Design of Pyramidal Fresnel Zone Lens for THz-band

In this paper, a pyramidal Fresnel zone (PFZ) lens, which is developed from both the planar square Fresnel lens and conical Fresnel zone lens, for THz-band is proposed. In our design, each square ring of the PFZ lens is arranged sequentially according to the pyramidal structure along the z-axis to achieve the regulation of the phase. The whole antenna system consists of a standard gain horn and the proposed PFZ lens. The key parameters of PFZ lens are also discussed to get the best performance of the antenna. Our result shows that a peak gain of up to 28.2dBi and a 3dB-bandwidth of 5.9° are achieved in the THz first atmospheric window 320GHz-380GHz.