Millimeter Wave Wide-Angle Scanning Circularly Polarized Antenna Array With a Novel Polarizer

A wide-angle scanning circularly polarized (CP) antenna array based on a novel polarizer is proposed. The working mechanism is that the linear polarization (LP) substrate integrated waveguide (SIW) slot antenna array can be converted into CP antenna array through the proposed hybrid polarizer. Specifically, the proposed hybrid polarizer consists of a dipole array polarizer with
$6\times $
6 elements and a metasurface polarizer with
$19\times19$
elements. The metasurface polarizer can realize the LP–CP conversion of the beams with a scanning angle range (−55°, 55°) and the dipole array polarizer can realize LP–CP conversion of beams with scanning angle ranges (−60°, −40°) and (40°, 60°) through reasonable design. Based on the complementary characteristics of the metasurface polarizer and dipole array polarizer for different scanning angles, the proposed hybrid polarizer gives the designed CP antenna array have good AR characteristics in the scanning angle range (−70°, 70°). Then, a
$6\times $
6 Butler matrix is designed to feed the proposed wide-angle scanning CP antenna array. Finally, a prototype of the wide-angle scanning CP antenna array is fabricated. The test results show that the AR of the proposed wide-angle scanning CP antenna array is less than 3 dB, the maximum scanning angle is −60°, and the maximum gain is more than 16.5 dBi in the operating frequency range 27.9–28.4 GHz.