| 摘要 |
A transistor microwave oscillator circuit is provided with a YIG resonator device coupled to one of the transistor terminals. The YIG device resonates at a frequency established by a magnetic field applied thereacross and determines the oscillation frequency of the transistor circuit. Another YIG device is provided as a frequency responsive output transformer and functions as a high Q filter. This YIG transformer is positioned within the same applied magnetic field and has a resonant frequency identical to the YIG resonator. That is, the center frequency of the bandpass filter is the same as the oscillator frequency. As the applied magnetic field is varied, both the oscillation frequency of the transistor and the center frequency of the filter vary an identical amount. This frequency tracking insures that the oscillations are optimally passed by the filter, while off-frequencies are maximally attenuated. Further, the YIG transformer functions as an output impedance matching device. The YIG transformer is loop or coil-coupled to the transistor output terminal and loop-coupled to the load. These coupling coils may easily be modified as to number of turns and proximity to the YIG spheres to effect an optimal impedance match in a manner similar to conventional transformer coupling.
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