Ensuring　a　low　cross-polarization　level　(CPL)　is　imperative　in　the　design　of　antennas　with　a　low　sidelobe　level　(SLL).　This　paper　introduces　an　innovative　approach　for　designing　wideband,　high-gain,　low-sidelobe,　and　low-cross-polarization　reflectarray　(RA)　and　transmitarray　(TA)　antennas.　The　methodology　leverages　a　groundbreaking　metasurface　endowed　with　the　capability　for　independent　amplitude　and　phase　manipulation　in　both　transmission　and　reflection　modes.　Initial　characterization　robustly　verifies　the　metasurface＇s　proficiency　in　independently　controlling　amplitude　and　phase　in　reflection　and　transmission　modes.　Importantly,　the　study　demonstrates　that　this　metasurface　enables　the　straightforward　attainment　of　low　CPL　in　the　design　of　low-SLL　RA　and　TA　antennas.　The　study　progresses　to　the　design,　fabrication,　and　testing　of　three　RA　and　TA　antennas.　The　obtained　simulated　and　measured　results　affirm　their　exceptional　performance　in　terms　of　wideband,　high-gain,　low-SLL,　and　low-CPL　characteristics.　©　2020　IEEE.