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.