PURPOSE: To stabilize an oscillation frequency by electrically compensate the influence of absolute humidity at the oscillation frequency, i.e. variation in the dielectric constant of internal air.
CONSTITUTION: A voltage-controlled oscillator 1 consists of a semiconductor active element 11, a dielectric resonator 12, and a frequency modulating circuit 13. A cavity resonator 2 discriminates the frequency of the oscillator 1. A detecting circuit 3 detects a microwave signal after the frequency discrimination. When the slope of the resonance curve of the resonator 2 is selected to obtain an oscillation signal frequency f0, the circuit 3 outputs frequency variation Δ/2 as a detection output voltage. This output voltage is supplied to the circuit after being amplified so that Δf0/f0 for Δ/ is compensated. Then, variation in oscillation frequency due to the humidity variation of the oscillator 1 is compensated electrically.
WADA KENZOU
MIZUMURA MOTOO
