Giulia Buttazzoni

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

An 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.

Power Synthesis for Reconfigurable Arrays by Phase-Only Control With Simultaneous Dynamic Range Ratio and Near-Field Reduction

An 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.

A deterministic approach to the synthesis of sparse arrays with far-field and near-field constraints

This paper presents a deterministic algorithm for the synthesis of sparse arrays with far-field and near-field constraints. Starting from an initial set of possible positions, the algorithm iteratively solves a sequence of convex optimization problems with the objective of minimizing the number of radiating elements among those of the initial set, in presence of constraints on the far-field pattern and on the amplitude of the electric field at prescribed points located in the near-field region of the antenna. The method is suitable for sparse arrays of arbitrary geometry. A numerical example is presented to show the effectiveness of the proposed approach.

Reconfigurable Antenna Arrays with Multiple Requirements: A Versatile 3D Approach

This paper proposes a deterministic method for the 3D synthesis of antenna arrays that jointly accounts for far-field pattern reconfigurability, polarization setting, dynamic range ratio reduction, and near-field control. The conceived algorithm, which generalizes some existing solutions, relies on a weighted cost function, whose iterative minimization is accomplished by properly derived closed-form expressions. This feature, combined with the possibility of selecting the weighting parameters, provides a fast and versatile approach, whose capabilities are numerically checked by considering different synthesis problems and array structures in the presence of mutual coupling.

Phase-controlled beam-scanning with near-field and DRR reduction for arbitrary antenna arrays

Phase-controlled beam-scanning arrays are structures useful for many applications. Adopting the approach introduced in [1], the scanning process is here treated as a special kind of pattern reconfiguration, where all the patterns radiated by the array have the same shape, but are shifted one from each other by a given angular step, so as to realize a discrete beam-scanning. An iterative algorithm is presented for the power synthesis of beam-scanning arrays of arbitrary geometry, based on the alternating projections method. The algorithm allows to reduce the electric field produced by the array in a given near-field region in order to avoid possible interferences and compatibility problems due to the environment surrounding the antenna. In order to ensure the phase-only control, the excitation amplitude of each array element is required to be constant during the scanning process, and only the excitation phases are modified. Furthermore, the amplitudes are not assigned, but are optimized, and the dynamic range ratio (DRR) of such amplitudes can be reduced below a given threshold. This allows to use a simpler and cheaper feeding network.