Sidelobe Level Suppression Research Articles

Analysis of Linear Antenna Array for minimum Side Lobe Level, Half Power Beamwidth, and Nulls control using PSO

This paper presents the optimization performance of non-uniform linear antenna array with optimized inter-element spacing and excitation amplitude using Particle Swarm Optimization (PSO). The aim of the proposed algorithm is to obtain the optimum values for inter-element spacing and excitation amplitude for a linear antenna array in a give n radiation pattern with suppressed Side Lobe Level (SLL), minimum Half Power Beamwidth (HPBW), improved directivity and placement of nulls in the desired direction. A vari ety of design examples are considered and the obtained results using PSO are validated by benchmarking with results obtained using other nature-inspired meta-heuristic algorithms such as the Real-coded Genetic Algorithm (RGA) and the Biogeographic Based Optimization (BBO) algorithm. The comparative results are show n that optimization of linear antenna array using the PSO provides considerable enhancement in the SLL, the HPBW, the directivity and the null control in the desired direction.

Compact Wideband and Low-Profile Antenna Mountable on Large Metallic Surfaces

This paper proposes a compact wideband and low-profile antenna mountable on large metallic surfaces. Six rows of coupled microstrip resonators with different lengths are printed on a Teflon block. The lengths of the microstrip resonators in different rows are gradually reduced along the endfire direction. The first four rows of resonators provide four resonances at different frequencies for bandwidth enhancement. The last two rows of resonators are used as two directors to suppress sidelobe levels at high frequencies. A trapezoidal launcher is applied to serve as a reflector and provide one resonance at the lowest frequency. A trapezoid-shaped capacitive-feed strip is utilized and also printed on the Teflon block to globally optimize the wideband impedance matching. The proposed antenna covers a relative bandwidth of 109% for VSWR $0.044\lambda _{L}$ and a volume of only $0.03\lambda _{L}^{3}$ ( $\lambda _{L}$ being the free-space wavelength at the lowest operating frequency). Within the operating band, the realized gain is better than 6.5 dBi and the radiation efficiency is higher than 95%.

An Efficient Method for Investigating and Optimizing Near Field Characteristics of Planar Antenna Arrays

Near field focusing of 2-dimensional planar antenna arrays is analyzed by using a very efficient analytical method, instead of time consuming numerical methods. This is especially important for the design and optimization process for dynamic beam forming and other near field applications. Antenna arrays show increased side lobes at larger beam steering angles in the near field. Conventional techniques such as inhomogeneous but symmetrical amplitude illuminations to assure a certain side lobe suppression level do not reduce the side lobes completely or sufficiently for the near field case, especially in the back fire direction. In this paper, asymmetrical amplitude weighting coefficients in combination with Chebyschev are used to further improve the side lobe suppression over a larger angular range.

Antenna Range Illuminator Based on a Septum Polarizer and a Dual-Mode Horn [Measurements Corner

In this article, an original design of a range illuminator based on a steppedseptum polarizer and a dual-mode horn is discussed. However, the designed polarizer can also be used with other waveguide antennas, such as pyramidal horns and corrugated horns. A simple procedure for determining the initial septum geometry for the subsequent optimization is described, and based on this, a twostep septum polarizer is developed. A carefully designed dual-mode horn antenna with a rectangular aperture is then utilized to increase the illuminator's gain and suppress sidelobe levels. Results of full-wave electromagnetic simulations are presented and compared to experimentally measured data with good agreement.

Wideband subwavelength‐profile circularly polarised array antenna using anisotropic metasurface

A cost-effective solution for the performance enhancement of circularly polarised array antennas by using a thin metasurface is proposed. The array is considered as reconfigurable, where an antenna engineer can arbitrarily add the metasurface onto the original array according to application requirements. Once added, the new array forms a subwavelength cavity having a compact form factor of 1.63λ o × 1.63λ o × 0.07λ o at 2.45 GHz. The array antenna is demonstrated to have remarkable enhancement on its performance metrics including boresight gain (12.8 dBic), axial-ratio bandwidth (46.5%) and 10 dBic gain bandwidth (24.4%). More interestingly, a sidelobe suppression level of 4.4 dB is achieved.

A sidelobe suppressing near-field beamforming approach for ultrasound array imaging.

