impedance of their associated pin diodes to equal 50 ohms thus when the diodes d1 and d2 are fully conductive the impedance from input port 18 to ground is 50 ohms and the impedance from the output port 19 to ground is 50 ohms with the quadrature coupler one half the input power is absorbed as p1 and one half is absorbed as p2 and the output or load power pl is substantially equal to 0 which corresponds to the second line of the chart of fig2 when both diodes d1 and d2 are nonconductive g1 and g2 both equal 0 substantially all of the available power pa is coupled to the load line 1 of the chart hence pl equals 1 and p1 and p2 are both equal to 0 for intermediate normalized values of g1 and g2 representing different conductivity levels of d1 and d2 the portion of the available power pa that is coupled to the load as pl is proportional to the square of the reflection coefficient associated with ports 18 and 19 the actual values of resistors 22 and 32 will of course be dependent upon the characteristics of the pin diode used on all the stray impedances at ports 17 to 20 and on the frequency of the if signal in the preferred embodiment the first if frequency is 920 mhz the pin diodes d1 and d2 exhibit.