24 GHz automotive radar planar Luneburg lens

A planar Luneburg lens whose permittivity distribution is modified by two types of hole density control in the central region and by dielectric thickness control in the edge region is reported. The lens was designed to operate at 24 GHz in Transverse Electromagnetic (TEM) mode. Experimental radiation patterns show good agreement with the simulation. The measured 3 dB beamwidth of the vertical polarised H-plane pattern is 5 degrees with 14 dB gain at 24 GHz for a 12.2 lambda, 15.24 cm diameter lens, cross polar levels were below -30 dB. Its small size and lightweight, 53% of material is removed, and better than 20% bandwidth makes it useful for vehicular use in the 24 GHz unlicensed Industrial, Scientific, Medical (ISM) equipment band and for 24 GHz short range radar applications.