JPH0614481Y2 - Dielectric filter and dielectric duplexer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a dielectric filter having an integral structure for use in a high frequency band such as microwaves. More specifically, the dielectric block has an annular shape and a plurality of resonances. A sub-hole is formed in the radial direction of the dielectric block, and an inner peripheral surface or an outer peripheral surface of the dielectric block is an open surface, and a metallized layer is formed on the outer surface excluding the open surface and the inner surface of the resonator hole. The present invention relates to a dielectric filter.

[Prior Art] A multi-stage resonator type dielectric filter using a dielectric ceramic such as barium titanate has a feature that it has a small loss and therefore a so-called high Q and a large permittivity, so that it can be miniaturized. It is widely used in mobile radio equipment for the microwave band such as telephones and satellite communication equipment.

All of the conventional integrated dielectric filters of this type use a rectangular parallelepiped dielectric block. That is, a plurality of resonator holes and connector holes are alternately arranged at a predetermined interval in the longitudinal direction of the rectangular parallelepiped dielectric block, and one of the surfaces of the dielectric block where the resonator hole is opened. It has a structure in which a metallized layer is formed on the entire outer surface except the (open surface) and the inner surface of the resonator hole.

In a dielectric filter having such a structure, each resonator hole corresponds to one resonance element, and the desired degree of filter characteristics can be obtained by providing an appropriate degree of coupling by means of the connector holes located between the resonator holes. Is causing.

There are various methods for connecting the external circuit. For example, a configuration in which a coupling capacitor is placed in the resonator holes located at both ends and via it, a coaxial type input / output pin terminal is provided in the resonator holes located at both ends. There is a configuration of inserting an input / output pin called an antenna rod in the vicinity of the resonator hole.

[Problems to be Solved by the Invention] However, in the dielectric filter having the conventional structure, the dielectric block has a relatively small width and height, but the length becomes longer as the number of stages of the resonance element increases, and the dielectric block is used as the dielectric block. Since it can be pulled out from the body block only in the same direction or in the opposite direction, there are great restrictions when incorporating it into a wireless device or the like.

In particular, when combining two types of dielectric filters with different center resonance frequencies to form an antenna duplexer, etc., each dielectric filter has an elongated shape as described above and the freedom of the input / output terminal drawing direction. Due to its low degree, it is more restricted when incorporated in a device than in the case of a single dielectric filter.

In addition, a spurious mode n times as high as the central resonance frequency f ₀ is generated, which includes an element that deteriorates the characteristics of the dielectric filter.

The object of the present invention is to solve the above-mentioned drawbacks of the prior art, to be compactly housed in the housing of the device, and to have a large degree of freedom in the direction of drawing out the input / output terminals, and especially to combine two dielectric filters. Another object of the present invention is to provide a dielectric filter having a new structure that can reduce the size of the dielectric duplexer and suppress spurious emission.

[Means for Solving the Problems] In the present invention which can achieve the above object, a plurality of resonator holes are radially formed in an annular dielectric block, and one of the inner peripheral surface and the outer peripheral surface of the dielectric block is formed. Is an open surface, and a metallized layer is formed on the outer surface other than the open surface and on the inner surface of the resonator hole.

Here, in order to adjust the degree of coupling between the resonator holes, unmetallized connector holes may be formed in the radial direction between the resonator holes of the dielectric block, or the connector holes may be provided. Instead, a conductor pattern for coupling or the like may be formed on the open surface side.

In order to suppress spurious, it is preferable that stepped portions are formed at the outer peripheral edge and the inner peripheral edge of the circular dielectric block.

A small-sized dielectric duplexer can be constructed by arranging the above-described dielectric filters in two stages in the central axis direction.

[Operation] Resonator holes formed in the radial direction of the annular dielectric block correspond to the respective resonance elements, and are coupled to each other to produce desired filter characteristics. If the resonator holes for input and output are separated from each other to some extent, there is no particular problem in the operation of the filter even if there is a dielectric material between them.

In the prior art, the input / output terminals are pulled out in the same direction,
In the present invention, the direction in which the input / output terminals are pulled out (the angle between the input / output terminals) can be changed in various ways, so that it is possible to attach the input / output terminals to the corners of the housing of a wireless device or the like.

If the shielding of the dielectric filter is perfect, the two dielectric filters can be stacked in the direction of their central axes,
Combined with the high degree of freedom in the direction of drawing out the input / output terminals, a compact dielectric duplexer can be assembled,
It can also be easily incorporated into equipment housings.

[Embodiment] FIG. 1 is a perspective view showing an embodiment of a dielectric filter according to the present invention, and FIG. 2 is a horizontal sectional view thereof. This embodiment is an example of a four-stage filter having four resonator holes.

The dielectric filter 10 is based on an annular dielectric block 12 made of a sintered body of a high dielectric constant ceramic material such as barium titanate. In this way, the dielectric block 1
The greatest feature of the present invention is that 2 has an annular shape.

The dielectric block 12 has four resonator holes 14a, ..., 14
The d is formed radially, and the coupler hole 16 is formed between the resonator holes in the radial direction. Here, the resonator hole 14
The intervals of a and 14b, 14b and 14c, 14c and 14d are set to be substantially equal and relatively narrow. On the other hand, the distance between the resonator holes 14a and 14d is set wide, and no connector hole is provided between them.

