Miniaturized GRIN Lens-in-Radome for Pattern Shaping in E-Band Automotive Radar

This communication presents a miniaturized gradient-index (GRIN) lens integrated into the radome of an automotive radar sensor at 76–81 GHz, i.e., in the E-band, for azimuth beam shaping. The fully dielectric lens is tightly integrated with a Multi-Layer Waveguide (MLW) array antenna, yielding a compact footprint of 0.47 λ × 1.2 λ. A farfield averaging over simulations with different radome widths suppresses diffraction from radome-guided modes, isolating the contribution of the lens–antenna system in the design phase. Measurements of an 8-channel prototype show that the integrated lens broadens the azimuth half-power beamwidth from 50° to 120° (≈ 140° at −5 dB) while maintaining better than 10 dB return loss and a gain ripple of 4.3–7.9 dB across the band. The proposed approach provides a competitive beamwidth in a smaller form factor, enabling integration in automotive corner radar sensors.