A Broadband E-Band Single-Layer-SIW-to-Waveguide Transition for Automotive Radar

An E-band air-filled rectangular waveguide (RWG) to single thin-layer (0.127 mm) substrate integrated waveguide (SIW) transition is proposed for automotive radar applications. The compact transition structure is realized using a symmetric narrow aperture coupled comb patches. With the mutual coupling effect between patches, a bandwidth greater than 22% for |S11| < -15 dB is achieved. A back-to-back prototype is fabricated and measured. The results show that the insertion loss of a single transition is less than 0.5 dB within 71-86 GHz, which covers the whole attractive frequency range for automotive radar. With broadband and compact size, the proposed transition presents potential for automotive radar.