Hybrid and Hexagonal Planar Arrays with Discrete Ring-based Amplitude Distributions for Sidelobe Minimization

Abstract

Hexagonal planar arrays are useful in radar, sonar, and wireless communications due to their ability to provide complete coverage in the azimuth plane. On the other hand, hybrid arrays that combine two different array structures, like a small central square subarray surrounded by a number of rings, are capable of providing better performance than the conventional array architectures. This paper introduces two new planar array structures that are efficiently optimized to best cope with these aforementioned applications. The first proposed design is a planar array with hexagonal structure based on discrete hexagonal-ring amplitude distributions, while the second design structure is the hybrid array architecture with a small central square subarray surrounded by a number of elements in the shape of a ring. The idea of first design structure is to re-represent the conventional element-based excitation amplitudes by discrete hexagonal-based excitation amplitudes in which they are ordered in descending from the center to the array edges. By this way, the amplitude excitations of the array elements become more compatible and practicable with the needed real-life discrete RF attenuators or amplifiers that are used for configuring the targeted excitation amplitudes. Moreover, the discrete hexagonal-based excitation amplitudes need a simpler feeding network than its element-based counterpart, thus, the array cost and complexity are greatly reduced. An optimization scheme based on a genetic algorithm is used to optimize these two proposed array structures to achieve ultra-low sidelobe levels while preserving mainlobe directivity. Simulation results confirm the effectiveness of the proposed array structures.