JPH0260201A - Device using dielectric resonator - Google Patents

Abstract

PURPOSE:To maintain a stable characteristic even if a peripheral temperature changes by providing a metallic plate constituting a resonant cavity in cooperation with a metallic case. CONSTITUTION:When the metallic case 12 and the metallic plate 14 are respectively provided on the upper surface and the lower surface of a circuit board 16, through holes 20 and 30, and a machine screw hole 32 are positioned and a machine screw 18 is inserted into the machine screw hole 32 through the through holes 20 and 30, the metallic case 12, the circuit board 16 and the metallic plate 14 are reciprocally and integrally fixed. Thus, space regulated by the metallic case 12 and the metallic plate 14 comes to the resonant cavity for a dielectric resonator 24. Since the metallic plate 14 is arranged on the lower surface of the circuit board 16 and is integrally fixed with the metallic case 12, and a ground pattern 28 is closely brought into contact with the metallic plate 14 in fitting structure as illustrated, the deformation of the circuit board due to a temperature change is restricted, and the capacity of the resonant cavity is prevented from changing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device using a dielectric resonator, and more particularly to a mounting structure for a dielectric resonator in which the dielectric resonator is arranged on a circuit board.

[Prior Art] An example of a conventional mounting structure for arranging a dielectric resonator on a circuit board is shown in FIG. In the prior art shown in FIG. 5, a slit 2 is formed in a desired part of the circuit board 1, a part of the metal case 3 is fitted into the slit 2,
is electrically connected and mechanically fixed to the grounding pattern 4 formed on the entire back surface of the circuit board 1, and the metal case 3
A resonance cavity is formed by the cooperation of the ground pattern 4 and the ground pattern 4. A dielectric resonator 5 supported on the circuit board 1 is disposed within the resonant cavity.

[Problem to be solved by the invention]

In a frequency band of several to several tens of Hz (Hz) where a dielectric resonator is used, a synthetic resin such as Teflon (trade name) is often used as the material for the circuit board 1.

When such a circuit board made of synthetic resin is used, its coefficient of thermal expansion is larger than that of the metal case 3.

Therefore, when the ambient temperature rises, for example, as shown in FIG. 6, the circuit board 1 bends downward, although it is restrained by the metal case 3 at the slit 2. In this case, the volume of the resonant cavity defined by the ground pattern 4 and the metal case 3 increases, and the position of the dielectric resonator 5 also shifts downward due to the deformation of the circuit board 1. As a result, the resonant frequency changes. This also occurs even if the ambient temperature decreases. As described above, with the conventional mounting structure, it is no longer possible to maintain stable characteristics such as the resonant frequency.

Therefore, the main object of the present invention is to provide a device using a dielectric resonator that can maintain stable characteristics regardless of changes in ambient temperature even when using a circuit board made of synthetic resin.

[Means to solve the problem]

This invention comprises a circuit board, a metal case with an opening at the bottom that is attached to the top surface of the circuit board, a dielectric resonator placed inside the metal case, and a resonant cavity that is attached to the bottom surface of the circuit board and cooperates with the metal case. This is a device using a dielectric resonator, which is equipped with a metal plate.

[Effect]

A metal case with an open bottom end is attached to the upper surface of the circuit board, a metal plate is attached to the lower surface of the circuit board, and a space defined by the metal case and the metal plate becomes a resonant cavity.

A metal plate attached to the bottom surface of the circuit board restrains thermal deformation of the circuit board. Therefore, even if a circuit board exists in a resonant cavity formed by a metal case and a metal plate and a dielectric resonator is supported on it, thermal deformation of the circuit board causes a change in the size of the resonant cavity. Does not occur.

As in another embodiment, if an opening is formed in the circuit board and the dielectric resonator is supported on the metal plate through the opening, it will not be affected by changes in the thickness of the circuit board.

〔Effect of the invention〕

According to this invention, since the resonant cavity is defined by the metal case and the metal plate, and the circuit board is restrained by both, especially the metal plate, there is no large change in the volume of the resonant cavity even if the ambient temperature changes. Does not occur. Therefore, according to the mounting structure according to the present invention, the dielectric resonator can maintain stable characteristics even if the ambient temperature changes.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

〔Example〕

FIG. 1 is an illustrative cross-sectional view showing a mounting structure according to an embodiment of the present invention. Device 10 using the dielectric resonator of this example
includes a metal case 12 and a metal plate 14, and the metal case 12 and metal plate 14 are integrally fixed together with a circuit board 16 by screws 18.

The metal case 12 is formed from a single conductive metal plate, for example, a brass plate, and is bent into a box shape with an open bottom end. A crocodile part is formed on a part or all of the periphery of the lower end opening of the metal case 12, and a screw 18 is formed on the flange part.
A through hole 20 is formed for insertion.

The circuit board 16 is made of, for example, glass fiber impregnated with a synthetic resin such as Teflon (trade name), and a dielectric resonator 24 is arranged by a spacer 22 in the center of the part of the circuit board 16 where the metal case 12 is arranged. is supported. Furthermore, a wiring pattern 26 for the dielectric resonator 24 and its related circuits is formed on the upper surface of the circuit board 16, if necessary.

A ground pattern 28 is provided on the entire bottom surface of the circuit board 16.
is formed. Then, the metal case 12 of the circuit board 16
A through hole 30 through which the screw 18 is inserted is also formed at a position opposite to the through hole 20 formed in the through hole 20 .

