A Novel Single-Layer Reflectarray Antenna Using Square Spiral Element

A novel single-layer reflectarray using square spirals is presented in this paper. The square spiral element employs four square spiral arms. By changing the length of the arm, a 450. phase variation range is realized. Besides, the element indicates stable responses for different incidence angles and the reflection phase curve is almost linear. Based on the good phase performance, a square reflectarray with side length of 99 mm is designed and simulated. The simulation results show good radiation performances and 1-dB gain bandwidth is about 31.3% at the center frequency of 15 GHz.