Phase-only synthesis of minimum peak sidelobe patterns for linear and planar arrays (original) (raw)
Related papers
The International Conference on Electrical Engineering
In this work, synthesis of linear array geometry is first formulated as a linearly constrained multi-objective optimization problem with the goals of minimum sidelobe level, null control and high directivity. Then solved by a Generalized Pattern Search (GPS) algorithm for the optimum element locations and excitation amplitudes. The constraints are imposed on the inter-element spacing and dynamic range ratio of the amplitude tapering to reduce mutual coupling effects between the elements. GPS methods are newly discovered, derivative-free methods where the current iterate is updated by sampling the fitness function at a finite number of points along a suitable set of search directions to find a decrease in the function value. Finally, two worked examples are presented that illustrate the use of GPS synthesis method, and the optimization goal in each example is easily achieved. Furthermore the full-wave simulations of the synthesized arrays are also completed to examine the mutual coupling effects. Finally the results of the GPS algorithm are validated by comparing with results obtained using the genetic algorithm, and the results of the uniform and Dolph-Chebyshev arrays, having the same number of element and the same aperture length.
Microwave and Optical Technology Letters, 2005
Equispaced linear arrays that have uniformly excited central elements and monotonically decreasing flanking segments have been shown to yield low-sidelobe patterns with specified constraints on the effective radiated voltage (ERV). An analytical method for generating these distributions using a constrained least-squares (CLS) method, with restrictions on both the peak amplitude of the elements and the ERV, has been discussed in a previous work. Simulated annealing (SA) is a versatile global-optimization technique that can be effectively used for similar purposes, but can also provide additional control over some other design parameters. In this paper, we inspect both methods-indicating some of their advantages and drawbacks-through some numerical results. Figure 5 Measured gain of the antenna (S ϭ 5 ϫ 5 cm 2 ) Lett 45: 60 -62, 2005; Published online in Wiley InterScience (www.
Reduction of Sidelobe Structure in Phased Arrays
A simple teclmique for, reducing the sidelobe stnicture in tlie radiation patteni of phased arrays is prcsenled. Tlus techniqne uses an auxiliary antenna consisting of two or four elements in conjunction with the liiain array. Tlie two 'elements produce a cosine pattern of constant amplitude. The four elenients can produce a sine pattern w:itIi vaqing amplitude depending npon rlie size of the auxiliay a n t e m . Adding or subtrdcting the pattern of the anxiliaq antenna lo the pattern or the iliain array will result in a new pattern with reduced sidelobes. Results of computer siniulations showed good iniproveineius in the sidelobe stnicture.
Synthesis of Wide Beam Array Patterns Using Quadratic-Phase Excitations
Synthesis of wide-beam array antennas is investigated using phase-only technique. A quadratic phase distribution for the element excitations is proposed, while the magnitudes are kept uniform. The beam width and maximum level of the radiated field of the proposed array were compared with those obtainable from the conventional broadside array. Compared to the case of broadside array, the proposed method showed many fold increase in the -10dB beam width. Moreover, a reduction of up to 7.6dB for a 10-element array, and 13.6dB for the 40-element array have been obtained in the maximum level of the pattern. The proposed technique offers simple design method, and considerable reduction in the number of required phase shifters. The required number of phase shifters for an N-element array is (N/2-1), and (N-1)/2 for even, and odd number of elements N respectively.
Synthesis of equally excited linear arrays
IEEE Transactions on Antennas and Propagation, 1977
Synthesis of linear arrays employing a perturbation technique to achieve sidelobe reduction by varying element positions alone or phases of antenna currents alone, keeping magnitudes of antenna currents equal, is discussed. Both the mean squared and mini-max error criteria are employed. The technique may also be used to yield patterns with all sidelobes equal.
The design of linear arrays to produce a desired radiation pattern, i.e., the pattern-synthesis problem, continues to be of interest, as demonstrated by the number of articles being published on this topic. Varieties of approaches have been developed to deal with this problem. The approach discussed here begins with a specifi ed set of element currents – such as choosing all to be of unit amplitude, for example – the radiation pattern of which is computed. A matrix is constructed, the individual coeffi cients of which are comprised of the contribution each element current makes to the maxima of this initial radiation pattern. A vector, the entries of which are the desired amplitudes of each maxima in the radiation pattern, is then multiplied by the inverse of this matrix. This operation generates a new set of element currents, the pattern maxima of which may change somewhat in angle relative to those of the initial pattern. This requires that the process be repeated as an iterative sequence of element-current and pattern computations. When the locations of the pattern maxima no longer change in angle and the maxima converge to their specifi ed values, the synthesis is complete. Results from this approach are demonstrated for several pattern types.
Synthesis of Linear Arrays with Sidelobe Level Reduction Constraint using Genetic Algorithms
International journal of …, 2008
The synthesis of uniformly spaced linear array geometries with minimum sidelobe level and beamforming capability using genetic algorithms is presented. The iterative process aims not only at matching the desired pattern to the desired one but minimizing the sidelobe level as well; through optimizing the element excitations. Various examples are included to demonstrate the design effectiveness and flexibility namely for switched smart antenna systems applications.
An Array with Crossed-Dipoles Elements for Controlling Side Lobes Pattern
This paper introduces an array with a new element structure to achieve asymmetric sidelobe pattern nulling which is a much desired feature in many applications such as communication systems, tracking radars, and imaging. The proposed element structure consists of combining two simple wire dipoles in the horizontal and vertical positions to form a crossed dipole element. The array patterns of the horizontal and vertical dipoles alone share some common radiation feature such angular null positions which are exploited to provide sidelobe nulling. By properly scaling the array pattern of the horizontal dipoles and added or subtracted its array pattern from that of the vertical dipoles, a new array pattern corresponds to the crossed dipoles elements with controlled sidelobes pattern can be obtained. The scaling factor selects which sidelobes to be cancelled. The method is equally applied to the uniformly and nun-uniformly excited arrays. The proposed idea is verified by simulating an arr...
A Two-Step Method for the Low-Sidelobe Synthesis of Uniform Amplitude Planar Sparse Arrays
Progress In Electromagnetics Research M, 2019
A two-step method combining the algorithms of iterative Fourier transform (IFT) and differential evolution (DE), called IFT-DE, is proposed in this paper for the low sidelobe synthesis of a uniform amplitude planar sparse array (PSA). Firstly, the entire aperture of the array is divided into a set of square lattices that are spaced at half wavelength. Then the elements are forced to be located on the lattices through performing IFT, so that a planar thinned array (PTA) is formed across the aperture. Undoubtedly the interval between adjacent elements of the PTA is an integer multiple of half wavelength. In the second step, for each column of PTA the elements spaced greater than or equal to a wavelength are selected as the candidates whose locations need to be optimized by DE procedure, as long as the renewed inter-element spacing is not less than half wavelength. Consequently, a PSA with reduced sidelobe level may be obtained. According to the aforementioned selection rule, only a small part of elements that account for the total number need to be relocated, which denotes that the number of individual parameters waiting for optimizing by DE is decreased considerably, and thereby greatly accelerates the convergence speed of the algorithm. A set of synthesis experiments for PSA ranging from small to moderate size are presented to validate the effectiveness of the proposed method.