Electron　standing　wave　(ESW)　states　excited　in　the　vacuum　gap　near　sample　surface　by　operating　the　scanning　tunneling　microscopy　in　field　emission　regime　have　been　widely　used　to　probe　the　local　electronic　properties　of　novel　materials　and　structures.　For　accurate　interpretation　of　the　ESW　states　spectra,　a　simple　numerical　approach　is　developed　based　on　a　one-dimensional　model,　and　the　transmission　coefficient　is　accurately　calculated　using　the　transfer　matrix　method.　Effects　correlated　with　the　potential　distribution　in　the　tunneling　gap　are　discussed.　By　this　method,　main　features　of　the　experimental　spectra　obtained　on　Si(111)7x7　surfaces　are　successfully　simulated.　Factors　affecting　the　spectra　are　discussed.　Copyright　(C)　2012　John　Wiley　&　Sons,　Ltd.