This　work　presents　a　new　omnidirectional　electromagnetic　acoustic　transducer　(EMAT)　employing　a　circumferential　periodic　permanent　magnet　array,　which　was　proposed　for　generating　and　receiving　shear-horizontal　(SH)　guided　waves　in　an　aluminum　plate.　The　novel　transducer　consisted　of　12　axially　polarized　sector　magnets　arranged　in　a　circle,　and　the　magnetic　field　directions　of　adjacent　magnets　were　opposite.　A　spiral　coil　was　arranged　under　the　magnet　array.　A　vertical　magnetic　field　generated　by　the　magnets　and　the　circumferential　eddy　current　generated　by　the　spiral　coil　formed　a　Lorentz　force　in　a　plate　acting　in　the　radial　direction　of　this　new　omnidirectional　EMAT.　By　controlling　the　sizes　of　the　sector　magnets,　the　omnidirectional　SH0　mode　(fundamental　SH　guided　wave　mode)　was　generated.　To　maximize　the　output　of　the　EMAT　at　the　given　excitation　frequency,　it　was　proposed　to　add　acrylic　spacers　between　the　sector　magnets　and　determine　the　size　of　the　magnet　based　on　the　frequency　bandwidth　of　the　excitation　signal　while　also　optimizing　the　omnidirectional　sound　field.　A　three-dimensional　(3D)　finite　element　model　of　the　EMAT　was　established　using　COMSOL　Multiphysics　to　perform　numerical　simulations,　and　the　effectiveness　of　the　optimization　method　was　verified.　The　effectiveness　was　verified　by　experiments.　The　simulations　and　experiments　showed　that　the　proposed　EMAT　could　generate　omnidirectional　SH0　mode　guided　waves　in　an　aluminum　plate.　©　2001-2012　IEEE.