A Novel Steerable Dual-Beam Metasurface Antenna Based on Controllable Feeding Mechanism

摘要

A novel steerable dual-beam metasurface antenna (MSA) with controllable feeding mechanism is proposed. The proposed MSA consists of 7 x 10 square metasurface cells and is fed by a completely symmetrical controllable network, which includes three dumbbell-shaped coupling slots etched on the ground and two-port stepped impedance line beneath the ground. The network can flexibly control the magnitude and phase of the coupling energy from the feeding line to the radiated metasurface cells via the slots, so as to realize two desired symmetrical beams. Owing to good directional radiation of the MSA, the beams of the proposed MSA exhibit better front-to-back ratio, higher gain, and higher channel isolation than those of traditional traveling-wave slot antennas. Moreover, benefiting from the controllable feeding mechanism, impedance matching, sidelobe suppression, and isolation of the ports can be further improved. Consequently, the two achieved beams are, respectively, oriented at +/- 30 degrees in azimuth plane with 10 dB beamwidth of about 120 degrees, high-peak gains of 12.8 dBi and cross level at two beams junction of about -10 dB; meanwhile, the isolation of the two ports is over 15 dB within the band of interests (5.23 and 5.40 GHz). For demonstration of the design strategy, one 1 x 2 dual-beam MSA array with gain of 14.8 dBi and similar beam performance is designed and fabricated. Due to the controllable steerable beams and the simple mechanism without complex beamforming networks, phase shifters or large footprint, the proposed steering dual-beam MSA array can be expected to find potential applications in multibeam base stations.