A four-port network has the scattering matrix shown below (the system characteristic impedance is Zo = 50 22). a) What is the return loss at port 4 when all other ports are matched? What is the insertion loss from port 3 to port 4, when all other ports are matched? b) What is the reflection coefficient seen at port 4 if a 75 2 resistor is placed at the terminal plane of port 1, and all other ports are matched? [S] = 0 0.5-45 0 0.75/30 0.5-45 0 0.6 Z-60 0 0 0.6 Z-60 0 0.65-30 0.75/-30 0 0.65-30 0.2/45