Dispersion analysis of coaxial line loaded with twist-symmetric half-rings

A coaxial line with half-rings connected to its external conductor is proposed in this paper, to investigate the dispersion properties of a twist-symmetric electromagnetic configuration. We demonstrate that the propagating modes in a twist-symmetric structure are more linear than a conventional structure. Additionally, the bandgap at the Brillouin zone boundaries can be manipulated by tuning the relative angular orientation or translation of the rings. This tuning is equivalent to changing the order of the twist symmetry from 4- to 2-fold. Our proposed geometry finds potential application in fully-metallic reconfigurable filters and phase shifters.