Multi-Beam Metasurface Antenna by Combining Phase Gradients and Coding Sequences

In this paper, we propose a strategy to achieve a single-feed multi-beam metasurface antenna by combining phase gradient and coding sequence. Theoretically, the multi-beam antennas with various far-field patterns can be realized via superimposing different kinds of phase coding sequences. As three proof-of-concepts, the 0101.../0101...coding sequence, chessboard coding sequence, and 1-bit sector coding sequence are selected to design double-beam, four-beam, and eight-beam circular-polarized reflector antennas, respectively. Furthermore, the four-beam reflector antenna is fabricated and measured to demonstrate the feasibility of our strategy. The fabricated antenna can produce four perfect pencil-shaped beams in a wide frequency range from 11 to 13 GHz. At central frequency, the realized gain is about 19.9 dB and the axial ratio is lower than 3 dB. Moreover, the circular polarization state of the reflective beams is consistent with the polarization state of spot source, which differs from the reflector antennas based on the polarization-insensitive unit cells. This paper connects the multi-beam patterns with binary digits, which provide the potential for reconfiguring the multi-beam patterns by computer programs.