This is a generic routine that I wrote years ago to do just that. It's designed to run from a button, hence the use of selection. It could easily be modified to receive a range and work with that.
<font face=Courier New><SPAN style="color:#007F00">'------------------------------------------------------------------------------</SPAN>
<SPAN style="color:#00007F">Sub</SPAN> InsertEveryOtherRow()
<SPAN style="color:#007F00">'If TypeName(Selection) <> "Range" Then BadSelectionMessage "InsertEveryOtherRow", TypeName(Selection)</SPAN>
<SPAN style="color:#00007F">Dim</SPAN> rngSelection <SPAN style="color:#00007F">As</SPAN> Range, rngToChange <SPAN style="color:#00007F">As</SPAN> Range, rngRowOne <SPAN style="color:#00007F">As</SPAN> Range
<SPAN style="color:#00007F">Dim</SPAN> sngDesiredHeight <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Single</SPAN>, lngRowCount <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Integer</SPAN>, i&
sngDesiredHeight = InputBox("Enter a desired height for the new rows", "Height", 3)
<SPAN style="color:#00007F">Set</SPAN> rngSelection = Selection
<SPAN style="color:#00007F">With</SPAN> rngSelection
<SPAN style="color:#00007F">If</SPAN> .Rows.Count = 1 And .Columns.Count = 1 <SPAN style="color:#00007F">Then</SPAN>
<SPAN style="color:#00007F">Set</SPAN> rngToChange = .CurrentRegion
<SPAN style="color:#00007F">Else</SPAN>
<SPAN style="color:#00007F">Set</SPAN> rngToChange = rngSelection
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">If</SPAN>
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">With</SPAN>
<SPAN style="color:#00007F">With</SPAN> rngToChange
<SPAN style="color:#00007F">Set</SPAN> rngRowOne = .Rows(1)
lngRowCount = .Rows.Count
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">With</SPAN>
<SPAN style="color:#00007F">For</SPAN> i = 1 <SPAN style="color:#00007F">To</SPAN> lngRowCount * 2 - 1 <SPAN style="color:#00007F">Step</SPAN> 2
<SPAN style="color:#00007F">With</SPAN> rngRowOne
.Offset(i, 0).EntireRow.Insert
.Offset(i, 0).RowHeight = sngDesiredHeight
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">With</SPAN>
<SPAN style="color:#00007F">Next</SPAN> i
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN>
<SPAN style="color:#007F00">'------------------------------------------------------------------------------</SPAN></FONT>
HTH