What is the advantage of the D-puck PIFA antenna over that of traditional PIFA antennas?

Traditional PIFAs are designed to be installed on a PCB need to be edge launched. That is, the PIFA must be placed on the edge of the PCB.

The D-puck PIFA antenna, however, has been designed such that it can be placed anywhere on the PCB. A design guide is available for antenna installation.