for your situation, I do not suggest you to design such phase shifter. the simplest method of tuning phase in high power situation is to add tuning tab manually. certainly drawback is the output matching will be destroyed. I guess your boss want to tune for power when several PA combined together. I have such experience too. But really difficult and troublesome.
the suggestion is to tune phase at the input when signal is small (< 30dBm). if you or your boss persist on the idea, try the following:
http://www.weinschel.com/PRDPhaseShifter.htm
It is expensive (>$2000/PCS)[br]<p align=right><font color=red>+5 RD币</font></p>