A Wide-Angle Polarization-Converted Beam Scanning Reflectarray Antenna for Millimeter-Wave Imaging

Abstract

Circularly polarized electromagnetic waves have unique advantages in removing artifacts in millimeter-wave imaging technology. In order to improve the working efficiency and detection accuracy of Ka-band millimeter-wave imaging systems, a polarization-converted beam scanning reflectarray antenna is proposed in this paper. The array antenna consists of a double-layer microstrip patch unit and a corrugated horn feed. The arrangement of the units on the front adopts the multi-focus design idea to meet the larger beam scanning range. The simulation results show that at a typical frequency of 35 GHz, the antenna achieves a gain variation of less than 2.3 dB within scanning angle $\text{of}\pm 30^{\circ}$ , the side lobe level of less than 18.6 dB, and the axial ratio of less than 1.3 dB. This performance index shows that the reflect array antenna can be applied in millimeter wave imaging system.