A Unidirectional Beam-Scanning Antenna Excited by Corrugated Metal–Insulator–Metal Ground Supported Spoof Surface Plasmon Polaritons

A unidirectional beam-scanning antenna is proposed. The antenna is constructed by placing a series of circular radiating elements on a 2-mm dielectric slab backed by a corrugated metal–insulator–metal (CMIM) ground. The CMIM structure is introduced not only as a ground but also as a waveguide for spoof surface plasmon polaritons (SSPPs). The beam-scanning function is realized through the phase difference of SSPPs fed to the radiating elements. In addition, the CMIM ground reflects downward radiation waves onto upward space, leading to a unidirectional pattern and enhanced radiation gain. Both the numerical simulation and experiment results demonstrate the good performance of the proposed antenna. They validate that the antenna achieves unidirectional radiation and scanning angle of 57° when the frequency varies from 6.2 to 9 GHz with the frequency sensitivity of 20.4°/GHz. The realized gains are higher than 8.11 dBi over the entire band. Compared with the published works, this paper provides a novel feed technology, a simpler structure, and higher frequency sensitivity. The high-frequency sensitivity is beneficial to reduce the bandwidth burden of the entire system. The antenna has potential applications in satellite communication.