JPH11220306A - Dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sufficient filter characteristic in a high frequency band by providing input/output electrodes consisting of conductor films like an island on one surface of each dielectric and providing the conductor films which are not connected to grounding electrodes on the surfaces forming these input/output electrodes, on the joining surfaces. SOLUTION: Input/output electrodes 13 and 14 are formed in the centers of the surfaces of rectangular-parallelopiped dielectrics 11 and 12 and the grounding electrodes 15 and 16 of conductor films surrounding these are formed. Excepting the joining surfaces of the two rectangular-parallelopiped dielectrics, conductor films are formed on the other surfaces and the potentials of those conductor films are equal (grounding potential) to those of the electrodes 15 and 16. The dielectrics are exposed on the joining surfaces to form the conductor films 18 for adjusting the connection at one part of these joining surfaces. The films 18 are connected with the earth electrodes to join these dielectrics on the exposed surfaces of the dielectrics. In addition, the electrodes 13, 14 are connected to an input/output signal line, the electrode 13 is connected to the strip line of the inputting and the signal wire of a coaxial line and the conductor films are connected to a grounding wire, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a small-sized dielectric filter suitable for use in a high frequency band of 5 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. In the conventional mobile communication, a frequency up to about 2 GHz band is used, and as a filter used in a mobile station, a combination of a dielectric coaxial resonator and a filter has been mainly used.

However, this dielectric coaxial resonator has a frequency of 5 GHz.
When used at the above frequencies, the size defined by the frequency becomes thin, making it difficult to obtain input / output coupling, and it is necessary to increase the outer diameter to ensure a high Q. 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 miniaturization of 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 provides a dielectric filter which has sufficient filter characteristics in a high frequency band of 5 GHz to 30 GHz, has a high Q, and meets the requirements of miniaturization and thinning. is there. And it is providing the dielectric filter which has an attenuation pole in such a dielectric filter.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by employing a structure completely different from the conventional structure.

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

[0007]

DETAILED 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, it is considered that the dielectric filter has a function close to that of 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.

In the present invention, by forming a conductor film connected to the ground potential on the joint surface, the coupling of the resonator is adjusted to form an attenuation pole of a predetermined frequency. This conductor film is connected to the ground electrode on the surface opposite to the surface on which the input / output electrodes are formed, but is not connected to the ground electrode on the surface on which the input / output electrodes are formed, but via the exposed gap of the dielectric. And close. That is, the frequency of the attenuation pole is adjusted by the inductance and the capacitance of the conductor film.

[0009]

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

FIG. 1 is a perspective view showing an embodiment of the present invention and shows a state before a dielectric filter is assembled. 2A shows a front view and FIG. 2B shows a bottom view after assembly. 6.0 × 6.
0 × 2.5 mm rectangular parallelepiped dielectric (dielectric constant 37) 11, 12 6.0
The electrodes 13 and 14 of 1.4 × 1.4 mm are formed in the center of the surface of × 6.0 mm, and the electrodes 15 and 16 of the conductor film surrounding the electrodes 13 and 14 are formed.

A conductive film is also formed on the other surface except for a joint surface between the two rectangular parallelepiped dielectrics, and the conductive films are formed on the electrodes 15,
16 (ground potential). At the joint surface, the dielectric is exposed, and an electrode 18 for adjusting the coupling is formed on the joint surface.
Are formed in a part thereof. In this example, the electrode 18 is connected to the ground electrode on the upper surface formed on the entire surface and has a width of 1.4 m.
m, the depth is 2.1 mm, and the gap between the electrode 18 and the ground electrode on the bottom surface where the input / output electrodes are formed is 0.4 mm. These dielectrics are joined at the exposed surface of the dielectric.

The input / output electrodes 13 and 14 are connected to input / output signal lines, the electrodes 13 are connected to input strip lines and signal lines of coaxial lines, and a conductor film surrounding them is connected to an earth line to form a filter. Be composed.

FIG. 2 is an explanatory diagram of the characteristics of the dielectric filter of FIG. 1. In the case of the above configuration, the center frequency is 6.09 GHz.
, 155MHz 3dB bandwidth, 0.9 insertion loss at peak
It was 8dB. And the attenuation pole was formed on the high frequency side of the pass band of the frequency 6.6 GHz.

