Design and operation of a negative-index parallel-plate metamaterial

We discuss the design and modeling challenges for a negative index (NI) metamaterial realized with patterned parallel-plate technology. The proposed negative-index metawaveguide (NIMW) is composed of a stack of plates with etched-out complementary split ring resonators (CSRRs), supporting a backward-wave transverse-magnetic (TM) mode in a given frequency range. The NIMW operational frequency is below the cutoff frequency of the TM mode in a uniform parallel-plate waveguide, inducing an effective negative permeability. The CSRR inclusions provide a strong resonance within the frequency band, inducing an effective negative permittivity. We present an optimized unit cell design, offering moderately broad bandwidth of operation. We also discuss the anisotropic nature of this metamaterial configuration and ways to significantly reduce it within the NI band.