Studies of a Two-dimensional Coaxial Bragg Structure with Double Helically Corrugated Surfaces

As an important member of periodic structures family, Bragg structures are widely employed in the many active and passive microwave devices, such as reflectors, couplers, filters and mode converters. In this paper, the transmission characteristics of a two dimensional coaxial Bragg structure with double frequency selective surfaces are investigated, where both of the inner and outer conductors are corrugated with helical ripples. Numerical results reveal that the transmission bandgap can be controlled by the relative angular position of the inner and outer conductors. This peculiarity may lead to potential applications of these structures in constructing tunable microwave devices.