High-Efficiency Metasurface Transmitarray Antenna Fed by Waveguide Cavity-Backed Slot Array

초록

In this letter, a metasurface-based high aperture efficiency transmitarray antenna (TA) is proposed. To improve the feeding efficiency, a rectangular waveguide cavity-backed slot array was adapted for the feed. Eight coupling slots (CSs) corresponding to the unit cell (2 × 4) were added to a cavity operating in TE₁₂₀ mode to improve efficiency and suppress grating lobes. The slot spacing was compactly designed to be 0.48 λ₀ and 0.4 λ₀ in the x-axis and y-axis directions, respectively, resulting in a 2 × 4 slot subarray structure. By varying the coupling height between the CSs corresponding to the unit cell and the metasurface (MS), the optimum height was found to be 0.13 λ₀, within the range of the reactive near-field region. To verify the beamforming performance of the proposed antenna, five types of MSs were designed to operate at beamforming angles θ of -40°, -20°, 0°, 20°, and 40°. The simulated and measured aperture efficiencies for a broadside beam were observed to be 78.2% and 59.3% at 10 GHz and 9.92 GHz, respectively. To our knowledge, the presented 8 × 8 TA achieved the highest simulated aperture efficiency. The measured results confirm that the proposed TA has high aperture efficiency and good beamforming characteristics. © 2002-2011 IEEE.

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