Dual Imaging Metamaterial Composed of Periodic Bi-Fold Transformation Media Made of 3-D Printed TiO2 Nanoparticles Mixed Resin

Broadband operation of a dual imaging metamaterial composed of periodic bi-fold transformation media made of 3-D printed TiO
₂
nanoparticles mixed resin is demonstrated. Peculiar refractions on the spatially discontinuous boundaries (SDBs) and refractions along with the coordinate transformations in the bi-fold transformation media are taken into account and the dual imaging conditions are derived based on the ray-tracing method. The dual imaging metamaterial operating with the incident angles of ±30° is designed and its operation is numerically demonstrated by the ray-tracing method and the equivalent circuit simulations. The bi-fold transformation media are implemented by the TiO
₂
mixed resin with the experimentally obtained permittivity of 3.2 with a mass fraction of 0.075. The operation of the fabricated metamaterial is also confirmed by the near-field measurements. The energy transmittances well correspond to those of the simulated results. The bandwidth evaluated by the energy transmittances shows broadband operation as wide as from 30 to 40 GHz.