A NOVEL SINGLE-LAYER ANISOTROPIC UNIT FOR TRANSMIT-REFLECT DOUBLE FUNCTION ARRAY

In this paper, a novel single-layer anisotropic unit with both reflection and transmission functions is proposed. The unit is a ring-encircled two mirror-symmetry fan-shaped patches, and is fabricated in one side of an F4B substrate. The unit structure is asymmetry with respect to x- and y-axes, and both transmitted and reflected cross-polarized fields are generated simultaneously when the co-polarized field is incident on the symmetry broken surface. Full 360[degrees] phase shift range is achieved by utilizing the cross-polarized field, and the transmitted and reflected coefficient magnitudes are above 0.49 close to the theoretical limit. Using this anisotropic unit, three single-layer transmit-reflect-arrays are designed: (1) Two high-gain beams in ([[theta].sub.1] = 0[degrees], [[phi].sub.1] = 0[degrees]) and ([[theta].sub.1] = 180[degrees], [[phi].sub.1] = 0[degrees]) directions. The gain is 20.9dBi, and the 3dB beam width is 8.9[degrees]. (2) Two OAM beams with l = 1 at ([[theta].sub.1] = 45[degrees], [phi]1 = 0[degrees]) and ([theta]2 = 135[degrees], [phi]2 = 0[degrees]). (3) Four OAM beams with l = 1 at ([[theta].sub.1] = 30[degrees], [phi]1 = 0[degrees]), ([theta]2 =--30[degrees] [phi]2 = 180[degrees]), ([theta]3 = 150[degrees], [[phi].sub.3] = 0[degrees]) and ([theta]4 =--150[degrees], [[phi].sub.4] = 180[degrees]). The simulated and measured results agree well and validate the design principle. The proposed metasurface has the following advantages: single-layer, transmission and reflection dual-functions, multi-beam, and high gain.