Applications of Artificial Dielectric Layers for mm-Wave Antennas

Artificial Dielectric Layers (ADLs) have recently been exploited to improve the radiation and impedance performance of integrated antennas at millimeter wave (mmWave) and terahertz (THz) frequencies. The ADLs are composed by layers of sub-wavelength periodic metal patches that can be arranged within a host medium to synthesize an equivalent anisotropic material. Thanks to the availability of closed-form expressions for the modeling, ADLs can be conveniently designed to realize matching layers and impedance transformers when used in the closed proximity of antennas, to improve their bandwidth and the front-to-back ratio. An overview of different applications that benefit from this concept is given. Moreover, recent developments on the use of ADLs for wideband flat lenses are described.