Antenna Pattern Synthesis Research Articles

Suppressing Range Ambiguity by Pattern Synthesis for SAR via Semidefinite Relaxation

Range ambiguities severely degrade the performance of the synthetic aperture radar (SAR) system. To make an improvement without increasing the system complexity, antenna pattern synthesis is a feasible method. To this end, a novel algorithm that can shape the mainlobe and suppress the range ambiguities simultaneously by relaxing the problem as a semidefinite relaxation (SDR) programming problem is proposed here for the first time. Compared to the algorithm with global optimization, the presented algorithm could find the desired pattern without the large occupation of computing resources and has great potential in raising the performance of SAR system. In addition, some simulations are carried out, and the results prove that the proposed algorithm has the superior ability to suppress the range ambiguities while controlling the beamwidth and dynamic range ratio (DRR).

Conformal antenna array radiation pattern synthesis by tilt correction to improve Direction-of-Arrival estimation accuracy

ABSTRACT This paper, considering the tilt effect, presents a hemispherical antenna structure modeled by an improved conformal antenna array with the maximum angular coverage of the elevation axis to increase the Direction-of-Arrival (DOA) estimation accuracy. For this purpose, a multiface conformal structure with 3 different tilts and 13 directive circular patch antennas is designed in the Full Wave Simulation Software (HFSS). By optimizing the angles α and β as two key parameters in this design, nine different structures are constructed and their impacts on the DOA performance are carefully studied. The Cramer–Rao Lower Bound (CRLB), Multiple Signal Classification (MUSIC), and Root Mean Square Error (RMSE) algorithms are utilized to evaluate all constructed structures and chose the most improved structure for DOA estimation. At the end, it is shown that the proposed hemispherical antenna structure has a better performance than previous conformal designs for DOA applications and spatial resource positioning in which the maximum elevation angle coverage by the antenna is highly required. It is noted that the tilt optimization method proposed in this paper can lead to design a near optimal conformal antenna array structure for DOA estimation for a wide elevation angle coverage which can be considered for next works.

A Deep Learning-Based Approach for Radiation Pattern Synthesis of an Array Antenna

In this article, we propose a deep neural network (DNN)- for the radiation pattern synthesis of an antenna. The DNN utilizes the radiation patterns as inputs and the amplitude and phase of the antenna elements as outputs. Consequently, the radiation patterns of the array antenna can be easily obtained from the outputs of the trained DNN, which are amplitude and phase of the antenna elements. However, it is difficult to determine the amplitude and phase of each antenna element from the desired pattern in an environment where inter-element coupling exists. For this purpose, 6,859 radiation pattern samples for a $4 \times 1$ array patch antenna were generated by changing the phases of the antenna elements, and those patterns were leveraged to train the proposed DNN with low complexity. The radiation patterns of the ideal square and triangular array shapes, which are practically infeasible to implement, were used as inputs to the DNN. It was confirmed that the radiation pattern generated from the output signals of the DNN was very similar to the input radiation pattern.

Moxon Antenna Array Design and Pattern Synthesis Technique

A four-element moxon antenna array is proposed in this paper. Its directive properties are shown with simulations and compared with the classical dipole array. In order to synthesize the pattern of moxon array, a hybrid method that consists of differential evolution (DE) and numerical electromagnetics code version 2 (NEC2) is also introduced. Basically, the cost function used by DE is designed with the help of NEC2 simulations to achieve more realistic optimum antenna array designs. Patterns having one and double sidelobe suppression at predetermined angles are successfully synthesized by using this method whereas the gain value is maintained properly. Robustness of the proposed method is also examined. For this aim, multiple executions of the method implementation are performed under same conditions. The results show that the method introduced in this paper is very stable in terms of the radiation pattern and convergence curves.

