Placement of itemsmounted to the windshield such as antennas, transponders and similar devicescannot be mounted more than six inches below the upper edge of the windshield,according to Federal Regulations -- section 393.60(e)(1) and (2). According tothe regulations, these items must be located outside the area swept by thewindshield wipers and outside of the driver’s sight lines to the road, highwaysigns or signals.