In this paper, two different architectures based on fully and partially clustered arrays are proposed to optimize the array patterns. In the fully clustered arrays, all the elements of the original array were divided into several equal subarrays, while in the partially clustered arrays, only the side elements were grouped into subarrays, and the central elements were left individually. The second architecture enjoys many advantages compared to the first one. The proposed clustered arrays use quantized amplitude distributions, thus, their corresponding patterns were associated with high side lobes. To overcome this problem, a constraint mask was included in the pattern optimization process. Simulation results show that the peak sidelobe level and the complexity of the feeding network in the partially clustered arrays can be reduced to more than −28 dB and 70.833%, respectively, for a total of 48 array elements, number of individual central elements = 24, number of clusters on both sides of the array Q = 4, and number of elements in each side cluster M = 6. Finally, the principles of the proposed clustered arrays were extended and applied to the two dimensional planar arrays.

In this paper, two different structures based on fully and partially irregular clustered elements are presented to optimize the radiation patterns of the large arrays. In the Fully Irregular Clustered Elements (FICE) structure, all the elements of an ordinarily large linear array are divided into multiple irregular and unequal-size clusters, while in the Partially Irregular Clustered Elements (PICE) structure, only the elements those located at the edges of the ordinarily linear array are grouped into unequal-size clusters. In this structure, the central elements are left without clustering (i.e., excited individually). The PICE structure has several advantages over the FICE structure. Since the quantized amplitudes (i.e., discrete distribution) are used with the proposed clustered structures, the corresponding clustered array patterns are usually associated with the undesirable high periodic sidelobes. In order to overcome this problem, the elements in the clusters are distributed a periodically. Simulation results demonstrate the ability of the proposed two structures, FICE and PICE, to significantly reduce the high periodic sidelobe level to -35dB and -40dB respectively for an array with a number of elements N=100 and unequal-size clusters.

In this paper, the required array patterns with controlled nulls are obtained by optimizing only the excitation phases of a small number of elements on both sides of the array. A genetic algorithm is used to appropriately find which elements of the array to be optimized and also to find the required number of the excitation phases. The performance of the proposed phase-only method is compared with some other exciting methods, and it is found to be competitive, fulfil all the desired radiation characteristics, and represent a good solution for interference mitigation. Moreover, the proposed phaseonly array is designed and validated under realistic electromagnetic effects using CST full wave modeling. Experimental results are found in a good agreement with the theoretical ones and show realistic array patterns with accurate nulls.

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