Suppose I have a design using a BCM20736S SIP that's made up of two PCBs stacked closely on top of each other with approximately 2mm of air between them. The SIP would reside on the top-most PCB and the ground plane rules stated in the datasheets will be followed as closely as possible. However, the PCB directly beneath it has a continuous ground plane without any keep-out areas. How significant of an effect will this have on RF performance?
It will affect the RF performance for sure.
This design would be similar to a design where a customer put a coin cell battery right underneath the 20736S and they couldn’t get more than 10m of range.
Does this answer your question?
This shorter range may be OK for a wearable design.