Proper design of intentional splits in the ground reference plane of PC boards to minimize emissions on I/O wires and cables

The question of whether or not to split the ground reference plane on PC boards has been a topic of debate within the EMC community for many years. Both proponents and opponents of splits cite cases where the split either solved their problems or caused problems. Indeed, most opinions on this subject approach a religious flavour, with little hard facts to back up the opinions. This work is intended to separate the various effects, both good and bad, of splitting a ground reference plane. While it is very bad (EMC-wise) to have a split in the reference plane in some circumstances, splits can be beneficial in other circumstances. The challenge to the EMC engineer is to be able to think clearly about the problem at hand, and make an informed decision.