Abstarct: Today, in many telecommunications applications, in addition to the need for high bandwidth utilization, antenna polarization characteristics are very important. Circular polarization is of great interest to researchers and researchers due to the advantages of linear polarization. The reason for this is that the left and right circular polarization is completely isolated. In fact, circular polarization has more flexibility than linear polarization.For example, the use of circular polarization in mobile communication greatly reduces interactions and reflections. In satellite applications, due to the presence of the Faraday rotation, we have to use an antenna with this polarization. Recently, the use of RGW technology in the design and construction of antennas and filters has attracted many designers. So the purpose of this thesis is design an array of linear cross slot antenna on RGW-baxsed circular polarization with coaxial feeding. An antenna design in this project was performed at Ku band, which was eventually designed by a circular polarization antenna with 322 MHZ impedance bandwidth and 742 MHG (AR) bandwidth at the central frequency. In the coming chapters, while reviewing the work done in this area and presenting a brief history of the development of this technology, the results of the design of this antenna are presented. The simulations performed in this project were done using CST Microwave Studio software.