The metallization layer 18 is formed on the upper and lower surfaces and the inner peripheral surface of the dielectric block 12 and on the inner surfaces of the resonator holes 14a, ..., 14d.
(For example, a conductor layer formed by baking a silver paste) is formed. In this case, the outer peripheral surface of the dielectric block 12 is an open surface and the inner peripheral surface is a short circuit surface. Four resonator holes 14a,
The two resonator holes 14 farthest from each other among 14d.
A and 14d are input and output sides, and in this embodiment, coaxial type input and output terminals 20a and 20b are inserted to be connected to an external circuit.

In addition, in the accompanying drawings, in order to make the drawings easy to understand, the portions where the base material of the dielectric material in which the metallized layer is not formed are exposed as they are are shown with fine dots. Further, although the metallized layer 18 is drawn to have a considerable thickness in these drawings, it is actually an extremely thin layer formed by baking a silver paste as described above.

In the present invention, each resonator hole 14a, ..., 14d constitutes one resonance element, and these constitute a four-stage filter. A dielectric exists between the resonator holes 14a and 14b on the input / output side, but since they are far apart from the other resonator holes, there is no particular problem and they operate as a filter.

In the above embodiment, the outer peripheral side is the open surface and the inner peripheral side is the short-circuit surface, but conversely, the outer peripheral side is the short-circuit surface and the inner peripheral side is the open surface. is there. In any case, the central resonance wavelength λ becomes approximately equal to four times the difference between the radius R ₁ of the outer peripheral surface and the radius R ₂ of the inner peripheral surface of the dielectric block.

3 and 4 are a perspective view and a vertical sectional view showing another embodiment of the present invention. Since the basic structure is the same as that of the above-mentioned embodiment, the corresponding portions are designated by the same reference numerals and the description thereof will be omitted. This embodiment is different from the above-mentioned case in that the outer peripheral edge and the inner peripheral edge of the dielectric block 12 are provided with step portions 22 and 24 in a circular shape. With such a structure, it is possible to suppress the generation of spurious modes that are twice and three times the central resonance frequency f ₀ .

FIG. 5 shows an example of a dielectric duplexer using the dielectric filter according to the present invention. Two circular dielectric filters as shown in FIG. 1 are combined in the central axis direction to form a dielectric duplexer. If the respective dielectric filters 10a, 10b are completely shielded, no inconvenience will occur even if they are combined in this way.

Such a dielectric duplexer can be used as an antenna duplexer for enabling the sharing of antennas for transmission and reception with different frequencies used, or as a duplexer for the local filter and the filter on the receiving side used in the circuit. Applicable.

Since the dielectric filter according to the present invention has a large degree of freedom in the direction in which the input / output terminals are pulled out, the input / output common pin terminals 26a and 26b are superposed so as to face the same direction as shown in FIG. If 28a and 28b are pulled out so as to face in opposite directions, it is possible to prevent unnecessary interference between the two. With such a configuration, the dielectric duplexer can be assembled compactly, and the orientation of the input / output pin terminals can be changed quite freely, so that it can be attached to the corners of the housing of the wireless device, etc. Can contribute to

[Advantage of the Invention] Since the present invention is a dielectric filter in which the dielectric block is formed in an annular shape and a plurality of resonator holes are formed in the radial direction as described above, the size can be reduced and the input / output terminals can be drawn out. It has a high degree of freedom and can be attached to a corner portion of a device housing, and there are few restrictions on use, which increases the degree of freedom in housing design and can contribute to downsizing of the device. In particular, when two such dielectric filters are stacked in the central axis direction to form a dielectric duplexer, the above advantages become more remarkable.

Further, by forming a step on the outer peripheral edge or the inner peripheral edge, the spurious mode can be reduced and a good filter operation can be performed.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the dielectric filter according to the present invention, FIG. 2 is a horizontal sectional view thereof, FIG. 3 is a perspective view showing another embodiment of the present invention, and FIG. FIG. 5 is a longitudinal sectional view showing an example of a dielectric duplexer according to the present invention. 10, 10a, 10b ... Dielectric filter, 12 ... Dielectric block, 14a, 14b, 14c, 14d ... Resonator hole, 16 ... Coupler hole, 18 ... Metallized layer, 2
0a, 20b ... Input / output terminals, 22, 24 ... Step portion, 3
0: Dielectric duplexer.

Claims (4)

[Scope of utility model registration request] 1. A plurality of resonator holes are radially formed in an annular dielectric block, and one of an inner peripheral surface and an outer peripheral surface of the dielectric block is an open surface, and an outer surface other than the open surface. A dielectric filter with a metallized layer formed on the inner surface of the resonator hole. 2. The dielectric filter according to claim 1, wherein non-metallized connector holes are formed in the radial direction of the dielectric block between the resonator holes. 3. A step portion is formed on one or both of an outer peripheral end surface and an inner peripheral end surface of a circular dielectric block.
Alternatively, the dielectric filter according to claim 2. 4. A dielectric duplexer in which the dielectric filters according to claim 1, claim 2 or claim 3 are arranged in two layers in the central axis direction of the dielectric block.