Broadband Dual Circularly Polarized Transmit Reflect Sparse Metasurface With Independent Bidirectional Quad-Beam

In this letter, a broadband dual circularly polarized (CP) transmit reflect sparse metasurface (TRSM) with full-space independent quad-beam control is proposed. The TRSM consists of two types of unit cells with opposite polarization responses. Unit cell 1 transmits right-hand circularly polarized (RHCP) waves and reflects left-hand circularly polarized (LHCP) waves, while unit cell 2 does the opposite. By employing a sparse array technique based on Genetic Algorithm (GA) to optimize the positions of two unit cells, the TRSM can independently control quad-beam in full-space when illuminated by a linear polarization (LP) feed source. Experimental results demonstrate maximum gains of 19.16 dBic (LHCP) and 19.32 dBic (RHCP) for the transmitted beams, with wide 3 dB axial ratio (AR) bandwidths of 44.1% and 48.3%. Similarly, the reflected beams achieve maximum gains of 17.62 dBic (LHCP) and 19.51 dBic (RHCP), with the 3 dB AR bandwidths of 35.3% and 35.4%. The TRSM meets the multi-access and full-coverage requirements of 6G communication networks.