A Near-Field Meta-Steering Antenna System With Fully Metallic Metasurfaces

In the near-field meta-steering method, the near electric-field phase distribution is dynamically altered by rotating a pair of phase-gradient metasurfaces that are typically made out of dielectric lattices or metal patterns printed on bonded dielectric substrates. As a lightweight alternate, a new class of fully metallic metasurfaces (MMs) is proposed in this article. The lack of dielectrics not only substantially reduces the cost and weight but also increases its potential in space and high-power applications. More importantly, the new MMs are designed such that they can be made by cutting narrow slots in fully planar thin metal sheets, retaining structural rigidity while reducing the complexity, cost, and weight. The same MM works for any polarization. Each cell in the new MMs has close to ideal phase shift and transmission magnitude greater than -0.9 dB. A prototype was designed and fabricated to validate this MM-based beam-steering concept in the Ku-band. The maximum measured steering range in zenith is +/- 42 degrees, with a full 360 degrees steering in the azimuth. The measured 3 dB gain bandwidth is 700-800 MHz (5.6%-6.4%), and the measured gain variation (scan loss) when steering over the whole range is 2.2-4.5 dB. The weight density and thickness of each MM are 0.88 g/cm(2) and 0.8 lambda(0), respectively. Including the feed, the total antenna height is 4.9 lambda(0).