Synthesis of Monopulse Antenna Patterns for Elliptical Phased Array Antennas With Different Peak Sidelobes Along the Principal Planes

This paper deals with the synthesis of monopulse antenna patterns, sum and difference ones, for planar phased array antennas with an elliptical aperture boundary featuring unequal ultra-low peak sidelobe levels (PSLLs) for the two principal planes of its far field. The used synthesis method is the iterative Fourier transform (IFT) approach. The elliptical planar phased array antenna involved in this synthesis contains 3656 open-ended waveguide radiating elements arranged in a triangular element grid and has an aperture width and height of 50λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> and 25λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> , respectively, where λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the wavelength at X-band center frequency 1.0f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> . The simulated monopulse pattern results will be compared with those of a 4680-element rectangular planar phased array antenna having the same width, height, radiator type and triangular grid as the elliptical array antenna. The monopulse patterns of the rectangular array antenna meet the same unequal ultra-low PSLL requirements as those of the elliptical array antenna. It will be shown that the elliptical array antenna with a slightly enlarged aperture containing 4170 elements features on receive comparable or even better far-field performance characteristics as that of the rectangular array antenna. All reported far-field pattern simulations take mutual coupling between the array elements into account.

Synthesis of radar antenna patterns with linear beam scanning and amplitude signal processing

In radars with linear beam scanning the angular resolution is determined by the width of the antenna pattern. The traditional way to increase this resolution is to enlarge the size of the antenna aperture, which is limited by technical capabilities. It is possible to achieve an increase in the angular resolution by using special methods for processing the received signals, which make it possible to synthesize the antenna pattern with the desired width. The aim of the work was to develop such method for synthesizing of radar antenna pattern with linear beam scanning and amplitude signal processing. A method for the synthesis of the antenna patterns with a given width, determined by the distance between the zeros of the first side lobes is proposed. This is reached by simultaneous processing of delayed signals in the output of the receiver and its summations. The method of pattern synthesis is based on the choice of the optimality criterion by minimizing the quadratic loss function. This function includes a term that minimizes the noise variance at the output of the receiver, as well as terms that take into account linear restrictions on the antenna pattern amplitude and width. The solution to the problem is carried out on the basis of the method of Lagrange multipliers with linear constraints.The capabilities of the method are shown in model examples of the synthesis of antenna patterns with different number of measurement channels. It is assumed that the initial diagram is described by a Gaussian function. The cases of uniform and nonuniform distribution of angles in the range of the initial antenna pattern are considered. The dependence of the signal-tonoise ratio on the number of directional patterns and the amplitude of the side lobes is investigated.

Pattern Synthesis of Time-Modulated Array Antenna Based on an Improved Invasive Weed Optimization Method

In this paper, pattern synthesis through time-modulated linear array is studied, and a novel strategy for harmonic beamforming in time-modulated array is proposed. The peak side lobe level is designed as optimization objective function, and the switch-on time sequence of each element is selected as optimization variable. An improved invasive weed optimization (IWO) algorithm is developed in order to determine the optimal parameters describing the pulse sequence used to modulate the excitation weights of array elements. Representative results are reported and discussed to point out potentialities and advantages of the proposed approach, which can obtain lower objective function values.

Multi-dimension to one-dimension transformation approach for multi-dimensional antenna array pattern synthesis

ABSTRACTA new multi-dimension to one-dimension transformation (MTOT) approach is presented to synthesize multi-dimensional antenna array pattern. In the new approach the multi-dimensional antenna array pattern synthesis issue is mathematically transformed into a one-dimensional (1D) pattern synthesis issue by taking advantage of the general characteristics of the pattern function, which makes all existing linear array pattern synthesis and beamforming methods applicable to addressing relevant multi-dimensional array pattern synthesis issues. The new method provides a general way for multi-dimensional array pattern synthesis. Simulations of the new approach are conducted to show its effectiveness. The simulation results show that the new method can well accomplish the pattern synthesis mission for different multi-dimensional array configurations.

Power Gain Pattern Synthesis of Array Antenna With Dynamic Range Ratio Restriction

By directly solving the power-gain pattern synthesis (PGPS) instead of the shaped-beam pattern synthesis (SBPS), the gain of the antenna array can be improved. However, the dynamic range ratio (DRR) of the optimized results for both PGPS and SBPS are uncontrollable, which can heavily increase the cost of a real system. In this letter, the DRR control scheme for the PGPS problem is discussed. The maximum desired DRR is added, yielding a new nonconvex problem to be solved. This nonconvex DRR restriction is approximated as a linear convex restriction condition, which explicitly provides the lower and upper bounds of the array weight. Finally, with the aid of an existing PGPS-algorithm structure, the designed derivative PGPS problem can be solved effectively. The advantage and effectiveness of the proposed algorithm are validated with simulation results.

