JPH10294602A - Dielectric resonator and dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric resonator with high Q and a dielectric excellent in filter attenuation and spurious characteristics through removal of spurious of a waveguide mode generated in a cavity by providing conductors conducting electrodes for resonator and the cavity at the facing parts of them. SOLUTION: Conductors 5 and 6 electrically connecting the resonance electrodes 2 and 3 and a cavity 4 are provided in the facing parts of the electrodes 2 and 3 and the cavity 4 for suppressing the spurious of the intra- cavity waveguide mode of the TM mode dielectric resonator with cavity 4 constitution for covering a dielectric plate 1 where the resonator electrodes 2 and 3 which face both main faces and are mirror-symmetrical are formed. Thus, the potential of the resonator electrodes 2 and 3 becomes equal to that of the cavity 4. The electromagnetic electromagnetic field of the spurious mode concentrated in the vicinity of the resonator electrodes 2 and 3 is suppressed, and the resonance by the resonator electrodes 2 and 3 does not couple with the spurious mode and Q of the resonator is increased. The conductors 5 and 6 serves also as a supporting stand of the dielectric plate 1 in the cavity 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dielectric resonator and a dielectric filter used in a microwave band or a millimeter wave band.

[0002]

2. Description of the Related Art In response to a rapid increase in demand for mobile communication systems in recent years and a demand for large-capacity and high-speed communication systems corresponding to so-called multimedia, a frequency band to be used is changed from a microwave band to a millimeter wave band. Is being expanded to Even in such a millimeter wave band, a TE01δ mode dielectric resonator conventionally used in a microwave band can be used in the same manner, but the resonance frequency is determined by the dimensions of the cylindrical dielectric material. Since the band is very small, strict processing accuracy is required. Also, TE
When configuring a filter using a 01δ mode dielectric resonator, it is necessary to arrange a plurality of TE01δ mode dielectric resonators at a predetermined interval with high positional accuracy in a waveguide,
Further, there is a problem that the structure for finely adjusting the resonance frequency of each of the resonators and finely adjusting the mutual coupling between the dielectric resonators becomes complicated.

Accordingly, the applicant of the present application has filed Japanese Patent Application No. Hei 8-2532.
No. 12 proposes a dielectric resonator and a dielectric filter which solve these problems. FIG. 8 shows a basic configuration of the dielectric resonator. In FIG. 8, (A) is (B)
FIG. 3B is a cross-sectional view of the portion BB in FIG. In the figure, reference numeral 1 denotes a dielectric plate,
Circular resonator electrodes 2 and 3 having a predetermined size are formed on both main surfaces to constitute a TM010 mode dielectric resonator. Reference numeral 4 denotes a cavity made of metal or the like.
The dielectric plate 1 is arranged inside the cavity 4 via the.

FIG. 9 is a sectional view of a dielectric filter in which three pairs of the dielectric resonators shown in FIG. 8 are formed on a single dielectric plate 1. In this example, three pairs of resonator electrodes 2a, 3a, 2b, 3b, 2c, and 3c are disposed on the dielectric plate 1 with the dielectric plate 1 interposed therebetween, and the cavity electrodes 17 and 18 The dielectric plate 1 is arranged using the input / output substrates 13 and 14 as a support. Microstrip lines 15 and 16 are formed on the input / output substrates 13 and 14, respectively.
Resonator with resonator electrodes 2a and 3a and resonator electrode 2
c, 3c and the microstrip line 1
5 and 16 are respectively capacitively coupled.

Conventionally, a microstrip resonator has been known in which a ground electrode is formed on substantially the entire surface of one surface of a dielectric plate and a circular resonator electrode is formed on the other surface. As shown in FIG. 8 and FIG. 9, if plane-symmetric (mirror-symmetric) resonator electrodes are formed on the dielectric plate,
Since the thickness of the dielectric plate for obtaining the same resonance frequency is twice as large as that of the above-mentioned conventional microstrip resonator, the thickness of the dielectric plate can be increased while suppressing the generation of spurious components. As a result, the Q of the resonator can be increased.

