Impedance Matching Technique With Perforated, Inhomogeneous Layers for Broadband Dielectric Lenses

In this paper, an innovative, novel method to eliminate the internal reflections at the lens/air boundary of the radar sensors with dielectric lenses made of dense materials is proposed. Instead of traditional broadband matching technique, which requires the tooling of three additional layers with different materials on the lens surface, an alternative matching technique compatible with fabrication with today's popular 3D printing technology is proposed. The proposed cylindrical perforated matching layer also consists of three layers whose electrical permittivity is equivalent to its conventional three-layer matching layer case. This is achieved by arranging the material density for each layer. Consequently, a simple, low-cost matching layer that is constructed by using the material of the lens is proposed for broadband lenses with dense materials. Its fabrication is simple and compatible with additive manufacturing technique. A hemispherical lens prototype consisting of circular corrugated matching layer is manufactured. The lenses are also simulated with a widely used full-wave EM analysis tool. Simulation results of the fabricated broadband lenses are confirmed successfully by the experimental results in 18-24 GHz frequency band.