Modeling Partially-Dielectric Unit Cells for OAM Transmitarrays

The presented study introduces a semi-analytical circuit model (CM) to fully characterize a dielectric unit cell structure made by blocks instead of applying the effective medium theory. A fitting strategy is used to a obtain a better understanding of the properties of the unit cell. Then, the approach is used to develop a semi-analytical model, showing a good agreement with the scattering parameters extracted from a full-wave simulator. By tuning the dielectric material, our model can describe the behaviour of unit cells with different permittivities and electrical sizes. Finally, as an application for the analyzed dielectric unit cells, transmitarrays to generate orbital angular momentum (OAM) waves are designed and 3D-printed. The measured results show good performance for different OAM modes at 31 GHz.