1-Bit Unit-Cell for Transmitarray at C-Band Based on 3-D Frequency Selective Structure

In this paper, a reconfigurable 1-bit (0°/180°) unit cell based on 3-D frequency selective structure (3-D FSS) is proposed for transmitarray operating at C-band. The structure is originated from the traditional two-way single-phase shifter, while the incident waves from space are converted to guiding waves through 3-D stacked slot line structures firstly. Then the guiding waves propagate along two different ways controlled by four PIN diodes, and finally convert to space waves again via 3-D stacked slot line structure. The two states have a phase difference of 180 deg., which is achieved by choosing two strip lines with different lengths. Simulation results show that the operating frequency band defined by |S21|<0.5dB and Δφ<180°±25°is from 3.5GHz to 4.4GHz for the proposed structure, i.e. a relative bandwidth of 22.8%.