[0006]

However, in the conventional dielectric resonators and dielectric filters shown in FIGS. 8 and 9, when the resonance mode due to the cavity occurs as spurious, desired characteristics cannot be obtained. was there.
That is, in the case of a dielectric resonator, the resonance mode due to the cavity is coupled to the resonance mode to be used (TM010 mode), so that Q is reduced. Further, in the case of using a dielectric filter, spurious is generated and the attenuation characteristic is deteriorated.

FIG. 10 is a view showing an electromagnetic field distribution in a resonance mode by a cavity in the dielectric resonator shown in FIG.
FIG. 11 is a diagram showing a broadband spurious characteristic of the dielectric resonator. Here, the dimensions of each part in FIG. 8 have the following relationship. a = 3.0, b = 2.4, d = 1.
7, t = 0.6, h = 0.5, εr = 24 The resonance mode shown in FIG. 10 is a spurious that can be called a TEM mode,
As shown in FIG. 11, this spurious component is generated on the lower frequency side than the resonance frequency of the resonance mode actually used. Also,
Since this spurious is broad, it almost reaches the propagation band at the center frequency of the filter, and satisfactory filter characteristics cannot be obtained. Therefore, a desired filter characteristic cannot be obtained simply by arranging the resonator electrodes on the dielectric plate.

An object of the present invention is to provide a dielectric resonator having a high Q by removing spurious components in a waveguide mode generated in a cavity and a dielectric filter having excellent attenuation characteristics and spurious characteristics.

[0009]

SUMMARY OF THE INVENTION The present invention comprises a dielectric plate on which resonator electrodes having substantially plane symmetry (mirror symmetry) opposed to both principal surfaces are formed, and a cavity covering the periphery of the dielectric plate. In order to suppress the spurious of the waveguide mode in the cavity in the TM mode dielectric resonator, a conductor for conducting between the resonator electrode and the cavity is provided as described in claim 1. Provide. As a result, the potential of the resonator electrode becomes the same as that of the cavity.
The spurious mode electromagnetic field concentrated near the resonator electrode as shown in FIG. 0 is suppressed, the resonator formed by the resonator electrode does not couple with the spurious mode, and the Q of the resonator increases. Further, since the conductor also functions as a support for disposing the dielectric plate in the cavity, a special support is not required.

As a conductor for conducting between the resonator electrode and the cavity, if the surface of the conductor contacting the resonator electrode is similar to the resonator electrode, the cavity The effect of reducing the space and the effect of ground connection to the cavity of the resonator electrode are further enhanced.

[0011] In addition, a conductor for conducting the opposing portion between the resonator electrode and the cavity is provided as described in claim 3,
If they protrude integrally from the cavity, the number of parts does not increase and the assembly structure is simplified.

Further, the cavity and the conductor are constituted by electrodes formed on a dielectric plate or an insulator plate as described in claim 4, thereby simplifying the cavity structure. And it is possible to use the input / output substrate and a part thereof.

According to a fifth aspect of the present invention, in the dielectric filter according to the fifth aspect, a plurality of pairs of resonator electrodes are arrayed on both main surfaces of the dielectric plate. A plurality of such dielectric resonators, and a coupling member for coupling to any of the dielectric resonators. Thereby, the excitation of the waveguide mode in the cavity is suppressed, and the spurious response is suppressed. Further, if the cavity space becomes narrower, the cutoff frequency for the waveguide mode in the cavity becomes higher, and the resonance frequency of the cavity becomes higher than the resonance frequency of the resonator by the resonator electrode,
The attenuation characteristic on the lower side of the pass band is improved. As a result, a dielectric filter having excellent attenuation characteristics and spurious characteristics can be obtained.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a dielectric resonator according to a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a sectional view of a dielectric resonator.
(A) is a sectional view of the BB part in (B), and (B) is a sectional view of the AA part in (A). In FIG. 1, reference numeral 1 denotes a relative dielectric constant εr = 24, and a side length b = 2.4 m.
m, a dielectric plate made of dielectric ceramics having a thickness t = 0.6 mm. Circular resonator electrodes 2 and 3 having a diameter d of 1.75 mm are provided on both main surfaces of the dielectric plate 1, respectively.
Are formed facing each other. Since the opposed circular resonator electrodes 2 and 3 are formed on both main surfaces of the dielectric plate 1 as described above, the opposed portions function as TM010 mode resonators. Reference numeral 4 denotes a cavity having a width a = 3.0 mm, and conductors 5 and 6 for conducting the two are integrally provided in the cavity 4 at portions facing the resonator electrodes 2 and 3 and the inner wall surface of the cavity. The surfaces of the conductors 5 and 6 that are in contact with the resonator electrodes are formed in a circular shape similar to the resonator electrodes, and have a diameter D of 1.5 mm. The distance h between the resonator electrodes 2 and 3 and the cavity opposed thereto is 0.5
mm.

