Terahertz Transmitarray Antenna Using Rotated Z-shaped Elements

A terahertz transmitarray antenna working at the center frequency of 300 GHz is proposed. The antenna is based on a new-type transmitting element, which is composed of a dual Z-shaped configurations, mirror symmetrically printed on the two layers of a thin quartz substrate. Wide phase modulation coverage is achieved by changing the rotated angle of the Z-shaped element, simultaneously with a small change of the overall size. Phase modulation coverage of 360 degrees is obtained with a stacked four-layer design. The transmitarray element has both wide bandwidth and linear phase response characteristics. The proposed structure is simple and also has a good performance on fabrication tolerance, which makes it suitable for terahertz band designs. A standard WR-2.8 waveguide is used to normally illuminate the stacked four-layer transmitarrays. Simulated results show stable radiation patterns and low sidelobe levels in a wide frequency band. The 3-dB gain bandwidth is 18%, and the cross polarization level is lower than -33 dB.