Partially Filled Half-Mode Substrate Integrated Waveguide Leaky-Wave Antenna for 24 GHz Automotive Radar

Abstract

A novel highly efficient leaky-wave antenna (LWA), based on a periodic set of holes created in a half-mode substrate integrated waveguide (SIW), is conceived for automotive radar. The computer-aided design of this partially filled SIW (PFSIW) LWA is carried out using a full-wave electromagnetic simulator. As a proof-of-concept, an LWA prototype having a plate size of 15 × 126 mm<inline-formula><tex-math notation= LaTeX >$^2$</tex-math></inline-formula> is fabricated through a standard low-cost printed circuit board (PCB) manufacturing process. Our manufactured prototype yields more than 25% impedance bandwidth, targeting the 24\xa0GHz automotive short-range-radar band. Moreover, the measured peak gain and total antenna efficiency reach up to 15.5 dBi and 85% at 24\xa0GHz. Furthermore, the main radiating direction steers continuously from 38<inline-formula><tex-math notation= LaTeX >$^\\circ$</tex-math></inline-formula> to 58<inline-formula><tex-math notation= LaTeX >$^\\circ$</tex-math></inline-formula> with an average half-power beamwidth of 12<inline-formula><tex-math notation= LaTeX >$^\\circ$</tex-math></inline-formula> when the operating frequency changes from 22 to 26\xa0GHz. In comparison, a 160 mm long dielectric-filled SIW (DFSIW) LWA yields a measured scanning range of 49<inline-formula><tex-math notation= LaTeX >$^\\circ$</tex-math></inline-formula> and a total antenna efficiency of 43.8%, whereas an 80.3 mm long air-filled SIW (AFSIW) LWA exhibits a measured scanning range of 9<inline-formula><tex-math notation= LaTeX >$^\\circ$</tex-math></inline-formula> and a total antenna efficiency of 80%. Therefore, PFSIW technology provides an optimal tradeoff between DFSIW and AFSIW for the envisaged short-range automotive radar application.