JPH06204747A - Output level adjustment method for microwave oscillator - Google Patents

Abstract

PURPOSE:To suppress the dispersion in an output level of the microwave oscillator by adjusting the impedance of a strip line between a coupling point of the strip line with a dielectric resonator and a FET being an oscillation active element. CONSTITUTION:A cut-groove 11 is formed to a part of a strip line 8 between a coupling point of the strip line 8 and a dielectric resonator 10 and a FET 1. The impedance of the part of the strip line 8 is increased by forming the cut-groove 11 and it is equivalent to adjust substantially the position of the resonator 10 in a parting direction from the FET 1. The resonator 10 is located a little closer toward the FET 1 from an optimum position on design in advance when the cut-groove 11 is provided to the strip line 8 to adjust an output level of the microwave oscillator. Then the cut-groove 11 of a proper size is formed to the strip line 8 while measuring the output level of the oscillator. Thus, dispersion in the output level is effectively suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output level adjusting method for a band reflection type microwave oscillator in which a resonance circuit is constructed by magnetically coupling a dielectric resonator to a strip line.

[0002]

2. Description of the Related Art Conventionally, a microwave oscillator is, for example, as shown in FIG.
It is configured by arranging each component on a dielectric substrate (not shown) in a circuit configuration as shown in FIG. That is, the choke coil 2 is provided between the drain of the field effect transistor (hereinafter referred to as FET) 1 as an active element for oscillation and the power supply terminal Vb, and the choke coil 3 and the bias resistor are provided between the source of the FET 1 and the ground point. 4 and are provided. Further, a ground stripline 5 is provided at the drain of the FET 1, and a stripline 6 and a capacitor 7 are provided between the source of the FET 1 and the output terminal OUT. The choke coils 2 and 3 are usually composed of a conductor film formed on a dielectric substrate.

Further, a strip line 8 and a terminating resistor 9 are provided between the gate of the FET 1 and the ground point. A resonant circuit is formed by magnetically coupling the TE ₀₁ δ mode dielectric resonator 10 to the strip line 8.

[0004]

In the microwave oscillator having the above-mentioned circuit structure, the distance L between the coupling point of the strip line 8 with the dielectric resonator 10 and the FET 1 which is the active element for oscillation is set. , Has a characteristic as shown in FIG. 4 in relation to the output level of the microwave oscillator. That is, when the dielectric resonator 10 is at a certain position, the output level becomes maximum, and when the dielectric resonator 10 deviates from that position, the output level decreases. The position where the output level becomes maximum differs depending on the microwave oscillator due to variations in the characteristics of the FET 1, and as shown in FIG. 5, even if the distance is L ₁ in _one oscillator, it is L in other oscillators. It becomes ₂ or L ₃ .

Therefore, in order to maximize the output level of all microwave oscillators, the dielectric resonator 1
The position of 0 would have to be adjusted for each microwave oscillator.

However, in the mass production process of microwave oscillators, it is extremely difficult to adjust the dielectric resonator 10 to the optimum position for each oscillator from the viewpoint of manufacturing efficiency, so the dielectric resonator 10 is preset. However, there is a problem that the output level varies greatly as a result.

Therefore, the present invention provides a method for adjusting the output level of a microwave oscillator, which can suppress the variation in the output level caused by providing the dielectric resonator at a preset position from the viewpoint of manufacturing efficiency. Is intended.

[0008]

In order to achieve such an object, in the output level adjusting method of the microwave oscillator of the present invention, the coupling point between the dielectric resonator and the active element for oscillation is provided. It is characterized in that a predetermined output level is obtained by adjusting the impedance of the strip line. As a specific means for adjusting the impedance, a cut groove is formed in the strip line or the width of the strip line is partially widened.

[0009]

When the cut line is formed in the strip line between the coupling point with the dielectric resonator and the active element for oscillation, the impedance of the strip line increases and the coupling point of the strip line with the dielectric resonator is increased. This means that the distance to the active element for oscillation is substantially increased.