As long as the diameter D of the conductors 5 and 6 is not larger than the diameter d of the resonator electrode, the spurious suppression effect increases as the diameter D increases.
It is effective to set it to about 1.0.

FIG. 2 is a diagram showing a broadband spurious characteristic of the dielectric resonator shown in FIG. Here, the TM010 mode is a mode to be used among the modes of the resonator using the dielectric plate and the resonator electrode. According to this dielectric resonator, the resonance frequency of the lowest-order resonance mode of the cavity is higher than the resonance frequency of the TM010 mode, and spurious due to the waveguide mode does not occur on the lower side than the resonance frequency of the cavity. A dielectric resonator with a high Q can be obtained. As is apparent from comparing FIG. 2 with FIG.
It can be seen that spurious is sufficiently suppressed on the lower frequency side than the TM010 mode.

Next, the configuration of a dielectric resonator according to a second embodiment will be described with reference to FIG. 3A and 3B are cross-sectional views of the dielectric resonator, in which FIG. 3A is a cross-sectional view taken along a line BB in FIG. 3B, and FIG. 3B is a cross-sectional view taken along a line AA in FIG. In the second embodiment, unlike the first embodiment shown in FIG. 1, the cross-sectional shape of the conductor in contact with the resonator electrode on the dielectric plate is rectangular. In FIG. 3, one width D of the conductors 5 and 6 is 1.5 mm, and the other width C is 0.7.
mm. Other structures are the same as those shown in FIG.

According to the dielectric resonator shown in FIG. 3, the resonance frequency of the lowest resonance mode of the cavity is TM010.
Since the resonance frequency becomes higher than the resonance frequency of the mode, and spurious due to the waveguide mode does not occur on the lower side than the resonance frequency of the cavity, a dielectric resonator having a high Q can be obtained.

FIGS. 4A and 4B show the structure of a dielectric resonator according to a third embodiment. FIG.
FIG. 3B is a cross-sectional view of a portion, and FIG. In FIG.
Is a dielectric plate having opposing circular resonator electrodes 2 and 3 formed on both principal surfaces, and the structure of this portion is the same as that shown in the first and second embodiments. Since the opposed plane-symmetric resonator electrodes 2 and 3 are formed on both main surfaces of the dielectric plate 1 as described above, the opposed portions function as TM010 mode resonators. Reference numerals 10 and 11 denote printed circuit boards, respectively, on which electrodes 20 are formed on substantially the entire upper surface of the printed circuit board 10 in the drawing.
The electrode 21 is formed in a portion in contact with. Similarly, an electrode 22 is formed on substantially the entire lower surface of the printed circuit board 11 in the drawing, and an electrode 2 is formed on the upper surface (the surface facing the dielectric plate 1) of the printed circuit board 11 in a portion in contact with the resonator electrode 3.
3 is formed. In the center of the printed circuit boards 10 and 11, through holes 7 and 8 are formed to conduct between the electrodes 20 and 21 and between the electrodes 22 and 23, respectively.
A plurality of through holes 24 and 25 having a semicircular cross section are formed on the outer peripheral surfaces of the printed boards 10 and 11, respectively. By setting the arrangement pitch of the through holes on the outer peripheral surface of the printed circuit board to be equal to or less than ４ of the guide wavelength λg, the wall surface of the cavity is equivalently constituted.

