Phased Antenna Array Generating Sub-Terahertz Radiation with a Defined State of the Orbital Angular Momentum

The paper presents the uniform circular array (UCA) model based on four microstrip octagon-shaped emitters operating in the W-band, specifically in the 77.5–78 GHz band. The diameter of the UCA is 4.8 mm, and the applied substrate material is RO4350B. The CST Studio Suite simulation shows that UCA has an operation band from 75 to 78 GHz, and the gain equals 8.57 dBi. A beamforming scheme is developed for the designed UCA configuration: a phase shift of 90 degrees between the ports is achieved. The possibility of generating an equal-amplitude signal with a defined OAM state (0, +1, −1) is demonstrated. A prototype UCA with a beamforming scheme on a RO4350B substrate in a multilayer structure has been fabricated. Further measurements of the obtained device require the development of a waveguide-complanar-microstrip type transition.