Efficient Synthesis of Antenna Pattern Using Improved PSO for Spaceborne SAR Performance and Imaging in Presence of Element Failure

For a synthetic aperture radar (SAR) system, the individual beam pattern pointing and shaping due to amplitudes and phase settings in transmit/receive modules (TRMs) are mainly used in the elevation direction over the total range of incidence angles. The criteria for the optimized antenna elevation beam pattern are profoundly linked to the overall SAR system performance requirements. In particular, a high sidelobe level (SLL) in the antenna pattern leads to a high range ambiguity-to-signal ratio (RASR), which degrades the quality of the SAR image. RASRs can be controlled by appropriate antenna SLL suppression at defined positions in the elevation pattern. This paper focuses on the improvement in the SAR system performance using an effective technique for optimizing antenna pattern synthesis. The desired antenna patterns can be synthesized referring to the optimized antenna mask templates using the newly devised cost function and improved particle swarm optimization (IPSO). Even though there are some defective TRMs in array phased antennas, one can regenerate an optimal pattern as close as possible to the desired one, owing to the proposed cost function and IPSO. Moreover, this paper provides a new perspective on RASR performance, which can be analyzed in SAR images, via the full-chain process from antenna pattern synthesis to SAR image formation. In addition, this is the first study to consider the problem of antenna pattern optimization with element failure, in terms of spaceborne SAR imaging, as well as SAR system performance. The simulations conducted in this study show that the optimized pattern obtained via the proposed technique can provide good SAR system performance, resulting in high-quality SAR images, even with defective TRMs.

안테나 소자 결함을 고려한 안테나 빔 패턴 재합성을 통한 위성 SAR 성능향상에 대한 연구

To meet the requirements of various satellite synthetic aperture radar(SAR) system performance parameters, the characteristics of the antenna pattern should be analyzed. In this paper, we propose a method to improve the SAR system performance using an effective technique for optimizing antenna pattern synthesis in the presence of element failure. The desired antenna pattern can be synthesized by referring to the optimized antenna mask templates using the particle swarm optimization algorithm. In the simulation, the performance of the proposed method is verified by analyzing characteristics related to the SAR system performance parameters using antenna pattern regeneration.

A hybrid GA-PSO optimization algorithm for conformal antenna array pattern synthesis

This paper introduces a hybrid genetic algorithm and particle swarm optimization algorithm (GA-PSO) dedicated to pattern synthesis of conformal antenna arrays. Taking advantages of both methods, the proposed hybrid GA-PSO optimization algorithm has fast convergence speed and high convergence accuracy when applied to antenna array pattern synthesis. To show the performance of the hybrid optimization algorithm, several typical test functions and optimization examples of a linear array pattern synthesis are illustrated. Finally, a 4 × 2 cylindrical conformal microstrip antenna array as a practical synthesis example is studied to demonstrate the proposed algorithm. The simulated and measured results have shown the proposed method is effective and reliable for conformal antenna array pattern synthesis.

A Comparative study on Linear Array Antenna pattern synthesis using Evolutionary Algorithms

Antenna array is defined as a collection of multiple radiating elements (antennas) which are placed in space in uniform or non-uniform manner to get a directional radiation pattern that a single antenna generally not adequate to achieve it. In antenna array pattern side lobe level and deep nulls are major problems which cause wastage of energy. This paper presents a brief survey on previous work on optimization of the linear antenna array to achieve a radiation pattern with maximum side lobe level (SLL) reduction along with control null placement in the specified directions. To get superior ability from antenna array it is requisite to modify or synthesize its geometric configurations (as linear, circular, and rectangular etc) or its electrical parameters such as excitation amplitude, phase or distance between array elements. Modern communication system demands compact array designs with high directivity and low side lobe levels. Aimed at this problem several optimization evolutionary algorithms are presented and compared in this paper, are genetic algorithm, ant colony algorithm (ACO), modified invasive weeds optimization algorithm (MIWO), Ant Lion Optimization (ACO), Gravitational Search Algorithm (GSA) and so on.

Performance Improvement of Spaceborne SAR Using Antenna Pattern Synthesis Based on Quantum-Behaved Particle Swarm Optimization

This study improves the performance of a spaceborne synthetic aperture radar (SAR) system using an antenna mask design method and antenna pattern synthesis algorithms for an active phased array SAR system. The SAR antenna is an important component that affects the SAR system performance because it is closely related to the antenna pattern. This study proposes a method for antenna mask design that is based on several previous studies as well as the antenna pattern synthesis algorithm, which is based on quantum-behaved particle swarm optimization (QPSO) for an active phased array SAR system. The performance of the designed antenna masks and synthesized patterns demonstrate that the proposed mask design method and antenna pattern synthesis algorithm based on QPSO can be used to improve the SAR system performance for spaceborne applications.

