Generally speaking, the structure to forbidden electromagnetic band gap (EBG) is defined as being periodic artificial structures (or sometimes not periodic) which prevent the propagation of the electromagnetic waves in a frequency band specified for all the angles of incidence and all the states of polarization. The EBG is normally realized by periodic arrangement of dielectric materials. Within this framework, a new type of metallic electromagnetic structure was finalized. A big impedance of surface and a very precise forbidden bandwidth of frequencies characterize it. It is the flat structure, that we shall call EBG in the shape of dome. To begin the study of this structure, we are going to analyze the coefficients of reflection and transmission feigned. We shall approach then the application of this structure on the environment close to a network of patch antenna, of a micro strip line and a guide of rectangular wave to show the importance of this material in microwave structures.