Option Explicit

Function ConcatenaEx(sep As String, ParamArray rng())

  Dim r As Range
  Dim i As Integer
  Dim idx As Integer
  Dim sResult() As String
  Dim x As Long, y As Long
  idx = 0
  
  For i = 0 To UBound(rng)
      Set r = rng(i)
      For x = r.Row To r.Row + r.Rows.Count - 1
  
          For y = r.Column To r.Column + r.Columns.Count - 1
              ReDim Preserve sResult(idx)
              sResult(idx) = Sheets(rng(i).Parent.Name).Cells(x, y)
              idx = idx + 1
          Next y
      Next x
  Next i
  
  Set r = Nothing
  ConcatenaEx = Join(sResult, sep)

End Function