Dual-band transmissive metasurface with 2π co-polarized phase and 1-bit cross-polarized phase control simultaneously

In this paper, a dual-band transmissive metasurface (MS) that simultaneously achieves 2π co-polarized phase and 1-bit cross-polarized phase control is proposed. The element consists of three-layer sequential orthogonal metal gratings and two-layer square patch etched with two double-split ring resonators (DSRRs) and a circular hole. By adjusting the gap width and rotation angle of the corresponding DSRR, full 2π co-polarized phase shift is independently achieved in two bands, with high transmission amplitude (> -2 dB). Moreover, by simultaneously reversing the rotation angles of DSRR in two layers, 1-bit cross-polarized phase control is realized, without affecting the co-polarized phase. For verification, two transmitarray antennas (TAs) are designed, fabricated, and measured. The 1^st TA achieves high-gain beam through continuous co-polarized phase compensation, while the 2^nd TA further suppresses the cross-polarization level (CPL) by introducing 1-bit random cross-polarized phase distribution. The results show that the latter achieves peak gains of 21.7 and 26.7 dBi at 9.2 and 15.7 GHz, respectively, with aperture efficiencies of 45.6% and 49.5%. And the CPL is reduced below -43.4 and -44 dB.