An Angle-Multiplexed Multifocal Method for D-Band 2-D Beam-Scanning Transmitarray Leveraging 3-D Transmission Line Component

This letter proposes an angle-multiplexed multifocal method for designing a 2-D beam-scanning transmitarray (TA). The angle-multiplexed method is commonly used to generate orbital angular momentum (OAM) multiplexing. The multifocal phase distribution is calculated using the angle-multiplexed and bifocal methods to achieve higher gain enhancement and 2-D beam-scanning with a low scan loss without optimization. The additive manufacturing technology is used to fabricate a 3-D transmission line component. In the terahertz band, the transmitting and receiving (Tx-Rx) unit cell impedance matching can be affected by the Pancharatnam–Berry (P-B) method, and a 3-D coaxial line is introduced to tackle this problem. For proof of concept, the prototype was fabricated. Feeded by a WR-06 waveguide probe, the proposed TA achieves a gain enhancement of 16.3 dB and ±30° 2-D beam-scanning, simulated and measured 3 dB gain bandwidths of 19.6% and 16.3%, and the measured axial ratio bandwidth of 30.7%.