High Gain and Low Gain Roll-Off Mechanically Beam-Steerable Transmitarray Antennas

This paper introduces the concept of offset unifocal phase symmetry the achieve mechanically beamsteerable transmitarray (TA) antennas with high gain and low gain roll-off. The proposed offset unifocal phase symmetry operations can compromise phase error, electric-field spillover and illumination efficiencies to maintain the gains of scanning beams and minimize the gain roll-off. It has been demonstrated that the mechanically beam-steerable TA antenna enabled by the offset unifocal phase symmetry can maintain the realized gains of scanning beams, suppress sidelobe levels, and reduce gain roll-off within the beam-steerable coverage compared with the counterparts of unifocal and bifocal mechanically beamsteerable TA antennas. The proposed offset unifocal phase symmetry operations, in principle, is a generalized approach and applicable to reflectarray antennas to improve beamsteerable performance as well.