A Broadband Low-Profile Transmitarray Antenna by Using Differentially Driven Transmission Polarizer With True-Time Delay

A broadband low-profile folded transmitarray (FTA) is proposed and investigated, in which a novel wideband transmission polarizer (TP) is used to realize low-profile design. The proposed TP, mainly consisting of a differential-fed grid-slotted patch antenna, can realize high-efficiency transmission and polarization selection simultaneously within a wideband frequency range. Moreover, the proposed TP can realize linear transmission phase because of the true-time delay (TTD) technique. Owing to the function of polarization selection and linear transmission phase, the TP can be used as antenna element for a FTA. A 140-element FTA is designed and fabricated by combining the TP with a broadband polarization rotation reflecting surface (PRRS). The measured radiation patterns agree well with the simulated results, and a peak gain of 24 dBi and maximum aperture efficiency of 44.7% are achieved. Furthermore, -1 and -3 dB gain bandwidth with 25.9% and 33.3% are also experimentally demonstrated in the proposed FTA, respectively.