A Wideband Transmitarray Using Triple-Layer Elements Combined With Cross Slots and Double Square Rings

In this letter, a triple-layer wideband transmitarray operating at 12 GHz is designed. The unit cell has three metal layers, which are etched on three dielectric substrates. On the top and bottom layers, cross slots are etched, while a double square ring is etched on the intermediate layer. The simulation is carried out by Ansys HFSS. The designed element generates nearly perfect parallel sets of phase curves over a large frequency range, so the wideband transmitarray can be realized. To validate the wideband characteristic, a 233-element transmitarray prototype is fabricated and tested. Its measured 1-dB gain bandwidth is 16.8% (11.5-13.6 GHz), and its measured maximum gain is 25.8 dBi at 12.4 GHz, leading to 46.5% aperture efficiency.