A K-Band Circular-Polarized Filtering Reflectarray by Orthogonal Phase Manipulation

In this paper, a K-band circularly polarized (CP) reflectarray (RA) has been proposed for millimeter-wave (mm-Wave) application. The unit cell consists of an isosceles triangular patch loaded with two slots, functioning as two sets of orthogonal multimode resonators. Unlike conventional magnitude-based filtering techniques, the design leverages reflection phase difference to achieve the desired filtering response. The optimized unit cell exhibits three reflection poles and two reflection nulls. The proposed RA presents a 3-dB gain bandwidth of 25.4%, a 3-dB axial ratio (AR) bandwidth of 32.68%, and out-of-band suppression levels of 36.1 dB at 16 GHz and 20.7 dB at 26 GHz.