JP2000134004A - Dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a small-sized dielectric filter with high reliability that can be used for a frequency band including frequencies in excess of 3 GHz or over. SOLUTION: The dielectric filter is structured to integrate a plurality of resonators each made of a dielectric material, and both end faces of the filter are formed with an island shaped input/output electrode 17, which is surrounded by ground electrodes. The resonators are interconnected via a dielectric material whose width is narrow and ground electrodes 18, 19 are formed on the other entire surfaces of the resonators. Thus, a plurality of the resonators are configured collectively in a form of a dielectric block and they are connected to configure the dielectric filter. The size of the dielectric material placed between the resonators is preferably selected smaller than that of both the resonators.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a structure of a small-sized dielectric filter suitable for use in a high-frequency band of 3 GHz or more, and relates to a coupling structure of a plurality of dielectric resonators and a coupling adjustment between the resonators. It is.

TECHNICAL FIELD OF THE INVENTION

[0002]

2. Description of the Related Art With the spread of mobile communication equipment, utilization of a frequency higher than a frequency band currently used is being studied. Conventional mobile communication uses frequencies up to the 2GHz band, and the filters used in mobile stations are mainly those combining dielectric coaxial resonators or blocking multiple dielectric resonators. Has been used for

However, when this dielectric coaxial resonator is used at a high frequency such as 5 GHz or more, the size defined by the frequency becomes small, making it difficult to obtain input / output coupling. Requires a larger outer diameter. For example, in order to secure the required Q at a frequency of 5 GHz, the outer diameter needs to be set to more than 10 mm.
This goes against the demand for miniaturization of electronic components and cannot be put to practical use. Alternatively, a TE mode resonator is used, but the structure is increased in size and the input / output coupling structure is complicated.

[0004]

SUMMARY OF THE INVENTION The present invention relates to
An object of the present invention is to provide a dielectric filter which has sufficient filter characteristics in a high frequency band such as GHz, has a high Q, and meets the requirements of miniaturization and thinning. In addition, the present invention provides a dielectric filter which has sufficient mechanical strength and can easily adjust the coupling.

[0005]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problem by employing a structure completely different from the conventional structure, and by a structure of a connecting portion of the dielectric substrate.

That is, in a dielectric filter in which two resonators are integrally formed in a dielectric block, input / output electrodes are formed by island-shaped conductive films on both end surfaces of the dielectric block, and the input / output electrodes are formed. The other side of the formed surface is connected with a narrow dielectric, and is formed on almost the entire remaining surface where the input / output electrodes are formed by being separated and insulated from the input / output electrodes and on the other surface of the dielectric block. It is characterized by having an earth conductor made of a conductor film.

Alternatively, in a dielectric filter in which a plurality of resonators are integrally formed in a dielectric block, input / output electrodes are formed by island-shaped conductive films on both end surfaces of the dielectric block, and the input / output electrodes are formed. The other side of the surface is connected to other resonators with a narrow dielectric, and is separated and insulated from the input / output electrodes, and almost the entire remaining surface on which the input / output electrodes are formed, and other portions of the dielectric block. The present invention is characterized in that an earth conductor made of a conductor film formed on the surface is provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The resonance mode of a dielectric filter according to the present invention has not been completely elucidated yet, but it is considered that the dielectric filter acts like a waveguide. It is conceivable that an island-shaped electrode on one surface of the dielectric substrate is used as the input / output coupling structure, and a resonator is coupled at a narrow dielectric portion to obtain filter characteristics.

A dielectric filter according to the present invention is formed by connecting two or more rectangular parallelepiped ceramic dielectric substrates to be dielectric resonators, and at least the following dielectric substrates are formed on the dielectric substrates at both ends. I / O electrode Ground electrode And a dielectric conductor narrower than the part of the dielectric substrate forming the resonator is connected, and a ground conductor is provided on the entire surface of the connection part with the dielectric substrate serving as the intermediate dielectric resonator. It is formed.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

1A and 1B show an embodiment of the present invention, wherein FIG. 1A is a perspective view and FIG. 1B is a front view. Rectangular dielectric substrate 1
1 and 12 are connected by a narrow dielectric material 15, and two resonators are formed integrally. A square or rectangular island-shaped conductor film 17 is formed at the center of the surface of the dielectric substrate 11 and used as an input / output electrode. The input / output electrodes of the dielectric substrate 12 are not shown in FIG. A conductor film 18 is formed around the input / output electrode 17 made of an island-shaped conductor film to serve as a ground conductor. Input / output electrode 17 and ground conductor
Separated from 18 and insulated. Although not shown, the same applies to the other dielectric substrate 12.

A conductor film 19 'is also formed on the entire other surfaces of the dielectric substrates 11 and 12, and is connected to a ground conductor surrounding the input / output electrodes. An earth conductor is also formed on the surface of the dielectric 15 of the connecting portion.

A dielectric of 10.0 × 10.0 × 2.5 mm (dielectric constant 3
7) Form a 3.0 × 3.0mm input / output electrode in the center of the 10.0 × 10.0mm surface of the dielectric block connected by a 4.0 × 4.0 × 0.5mm part, and ground around it at 0.5mm intervals A conductor was formed. Ground conductors were also formed on other surfaces.

