A　new　design　of　Window　Function　modulated　electromagnetic　acoustic　transducers　(EMATs)　to　generate　unidirectional　Rayleigh　waves　is　proposed.　The　novel　EMATs,　Rectangular-Window-Meander-Line-Coil　EMATs　(RWMLC-EMATs)　and　Kaiser-Window-Meander-Line-Coil　EMATs　(KWMLC-EMATs),　contain　two　variable　length　meander　line　coils　with　a　spacing　of　one　quarter　of　Rayleigh　waves＇　wavelength;　the　excitation　signals　for　these　two　coils　have　a　phase　difference　of　90　degrees.　The　structure　of　the　variable　wire　length　determines　the　level　of　the　sidelobes　suppression;　the　structure　of　two　meander　line　coils　combined　with　the　excitation　signals　with　a　phase　difference　of　90　degrees　determine　that　Rayleigh　waves　only　propagate　along　one　direction.　RWMLC-EMATs　and　KWMLC-EMATs　are　analyzed　via　a　wholly　analytical　method　and　are　validated　with　experiments,　which　proves　the　feasibility　of　the　proposed　EMATs　structure.　In　addition,　the　effect　of　the　wire　step　and　the　longest　wire　length　are　investigated　analytically　and　experimentally.　Results　indicate　that,　wire　step　mainly　affects　the　suppressed　level　of　sidelobes　-　a　large　wire　step　leads　to　a　small　suppressed　level　of　sidelobes.　This　work　can　be　used　for　Rayleigh　waves　EMATs　design　and　optimization　to　improve　their　defect　detection　capability.