Investigations on Improving Wide Angular Beam Scanning of Conformal X-Band Array Antennas by Tunable Metasurfaces

This paper presents an investigation on improving the radiation characteristics of a conformal X-band array antenna by means of a low profile dual-polarized tunable metasurface structure. The considered configuration consists of several tunable metasurface planar circuit boards arranged in a faceted manner and excited by a conformal antenna array. The electromagnetic transmission properties of the tunable meta-surface structure are controlled by applying DC bias voltages to the varactor diodes integrated into the metasurface's unit-cell structure. The transmission phase response of this tunable metasurface can be tuned in a range up to 170° for both polarizations. Experimental investigations are performed on a demonstrator consisting of a faceted planar tunable metasurface configuration integrated with a conformal antenna array. The tunable metasurface performs phase compensation (like a lens) and beam steering. The measurement results demonstrate that the tunable metasurface slightly improves the beam scanning capabilities of the conformal antenna array in the horizontal plane for both polarizations at 10 GHz.