JPS60143004A - Dielectric resonance circuit - Google Patents

Abstract

PURPOSE:To obtain a small-sized dielectric resonance circuit whose resonance frequency is variable by inserting a conductor of layered structure of plural kinds of materials different from a thermal expansion coefficient to an air gap formed by removing a part of an insulator base and changing the position and volume of the conductor. CONSTITUTION:The air gap 34 is formed by removing a part of the insulation board 31 and a dielectric resonator 33 is placed to a position near a strip line 32 on the board 31 so as to cover the air gap 34. The conductor 35 a part of which is threaded is fixed through a screw hole provided to the bottom of a case 36 and a part of the conductor 35 is inserted in the air gap 34. A part of the conductor 35 is constituted by an adjusting plate 39 of different thermal expansion coefficient from that of the conductor itself, the relative position between the case 36 and the metallic body is changed by turning the conductor 35 and the position and volume of the part inserted in the air gap 34 are changed so as to change the resonance frequency. The temprature change of the dielectric resonator is compensated by selecting type of material and thickness of the adjusting plate 39.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dielectric resonant circuit which is a microwave band resonant circuit.

This resonant circuit consists of a dielectric resonator made of a material with low loss and good temperature characteristics, such as TiOx ceramic, and a microwave integrated circuit consisting of an insulating substrate and a strip line formed on its top surface. It is made by combining circuits (hereinafter abbreviated as MIC). As a dielectric resonator,
Cylindrical or rectangular parallelepiped shapes are generally used because they are easy to process and have a high Q value. The resonant frequency when a dielectric resonator, which is usually molded into a certain shape, is coupled with an MIC depends on the processing accuracy, the difference in the positional relationship between the strip line and the dielectric resonator, and the difference between the housing wall and the dielectric resonator. It was very difficult to obtain a consistent design value because of the differences in the positional relationship between the two. Therefore, there is a need for a mechanism that can continuously vary the resonant frequency without changing the shape of the already molded dielectric resonator.

Conventional mechanisms for mechanically changing the resonant frequency include:
As shown in FIG. 1, a metal plate 15 is provided above the dielectric resonator 13 provided close to the strip line 1, and by moving this metal plate up and down, a mechanism for changing the resonant frequency is provided. It was used. Since such a mechanism is provided within the casing 16, the shape of the casing is inevitably large, which increases the risk of unnecessary modes occurring. There were drawbacks such as larger temperature changes causing larger fluctuations in the resonant frequency.

The purpose of this invention is to eliminate the above-mentioned drawbacks, and to make it possible to adjust the resonant frequency by changing the volume 9 position of the conductor.
It is possible to compensate for temperature changes in the frequency of a dielectric resonator by taking advantage of the fact that the two volumetric positions within the conductor's gap change slightly due to thermal expansion caused by temperature changes. An object of the present invention is to provide a dielectric resonant circuit that can be accommodated in the body.

According to the present invention, an insulating substrate, a microwave integrated circuit such as a strip line formed on the upper surface of the insulating substrate, a dielectric resonator coupled thereto, and a microwave integrated circuit formed by removing a part of the insulating substrate. A conductor with a layered structure made of multiple materials with different coefficients of thermal expansion is inserted into the void, and by changing the position and volume of the conductor,
A dielectric resonant circuit characterized in that the resonant frequency is made variable is obtained.

In the resonator according to the present invention, it is possible to realize a dielectric resonant circuit in which one volume position in the gap of the conductor has a small thermal expansion shape due to temperature changes and has good temperature stability.

Hereinafter, this invention will be explained in detail by way of examples.

FIG. 2 is a diagram for explaining a dielectric resonant circuit which is an embodiment of the present invention. In the same figure, 31 is
The dielectric resonator 33 is an insulating substrate having a gap 34 formed by removing a portion thereof, and the dielectric resonator 33 is placed on the insulating substrate at a position close to the strip line 32 so as to cover the above-mentioned gap. is placed in Conductor 3 with a threaded part formed
5 is fixed through a screw hole provided at the bottom of the weight body 36. A portion of the conductor is inserted into the gap bored in the insulator substrate. By rotating the conductor, the relative position of the conductor and metal body changes, and the position of the part inserted into the gap of the conductor changes.

The volume changes, which changes the resonant frequency.

As is clear from FIG. 2, the height h of the internal space of the casing only needs to be greater than the sum of the height of the dielectric resonator and the thickness of the insulating substrate.

By the way, temperature changes in the resonant frequency of a resonant circuit equipped with the above-mentioned frequency adjustment mechanism are due to minute frequency changes due to the temperature characteristics of the dielectric resonator and thermal expansion phenomena, and the volume of the conductor inserted into the gap changes.

It appears as an addition of minute changes in frequency due to changes in position. Therefore, if the former minute change is compensated for by the frequency minute change due to the latter cause, a dielectric resonant circuit with good frequency stability can be obtained.

In FIG. 2, a part of the conductor 35 is composed of an adjustment plate 39 made of a material having a different coefficient of thermal expansion from that of the conductor body.

Now the conductor, the side of the casing has a coefficient of thermal expansion γ. If the adjustment plate 39 is made of a material with a coefficient of thermal expansion γ, then r>γ. In this case, as the temperature rises, the volume of the conductor portion inserted into the gap increases. r<
In the case of ro, the opposite trend occurs. Depending on whether the temperature coefficient of the dielectric resonator is positive or negative and the magnitude of the absolute value, a material with an appropriate coefficient of thermal expansion is selected as the material for the adjustment plate, and the thickness of the adjustment plate is selected. Combinations can be obtained that compensate for temperature variations in the resonator.

As explained above, according to the present invention, it is possible to obtain a dielectric resonator with a small shape, and the material of the conductor, conductor support, or casing has an appropriate coefficient of thermal expansion. By making this selection, it is possible to obtain a dielectric resonator with good frequency stability against temperature changes, which is highly effective.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional resonant frequency adjustment mechanism, and 11 is an insulating substrate. FIG. 2 is a diagram showing an embodiment of the first aspect of the present invention. ′〜゛、

Claims (1)

[Claims] A microwave integrated circuit consisting of an insulating substrate and a strip line formed on the upper surface thereof, a dielectric resonator coupled thereto, a gap formed by removing a part of the insulating substrate, and this gap. A dielectric characterized by having a conductor having a layered structure of multiple types of materials with different coefficients of thermal expansion inserted therein, and by changing the position and volume of this conductor, the resonant frequency can be varied. Body resonant circuit.