An Ultrathin Single-Layer Metal-Only Transmit-Reflect-Array With Independent Bidirectional Dual-Circularly Polarized Beams Using a Linearly Polarized Feed

In this communication, an ultrathin (0.01λ0) singlelayer metal-only transmit-reflect–array (MOTRA) with independent bidirectional dual circularly polarized (CP) beams using a linearly polarized (LP) feed is proposed. By varying structural parameters and rotating elements, both independently controlled left-hand circularly polarized (LHCP) and right-hand circularly polarized (RHCP) beams are simultaneously obtained on each side of the antenna, under the illumination of a LP feed. For validation, a MOTRA operating at X-band is designed and fabricated. Measured results show that 3-dB bandwidth of gain (axial ratio) is 12% (18%) / 14% (25%) at 40° / -30° for LHCP / RHCP transmission, and 15% (22%) / 13% (21%) at 30° / -40° for LHCP / RHCP reflection, respectively. Furthermore, reasonable total peak aperture efficiencies are also obtained for transmission and reflection modes. These appealing characteristics together with its simple, ultrathin, and low-cost all-metal configuration make the design very suitable for bidirectional polarization multiplexed communication systems.