JP2558672B2 - Microwave oscillator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a microwave oscillator whose oscillation is stabilized by a dielectric resonator.

2. Description of the Related Art In a microwave oscillator whose oscillation operation is stabilized by a dielectric resonator, as shown in FIG. 3, a metal is placed above the dielectric resonator 4 from outside the oscillator housing 1 as shown in FIG. The screw 2 is inserted to adjust the oscillation frequency.

Here, 7 is a dielectric substrate on which a microstrip line is drawn, 6 is a field effect transistor (FET) for oscillation, and 5
Is a support for the dielectric resonator 4.

However, in this case, as the metal screw 2 is inserted, not only the oscillation frequency but also the oscillation output level changes,
When the insertion length of the metal screw 2 reaches a certain length, the FET 6 from the microstrip line magnetically coupled to the dielectric resonator 4
There was a phenomenon that the negative resistance seen from the side became small, and the oscillation became unstable or stopped. Therefore, if the desired oscillation frequency enters the oscillation stop region, adjustment becomes impossible.

It is an object of the present invention to solve the problem that a conventional oscillator has, that is, the oscillation becomes unstable or stops due to the insertion length of a metal body.

Means for Solving the Problems In order to solve the above problems, the present invention adds a dielectric plate of a microstrip line and a metal plate arranged with a gap to the inner wall of the housing. Since the electromagnetic field is concentrated near the dielectric resonator, the addition of a metal plate may change the oscillation mode due to the influence.
The electromagnetic field exponentially decreases outside the dielectric resonator. Therefore, if a metal plate is added at a position sufficiently distant from the dielectric resonator, the oscillation mode will not change.

Operation By thus adding a metal plate to the upper wall of the oscillator housing with a gap between the dielectric substrate and the metal plate, the oscillation frequency can be adjusted stably without affecting the output level.

Embodiment An embodiment of the present invention will be described with reference to FIGS. In this embodiment, an FET 6 is used as an active element, a microstrip line on a dielectric substrate 7 is connected to its gate, and these are housed above a dielectric resonator 4 magnetically coupled to the microstrip line. The metal screw 2 is inserted from the outside of the housing 1 to change the oscillation frequency. The metal plate 3 is fixed to the inner wall of the oscillator housing 1 with an adhesive or the like.

Further, FIG. 2 shows changes in the oscillation frequency and the oscillation output with respect to the distance between the metal screw 2 and the dielectric resonator 4 in the microwave oscillator of 10 GHz having this structure. According to FIG. 2, when the metal plate is not added as in the conventional example (broken line), the oscillation output level is largely changed by inserting the metal screw 2, but by adding the metal plate 3 (solid line). , The oscillation output level is hardly changed (oscillation mode is not changed), and only the oscillation frequency can be stably increased.

That is, according to the present invention, the metal plate 3 is oscillated at a position on the upper wall of the casing sufficiently separated from the dielectric resonator through the dielectric substrate 7 and the air gap without changing the oscillation output level. By providing only the frequency at a position where it rises according to the insertion length of the metal body, the negative resistance seen from the FET 6 side of the microstrip line magnetically coupled to the dielectric resonator 4 becomes large, and the oscillation frequency can be adjusted. It can be performed stably without affecting the output level.

Although it is conceivable to dispose the metal plate 3 near the dielectric resonator 4, the oscillation mode may change due to the influence of the metal plate 3. Therefore, it is preferable to dispose it at a position sufficiently distant from the dielectric resonator 4 as in the above embodiment.

EFFECTS OF THE INVENTION As described above, according to the present invention, in the microwave oscillator whose oscillation operation is stabilized by the dielectric resonator, the metal plate is arranged on the upper wall of the oscillator housing with the dielectric substrate and the gap. This makes it possible to eliminate oscillation instability caused by the metal body inserted above the dielectric resonator. Therefore, the phenomenon that the oscillation frequency cannot be adjusted can be eliminated.

[Brief description of drawings]

1A and 1B are cross-sectional views of a microwave oscillator according to an embodiment of the present invention, and FIG. 2 is a diagram showing an embodiment of the present invention and a metal screw and a dielectric in a conventional 10 GHz microwave oscillator in which a metal plate is not added. FIG. 3 is a characteristic diagram showing a comparison between changes in the oscillation frequency and the oscillation output with respect to the distance of the body resonator, and FIG. 3 is a sectional view of a conventional oscillator. 1 ... Oscillator housing, 2 ... Metal screw, 3 ... Metal plate, 4
... Dielectric resonator, 7 ... Dielectric substrate with microstrip line drawn

Claims (1)

(57) [Claims] 1. A dielectric substrate having a microstrip line connected to the gate of a field effect transistor at the bottom of a housing, and an oscillation stabilizing dielectric magnetically coupled to the microstrip line on the dielectric substrate. A microwave oscillator in which resonators are arranged and housed in a housing, and a metal body for adjusting an oscillation frequency is inserted into the housing so as to be located above the dielectric resonator, the microwave oscillator comprising: A metal plate is provided at a position on the upper wall of the body that is sufficiently distant from the dielectric resonator and that raises only the oscillation frequency according to the insertion length of the metal body without changing the oscillation output level. A microwave oscillator, which suppresses a change in oscillation output due to insertion of a body.