Reconfigurable Antenna With Uni- and Bidirectional Radiation Patterns Based on Metasurface and Fresnel Zone Plate Lens

A reconfigurable antenna with unidirectional and bidirectional radiation patterns is proposed in this letter. An open-ended waveguide (OEWG) antenna serves as the feeding source to excite the Fresnel zone plate lens above it. Further, an anisotropic polarization-sensitive metasurface is placed at the end of the feeding antenna and parallelly to the Fresnel lens to manipulate the reflected waves from the lens. By mechanically rotating the feed orthogonally, the two radiation modes can be alternated. The proposed antenna operates at a central frequency of 28 GHz. The forward transmitted waves are in the boresight direction for both operation modes. The backward reflected wave for the bidirectional mode has a 90° polarization rotation and an elevation angle of −150°. The measured peak gain for the unidirectional mode is 20.3 dBi, and those for the bidirectional mode are 16.7 dBi and 14.8 dBi for the transmitted and reflected beams, respectively. The measured gain difference for the bidirectional mode is less than 2.96 dB from 26.5 to 29.5 GHz, while the gain fluctuation is small for both modes within the operation band, indicating good performance.