A Low-Cost Bidirectional Dual-Circularly Polarized Beam-Scanning Reflect-Transmit Antenna Based on Multifunctional Metasurface

In this communication, a low-profile and low-cost bidirectional dual-circularly polarized (dual-CP) beam-scanning reflect-transmit antenna based on the multifunctional metasurface (MFM) is proposed and demonstrated. The proposed bidirectional dual-CP beam-scanning antenna consists of only two MFMs and two feeds integrated at the center of each metasurface, offering advantages of simple structure and low cost. The two MFMs are constructed with subwavelength single-arm spiral microstrip lines in a receiver-transmitter (Rx-Tx) configuration, which can independently and simultaneously modulate the phase of the reflection and transmission coefficients of the dual-CP polarized electromagnetic waves just using a simple rotation technique. For validation, a prototype with a center frequency of 15 GHz is designed, fabricated, and measured. When operating in LHCP mode, the proposed antenna provides ±40° beam scanning for the front direction with a scan loss of 1.40 dB. When operating in RHCP mode, it can also provide ±40° beam scanning for the back direction with a scan loss of 1.45 dB. The proposed antenna achieves peak gains of 19.4 and 20.0 dBic in the +z/-z directions, respectively. With its compact design, low-cost fabrication, and bidirectional beam-steering capability, this antenna is highly promising for low-cost wireless communication systems.