JP2000068710A - Dielectric filter and its characteristic adjusting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a small dielectric filter which can be used in a high frequency band of at least 30 GHz and is provided with an attenuation pole. SOLUTION: The structure of the filter is obtained by joining rectangular parallelopiped dielectrics 11 and 12 and input/output electrodes 13 and 14 which are surrounded by ground electrodes are formed on one surface of the respective dielectrics. A ground electrode is formed also on the surface excepting for the joining surfaces of the dielectrics and a resonator is connected on the exposed joining surface of the dielectrics to constitute a filter. An attenuation pole is obtained by strip-shaped conductor films 18 and 19 extending to a surface opposed to a surface forming the input/output electrode from the joining surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small dielectric filter suitable for use in a high frequency band of 3 GHz or more.

[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. Up to about 2 GHz band has been used in mobile communication so far, and a filter combined with a dielectric coaxial resonator has been mainly used as a filter used in a mobile station.

However, when this dielectric coaxial resonator is used at a frequency of 3 GHz or more, the size specified by the frequency becomes thin, making it difficult to obtain input / output coupling and securing a high Q. Requires a larger outer diameter. For example, in order to secure the required Q at a frequency of 5 GHz, an outer diameter of more than 10 mm is required. This goes against the demand for downsizing electronic components and is not practical. Alternatively, a TE mode resonator is used, but the structure becomes large and the input / output coupling structure becomes 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. And it is providing the dielectric filter which has an attenuation pole in such a dielectric filter.

[0005]

The present invention solves the above-mentioned problems by adopting a structure completely different from the conventional structure and adding an electrode for adjusting the characteristics.

That is, in a dielectric filter in which two rectangular parallelepiped dielectrics are joined, an input / output electrode made of an island-shaped conductive film is provided on one surface of each dielectric, and is separated and insulated from the input / output electrode. An earth electrode is formed by a conductive film formed on almost the entire remaining surface of the surfaces and on almost the entire other surface except for the joint surface, and at least one of the joint surfaces has one end grounded on the surface on which the input / output electrode is formed. It is characterized in that it has a strip-shaped conductor film which is connected to a conductor, the other end of which extends to a surface facing the surface on which the input / output electrodes are formed and which is not connected to the ground electrode on that surface.

In a method for adjusting the characteristics of a dielectric filter in which two rectangular parallelepiped dielectrics are joined, an input / output electrode formed of an island-shaped conductor film is formed on one surface of each dielectric, and An earth electrode is formed by a conductor film which is formed so as to be separated and insulated from almost all of the remaining surfaces and almost the entire other surface except for the bonding surface, and one end of at least one of the bonding surfaces has an input / output electrode. The strip-shaped conductor film is connected to the ground conductor on the formed surface, and the other end extends to a surface opposite to the surface on which the input / output electrode is formed, and is not connected to the ground electrode on the surface. The characteristic is that the pass band characteristic is adjusted by changing the area of the conductor film.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Although the analysis of the resonance mode of the dielectric filter according to the present invention has not been completely performed yet,
It is considered that it has a function close to a waveguide. It is considered that an island-shaped electrode on one surface of the dielectric is used as the input / output structure, and a resonator is coupled at the joint surface where the dielectric is exposed, thereby obtaining filter characteristics.

[0009]

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

1A and 1B show an embodiment of the present invention. FIG. 1A is a perspective view seen from above, and FIG. 1B is a perspective view seen from below. This shows a state before the dielectric is joined. 1
0.0 × 10.0 × 2.5mm rectangular parallelepiped dielectrics 11, 12 10.0 × 10.0
4.0 × 4.0 mm electrodes 13 and 14 are formed at the center of the surface of mm,
Electrodes 15 and 16 are formed so as to surround them at intervals of 0.5 mm.

A conductive film is formed on the other surfaces of the two dielectrics 11 and 12 except for the joint surface.
16 (ground potential). The dielectric is exposed at the joint surface, and a characteristic adjusting electrode 18 is formed on a part of the joint surface. This electrode 18 has a width of 0.7 m in this example.
Two of them are formed at an interval of 7.0 mm in m and are connected to the ground conductors 15 and 16 on the surface on which the input / output electrodes are formed. On the side facing the surface on which the input / output electrodes are formed,
It is formed so as to be connected to the electrode 19 formed on the surface.