A method is proposed to suppress sidelobe level for near-field beamforming in ultrasound array imaging. An optimization problem is established, and the second-order cone algorithm is used to solve the problem to obtain the weight vector based on the near-field response vector of a transducer array. The weight vector calculation results show that the proposed method can be used to suppress the sidelobe level of the near-field beam pattern of a transducer array. Ultrasound images following the application of weight vector to the array of a wire phantom are obtained by simulation with the Field II program, and the images of a wire phantom and anechoic sphere phantom are obtained experimentally with a 64-element 26 MHz linear phased array. The experimental and simulation results agree well and show that the proposed method can achieve a much lower sidelobe level than the conventional delay and sum beamforming method. The wire phantom image is demonstrated to focus much better and the contrast of the anechoic sphere phantom image improved by applying the proposed beamforming method.

A 60 GHZ END-FIRE HIGH-GAIN TAPERED SLOT ANTENNA WITH SIDE-LOBE SUPPRESSION

A simple end-fire high-gain antenna with side-lobe level suppression is proposed for 60 GHz technology in this paper. The antenna has a tapered slot radiation patch which is obtained by subtracting a quarter of ellipse from a bigger quarter. Two reflecting circle units (RCU) are located at both sides of radiant patch to suppress side-lobe level of radiation patterns. The antenna has a simple two-layered planar structure with on via and is fabricated on a Rogers 4350 substrate with a compact size of 15 mm × 15 mm. Simulated and measured results match well, and both show its good characteristics of impedance matching, stable radiation patterns and steady peak gains above 10 dBi across 57-64 GHz, which makes it fit 60 GHz wireless communication systems.

Synthesis of Circular Array Antenna for Sidelobe Level and Aperture Size Control Using Flower Pollination Algorithm

Sidelobe level suppression is a major problem in circular array antenna (CAA) synthesis. Many conventional numerical techniques are proposed to achieve this which are time consuming and often fail to handle multimodal problems. In this paper, a method of circular array synthesis using nature inspired flower pollination algorithm (FPA) is proposed. The synthesis technique considered here adapts one and two degrees of freedom, namely, amplitude only and amplitude spacing. The effectiveness of the FPA is studied by comparing the results with genetic algorithm (GA) and uniform circular array antenna (UCAA) with uniform spacing. Also the effect of additional degree of freedom on the aperture size and the computational time is analyzed. A relative side lobe level (SLL) of −25 dB is achieved using the algorithm under both no beam scanning (0°) and beam scanning (15°) conditions for 20 and 40 elements of CAA.

Shaped Beam Pattern Synthesis of Antenna Arrays Using Composite Differential Evolution with Eigenvector-Based Crossover Operator

This paper addresses the problem of designing shaped beam patterns with arbitrary arrays subject to constraints. The constraints could include the sidelobe level suppression in specified angular intervals, the mainlobe halfpower beamwidth, and the predefined number of elements. In this paper, we propose a new Differential Evolution algorithm, which combines Composite DE with an eigenvector-based crossover operator (CODE-EIG). This operator utilizes eigenvectors of covariance matrix of individual solutions, which makes the crossover rotationally invariant. We apply this novel design method to shaped beam pattern synthesis for linear and conformal arrays. We compare this algorithm with other popular algorithms and DE variants. The results show CODE-EIG outperforms the other DE algorithms in terms of statistical results and convergence speed.

Nulls and side lobe levels control in a time modulated linear antenna array by optimizing excitations and element locations using RGA

In this paper a novel approach based on the Real coded Genetic Algorithm (RGA) is proposed to improve nulling performance as well as suppression of Side Lobe Level (SLL) of a Time Modulated Linear Antenna Arrays (TMLA). RGA adjusts the static excitation amplitudes as well as the location of each element from the origin to place deeper nulls in the desired direction. Three design examples are presented that illustrate the use of the RGA, and the optimization goal in each example is easily achieved.

