High-performance 2D beam scanning circularly polarized pattern reconfigurable antenna array based on metasurface element

This paper presents a novel 2D pattern reconfigurable circularly polarized antenna, which features wide-angle and angle domain wide axial-ratio (AR) scanning characteristics. Wide AR means that the AR is less than 3 dB in the wide angle scanning range. By introducing a 1-bit circularly polarized antenna A at the diagonal position of circularly polarized antenna B, the 2D pattern reconfigurable circularly polarized antenna can be achieved. The 1-bit antenna A is loaded with two PIN diodes to achieve phase switching between 0° and 180°. Due to the structural difference, there is a 90° phase difference between antenna A and B. Consequently, by controlling antenna A, the phase difference between antenna A and B is switched from -90° to 90°. The corresponding radiation pattern is switched from P-mode to N-mode. Owing to the diagonal placement of antennas A and B, a phase difference is introduced in both the xoz and yoz planes, thereby enabling the 2D pattern reconfigurability. The designed 2D pattern reconfigurable circularly polarized antenna only requires two PIN diodes, making it a simple and low-cost design. Moreover, by etching slots on the ground plane, the AR characteristics of the unit cell are enhanced. The proposed 2D pattern reconfigurable circularly polarized antenna is arranged into a 4×4 array. The array has a scanning range of -60° to 60° in the xoz and yoz planes, with a gain variation of 2.58 dBi and a sidelobe level greater than 7.94 dB. An AR of less than 3 dB is achieved for beam scanning in the xoz and yoz planes from −60° to 60°. A 4×4 pattern reconfigurable circularly polarized antenna array is fabricated for verification. The measured results are in good agreement with the simulation results. The proposed design methodology for pattern reconfigurable subarray is of significant importance, particularly due to its ability to greatly simplify the complexity of the array, providing an excellent starting point for the practical application of pattern reconfigurable antenna arrays.