FIG. 2 shows the characteristics of the above-described dielectric filter. The filter characteristic is such that the center frequency is 3.86 GHz, the 3 dB bandwidth is 185 MHz, and the insertion loss is 0.41 dB. A steep attenuation characteristic was shown above the lower side of the pass band.

FIG. 3 is a perspective view showing another embodiment of the present invention. Of the rectangular parallelepiped dielectric substrates 31, 32, and 33, a square or rectangular island-shaped conductor film 37 is formed at the center of the surface of the dielectric substrates 31, 32 at both ends and used as input / output electrodes. The input / output electrodes of the dielectric substrate 32 are not shown in FIG. A conductor film 38 is formed around the input / output electrode 37 made of the island-shaped conductor film to serve as a ground conductor. The input / output electrode 37 and the ground conductor 38 are separated and insulated. Although not shown, the same applies to the other dielectric substrate 32.

A conductor film 39 is formed on the other surfaces of the dielectric substrates 31 and 32, the entire surface of the intermediate dielectric substrate 33, and the entire surface of the connecting portions 35 and 36, and is connected to a ground conductor surrounding the input / output electrodes.

A dielectric of 10.0 × 10.0 × 2.5 mm (dielectric constant 3
7) With dielectric substrate of both ends, 10.0 × 8.0 × 2.5mm in the middle
In the center of the 10.0 × 10.0 mm surface of the dielectric block connected with a dielectric of 10.0 × 3.0 × 0.5 mm with the dielectric substrate of
Input / output electrodes of 5.0 × 5.0 mm were formed, and ground conductors were formed around them at intervals of 0.5 mm. The whole surface was covered with a ground conductor to obtain a dielectric filter.

FIG. 4 shows the characteristics of the above-described dielectric filter. The filter characteristic has a center frequency of 4.24 GHz, a 3 dB bandwidth of 185 MHz, and an insertion loss of 0.55 dB. The lower and upper passbands exhibited almost symmetrical attenuation characteristics.

FIGS. 5A and 5B show another embodiment of the present invention, in which FIG. 5A is a perspective view and FIG. 5B is a front view, which is different from the structure shown in FIG. The dielectric substrates at both ends are 10.0 ×
An input / output electrode of 4.0 × 3.0 mm was formed at the center of a 10.0 × 8.0 mm surface of a dielectric of 8.0 × 2.5 mm (relative permittivity 37), and a ground conductor was formed around the periphery at an interval of 0.5 mm. The dielectric substrate sandwiched in the center is 10.0 × 6.9 × 2.5 mm, and the connecting part is 6.9 × 3.0
× 0.5 mm.

FIG. 6 shows the characteristics of the above-described dielectric filter. The filter characteristics are as follows: the center frequency is 4.47 GHz, the 3 dB bandwidth is 120 MHz, and the insertion loss is 0.91 dB. A steep attenuation characteristic was shown above the lower side of the pass band.

[0021]

According to the present invention, it is possible to obtain a dielectric filter similar to that obtained by overlapping and joining dielectric substrates, and to obtain a dielectric filter which is extremely small and can be used in a high frequency band.

Further, since the dielectric resonators can be coupled to each other via the connecting portion, the coupling state can be adjusted depending on the size of the connecting portion, and the bandpass characteristics can be adjusted. Further, since the connecting portion is covered with the ground conductor, it is less susceptible to an external electromagnetic field.

[Brief description of the drawings]

FIG. 1A is a perspective view showing an embodiment of the present invention, and FIG.
Is a front view

FIG. 2 is an explanatory diagram of characteristics of a dielectric filter according to the present invention.

FIG. 3 is a perspective view showing another embodiment of the present invention.

FIG. 4 is an explanatory diagram of characteristics of a dielectric filter according to the present invention.

5A is a perspective view showing another embodiment of the present invention, FIG.
(B) is a front view

FIG. 6 is an explanatory diagram of characteristics of a dielectric filter according to the present invention.

[Explanation of symbols]

 17, 37: I / O electrode 18, 19, 38, 39: Ground conductor 15, 35, 36: Ground conductor

Claims (3)

[Claims] 1. A dielectric filter in which two resonators are integrally formed in a dielectric block, comprising input / output electrodes made of an island-shaped conductive film on both end faces of the dielectric block.
The other side of the surface on which the input / output electrodes are formed is connected by a narrow dielectric, and is separated and insulated from the input / output electrodes to substantially the remaining surface of the surface on which the input / output electrodes are formed. A dielectric filter comprising an earth conductor formed by a conductor film formed on a surface. 2. A dielectric filter in which a plurality of resonators are integrally formed in a dielectric block, comprising: an input / output electrode formed of an island-shaped conductive film on both end surfaces of the dielectric block;
The other side of the surface on which the input / output electrodes are formed is connected to another resonator by a narrow dielectric, and is separated and insulated from the input / output electrodes and substantially the entire remaining surface on which the input / output electrodes are formed. A dielectric filter comprising an earth conductor formed of a conductor film formed on another surface of the body block. 3. The width of an intermediate dielectric resonator is smaller than the width of a dielectric resonator on which input / output electrodes are formed.
The dielectric filter as described in the above.