Circular Collaborative Beamforming for Improved Radiation Beampattern in WSN

This paper presents a novel collaborative beamforming (CB) method of wireless sensor network (WSN) by organizing sensor node location in a circular arrangement. Appropriate selection of active CB nodes and cluster is needed each time to perform CB. The nodes are modeled in circular array location in order to consider it as a circular antenna array (CAA). This newly proposed circular collaborative beamforming (CCB) is further presented to solve two different objectives, that is, sidelobe level (SLL) suppression and first null beamwidth (FNBW). Analyses obtained are compared to those from previous work. The findings demonstrate a better CB performance of intelligent capability, and the difference is shown in normalized power characteristic.

Receiver Design for Range and Doppler Sidelobe Suppression Using MIMO and Phased-Array Radar

This paper investigates the receiver instrumental variable (IV) filter design for sidelobe suppression using multiple-input-multiple-output (MIMO) and phased-array radar. First, we analyze the performance of existing integrated sidelobe level (ISL) and the zero sidelobe (ZS) methods for range sidelobe suppression, and show the latter's superiority. The limitation of MIMO radar sidelobe suppression in a large number of range bins is discussed. It is shown that the phased-array radar avoids this limitation. Then we consider joint range and Doppler sidelobe suppression, and the solutions for both MIMO and phased-array radar are derived, classified, and analyzed. The conclusions are drawn through performance trade-off. The use of phased-array radar compromises the waveform diversity of MIMO radar. However, with the objective of range, and joint range and Doppler sidelobe suppression, phased-array radar has better performance in terms of computational complexity, sidelobe suppression level and signal-to-noise ratio (SNR) loss. This will relieve the design workload for large scale radar systems. In addition, we show via simulations that the bounds of clear area of matched filter output (ambiguity function) are inapplicable for the IV filter design.

Taylor 가중치와 LSMI 알고리즘을 이용한 광대역 적응형 빔형성 연구

This paper represents an adaptive beamforming technique to suppress interference or jamming signals in wideband. In order to maintain low side lobe level(SLL) at an antenna element level, Taylor-weighting was used. Also, to make a nulling beam pattern toward jammer's directions in wideband, we used the modified Loaded Sample Matrix Inversion(LSMI) algorithm and Tapped Delay Line(TDL). To verify the proposed algorithm, we applied it to a rectangular array antenna. Finally, the results show beam pattern with low SLL and jammers suppression.

인공 자기 도체를 이용한 스캔 가능한 패브리 패롯 공진기형 안테나 설계

이 논문에서는 인공 자기 도체를 이용한 패브리 패롯 공진기형 안테나에서 배열 급전을 이용하여 스캔 기능을 갖는 안테나의 방사 특성을 분석하였다. 제안하는 안테나는 AMC 면의 도입으로 공진 길이가 1/4 파장으로 감소되었고, 배열 급전기의 도입에 의하여 방사되는 빔의 조향각의 제어가 가능하다. 12 GHz의 주파수에서 배열 급전 요소 간의 간격을 1.4 파장으로 하여 어퍼쳐 크기의 증대에 의하여 약 19 dB의 이득, 14 dB의 SLL 억압비 그리고 <TEX>$90^{\circ}$</TEX>의 급전 위상차에서 <TEX>$8^{\circ}$</TEX>의 스캔 각도를 얻었다. Fabry-Perot cavity(FPC) antennas with artificial magnetic conductor(AMC) surface are designed in order to provide scan capability by <TEX>$4{\times}1$</TEX> array feed inside the cavity. The proposed antenna, excited by <TEX>$4{\times}1$</TEX> thinned array, not only achieve higher directivities but also improve suppression of sidelobe level(SLL) relative to that of the thin array alone. The FPC antenna with the height of a quarter wavelength generate maximum gain of 19 dB, SLL suppression of 14 dB and maximum scan angle of <TEX>$8^{\circ}$</TEX> under the feed phase difference of <TEX>$90^{\circ}$</TEX> at the design frequency of 12 GHz.

