  We propose an uplink massive MIMO system using an array of holographic
metasurfaces as a sector antenna. The antenna consists of a set of rectangular
waveguide-fed metasurfaces combined along the elevation direction into a planar
aperture, each with subwavelength-sized metamaterial elements as radiators. The
metamaterial radiators are designed such that the waveguide-fed metasurface
implements a holographic solution for the guided (or reference) mode,
generating a fan beam towards a prescribed direction, thereby forming a
multibeam antenna system. We demonstrate that a narrowband uplink massive MIMO
system using the metasurfaces can achieve the sum capacity close to that
offered by the Rayleigh channel at 3.5 GHz. We show that metasurfaces
supporting multiple fan beams can achieve high spatial resolution in the
azimuth directions in sub-6 GHz channels, and thereby form uncorrelated MIMO
channels between the base station and users. Also, the proposed metasurface
antenna is structurally simple, low-cost, and efficient, and thus is suitable
to alleviate RF hardware issues common to massive MIMO systems equipped with a
large antenna system.
