1,720,983 research outputs found
DESIGN OF PATTERN RECONFIGURABLE SPARSE ANTENNA ARRAYS
No full textThis paper presents a fully deterministic approach for the design of phase-controlled, reconfigurable, sparse antenna arrays. The objective is that of synthesizing a sparse array which radiates, by phase-only control, a number of desired far-field co-polar patterns, simultaneously controlling the cross-polar patterns and the dynamic range ratio (DRR) of the excitations. The proposed procedure, which optimizes the number, the positions and the excitations of the array elements, is divided in two steps. First, the geometrical synthesis is performed in order to obtain the number and the positions of the array elements. Then, the excitations of these elements are determined with a suitable fixed-grid synthesis algorithm. The optimality of the solution is not guaranteed, but numerical examples provided satisfactory results
Far-Field Synthesis of Sparse Arrays with Cross-polar Pattern Reduction
No full textThis paper presents a fully deterministic iterative algorithm for the far-field synthesis of antenna arrays with reduction of the cross-polar component. The algorithm synthesizes the excitations as well as the positions of the array elements, providing a sparse geometry. Starting from an initial set of possible positions, the proposed algorithm iteratively solves a sequence of convex optimization problems. At each iteration a suitable objective function is minimized, which allows to reduce the number of radiating elements, among those of the initial set, in presence of constraints on the far-field co-polar and cross-polar patterns. The adopted formulation leads to a second order cone problem (SOCP), which is iteratively solved with CVX, a Matlab-based modeling system developed at the Stanford University and available on the Internet
Reducing the sidelobe power pattern of linear broadside arrays by refining the element positions
No full textIn this letter a simple and fast method is presented for improving linear array radiation patterns produced by existing synthesis algorithms. Given a linear aperiodic array with elements lying at specified positions, having uniform distribution of the excitations and radiating a pencil beam {in the broadside direction}, the proposed approach iteratively modifies the positions of the elements in order to reduce the power radiated in the sidelobe region. Numerical examples show the effectiveness of the method, and the effects of sidelobe power reduction on other parameters of the antenna are examined
An Efficient and Versatile Technique for the Synthesis of 3D Copolar and Crosspolar Patterns of Phase-Only Reconfigurable Conformal Arrays With DRR and Near-Field Control
No full textAn accurate and flexible iterative algorithm of power synthesis for reconfigurable arrays is proposed. The algorithm is based on an alternating projection approach, and is suitable for arrays of arbitrary geometry, thus including conformal and sparse arrays. It allows to generate a number of copolar and crosspolar radiation patterns satisfying assigned requirements, switching each pattern into any of the others by phase-only control of the excitation applied to each array element. Moreover, the algorithm allows to reduce the dynamic range ratio (DRR) of the excitations and the maximum electric field amplitude in a region close to the antenna. A modified version of this algorithm including the previous one as a particular case, is then proposed, which introduces, as an additional capability, the reduction of the power radiated in the side lobe region, in presence of the above constraints, and the squared amplitude of the electric field in an assigned region close to the antenna. This allows to significantly improve the final results. Numerical examples, including a comparison with existing literature, show the effectiveness of the proposed algorithm
A SIMPLE AND EFFECTIVE ALGORITHM FOR THE POWER SYNTHESIS OF RECONFIGURABLE ARRAYS WITH NEAR-FIELD NULLS
No full textA powerful iterative method is presented for the synthesis of arbitrary
reconfigurable antenna arrays. The algorithm yields very good results also for arrays consisting of a large number of elements. The reconfigurability is achieved by phase-only control. The excitation amplitudes may be different for different array elements, and are not preassigned, but are optimized.
Furthermore, the electric field vanishes in a number of prescribed points located in the near-field region, so that a strong field reduction is obtained in a neighborhood of them
Co-polar and cross-polar pattern synthesis for reconfigurable antenna arrays
No full textA numerical method is presented for the power synthesis of co-polar and crosspolar
patterns of phase controlled reconfigurable arrays. The method is suitable
for arrays of arbitrary geometry, including conformal ones
Synthesis of co-polar and cross-polar patterns with dynamic range ratio reduction for phase-only reconfigurable arrays
No full textPower Synthesis for Reconfigurable Arrays by Phase-Only Control with Simultaneous Dynamic Range Ratio and Near-Field Reduction
No full textAn iterative method of power synthesis for reconfigurable arrays of arbitrary geometry is presented, which is based on the method of successive projections. The algorithm allows to synthesize a number of desired patterns, each reconfigurable into any of the others by phase-only control. The excitation amplitudes are optimized, and their dynamic range ratio (DRR) is reduced below a given threshold. Furthermore, the radiated field can be reduced below a prescribed level in a given region close to the antenna. As a particular important case, the method allows to perform a “discrete” phase controlled beam-scanning
Density Tapering of Linear Arrays Radiating Pencil Beams: A New Extremely Fast Gaussian Approach
Get PDFIn this communication, a very simple and extremely fast algorithm is proposed for the pencil beam synthesis of linear sparse arrays having uniform distribution of the excitations. The key idea is that of selecting, as a desired pattern, a Gaussian function having small standard deviation, so as to obtain a narrow beam. This immediately provides the excitation density of the corresponding continuous array of infinite length. Starting from this result and considering a linear array of length L with N elements having equal excitations, an extremely fast and accurate algorithm based on a density tapering approach is proposed that yields suitable positions of the elements, in such a way as to provide an array factor that well approximates the desired pattern. Numerical examples are presented to show the effectiveness of the developed procedure, also when compared with state-of-the-art algorithms. The proposed approach does not consider the mutual coupling between the array elements, but it is numerically shown that this effect produces quite acceptable degradation on the synthesized patterns. Finally, it is shown that also problems involving thousands of elements can be solved in a very accurate way in few milliseconds
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