The input / output portion of the dielectric filter according to the present invention is capacitively coupled, and its capacitance changes depending on the size of the input / output electrodes. Therefore, the input / output coupling capacitance can be adjusted by adjusting the size.

The coupling state between the resonators changes depending on the conductor film formed on the bonding surface. When the width of the conductor film is small, the coupling coefficient increases, and the pass band width as a filter increases. Conversely, when the width of the conductor film is increased, the coupling coefficient is reduced, and the pass band width as a filter is reduced.

Then, the conductor film on the bonding surface is obtained by adding inductance by the conductor pattern and capacitance by the gap from the surface facing the surface on which the input / output electrodes are formed to the surface on which the input / output electrodes are formed. By selecting the values of the inductance and the capacitance, the frequency at which the attenuation pole occurs can be adjusted.

[0017]

According to the present invention, a dielectric filter which can be used in a frequency band of 5 GHz or more and has good characteristics can be obtained. The conductor film on the joining surface makes it possible to add an attenuation characteristic to the filter characteristic.

Further, not only the size and thickness can be reduced, but also the attenuation characteristics can adjust the size of the conductive film formed on the joint surface of the rectangular parallelepiped dielectric, so that a dielectric filter which is easy to manufacture and inexpensive can be obtained. can get.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of the present invention.

2A is a front view and FIG. 2B is a bottom view of the embodiment of the present invention.

FIG. 3 is an explanatory diagram of characteristics of the dielectric filter of FIG. 1;

[Explanation of symbols]

 11, 12: Dielectric 13, 14: I / O electrode 15, 16: Earth electrode 18: Conductive film

Claims (4)

[Claims] 1. A dielectric filter in which two rectangular parallelepiped dielectrics are joined to each other, and each of the dielectrics is provided with an input / output electrode made of an island-shaped conductor film on one surface thereof and separated and insulated from the input / output electrode. It is provided with a ground electrode made of a conductive film formed on almost the entire remaining surface of those surfaces and on the whole other surface except the joint surface, and is connected to the ground electrode on the surface facing the surface on which the input / output electrodes are formed. A dielectric filter comprising a conductor film that is not connected to a ground electrode on a surface on which an output electrode is formed, on at least one of bonding surfaces. 2. A dielectric filter in which two rectangular parallelepiped dielectrics are joined to each other, comprising an input / output electrode formed of an island-shaped conductor film at the center of one surface of each dielectric, and separated from the input / output electrode by insulation. And an earth electrode formed of a conductive film formed on the entire surface of the other surface except for the bonding surface, surrounding the input / output electrodes, and the conductive film is formed on at least one part of the bonding surface. A dielectric film, wherein the conductive film is connected to a ground electrode on the surface facing the surface on which the input / output electrodes are formed, and is not connected to the ground electrode on the surface on which the input / output electrodes are formed. . 3. A dielectric filter in which two rectangular parallelepiped dielectrics are joined to each other, each of which 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. It is provided with a ground electrode made of a conductive film formed on almost the entire remaining surface of those surfaces and on the whole other surface except the joint surface, and is connected to the ground electrode on the surface facing the surface on which the input / output electrodes are formed. A dielectric filter, comprising: a conductive film that is not connected to a ground electrode on a surface on which an output electrode is formed, on at least one part of a bonding surface, and an input / output electrode is connected to an input / output signal line. 4. A dielectric filter in which two rectangular parallelepiped dielectrics are joined to each other, and each of the dielectrics has an input / output electrode made of an island-shaped conductor film on one surface thereof and is isolated and insulated from the input / output electrode. It has a ground electrode made of a conductive film formed on almost the entire remaining surface of those surfaces and the whole other surface except for the bonding surface, and has a conductive film on at least one part of the bonding surface, and the conductive film has input / output portions. A dielectric connected to the ground electrode on the surface opposite to the surface on which the electrodes are formed, not connected to the ground electrode on the surface on which the input / output electrodes are formed, and the coupling is adjusted by the conductor film; filter.