Half-mode substrate integrated waveguide leaky-wave antenna based on a dielectric layer with periodic perforations

A low-cost multilayer antenna is proposed for the next-generation automotive radar systems at millimeter waves. The antenna consists of a multilayer half-mode substrate integrated waveguide (HM-SIW) leaky-wave antenna (LWA) based on a dielectric layer with periodic perforations. Its stack-up consists of a 0.5-mm-thick Rogers 4350B substrate and two 1.0-mm-thick FR4 substrates assembled by 1.4-mm-diameter alignment pins and fixations. Measurements of a 126-mm-long fabricated prototype revealed a −10-dB impedance bandwidth of 6.9 GHz, covering the 22 GHz to 28.9 GHz band. The measured gain equals 15.5 dBi at 24 GHz, resulting in a total efficiency of more than 85%. Moreover, the measured radiation patterns in the [22–26] GHz band exhibit an average 3-dB beamwidth of 11.5° and sidelobe levels (SLL) better than 20 dB up to a scan angle of 20°