Further, when the width of the strip line between the coupling point with the dielectric resonator and the active element for oscillation is partially widened, the impedance of the strip line becomes small, and the distance of the strip line is substantially the same. Has become shorter.

That is, even if the position of the dielectric resonator is not adjusted, the same operation as adjusting the position is achieved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention, and FIG. 2 shows a second embodiment of the present invention. Since the basic configuration of the microwave oscillator shown in these embodiments is similar to that of the conventional one shown in FIG. 3, only its essential parts are shown here, and the same or corresponding parts as those of the conventional one are designated by the same reference numerals. The detailed description is omitted by adding.

That is, FIG. 1 shows an example in which the output level is adjusted by increasing the impedance of the strip line, and a cut groove is formed in the portion between the coupling point of the strip line 8 with the dielectric resonator 10 and the FET 1. 11 is formed. By forming the cut groove 11 in this way, the impedance of that portion of the strip line 8 becomes large, and the same operation as adjusting the position of the dielectric resonator 10 substantially away from the FET 1 is achieved.

When the cut line is formed in the strip line 8 to adjust the output level of the microwave oscillator,
For example, the dielectric resonator 10 is provided in advance a little closer to the FET 1 side than the optimum design position, and the cut line 11 having an appropriate size is formed in the strip line 8 while measuring the output level of each oscillator. Then,
It is possible to effectively suppress variations in output level.

FIG. 2 shows an example of adjusting the output level by reducing the impedance of the strip line. When the strip line 8 is formed, the coupling point of the strip line 8 with the dielectric resonator 10 is shown. And F
Impedance adjusting lands 12 are provided at the same time in the vicinity of the portion between ET1 and ET1. The impedance adjusting land 12 is formed of a plurality of lands 12a, 12b, 12c arranged at a predetermined interval. Then, first, the land 12a is first connected to the strip line 8 by solder or wire. As a result, the width of the strip line 8 is partially widened, and the impedance of the strip line 8 is reduced. When it is necessary to further reduce the impedance, the remaining land 12
b and 12c are sequentially connected.

When the output level of the microwave oscillator is adjusted by partially widening the width of the strip line 8 as described above, for example, the dielectric resonator 10 is set a little farther from the FET 1 than the optimum design position. Provided,
By connecting the lands 12a, 12b, 12c of the impedance adjusting lands 12 to the strip line 8 in order while measuring the output level of each oscillator, it is possible to effectively suppress variations in the output level.

Further, the impedance adjusting land 12 is provided as shown in FIG. 2, the dielectric resonator 10 is provided at an optimum position in design, and a kerf is provided for each microwave oscillator as shown in FIG. 11 may be formed or the impedance adjusting land 12 may be connected as shown in FIG. 2 to obtain a predetermined output level, or both means may be used to obtain a predetermined output level. You may do it.

[0019]

As described above, according to the present invention, in the band reflection type microwave oscillator, the impedance of the strip line between the coupling point with the dielectric resonator and the active element for oscillation is adjusted. Since the predetermined output level is obtained, it is possible to suppress the variation in the output level caused by providing the dielectric resonator at the preset position.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a main part of a microwave oscillator for explaining a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a main part of a microwave oscillator for explaining a second embodiment of the present invention.

FIG. 3 is a circuit diagram of a conventional microwave oscillator.

FIG. 4 is a diagram showing an output level characteristic of a microwave oscillator.

FIG. 5 is a diagram showing that the output level characteristic of the microwave oscillator differs for each oscillator.

[Explanation of symbols]

 1 FET 2,3 Choke coil 4 Bias resistance 5,6,8 Stripline 7 Capacitor 9 Termination resistance 10 Dielectric resonator 11 Cut groove 12 Impedance adjustment land

Claims (1)

[Claims] 1. A method for adjusting the output level of a band reflection type microwave oscillator, wherein a resonance circuit is constituted by magnetically coupling a dielectric resonator to a strip line connected between an active element for oscillation and a terminating resistor. The output of the microwave oscillator is characterized in that a predetermined output level is obtained by adjusting the impedance of the strip line between the coupling point with the dielectric resonator and the active element for oscillation. Level adjustment method.