3D Printed OAM Reflectarray Using Half-Wavelength Rectangular Dielectric Element

A 3D printed dielectric reflectarray is studied to generate orbital angular momentum (OAM) beam. The array element consists of a half-wavelength rectangular dielectric block and a metallic ground. It is found that the loss tangent and permittivity of the rectangular dielectric element independently affect the reflection magnitude and reflection phase, respectively. Four OAM modes (l = 1, 2, 3, 4) are theoretically studied. A prototype of the mode l = 1 working at Ka band is fabricated and measured. The maximum gain in the radiation direction (θ = 4°) is 20.4 dBi at 30 GHz. A wide OAM bandwidth of 21.7% for the mode weight coefficient larger than 60% is also obtained. The proposed antenna shows its potential applications in OAM communications.