Double‐layer wideband reflectarray using polynomial optimization technology

Abstract

In this article, a novel double-layer wideband reflectarray antenna using polynomial optimization technology is proposed. The reflectarray element has two main variable parameters. When each of the variables is adjusted, the reflectarray element cannot achieve 360° phase shift. However, as the two variables work together, 360° phase shift is easy to be achieved. The polynomial technology is used to connect the two variables, and the differential evolution algorithm is adopted to optimize the element to obtain the appropriate polynomial coefficients. The phase shift curves of different frequencies are parallel to each other and the slopes of the phase shift curves are consistent, which makes the proposed element achieve wideband characteristics. In order to verify the correctness of the proposed design method and reflectarray element, a 441-element reflectarray antenna was designed, processed, and measured. The proposed reflectarray antenna achieves 35% 1-dB gain bandwidth. At 12 GHz, the gain and efficiency of the proposed reflectarray antenna are 29 dBi and 62% respectively. In the whole bandwidth, the sidelobe was less than –16 dB and the cross-polarization was less than –38 dB. It is proved that polynomial automatic optimization technology can guide the design of the multi-variable wideband reflectarray antenna.