Dual-beam Transmitarray Based on Guided-Wave Frequency Selective Surface

In this paper, we propose a dual-beam transmitar-ray composed of two types of guided-wave frequency selective surface. Two transmission units with 180° phase shift stability are designed based on the guided-wave frequency selective surface (FSS). Within the frequency range of 2.89-6.98GHz, the transmission amplitude $\left(\left|S_{21}\right|\right)$ is less than 1dB, and the phase error is less than 30°. Then, based on 1-bit digital coding theory, the phase distribution for a 30° beam deflection at the center frequency of 5GHz is determined. The designed array has a dimension of $8 \lambda_{0} \times 8 \lambda_{0} \times 0.93 \lambda_{0}$ ($\lambda_{0}$ is free space wavelength at 5 GHz), and simulation results show that beam scanning can be achieved from 4.5GHz to 6.5GHz, with a covering range of 20°-35°.