FIG. 2 is a plan view of the dielectric filter according to the present invention after assembly. The electrode 19 formed on the surface opposite to the surface on which the input / output electrodes are formed and connected to the electrode on the joint surface is separated from the ground conductor on this surface by a distance. It has been found that the pass band characteristics, particularly the attenuation pole characteristics, change depending on the size of the electrode 19.

The width of the electrode 19 was set to 0.5 mm, and the characteristics were measured while changing the length. The electrode 19 is formed at a portion where the dielectric of 3.0 × 1.1 mm is exposed.

FIG. 3 shows the characteristics when the length of the electrode 19 is 1.6 mm. The center frequency is 3.69 GHz, and the center frequency is 3.58 G.
An attenuation pole was formed at a frequency of Hz. That is, an attenuation pole is obtained below the pass band. FIG. 4 shows the case where the length of the electrode is 1.2 mm. The center frequency is 3.74 GHz and an attenuation pole is formed at 3.66 GHz, which is also below the pass band.

FIG. 5 shows the characteristics when the length of the electrode 19 is 1.0 mm. The center frequency is 3.78 GHz and 3.91 GHz.
An attenuation pole was formed at a frequency of Hz. That is, an attenuation pole is obtained above the pass band. FIG. 6 shows the case where the length of the electrode is 0.8 mm, the center frequency is 3.78 GHz, and an attenuation pole is formed at 3.94 GHz, which is also above the pass band.

As described above, the center frequency and the attenuation pole change depending on the dimensions of the electrode 19 shown in the figure. The frequency characteristics can be adjusted by trimming this electrode.

[0017]

According to the present invention, a dielectric filter which can be used in a frequency band of 3 GHz or more and has good characteristics can be obtained. An attenuation characteristic can be added to the filter characteristic by the conductor film on the surface.

Further, not only the size and thickness can be reduced, but also the attenuation characteristics can be adjusted by trimming the conductive film, so that a dielectric filter which is easy to manufacture and inexpensive can be obtained.

[Brief description of the drawings]

1A and 1B show an embodiment of the present invention, wherein FIG. 1A is a perspective view from above, and FIG. 1B is a perspective view from below.

FIG. 2 is a plan view showing an embodiment of the present invention.

FIG. 3 is an explanatory diagram of characteristics of a dielectric filter according to the present invention.

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

FIG. 5 is an explanatory diagram of characteristics of a dielectric filter according to the present invention.

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

[Explanation of symbols]

 13, 14: I / O electrode 15, 16: Earth electrode 18, 19: (Adjustment) electrode

Claims (3)

[Claims] 1. A dielectric filter in which two rectangular parallelepiped dielectrics are joined to each other, and each of the dielectrics has an input / output electrode formed of an island-shaped conductive film on one surface thereof and is separated and insulated from the input / output electrode. An earth electrode is formed by a conductive film formed on almost the entire remaining surface of the surfaces and on almost the entire other surface except for the joint surface, and at least one of the joint surfaces has one end grounded on the surface on which the input / output electrode is formed. Connected to the conductor,
A dielectric filter comprising a strip-shaped conductor film whose other end extends to a surface opposite to a surface on which input / output electrodes are formed and is not connected to a ground electrode on the surface. 2. A dielectric filter in which two rectangular parallelepiped dielectrics are joined to each other, and each of the dielectrics has an input / output electrode formed of an island-shaped conductive film on one surface thereof and is separated and insulated from the input / output electrode. An earth electrode is formed by a conductive film formed on almost the entire remaining surface of the surfaces and on almost the entire other surface except for the joint surface, and at least one of the joint surfaces has one end grounded on the surface on which the input / output electrode is formed. Connected to the conductor,
A dielectric filter comprising a strip-shaped conductor film having the other end extending over a surface facing the surface on which the input / output electrodes are formed and facing the ground electrode at a distance from the surface. 3. A method for adjusting the characteristics of a dielectric filter in which two rectangular parallelepiped dielectrics are joined, wherein an input / output electrode formed of an island-shaped conductive film is formed on one surface of each of the dielectrics. An earth electrode is formed by a conductor film which is formed so as to be separated and insulated from almost all of the remaining surfaces and almost the entire other surface except for the bonding surface, and one end of at least one of the bonding surfaces has an input / output electrode. The strip-shaped conductor film is connected to the ground conductor on the formed surface, and the other end extends to a surface opposite to the surface on which the input / output electrode is formed, and is not connected to the ground electrode on the surface. A passband characteristic is adjusted by changing the area of the conductive film.