Broadband, Low-Profile, Planar Reflectarray Antenna Based on an Achromatic Metasurface

This communication presents a broadband, low-profile, and planar reflectarray (RA) antenna based on an achromatic metasurface. The achromatic metasurface has advantageous broadband focusing capabilities compared to conventional RAs. Six types of unit cells offering versatile phase responses are employed to design an achromatic metasurface optimized by a convolutional algorithm. A broadband achromatic RA antenna with a diameter of 270 mm is simulated, fabricated, and tested. The test results agree well with the simulated results. Notably, the 3 dB realized gain of the RA antenna reaches a fractional bandwidth of 58.2% at a range of 8.9–16.2 GHz. Furthermore, the RA antenna significantly enhances the feeding antenna’s gain from 7.3 to 17 GHz. The reflecting metasurface also has a low profile of
$0.11~\lambda \text{L}$
, where
$\lambda \text{L}$
is the wavelength in free space at 7.3 GHz. With excellent broadband performance, high gain, low profile, and ease of fabrication, the developed RA antenna serves as a promising device for long-distance integrated communication systems.