Do you think the size of ground plane for antenna design is considerable? For example, if I design a 2.4 GHz monopole or planar inverted-F antenna, the size of ground plane should I need in practice??
These chips are patch antennas. The fringing fields at the edges of the patch do the radiating. The bottom layer (ground) does not have to extend that far beyond the top layer (patch) for all of the fringing field to go from the edge of the patch to the ground.