Hyperbolic dispersion and negative refraction in a periodic perfect magnetic conductor and perfect electric conductor parallel-plate waveguide structure

We present a numerical demonstration that a periodic structure composed of alternating perfect magnetic conductor (PMC) and perfect electric conductor (PEC) parallel-plate waveguides (PPWs), filled with dielectric materials of permittivity ɛ 1 and ɛ 2 , and separated by a gap h , exhibits hyperbolic dispersion and negative refraction. This phenomenon is enabled by surface waves confined at the PMC–PEC interfaces and disappears when the dielectric permittivities are equal ( ɛ 1 = ɛ 2 ), eliminating surface wave support. Furthermore, the hyperbolic nature of the dispersion is confirmed by simulated radiation patterns from a point dipole source embedded in the periodic structure. • We introduce a periodic PMC–PEC parallel-plate waveguide (PPW) structure that naturally exhibits hyperbolic dispersion without requiring auxiliary elements such as thin wires. • Negative refraction is numerically demonstrated and verified through photonic band structures, equi-frequency contours (EFCs), and dipole radiation patterns. • The hyperbolic response originates from PEC–PMC interface surface waves, which resemble surface plasmons but do not follow Drude-type dispersion. • Effective anisotropic parameters are numerically retrieved, confirming the hyperbolic nature of the proposed structure.