Design of the One-bit Unit Cell for A Broadband Reflectarray

In this paper, the unit cell of a broadband beam-steerable reflectarray antenna is proposed. The unit cell consists of tightly coupled dipoles and two delay lines. Radio frequency (RF) switches are placed on the delay lines to adjust the reflection phase of the element. The proposed unit cell achieves one-bit phase shifting over a wide bandwidth. To verify the design, a reflectarray composed of the proposed unit cell is simulated. The reflectarray consists of 27x9 units and a feeding antenna which is a log-periodic dipole array (LPDA). The reflectarray works from 3.5 GHz to 5 GHz and the scanning range of the main beam is from - 15° to +15° .