PURPOSE: To easily vary an oscillation frequency band by using the same substrate by connecting 1st and 2nd tip open stubs to a microstrip line at an interval of nearly 1/4 wavelength.
CONSTITUTION: The tip open stubs 13a and 13b are connected to the microstrip lines 5a between the gate terminal 8 to a field effect transistor FET 7 and the anode terminal 3 of a varactor diode 1 at two positions which are at an intervals of nearly 1/4 wavelength. Then the stubs at the positions are adjusted finely in length. The electric length between the anode terminal 3 of the varactor diode 1 and the gate terminal 8 of the FET 7 can be varied by the fine adjustment. This is equivalent to variation in the electric length of the microstrip line 5a, so the oscillation frequency band of a voltage-controlled oscillator can be varied by adjusting the stubs finely even when the same substrate is used.
IIDA AKIO
MATSUNAGA MAKOTO
