A Novel Microstrip-Valley Photonic Topological Waveguide for Robust Microwave Transmission

Abstract

Topological insulators exhibit considerable immunity to path defects, and their lightweight advantage makes them easier to integrate compared to metallic waveguides and coaxial cables, offering a novel approach to support scattering-resistant transmission and transmission along bent paths. By adjusting the unit cell morphology of valley photonic crystals, this paper designs a C₃-symmetric microstrip valley photonic lattice based on a sector-shaped structure, which opens the degeneracy at the K(K′) points in the Brillouin zone and forms a topologically nontrivial photonic bandgap. Simulations and experiments demonstrate that this waveguide exhibits excellent filtering selectivity within the frequency range of 10.5–11.5 GHz, enabling unidirectional transmission and low-insertion-loss transmission of electromagnetic waves in the communication band. Compared with traditional metallic rectangular waveguides, the insertion loss variation caused by introducing a Z-shaped bending path is minimal, indicating remarkable robustness against path defects.