Fully printed volumetric negative-refractive-index transmission-line slabs using a stacked shunt-node topology

A volumetric negative-refractive-index transmission-line (NRI-TL) slab is proposed using a stacked shunt-node topology. The slab is analyzed using multiconductor transmission line (MTL) theory and verified by Ansoftpsilas HFSS. A fully printed design employing interdigital capacitors and spiral inductors is derived from the lumped-element counterpart and demonstrates low-loss and broadband properties. A strategy for placing some of the required vias is introduced which dramatically simplifies the fabrication process while still suppressing the parallel-plate waveguide (PPW) parasitic mode. Using these innovations, a volumetric NRI-TL slab lens is fabricated and the focusing experimental results show that the proposed slab lens can overcome the diffraction limit by more than a factor of two.