A MULTI-OBJECTIVE MEMETIC OPTIMIZATION APPROACH TO THE CIRCULAR ANTENNA ARRAY DESIGN PROBLEM

The paper provides a novel approach to the design of non- uniform planar circular antenna arrays for achieving maximal side lobe level suppression and directivity. The current excitation amplitudes and phase perturbations of the array elements are determined using an Adaptive Memetic algorithm resulting from a synergy of Difierential Evolution (DE) and Learning Automata that is able to signiflcantly outperform existing state-of-the-art approaches to the design problem. Moreover, existing literature considers the design problem as a single- objective optimization task that is formulated as a linear sum of all the performance metrics. Due to the con∞icting nature of the various design objectives, improvements in a certain design measure causes deterioration of the other measures. Following this observation, the single-objective design problem is reformulated as a constrained multi-objective optimization task. The proposed memetic algorithm is extended to the multi-objective framework to generate a set of non-dominated solutions from which the best compromising solution is selected employing a fuzzy membership based approach. An instantiation of the design problem clearly depicts that the multi- objective approach provides simultaneous side lobe level suppression and directivity maximization in comparison to the single-objective scenario.

Robust Adaptive Beamforming Imaging Approach for Stepped-Frequency through-the-Wall Radar

A robust Capon adaptive beamforming imaging method was proposed for stepped-frequency through-the-wall radar. According to the ideal of robust Capon beamforming (RCB) under the steering vector uncertainty set, Capon optimal weight vector in frequcency domain is obtained by accurately estimating Compensation function vector. Then signal energy is estimated by freqency weighting, and coherence factor (CF) weighting is applied to suppress sidelobe level. Therefore, this method not only achieves higher resolution and much better interference suppression capabilities, but also improves imaging contrast.

Constructing the 2D radio images of objects with the use of multifrequency signals with coded carrier-frequency hopping (Costas signals)

An approach to constructing radial Doppler 2D radio images (RIs), in which the synthetic aperture method is applied to multifrequency signals with Costas-coded hopping of carrier frequencies, is investigated. The case of completely coherent signals and the case of their strong phase distortions have been discussed. Side lobe level suppression method based on multiplicative processing of 2D RIs constructed with the use of different frequency codes is proposed. Selection of code bases ensuring minimization of the side lobes level of the resulting 2D RI has been substantiated. The results simulation based on mathematical bright points are presented.

Sparse Linear Array Synthesis With Multiple Constraints Using Differential Evolution With Strategy Adaptation

This letter addresses the problem of designing sparse linear arrays with multiple constraints. The constraints could include the minimum and maximum distance between two adjacent elements, the total array length, the sidelobe level suppression in specified angular intervals, the main-lobe beamwidth, and the predefined number of elements. Our design method is based on differential evolution (DE) with strategy adaptation. We apply a DE algorithm (SaDE) that uses previous experience in both trial vector generation strategies and control parameter tuning. Design cases found in the literature are compared to those found by SaDE and other DE algorithms. The results show that fewer objective-function evaluations are required than those reported in the literature to obtain better designs. SaDE also outperforms the other DE algorithms in terms of statistical results.

Application of a Comprehensive Learning Particle Swarm Optimizer to Unequally Spaced Linear Array Synthesis With Sidelobe Level Suppression and Null Control

We present unequally spaced linear array synthesis with sidelobe suppression under constraints to beamwidth and null control using a design technique based on a Comprehensive Learning Particle Swarm Optimizer (CLPSO). CLPSO utilizes a new learning strategy that achieves the goal to accelerate the convergence of the classical PSO. Numerical examples are compared to the existing array designs in the literature and to those found by the other evolutionary algorithms. The synthesis examples that are presented show that the CLPSO algorithm outperforms the common PSO algorithms and a real-coded genetic algorithm (GA).

Suppression of side lobe level on the cone characteristics of the directivity pattern of an antenna as an important factor in its directivity index and effective aperture

This paper will present a universal procedure for precise de‐embedding of the directivity index and effective aperture dependence of the suppressed side lobes on measured cone directivity patterns of sonar antennas. The procedure is derived on an idealized model of cone characteristics and directivity patterns of antennas. It is universally applicable to any contemporary sonar or hydroacoustic communication system with a cone directivity pattern. In accordance with the given expressions of directivity index and effective aperture of circle baffled pistons, this paper will present substitute analytical functions for hypothetical circle antennas with suppressed minor lobes. The presented graphs of functional behavior in a two‐dimensional system, and in a three‐dimensional coordinate system, are an excellent base for standardization, unification and quality evaluation of sonar or radar systems and also medical scanners. Key words: directivity index of sonar antenna, idealized model of cone directivity pattern, level of suppressed side lobes, effective aperture