Carbon nanotube based millimeterwave fishnet metamaterials

Fishnet metamaterials consist of two or more conducting fishnet layers separated by homogeneous dielectric layers. Different from other planar multilayer metamaterial structures fishnet metamaterials do not require vias for through-contacting between the layers. This allows low-cost production of three-dimensional metamaterials by spray coating with organic (carbon nanotubes CNTs) or metallic (silver) nano pigment inks. Spray coating has proven to be a low cost fabrication technique for high throughput. Numerical studies are pursued in this contribution to investigate fishnet metamaterial using nano pigment inks. In this work we compare fishnet metamaterial structures fabricated from spray coated layers of variable sheet conductance with fishnet metamaterial structures fabricated from highly conductive material with superimposed homogeneous CNT layers of low sheet conductance. In these cases the spray coated CNT layers allow to adjust the area resistance of the conductive layers for optimum broad-band design. The tunable resistance of sprayed thin films allows for an enhanced tailoring of the effective parameters of the metamaterial structures and, hence, for an enhancement of their bandwidth of negative refractive index.