JPS632402A - Filter device - Google Patents

Abstract

PURPOSE:To effectively reduce the weight of a filter device without spoiling the stability of its characteristic, by providing an earth sheet composed of a synthetic resin-made case main body housing coaxial resonators and coupling capacitors, case lid, and metallic sheet. CONSTITUTION:Coaxial resonators 11-13 and coupling capacitors 14-17 are housed in a synthetic resin-made case main body 31 in a state where the capacitors 14-17 can couple the resonators in series. Moreover, an earth sheet 32 made of a metallic material, such as a metallic foil, etc., is provided along the inner surface of the case main body 31 and an earth sheet 33 which is constituted of the same material as that constituting the earth sheet 32 is provided on the upper surfaces of the resonators 11-13 and capacitors 14-17. Since the case housing the resonators 11-13 and capacitors 14-17 and case lid are made of the synthetic resin, the weight of this filter device can be reduced. Moreover, since the resonaters 11 and 13 are wrapped by the earth sheets 32 and 32, the weight reduction can be achieved effectively without spoiling the stability of the characteristic of this device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an improvement in the physical structure of a filter device using a dielectric coaxial resonator.

[Prior Art] Japanese Patent Publication No. 55-50601 discloses a filter device using a dielectric coaxial resonator.

Here, as shown in FIG. 5, λ/2 dielectric coaxial resonators 1...4 are housed in a metal case 10 in a state where they are coupled in series by coupling capacitors 5...9.

[Problems to be Solved by the Invention] The metal case 11 is in contact with the outer conductors of the coaxial resonators 1 . . . 4 and is configured to also perform a shielding function. However, since the metal case 10 is obtained by processing a relatively thick metal plate, it is inevitably heavy. Therefore, it has been difficult to reduce the weight of the filter device, even though there is a demand for the filter device to be smaller and lighter along with other electronic components or devices.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a filter device that can effectively achieve weight reduction without impairing the stability of its characteristics.

[Means for solving m points between points] The filter device of the present invention includes a plurality of dielectric coaxial resonators, a coupling capacitor sandwiched between the coaxial resonators so as to couple the coaxial resonators, and a coaxial resonator. The device includes a synthetic resin case that houses the coaxial resonator and the coupling capacitor, and a ground sheet made of a metal sheet placed inside the case so as to enclose the coaxial resonator and the coupling capacitor.

[Operations and Effects of the Invention] In the present invention, the case is replaced with a synthetic resin case instead of a conventional metal plate, so that the weight of the entire filter device is greatly reduced. Therefore, the weight of the filter device of the present invention can be reduced as well as other parts and devices, so that the weight of the entire system using the filter device of the present invention can be reduced.

In addition, a grounding sheet made of a metal sheet that does not add much weight is arranged inside the synthetic resin case, and the coaxial resonator and coupling capacitor are surrounded by the grounding sheet, so they are reliably shielded and therefore Filter characteristics do not deteriorate.

[Description of Embodiment] As shown in FIGS. 1 and 2, the plurality of λ/2 dielectric coaxial resonators 11...13 are connected to coupling capacitors 14...
・Connected in series with 17. In addition, in FIG. 2, coaxial resonators 11...13 and coupling capacitors 14...
・No. 17 is not shown in cross section for ease of understanding.

As shown in FIG. 3, the coaxial resonator 11 includes a dielectric 21, an inner conductor 22 formed on the inner circumference of the dielectric 21, and an outer conductor 23 formed on the outer circumference. The other coaxial resonators 12, 13 are similarly constructed.

On the other hand, as shown in FIG. 4, the coupling capacitor 14 has a dielectric 25 and electrodes 26, 27 formed opposite both sides of the dielectric 25.
・No. 17 is similarly configured.

The above coaxial resonators 11...13 and the coupling capacitor 1
4...17 are housed in a synthetic resin case body 31 with coupling capacitors 14...17 coupling the coaxial resonators 11...13 in series. However, in order to shield the coaxial resonators 11, . Moreover, as shown in FIG. 1, the coaxial resonator 11...
13 and the coupling capacitors 14 . is pasted on.

Note that 35 and 36 indicate terminals for connecting the filter device of this embodiment to external equipment.

As is clear from the above configuration, in the filter device of this embodiment, the case for housing the coaxial resonators 11...13 and the coupling capacitors 14...17 is made of a synthetic resin case body 31 and case lid 34. It can be seen that the weight can be significantly reduced compared to conventional metal cases. Furthermore, it can be seen that since the coaxial resonators 11, . . . , 13 are surrounded by the earth seams 32, 33, they are reliably shielded, and the filter characteristics are not impaired.

Note that in the conventional filter device shown in FIG. 5, a conductive adhesive is used to ensure electrical connection between the metal case 10 and the outer conductors of the coaxial resonators 1...4. ,
Alternatively, an elastic metal ground plate was usually inserted between the metal case 10 and the coaxial resonator 1. On the other hand, in the above embodiment, each coaxial resonator 11...13 is
It can be seen that the outer conductor of the device can be reliably grounded, and that the grounding characteristics can be stabilized with a simple structure.

In particular, in this embodiment, coupling capacitors 14...17
Since the outer dimensions of the grounding sheets 32 and 33 are made equal to the outer dimensions of the coaxial resonators 11...13, the grounding sheets 32 and 33 are held between the filter structure and the synthetic resin case over almost the entire area. , the above earthing characteristics are considered to be more stable.

Note that the coupling capacitors 14 and 17 are not essential, and it is sufficient to have coupling capacitors sandwiched between the coaxial resonators 11 . . . 13 .

It is pointed out that this invention can be applied to an integrated filter device that integrates a coaxial resonator and a coupling capacitor, and that it can also be constructed using a λ/4 coaxial resonator. I'll keep it.

[Brief explanation of drawings]

1 and 2 are an exploded perspective view and a sectional view of an embodiment of the present invention. 3 is a perspective view showing a coaxial resonator used in the embodiment shown in FIG. 1, and FIG. 4 is a perspective view showing a coupling capacitor used in the embodiment shown in FIG. FIG. 5 is a sectional view showing an example of a conventional filter device. In the figure, 11...13 are coaxial resonators, 14...
Reference numeral 17 denotes a coupling capacitor, 31 a synthetic resin case body constituting the case, 32 and 33 a grounding sheet, and 34 a synthetic resin case lid constituting the case.

Claims (1)

[Scope of Claims] A plurality of dielectric coaxial resonators, a coupling capacitor sandwiched between the coaxial resonators so as to couple the coaxial resonators, and a synthetic resin case housing the coaxial resonators and the coupling capacitor. A filter device comprising: a ground sheet made of a metal sheet disposed within the case so as to surround the coaxial resonator and the coupling capacitor.