A Microwave Power Limiter (Correspondence)

Through the use of the familiar hybrid directional coupler and two PIN junction diodes as load impedances, the power delivered to the port not directly coupled to the input may be limited to any desired level, without rigid tolerances on the diode impedances. Starting with the scattering matrix of the hybrid and specifying arbitrary load reflection coefficients, the general properties of the device will be derived, and then its power-limiting capabilities will be examined in conjunction with the properties of the PIN diode.