PURPOSE: To remove the leakage of oscillation signals and to switch the frequency of oscillation without deteriorating Q by using a series circuit obtained by connecting plural diodes having the same polarity in series as a switching means for switching the frequency of oscillation.
CONSTITUTION: The oscillation frequency switching circuit 16 consists of a capacitor 18, plural diodes 20, 22 successively connected to the capacitor 18 in series with the same polarity, and a high frequency leakage preventing resistor 24 of which one end is connected to the connection point 23 between the capacitor 18 ad the diode 20. The switching means 26 is constituted by the plural diodes 20, 22 and a series circuit consisting of the means 26 and the capacitor 18 is connected to a dielectric resonator 14 in parallel. Diodes having sufficiently lower series electrostatic capacity than that of the capacitor 18 and larger forward and backward conductive voltages V1, V2 in the voltage/current characteristics of the whole means 26 than the peak voltages VP of oscillation signals applied to both the ends of the means 26 are selected as the diodes 20, 22.
KURODA YUUJI
TAMURA SADAHIRO
