A signal arriving at one port is divided equally between the two adjacent ports but does not appear at the opposite port. In the schematic diagram, the signal into W splits between X and Z, and no signal passes to Y. Similarly, signals into X split to W and Y with none to Z, etc.
a signal arriving at one port is divided equally between the two adjacent ports but does not appear at the opposite port in the schematic diagram the signal into w splits between x and z and no signal passes to y similarly signals into x split to w and y with none to z etc