A Single-Layer Low-Profile Broadband Metasurface Antenna Array for Sub-6 GHz 5G Communication Systems

Abstract

This article presents a planar, low-profile, and single-layer metasurface (MTS)-based wideband 4 × 4 array antenna operating in the 5G sub-6 GHz band. The proposed antenna consists of 4 × 4 unequal size MTS unit cells fed by a simple parallel microstrip feed network in the form of a thin strip cross dipole. The wide impedance bandwidth (IBW) and improved boresight gain characteristics are realized due, respectively, to the excitation of multiple TM resonance modes that are closely spaced and the relatively large lateral size that supports in-phase currents. With an overall size of 1.40λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×1.22λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.054λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> (where λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the free-space wavelength at the center frequency of 5.64 GHz), the proposed antenna realizes an IBW of 41.13% (4.48-6.80 GHz), a peak boresight gain of 10.14 dBi, low cross-polarization in the E- and H-planes, and higher front-to-back ratio. Because of the advantages of low-profile, planar and single-layer structure, as well as equal E- and H-planes 3 dB beamwidth, the proposed antenna is a competitive candidate for several modern wireless communications systems, including 5G in the sub-6 GHz band.