I finally got around to trying this.  The IMergedCellEvaluator worked with some tweaking.  Here's what I ended up using for the ShouldCellsBeMerged logic:

Function ShouldCellsBeMerged(ByVal row1 As UltraGridRow, ByVal row2 As UltraGridRow, ByVal column As UltraGridColumn) As Boolean Implements IMergedCellEvaluator.ShouldCellsBeMerged
   Dim Pol1 As String = DirectCast(row1.GetCellValue(column), String)
   Dim Pol2 As String = DirectCast(row2.GetCellValue(column), String)
   Dim Name1 As String = row1.Cells("AntennaName").value
   Dim Name2 As String = row2.Cells("AntennaName").value
   Return (Pol1 = Pol2) And (Name1 = Name2)
End Function

Many thanks for all the help.

There's no built-in property setting to get the mergind to be dependent on two different columns. But you can code this.The way to do is it you create a class that implements the IMergedCellEvaluator interface. This interface allows you to programmatically determined if two cells should be merged. So in this case, you would create one and assign it to the Polarization column and only merged the cells if the have the same values for both columns.

it looks to me like you are sorting by polarization and then name, try sorting name first and then polaization

The problem is that this isn't giving me what I want.  See the attachment.  The top is what I'm after -- merging of the polarization column within the value of the name column.  The bottom is what the grid is giving me.