The 4-SQ PCB is designed to be used with hybrid couplers similar to the COMTEK boxes. This requires a bit more skills than building the other antenna switches, since to get the best functionality the box requires some tuning. It is pretty well described on TK5EP website and also in the ON4UN book.
The 4-SQ PCB as all other switches has got at least 105 um copper thickness and handles OM-3500 power levels without any problem.
4-SQ schematic – Note that the 800pF capacitor value is different depending on which band it’s built for
Top view of the board – If used as a drilling template, make sure to print it as 1:1 scale.