Characteristics of digitised millimetre-wave metal reflectarray antennas

Reflectarray antennas composed of rectangular grooves with a digitised phase-shift element are designed for the millimetre-wave region. The digitised metal antennas have been realised by quantising the phase shift of each rectangular groove. For 4 bit quantised antennas, the far-field patterns are very similar to those of the non-digitised case and especially show that the measured gain of the 2 bit reflectarray is only 1 dB lower than that of a non-digitised reflectarray antenna. These results will contribute to saving manufacturing cost and time and the guidance of the phase shifter for an active metal reflectarray antenna for millimetre-wave wireless networking or imaging systems.