Accurate Ray-Path Modeling for Wide-Angle Multi-Beam Flat GRIN Lens Design

In this study, we present an innovative design methodology for gradient-index (GRIN) lenses engineered to generate multiple beams from distinct focal points.Comprehensive numerical investigations reveal that the current state-ofthe-art multi-beam lens design, synthesized on the assumption of linear and parallel ray paths, suffers from ray-path errors that limit its applicability to lenses of arbitrary dimensions.To address these constraints, a more accurate synthesis technique is proposed, providing general formulas applicable to a wide variety of lens profiles.Comparative analyses between the conventional and the new method demonstrate that the latter achieves enhanced realized gains consistently for all multiple beams over a broad frequency range.Experimental validation was carried out using a 3D-printed lens featuring seven independent beams in an angular range of 44.The measured gain variations between multiple beams remain below 2.93 dB across the 12.3-19 GHz band.