The　forward　model　of　eddy-current　(EC)　testing　can　predict　the　measurement　signals,　provided　the　known　measurement　conditions　and　physical　properties　of　test　pieces.　In　the　analytical　forward　model,　the　test　pieces　are　characterized　by　the　reflection　coefficient　(RC),　which　describes　the　reflection　characteristics　of　test　pieces　regarding　incident　electromagnetic　(EM)　waves　and　determines　the　phase　of　EC　signals.　The　RC　is　calculated　analytically　with　boundary　conditions,　which　is　sophisticated　for　analyzing　complex　geometries.　In　this　study,　the　analytical　model　of　plate　and　pipe　testing　using　second-order　vector　potential　(SOVP)　is　investigated.　It　is　found　that　the　numerical　RC　can　be　obtained　from　the　source　EM　field　in　the　air　and　counterparts　in　the　presence　of　test　pieces.　In　numerical　simulations,　the　numerical　RC　is　compared　with　the　analytical　RC　for　plate　and　pipe　in　a　2-D　axisymmetric　model.　In　the　3-D　model,　the　calculated　numerical　RC　corresponds　to　the　dimensions　of　the　measured　plate　and　pipe　with　defects.　In　both　2-D　and　3-D　models,　the　phase　of　coil　inductance　from　the　numerical　RC　aligns　with　the　finite-element　solutions.　It　is　validated　that　the　RC　is　a　characteristic　of　test　pieces　independent　of　the　source　field.　©　2024　IEEE.