Johanson offers chip antenna models with various no-ground plane requirements for applications where there is a space constraint on the PCB.  The yellow no-ground plane area of antenna 2450AT43A100 is 190 mm square.  Antenna 2450AT43B100 has a decreased no-ground plane area of 40 mm square while antenna 2450AT43D100’s no-ground plane is further reduced to only 26 mm square.  This gives the designer the flexibility to integrate the small profile chip antenna into the design phase even with tight layout constraints.  The trade off for chip antennas with a minimal no-ground plane would be an increased thickness in profile height.