Low-Profile Slot Transmitarray Antenna

A novel ultrathin slot-based transmitarray antenna is presented. The related unit cell consists of two thin dielectric layers placed on top of each other, with annular ring slots placed on the outer layers and a PBG element placed on the common interface. The combination of the two annular ring slots and the PBG element acts as a bandpass filter for the transmitted wave. The design of the elements can be carried out through a simple circuit-based analysis approach. The proposed two-layer structure, the unit cell, has a thickness of 0.033 lambda(o) and provides the required 360 degrees of phase shift. Furthermore, over the bandwidth, the unit cell can have up to 7 degrees of phase error for incident angles of up to 50 degrees. The unit cell and the full transmitarray prototype are fabricated, and the results were compared with simulation and discussed. The full transmitarray has -1 dB gain bandwidth of 5.7% and efficiency of 38% at the center frequency. The structure is simulated via HFSS and CST software package.