Design of Low-Profile Transmitarray Antennas With Wide Mechanical Beam Steering at Millimeter Waves

Mechanical beam steering using a single transmitarray (TA) can be a cost-effective solution for a high-gain antenna with wide-angle scanning. Elevation scanning can be achieved by a linear displacement of the feed in the focal plane parallel to the aperture of diameter D. When designing compact terminals with a short focal length F and with high gain, the aberrations caused by this mechanical movement become the main limiting factor for the maximum scanning range. This work presents a novel design method for devising the TA phase correction with an even distribution of these aberrations among all beam directions. A significant improvement in the scanning performance is achieved when compared with the conventional single-focus phase correction approach. To validate the proposed approach, we consider a TA design at the Ka-band (30 GHz) F/D congruent to 0.34. A multifocal TA design was manufactured using 3-D printed unit cells. To highlight the proposed concept, the antenna configuration is stripped to the bare minimum: a perforated dielectric slab with in-plane mechanical movements in front of an open-ended standard waveguide used as feed. This antenna scans up to 50 degrees, with a gain of 25 dBi at 30 GHz, 2.5 dB of scan loss, sidelobe level (SLL) <-10, and 1 dB bandwidth of 6.7%.

Automated summary

Mechanical beam steering using a single transmitarray can achieve wide-angle scanning for a high-gain antenna, but aberrations caused by the mechanical movement limit the scanning range. This study presents a novel design method for correcting these aberrations and improving scanning performance. A multifocal transmitarray design was manufactured and demonstrated with a scanning range of 50 degrees and a gain of 25 dBi at 30 GHz.