Low-cost two-layer terahertz transmitarray

A flat terahertz transmitarray with a two-layer element is investigated. The proposed element can provide 360° phase coverage with a transmission coefficient better than -3.52 dB at 250GHz. Then a transmitarray based on the element is designed with a low focal-to-diameter ratio of 0.3. Simulation results reveal that the transmitarray has large backward radiation. A WR-03 open-ended waveguide with a thick wall is used to feed the transmitarray, thus the backward radiation is further reflected to the forward direction and the gain is increased by 1.7 dB at 250GHz. Then the transmitarray is fabricated using standard, low-cost printed-circuit-board technology, and the measured results show that a peak gain of 28.8dBi with an aperture efficiency of 32% is achieved. In general, the proposed transmitarray has simple structures and can be fabricated by standard printed-circuit-board technologies which are suitable for applications in low-cost terahertz systems.