Application of Twist Symmetry to a Cylindrical Dielectric Waveguide

Abstract: The application of higher order symmetry to waveguide design is an active field and is showing evidence of improvement over traditional waveguide designs. There are two forms of higher symmetry: glide symmetry and twist symmetry. Glide and twist symmetry have previously been applied to bounded waveguide, and a recent work applied glide symmetry to the design of a dielectric slab waveguide. This work is the first application of twist symmetry to the design of a dielectric waveguide. In this work a twist symmetric dielectric rod waveguide was designed and simulated using the eigenmode, truncated structure and multimode method. The twist symmetric dielectric rod waveguide is demonstrated to have stopbands, analogous to those demonstrated in metal waveguides based on glide symmetry. In addition the waveguide also shows circular polarization based birefringence and circular polarization based stopbands. A novel unit cell was created which demonstrates the phenomenology of dielectric twist symmetry in the X-band. The dispersion diagram of this structure is calculated using the eigenmode and multimode method and the S-parameters of the novel waveguide were calculated using the truncated structure method. There is strong agreement in the propagation and attenuation characteristics from all three computational methods. The novel unit cell has potential applications as an inline polarization based filter for the fundamental HE11 mode of dielectric rod waveguides. With potential applications to communication and sensing systems.