The dielectric plate 1 is sandwiched between the printed circuit boards 10 and 11 having the electrodes and the through holes as described above, and the bonding surfaces between the electrodes 2 and 3 for resonators and the electrodes 21 and 23 are made of a conductive adhesive or Join with solder. Then, a plurality of through holes 2 on the outer peripheral surface of the printed circuit boards 10 and 11
In order to electrically connect the printed circuit boards 4 and 25 to the ground, the printed circuit boards 10 and 11 are surrounded by a metal foil 12 and joined by soldering or the like. According to the dielectric resonator according to the third embodiment, since the cavity can be formed by the printed circuit board, the cost can be reduced as a whole.

Next, the structure of a dielectric filter according to a fourth embodiment will be described with reference to FIG. 5A is a cross-sectional view of the BB portion in FIG. 5B, and FIG. 5B is a cross-sectional view of the AA portion in FIG. In FIG. 1, reference numeral 1 denotes a dielectric plate, on both main surfaces of which are electrodes 2a, 2b,
2c and 3a, 3b, 3c are respectively opposed to each other to constitute three TM010 mode resonators. 17,1
Reference numeral 8 denotes a two-part cavity, and the resonator electrodes 2a,
Conductors 5a, 5b, 5c, 6a, 6b, 6c, which are electrically connected to 2b, 2c, 3a, 3b, 3c, respectively, are projected. Reference numerals 13 and 14 denote input / output substrates, respectively, on which microstrip lines 15 and 16 are formed. These input / output substrates 13 and 14 are fixed between the cavities 17 and 18. Input / output substrate 13,1
4, microstrip lines 15 and 16 are formed. A resonator formed by the resonator electrodes 2a and 3a and a resonator formed by the resonator electrodes 2c and 3c are capacitively coupled to the microstrip lines 15 and 16, respectively. I have. With this structure, a band-pass filter including a three-stage resonator having the microstrip lines 15 and 16 as input / output units is obtained.

FIG. 6 is a diagram showing the configuration of the dielectric filter according to the fifth embodiment. The dielectric filter according to the fifth embodiment differs from that shown in FIG. 5 in that the conductors 5a, 5b, 5c, 6a, 6b, and 6c protrude integrally from the cavities 17 and 18 and are in contact with the resonator electrodes. The cross-sectional shapes are each rectangular. Other configurations are the same as those shown in FIG. According to this structure also, spurious in the cavity can be suppressed, and a dielectric filter having excellent attenuation characteristics and spurious characteristics can be obtained.

FIG. 7 is a diagram showing the configuration of the dielectric filter according to the sixth embodiment. In FIG. 7, reference numeral 1 denotes a dielectric plate, whose two main surfaces are provided with resonator electrodes 2a, 2b, 2c and 3c.
a, 3b, and 3c are opposed to each other, and TM0
Three resonators of 10 modes are configured. 10,11
Are printed circuit boards, and ground electrodes 20 and 22 are formed on the outer surfaces, and electrodes are formed on portions of the dielectric plate 1 facing the resonator electrodes. Also, as in the case of the dielectric resonator shown in FIG. 4, through holes 7a, 7b, 7c, 8a, 8b, 8c are formed to guide the electrodes conducting to the respective resonator electrodes to the ground electrode. . Further, a plurality of through holes 24 extending from the ground electrode 20 are formed on the outer peripheral surface of the printed board 10, and a ground electrode is formed at a predetermined location on the upper surface of the printed board 11 in the drawing. A metal foil 12 surrounding the outer peripheral surface of the printed circuit board 10 and electrically connected to the plurality of through holes 24 and connected to the ground electrode on the printed circuit board 11 is provided. With this structure, the microstrip lines 15 and 16 are used as input / output units.
A bandpass filter consisting of a stage resonator is obtained.

