The present work is concerned with the study and modeling of single and multilayer annular slot antennas by the wave concept iterative method (W.C.I.P). In the first part, we propose a formulation of the iterative method in the cylindrical coordinate system to study the circular structures that exist on the interface of a cylindrical guide. To validate this formulation, the simulation results obtained have been compared with results simulated by the CST software. The second part concerns the study of circular antennas with single layer annular slots. We manage to show that by adding slots around the central circular patch we improve the directivity of these antennas. The last part is dedicated to multilayer antennas with the aim to improve the gain. At the end of each part we investigate the effect of parameters such as dielectric height or permittivity on the operating frequency and radiation of this antenna.