Conical horn antennas with enhanced functionalities through the use of metamaterial concepts

In this contribution, we report the results obtained by our group concerning the use of different metamaterial concepts to enhance performances and functionalities of conical horn antennas. First, we present an annular metamaterial lens to be placed on the aperture of a truncated horn antenna. The lens, consisting of an epsilon-near-zero metamaterial, is properly designed in order to compensate the phase delay of the field propagating along the short flare of the horn with respect to the one propagating along the axis. The phase compensation obtained through the lens results in a uniform phase distribution on the aperture that allows achieving the performances of an optimum antenna over the entire mono-modal frequency band. Then, we show a compact and planar component consisting of a metamaterial-inspired inclusion milled in a metallic screen and placed between the waveguide and the conical horn. At its operating frequencies the proposed inclusion allows transforming the linearly polarized field propagating along the waveguide into a circular one radiated by the conical horn. Moreover, due to its intrinsic narrow operation band, the proposed component acts as a compact filtering module able to reduce the out-of-band noise contribution and, thus, increase the signal-to-noise ratio of the antenna receiving system.