Phase-only pattern synthesis based on gradient-descent optimization

By applying phase-only technique in array antenna pattern synthesis, antenna arrays can form desired patterns with the use of phase shifters only. A novel phase-only pattern synthesis algorithm is proposed for the passive phased array seeker. This algorithm synthesizes the main beam of the antenna pattern through least-squares approximation, thus minimizing the errors between the actual and the desired main beams. The synthesis problem can be solved by applying gradient-descent optimization. The item for suppressing side lobes is added to the above synthesis problem. To obtain a side lobe level as low as possible, the algorithm assigns different weights to different directions in the side lobe region. The algorithm is run repeatedly and the weights are adjusted adaptively according to the normalized power in the side lobe directions. Detailed examples are presented to demonstrate the accuracy and effectiveness of the proposed approach.

A novel hybrid IWO/WDO algorithm for nulling pattern synthesis of uniformly spaced linear and non-uniform circular array antenna

This paper introduces a new, fast, efficient and global optimization algorithm called hybrid invasive weed optimization (IWO) and wind driven optimization (WDO). The hybrid algorithm is verified with six standard benchmark functions and implemented to the nulling pattern synthesis of a uniform linear array (ULA) and non-linear circular array (NUCA) antenna having a minimum side lobe level (SLL), and beam width to minimize the interference effect by optimizing the parameters of array elements. Two examples of ULA pattern synthesis with broad null at desired direction are considered to illustrate the efficacy of the proposed algorithm. The results are compared with those obtained by BEES, PGSA, BFO, WDO and MTACO algorithms. Further, one design example of NUCA antenna is considered and the results obtained by hybrid algorithm is compared with those obtained by other evolutionary algorithms such as GA, PSO, CS, FA, BBO, COA, and MIWO. Simulation studies demonstrate the improved performance of hybrid IWO/WDO algorithm in terms of synthesizing broad null, minimum SLL, beam width control and the rate of convergence for nulling pattern synthesis of ULA and NUCA antenna compared to other twelve reported algorithms.

컨포멀 위상 배열 안테나의 패턴 합성에 대한 고찰

컨포멀 위상 배열 안테나의 패턴 합성에 대한 고찰

향상된 적응형 유전 알고리즘을 이용한 회전체형 컨포멀 배열 안테나의 패턴 합성

향상된 적응형 유전 알고리즘을 이용한 회전체형 컨포멀 배열 안테나의 패턴 합성

Using Prony's Method To Synthesize Discrete Arrays for Prescribed Source Distributions and Exponentiated Patterns

Antenna pattern synthesis remains an important topic in electromagnetics. One goal of continuing interest has been that of developing an array of discrete sources that replicate the radiation pattern of continuous sources such as an aperture radiator or some current distribution. Another is to determine a discrete array that produces a prescribed radiation pattern. This paper outlines a procedure based on Prony's method for finding discrete-source arrays to accomplish these goals. A variety of problems are presented to demonstrate the performance of Prony pattern synthesis. In addition, discussed is the use of singular-value analysis to establish the rank of a given pattern, the synthesis of arrays that produce exponentiated patterns, and the effect of noisy source strengths on the realized patterns.

A PATTERN SYNTHESIS METHOD FOR LARGE PLANAR ANTENNA ARRAY

The pattern synthesis for large antenna arrays is very important because of its wide applications. Several antenna array synthesis techniques for planar antenna array have been developed in the past years. In this paper, a hybrid method for solving antenna array pattern synthesis problem is introduced. The proposed method has three steps. Firstly, the iterative fast Fourier transforms (IFT) is used to generate a number of initial array excitations based on aim pattern. Then, the global optimization method differential evolution strategy (DES) is used to optimize these excitations based on initial excitations. After that, if the optimized pattern does not satisfy the goal, the simulated annealing (SA) method is applied to optimize the excitations until the goal is achieved or the maximum iteration is reached. Several simulation results show that the desired pattern can be effectively synthesized by using the proposed method.