We　propose　single/dual　circularly-polarized　(CP)　antennas　based　on　reflective　metasurfaces　with　cross-polarization　conversion.　By　suspending　a　probe-fed　printed　bow-tie　dipole　or　a　crossed　bowtie　dipole　above　the　reflective　polarization-conversion　metasurface　and　appropriately　tuning　the　distance　between　them,　a　single-CP　or　a　dual-CP　antenna　is　generated.　The　theoretical　design　principle　on　this　novel　CP　antenna　structure　has　been　discussed.　Simulations　and　experiments　are　conducted　to　validate　the　design　principle.　The　measured　results　show　that　the　proposed　single-CP　antenna　has　achieved　a　3-dB　axial　ratio　(AR)　bandwidth　of　8.0%,　from　12.67　to　13.72　GHz,　and　a　peak　gain　of　8.03　dBi,　while　the　dual-CP　antenna　exhibits　a　dual-CP　AR　bandwidth　of　7.1%,　from　13.09　to　14.05　GHz,　and　peak　gains　of　8.49　dBi　and　7.03　dBi　for　left-handed　circular　polarization　(LHCP)　and　right-handed　circular　polarization　(RHCP),　respectively.　The　measured　isolation　between　the　two　ports　of　the　dual-CP　antenna　is　less　than　−20　dB.　The　operating　frequency　of　the　proposed　antennas　can　be　easily　scaled　to　other　frequencies　that　are　applied　to　some　specific　wireless　applications.　©　2021,　Electromagnetics　Academy.　All　rights　reserved.