Microwave Equivalent Circuits of Gunn Diode Packages in Microstrip Line

Equivalent circuits of Gunn diode packages located at the end of a microstrip line are determined by measuring frequency dependence of reflection coefficient of the short- and open-circuited packages. For X-band, equivalent circuits for three types of Gunn diode packages and two types of their assembly into microstrip lines are derived. The microstrip lines are manufactured on 1 mm thick alumina substrate, their characteristic impedance ranges from 23 to 75 Q. Besides the inductances and capacitances, the equivalent circuits consist also of resistances representing the radiation losses. They enable to design oscillators more accurately since they transform in a defined manner impedance of the passive parts of an oscillator and load to the Gunn diode chip terminals.