblems solved sufficiently by the manifold optimization and standard quadratic problem. Numerical simulation results demonstrate the performance of the proposed method.