ETD

• antenna arrays
• artificial dielectric layers
• automotive radar
• beam scanning
• cavity-backed slot antenna
• D-band
• dielectric lens antennas
• flat GRIN lens
• high-gain antennas
• matching layers
• permittivity gradient
• profile reduction
• terahertz frequencies
• wide-angle scanning

Automotive radar in the 134–141 GHz D-Band demands both high angular resolution (SRR) and high gain (LRR). This work designs a low-profile flat GRIN lens using annular dielectric layers (ADLs) to reproduce radial and later azimuthal permittivity gradients, optimized by a MATLAB ray-tracing tool and implemented in CST. Quarter-wavelength matching layers reduce reflections; the feed is a cavity-backed double-slot element whose dimensions were tuned by MoM analysis and an anisotropic matching slab. An 8 element array (spacing for −3 dB overlap) initially showed gain loss at large scan angles; remedies included side reflectors, edge-element tilt and conjugate field weighting. Vertical displacement of the array enabled further profile reduction; adding azimuthal permittivity variation recovered focal performance. The azimuthal flat lens achieves ~50% profile reduction versus a curved dielectric lens with comparable broadside gain, though scan-angle roll-off is influenced by the matching layers and broadside-optimized design.