Research Article Design and Optimization of a Coherent Beamforming Network for an Aperiodic Concentric Ring Array Armando Arce , 1 Enrique Stevens-Navarro , 2 Marco Cardenas-Juarez , 2 Ulises Pineda-Rico , 2 Jorge Simon , 3 and Marco A. Panduro 4 1 Catedras CONACYT and with Faculty of Sciences, Universidad Autonoma de San Luis Potosi (UASLP), 78290 San Luis Potosi, Mexico 2 Faculty of Sciences, Universidad Autonoma de San Luis Potosi (UASLP), San Luis Potosi, Mexico 3 Catedras CONACYT and Centro de Investigacion y Desarrollo en Telecomunicaciones Espaciales, Universidad Autonoma de Zacatecas (UAZ), 98000 Zacatecas, Mexico 4 Department of Electronics and Telecommunications, CICESE Research Centre, 22860 Baja California, Mexico Correspondence should be addressed to Armando Arce; armando.arce@uaslp.mx Received 18 December 2018; Accepted 12 February 2019; Published 6 May 2019 Academic Editor: Luciano Tarricone Copyright © 2019 Armando Arce et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In this work, a flexible and reconfigurable feeding network design for a nonuniform aperture on circular concentric ring arrays is proposed and analyzed. The network subsystem delivers coherent in-phase outputs with a Gaussian-like amplitude distribution, in a modular and basic topology based on sets of alternated power combiners and dividers. A complete antenna system in a monobeam configuration with a coherent network based on grouped inputs (blocks) per ring for an aperiodic concentric ring array with beam scanning and beam shaping properties is synthesized and analyzed. Additionally, a comparative analysis based on nonuniform and uniform concentric ring arrays fed by the proposed coherent network configuration is conducted and assessed. The optimization of the aperiodic layout on the antenna aperture (radii and interelement antenna spacings) is done by the differential evolution algorithm. Numeric experimentation demonstrates the performance advantages and capabilities of the proposed coherent network configuration with a nonuniform aperture over its uniform counterpart, with an improvement in average equal to −8.7 dB of side lobe level and 3.9 dB of directivity. Furthermore, the numeric examples show a complexity reduction on the coherent feeding network configuration based on the number of control signal inputs compared with a conventional phased antenna array; in the proposed configuration, the main beam is steered and shaped with N-1 control feeding ports per ring in this antenna system. 1. Introduction Antenna arrays are an essential part of modern commu- nication systems in various applications, offering an improved solution over single-element antennas. Thus, multiple antennas can radiate and synthesize contoured beams with advanced capabilities and features such as high-directive beams, electronic beam scanning (phased array), power pooling, among others. Nowadays, there is a great interest in the development of advanced array systems where the focus is minimizing the total antenna system cost while maximizing the overall antenna system performance [1]. In this context, aperiodic arrays could improve the performance and in some cases could also reduce the number of antenna elements; however, their synthesis and optimization is a challenging task, where the additional degree of freedom is given by the layout that is employed to optimize the antenna array. This aperiodicity of the layout can also have meaningful additional complexity for the antenna system design and implementation if its corresponding feeding system is added. An antenna system is not complete without its underly- ing feeding system, i.e., in every array, it can be discerned two main components: the first one are antenna elements, which are physically distributed over a specific area. The second is the beamforming network (BFN) subsystem; this Hindawi International Journal of Antennas and Propagation Volume 2019, Article ID 4601718, 10 pages https://doi.org/10.1155/2019/4601718