2-Bit Polarisation Rotating Metasurface Based Lens Antenna in Ku Band for SatCom Application

A low profile 2-bit phase gradient metasurface lens antenna is designed and developed to achieve highly directive beam in the Ku band for SatCom application. The metasurface is made up of periodic arrangements of a subwavelength sized unit cell elements operating in the 14.35-15.35 GHz frequency range. These unit cells are designed by using mutually orthogonal 'V'-shaped slots, resulting in wideband, near-unity transmission characteristics for single polarization. A full 360° phase shift coverage is realized by adjusting the slot lengths. The cells are quantized to produce four discrete transmission phase levels with a constant phase difference of 90°, resulting in four binary states. These binary phase states are distributed across the metasurface to create a highly directive beam in the desired direction using a spherical to planar phase distribution method. The metasurface lens consists of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$17 \times 17$</tex> elements, forming an aperture size of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$102 ~\text{mm} \times 102 ~\text{mm}$</tex> with a thickness of 1.6 mm. It is illuminated by a low profile microstrip patch antenna, operating in 13.3-16.7 GHz frequency range, positioned 20.19 mm away from the metasurface, resulting in a highly directive beam at boresight direction within the 13.3-16 GHz frequency band, with a maximum gain of 16 dB. The antenna demonstrates wideband characteristics with an 18.4 % bandwidth and a compact size with a minimal f/D ratio of 0.19.