# Optimization of a Coherent Dual-Beam Array Feed Network for Aperiodic Concentric Ring Antennas
); [EMAIL_ADDRESS] (F.R.C.-S.)  
Universidad Autonoma de San Luis Potosi (UASLP), San Luis Potosi 78290, Mexico  
1  
Universidad Autonoma de San Luis Potosi (UASLP), San Luis Potosi 78290, Mexico  
1  
Universidad Autonoma de San Luis Potosi (UASLP), San Luis Potosi 78290, Mexico  
[EMAIL_ADDRESS] (F.R.C.-S.); [EMAIL_ADDRESS] (U.P.-R.); [EMAIL_ADDRESS] (M.C.-J. ); [EMAIL_ADDRESS] (F.R.C.-S.)  
Universidad Autonoma de San Luis Potosi (UASLP), San Luis Potosi 78290, Mexico  
1  
Universidad Autonoma de San Luis Potosi (UASLP), San Luis Potosi 78290, Mexico  
1  
Universidad Autonoma de San Luis Potosi (UASLP), San Luis Potosi 78290, Mexico  
[EMAIL_ADDRESS] (F.R.C.-S.); [EMAIL_ADDRESS] (U.P.-R.); [EMAIL_ADDRESS] (M.C.-J. ); [EMAIL_ADDRESS] (F.R.C.-S.)  
Universidad Automa de San Luis Potosi (UASLP), San Luis Potosi 78290, Mexico  
1  
Universidad Automa de San Luis Potosi (UASLP), San Luis Potosi 78290, Mexico  
1  
Universidad Automa de San Luis Potosi (UASLP), San Luis Potosi 78290, Mexico  
[EMAIL_ADDRESS] (F.R.C.-S.); [EMAIL_ADDRESS] (U.P.-R.); mcardenas@fc. framework, the aperiodicity of antenna arrays could be a solution to enhance the antenna system's capabilities and even minimize the use of some radiators. Nevertheless, the design and optimization of aperiodic arrays usually become a complex target, where in addition to the complexity of the aperiodicity of the layout, the inclusion of a multiple-beam feeding system in the synthesis makes this task more challenging. Specifically, dual-beam antenna systems are useful in different mobile applications including terrestrial and space systems, such as microwave close-range sensors, automotive radar sensors, synthetic aperture radar (SAR) systems, tracking satellites, autonomous sensor networks, and base stations, among others [5, 6]. Nevertheless, there are varying approaches to conform two beams with pros and cons, and trade-offs between them. Some antenna system architectures involve the use of certain types of radiators and feeders working together [7]--typical examples include planar leaky wave antennas (LWA) with different methods of feeding network to control the leaking rate, direction, and polarization [8]. Similarly, transmit arrays as a beamforming network are another example of a dual-beam solution grounded on the behavior of frequency selective surfaces and transmitting/receiving elements [9, 10]. In the same vein, phased arrays are a cornerstone for dual/multi-beam beamforming and beam steering in infrastructure applications [11], sometimes combined with reflectarray apertures [12] or even feeding the array with a peripherally excited (PEX) metallic cavity [4]. Some other typical applications use classical lossless matrices or hybrids using related circuitry as beamforming networks [13, 14]. However, the aforementioned dual-beam approaches deal with different drawbacks, including a cumbersome mechanism for beam scanning or fixed beams, interference between signals caused by adjacent antennas, and limited beam pointing or beam shaping, among others. Nevertheless, an alternative proposal is based on coherent in-phase networks, improving flexibility and reconfigurability with refined beam shaping and scanning (electronically) capabilities. In previous years, a coherent feeding system relying on identical substructure components known as coherently radiating periodic structures was presented in [15]. The feeding system for a phased array was described in [16], showing the working principles to implement a beamforming network topology in a basic antenna array, minimizing the difficulty of the associated control to scan the beam. As an antenna synthesis problem with optimization, the antenna system with a periodic aperture in different antenna geometries and parameters has been widely studied, and some related investigations can be found in [17, 18, 19].