Sidelobe Suppression of Metalens Antenna by Amplitude and Phase Controllable Metasurfaces
Qun Lou, Zhi Ning Chen
Abstract
Amplitude and phase controllable metasurfaces are proposed to suppress the sidelobe levels (SLLs) of a metasurface lens (metalens). The amplitude-control metasurface is responsible for controlling the transmission amplitude with its unit cells’ phase shift variation less than ±10°. The phase-control metasurface is responsible for transferring the spherical incident waves to plane waves with its unit cell covering 360° transmission phase shift, while the transmittance remains higher than −1 dB. Both the metasurfaces are with symmetrical structures for dual-polarization. By integrating the amplitude and phase controllable metasurfaces, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$9.7\lambda _{0} \times 9.7\lambda _{0}$ </tex-math></inline-formula> metalens operating at 28 GHz 5G bands is designed and successfully suppresses the SLL. Within the 3 dB gain bandwidth from 26.0 to 29.0 GHz, this metalens antenna achieves the SLL lower than −20.9 dB in H-plane and lower than −17.3 dB in E-plane. The maximum gain is 23.4 dBi at boresight, and the achieved SLL is −16.3 dB as its scanning angle reaches the maximum of ±29°. Compared with the phase-only metalens, the proposed metalens antenna realizes the maximum and minimum SLL suppression of 9.8 and 3.4 dB within the 3 dB gain bandwidth at a price of a gain drop of 0.8 dB at the designed frequency.