Broadband Folded Transmitarray Antenna With Ultralow-Profile Based on Metasurfaces

A broadband folded transmitarray antenna (FTA) with ultralow-profile, high-gain, and high polarization purity is proposed in this communication. It consists of a focusing metasurface (MS) with the function of reflecting and transmitting two orthogonal linear-polarized waves, a reflection-type linear polarization conversion MS, and an open waveguide as a feed. With elaborate design, a −3 dB gain bandwidth of 43.5% from 9 to 14 GHz, a peak gain of 23.5 dBi, and a maximum aperture efficiency of 32.8% are achieved. Meanwhile, the −20 dB cross-polarization level at the broadside direction covers the entire operating band. Furthermore, it is worth mentioning that the profile of the proposed FTA is reduced to about 1/3 of the focal length and the profile-to-diameter ratio is only 0.22. The significant promotions in performance indicate the remarkable application value in portable communication systems.