Wideband Transmitarray Antenna Based on Two-Layer Aperture-Coupled Metasurface Unit Cell

In this paper, a transmitarray antenna is designed and fabricated based on a two-layer aperture-coupled patch unit cell. The unit cell is composed of two layers of dielectric substrate with a simple narrow rectangular aperture between the layers. Through characteristic mode analysis, it is shown that while a single patch on each layer does not provide the 360° phase range required in the transmitarray antenna design, if the same patch is divided into several sub-patches, named metasurface, the 360° phase range is achieved. It is also shown that metasurface sub-patches provide a wide gain bandwidth and high aperture efficiency for transmitarray antennas. In addition, a 13 × 13 metasurface-based transmitarray antenna is designed and fabricated. When using a 3 × 3 metasurface unit cell, the measured -1 dB gain bandwidth is 19% and its measured gain is 25.7 dB at the center frequency of 10.5 GHz, exhibiting 50% overall aperture efficiency.