In　this　paper,　a　novel　Ka-band　circularly-polarized　(CP)　planar　metasurface　antenna　is　proposed,　which　is　based　on　an　innovation　technique　for　suppressing　grating　lobes　in　antenna　arrays　featuring　large　element　spacing　(LES).　It　consists　of　two　essential　components:　a　substrate-integrated-waveguide　(SIW)　array　with　an　element　spacing　of　2λ　and　a　metasurface　lens　(meta-lens).　The　LES　SIW　array　and　the　compact　transparent-like　meta-lens　are　first　developed　separately,　to　achieve　CP　performance　with　grating　lobes　and　circular-to-circular　polarization　transformation　with　continuous　compensation　phases,　respectively.　They　are　then　integrated　to　construct　the　metasurface　antenna,　where　the　grating　lobes　from　the　SIW　array　are　effectively　suppressed　and　the　gain　is　significantly　improved.　Simulations　are　carried　out　to　validate　the　antenna　design,　yielding　impressive　results,　including　a　peak　gain　of　26.92　dBic　and　an　expansive　3-dB　axial　ratio　(AR)　bandwidth　of　over　23%.　This　innovative　antenna　design　provides　an　alternative　way　to　realize　high-gain　antenna　arrays,　offering　distinct　advantages　of　design　simplicity　and　the　ability　to　overcome　difficulties　associated　with　processing,　tuning,　and　reliability,　especially　in　the　millimeter-wave　band.　©　2024　18th　European　Conference　on　Antennas　and　Propagation,　EuCAP　2024.　All　Rights　Reserved.