REFLECTARRAYS ANALYSIS FOR WIRELESS COMMUNICATIONS APPLICATIONS
Reflectarrays, reflective arrays, microwave reflectors, frequency selectivity, FSS, microstrip geometries.
Wireless communications systems have become increasingly popular because of the diversity of services and mobility. However, to meet the requirements for different communication systems, such as mobile telephony, digital TV, Bluetooth, WiFi, WiMAX, and RFID, small, light, and low-cost circuits and components are required to operate at different frequency bands. This has been a constant challenge for microwave engineers, especially for antenna designers. In addition to communication between users, it is necessary to provide high capacity links that can connect different points of telecommunications networks. Although several optical links are used, radio links are indispensable. In this context, given the limitations of the availability of towers and other spaces for installation of antennas, several telecommunications systems, with their own frequency and power requirements, share restricted spaces. Therefore, limiting interference between different systems, as well as maximizing the use of antennas, becomes increasingly important. In view of this demand, the use of reflectarrays has attracted the attention of several research groups, either to minimize undesirable signals or to associate the characteristics of planar microstrip structures to those of conventional reflectors. Due to its constructive nature, the microstrip reflectarrays have characteristics suitable for use in wireless communication systems. Usually, they are reflectors of thin profile that consist in the arrangement of radiating patch elements, uniformly placed on microstrip substrates and fed by incident waves. In addition, they are small, low weight, low cost, and ease of manufacture. This dissertation proposal aims to analyze and propose new reflectarrays geometries for wireless applications. The analysis is proposed to determine the reflective frequency behavior of reflectarrays with conducting patch elements of several shapes, including four-armed stars and fractals.