In each of the above embodiments, an example is shown in which a circular resonator electrode is formed. However, the present invention is not limited to this, and may be rectangular or elliptical.

[0026]

According to the first aspect of the present invention, the resonator electrode has the same potential as the cavity, thereby suppressing a spurious mode electromagnetic field having the cavity as a resonance space.
The resonator formed by the resonator electrode does not couple with the spurious mode, and the Q of the resonator increases. Further, since the conductor also functions as a support for disposing the dielectric plate in the cavity, a special support is not required.

According to the second aspect of the invention, the effect of reducing the cavity space and the effect of grounding the resonator electrode to the cavity are further enhanced.

According to the third aspect of the present invention, the number of parts does not increase and the assembly structure is simplified.

According to the fourth aspect of the present invention, the cavity structure is simplified, for example, the cavity can be formed by using a printed board, and the input / output board can be used as a part thereof. Become.

According to the fifth aspect of the invention, the excitation of the waveguide mode in the cavity is suppressed, and the spurious response is suppressed. In addition, if the cavity space becomes narrower, the cutoff frequency for the waveguide mode in the cavity becomes higher, and if the resonance frequency of the cavity becomes higher than the resonance frequency of the resonator by the resonator electrode, if the resonance frequency of the cavity becomes higher, The damping characteristics are improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a dielectric resonator according to a first embodiment.

FIG. 2 is a diagram showing a broadband spurious characteristic of the dielectric resonator.

FIG. 3 is a cross-sectional view illustrating a structure of a dielectric resonator according to a second embodiment.

FIG. 4 is a cross-sectional view and a plan view illustrating a structure of a dielectric resonator according to a third embodiment.

FIG. 5 is a cross-sectional view illustrating a structure of a dielectric filter according to a fourth embodiment.

FIG. 6 is a cross-sectional view illustrating a structure of a dielectric filter according to a fifth embodiment.

FIG. 7 is a cross-sectional view and a plan view of a dielectric filter according to a sixth embodiment.

FIG. 8 is a cross-sectional view showing a structure of a conventional dielectric resonator.

FIG. 9 is a cross-sectional view illustrating a structure of a conventional dielectric filter.

FIG. 10 is a diagram illustrating an example of a magnetic field distribution of a waveguide mode in a cavity.

FIG. 11 is a diagram showing a broadband spurious characteristic of a conventional dielectric resonator.

[Explanation of symbols]

 1-dielectric plate 2,3-resonator electrode 4-cavity 5,6-conductor 7,8-through hole 10,11-printed board 12-metal foil 13,14-input / output board 15,16-micro Strip lines 17, 18-Cavities 19-Supports 20, 22-Earth electrodes 21, 23-Electrodes 24, 25-Through holes

Continued on the front page (72) Inventor Hiroshi Ida 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto, Japan Murata Manufacturing Co., Ltd. (72) Inventor Kiyoshi Kanagawa 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Co., Ltd.

Claims (5)

[Claims] 1. A TM mode dielectric resonator comprising: a dielectric plate having resonator electrodes facing each other on both sides substantially symmetrical to each other; and a cavity covering the periphery of the dielectric plate. A dielectric resonator, wherein a conductor for conducting between the resonator electrode and the cavity is provided at a portion facing the cavity. 2. The dielectric resonator according to claim 1, wherein a surface of the conductor in contact with the resonator electrode has a shape similar to the resonator electrode. 3. The dielectric resonator according to claim 1, wherein the conductor is constituted by a member integrally projecting from the cavity. 4. The dielectric resonator according to claim 1, wherein said cavity and said conductor are constituted by electrodes formed on a dielectric plate or an insulator plate. 5. A plurality of pairs of resonator electrodes are arrayed and formed on both main surfaces of said dielectric plate, and a plurality of dielectric resonators according to any one of claims 1 to 4 are provided. A dielectric filter comprising a coupling member coupled to a resonator.