Like the metal case 12, the metal plate 14 is also made of, for example, a brass plate, and the metal plate 14 has a screw hole 32 having a female thread for screwing the screw 18 at a position facing the through holes 20 and 30. It is formed.

In this way, after arranging the metal case 12 and the metal plate 14 on the upper and lower surfaces of the circuit board 16, and aligning the through holes 20 and 30 and the screw holes 32, screws 18 are inserted through the through holes 20 and 30. When screwed into the hole 32, the metal case 12, circuit board 16 and metal plate 14 are removed.
are integrally fixed to each other. In this way, the space defined by the metal case 12 and the metal plate 14 becomes a resonant cavity for the dielectric resonator 24.

Note that the metal plate 14 is electrically connected and mechanically fixed to the ground pattern 28 on the entire lower surface of the circuit board 16 using a conductive adhesive or solder.

Thereby, the entire metal plate 14 restrains the thermal deformation of the circuit board 16.

In this embodiment, since synthetic resin is used for the circuit board 16, the thermal expansion coefficient of the circuit board 16 is higher than that of the metal case.
2 and the thermal expansion coefficient of the metal plate 14, but the thermal expansion coefficient of the circuit board 1
Since the circuit board 6 is restrained by the metal plate 14, the circuit board 16 will not expand or contract significantly in response to temperature changes. That is, in the conventional mounting structure as shown in FIG. 5, when the temperature rises, the circuit board 1 bends and the volume of the resonant cavity changes as shown in FIG. 6, but in the mounting structure shown in FIG. In this case, since the metal plate 14 is arranged on the lower surface of the circuit board 16 and is fixed integrally with the metal case 12, and the ground pattern 28 is in close contact with the metal plate 14, the deformation of the circuit board 16 due to temperature changes is restrained. The volume of the resonant cavity does not change as shown in FIG.

As another embodiment of the present invention, as shown in FIG. 2, it is conceivable to attach the dielectric resonator 24 directly to the metal plate 14 via a spacer 22.

In this case, the circuit board 16 must have an opening 34 through which the spacer 22 is inserted. However, when the opening 34 is formed in the circuit board 16, the restraint of the circuit board 16 by the metal plate 14 is partially released by the opening 34. Then, when the temperature rises, since the coefficient of thermal expansion of the circuit board 16 is large, it is expected that the members of the circuit board 16 near where the opening 34 is formed will be lifted upward, as shown in FIG. . As a result,
Naturally, the ground pattern 28 formed on the lower surface of the circuit board 16 also follows and is lifted upward. Then,
A portion of the ground pattern remote from the metal plate 14 is added to the resonant cavity or acts as an actance. The "gap" between this ground pattern and the metal plate 14 is extremely unstable, and therefore the stability of the entire resonant cavity is inhibited.

Therefore, as an embodiment in which the dielectric resonator 24 is directly fixed to the metal plate 14 via the spacer 22, a structure as shown in FIG. 4 can be considered.

In FIG. 4, in this embodiment, the ground pattern in the portion where deformation may occur as shown in FIG. 3 is removed. That is, in the resonant cavity defined by the metal case 12 and the metal plate 14, the circuit board 1
The ground pattern 28 on the lower surface of 6 has been deleted. Therefore, even if a part of the circuit board 16 is deformed due to temperature change as shown in FIG. 3, the ground pattern 28
Note that there is no such thing as acting as a reactance.
In the embodiment of FIG. 4, it is conceivable to enlarge the opening 34 so as to eliminate all of the portion of the circuit board 16 that exists within the resonant cavity.

This eliminates the instability of characteristics caused by the ground pattern. However, that method can only be used if no wiring pattern is required within the resonant cavity. Therefore, if there is no need to wire an active element or the like within the resonant cavity, the circuit board within the resonant cavity may be omitted.

[Brief explanation of the drawing]

FIG. 1 is an illustrative cross-sectional view showing one embodiment of the present invention. FIG. 2 is an illustrative view showing an example of another embodiment of the invention. FIG. 3 is an illustrative view showing the state of deformation that occurs in the embodiment shown in FIG. FIG. 4 is an illustrative view showing another embodiment of the invention. FIG. 5 is an illustrative view showing a conventional mounting structure. FIG. 6 is an illustrative view for explaining a deformed state of the conventional mounting structure shown in FIG. In the figure, 12 is a metal case, 14 is a metal plate 16 is a circuit board, 18 is a screw, 22 is a spacer, 24 is a dielectric resonator, 26 is a wiring pattern, 28 is a ground pattern, 3
4 indicates an opening.

Claims (1)

[Scope of Claims] 1. A circuit board, a metal case with an opening at the bottom that is attached to the upper surface of the circuit board, a dielectric resonator that is disposed inside the metal case, and a dielectric resonator that is attached to the lower surface of the circuit board and that is connected to the metal case. A device using a dielectric resonator, comprising metal plates that cooperate to form a resonant cavity. 2. the dielectric resonator is supported on the circuit board;
A device using the dielectric resonator according to claim 1. 3. The device using a dielectric resonator according to claim 1, wherein an opening is formed in the circuit board, and the dielectric resonator is supported on the metal plate through the opening. 4. A device using a dielectric resonator according to claim 1, wherein a ground pattern is not formed on the lower surface of the circuit board in a portion located within the resonant cavity. 5. The dielectric material according to claim 1, wherein the metal case, the circuit board, and the metal plate each have holes corresponding to each other in position, and are integrally fixed by screws through the holes. A device that uses a resonator.