Where is the antenna located on the 2007 Highlander Hybrid, I do not have a clue

It is incorporated into the glass.

Thank you for your very quick response So just to be clear, the wire grid at the top of the windshield is actually incorporated into the glass?

Yes - it is not replaceable as a separate part. Now there may be some aftermarket antenna that can be used without glass replacement - if it becomes necessary.. Antenna failures are extremely rare.