In　this　paper,　a　dual　circularly-polarized　(CP)　multi-beam　antenna　is　proposed　for　future　vehicular　radar　applications.　The　antenna　is　composed　of　two　pillbox　reflector　beamforming　networks　(BFNs)　and　a　series-fed　microstrip　line　based　dual　CP　leaky-wave　antenna　(LWA)　array,　which　has　a　symmetrical　structure　and　can　obtain　both　left　hand　circular　polarization　(LHCP)　and　right　hand　circular　polarization　(RHCP)　by　switching　the　exciting　current　direction　of　the　microstrip　line.　Besides,　a　shorted　stub　is　loaded　in　the　LWA　to　suppress　the　open-stop　band　(OSB),　and　thus　achieve　the　broadside　radiation　and　good　impedance　matching　of　the　LWA.　To　realize　the　dual-polarized　radiation　characteristic　with　low-cost　passive　beam　scanning　capability,　two　pillbox　BFNs　are　connected　at　both　sides　of　the　LWA　to　share　the　LWA　aperture.　The　two　different　BFNs　can　excite　different　CP　radiation　patterns.　A　prototype　of　the　proposed　antenna　is　fabricated　in　the　frequency　band　23.5-24.5　GHz,　and　the　measured　results　approve　that　the　proposed　antenna　can　realize　±36°　beam　scanning　range　with-4.0　dB　crossover　level,　and　the　gain　is　higher　than　17.7　dBi　in　the　operating　band.　The　advantages　of　the　proposed　antenna,　including　low-profile,　low-cost,　passive　beam　scanning　ability,　and　dual　circular　polarization,　make　it　an　attractive　choice　for　low-cost　millimeter-wave　radar　applications.　©　1967-2012　IEEE.