Abstract
This paper demonstrates the ability of the reflectarray antenna (RA) to perform orbital angular momentum (OAM) beamsteering with low divergence angles at the fifth generation (5G) millimetre-wave (mmWave) bands. To provide steered OAM beams,
it is necessary to regulate the scatterer’s geometries smoothly throughout the focal area to follow the required twisted distribution.
The traditional numerical method to compensate for the phase is modified to enable the 3D scanning property of OAM beams,
so it is possible to avoid the feeder blockage and produce high-gain steered OAM beams. Likewise, reducing the inherent beam
divergence of OAM beams can be obtained by examining the most satisfactory phase distribution of the scatterers by fitting the
focal length. The simulated radiation pattern is validated by the measured radiation pattern of the fabricated RA in the frequency
range between 28.5 GHz and 31.5 GHz.