Evaluation of Losses in 3-D-Printed Geodesic Lenses Using a Ray-Tracing Model

This article applies an in-house generalized ray-tracing (RT) model to efficiently compute both the radiation pattern and the efficiency of geodesic lenses with nonrotationally symmetric shapes. Losses due to ohmic effects and surface roughness are included in the model. These losses are very relevant for monolithic geodesic lens antennas as postprocessing techniques cannot be applied to reduce the surface roughness of internal part of the metallic plates. The model is validated by comparison with full-wave simulations for three different lenses: a circular flat parallel-plate waveguide (PPW), an elliptically compressed geodesic lens, and a water-drop lens. These results show a reduction in computational time by a factor of 600 using the RT model. A non-rotationally symmetric water drop lens has been manufactured in a monolithic piece using the laser powder-bed fusion (LPBF) technique with successful experimental results.