JPH11195904A - Dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a filter capable of being made small in size and thin in thickness by providing an input-output electrode constituted of an island-shaped conductor film on one surface of respective dielectric, providing a conductor film that surrounds the conductor film over the entire surface separating and insulating from the conductor film and also providing a conductor film over the other entire surface except a composition plane. SOLUTION: Electrodes 13 and 14 are formed at central parts on the surfaces of dielectrics 11 and 12 of rectangular parallelepipeds and conductor film electrodes 15 and 16 which surround them are formed. Conductor films are also formed over the other entire surface except a composition plane and the conductor films have the same potential with the electrodes 15 and 16. Dielectrics are exposed at the composition plane and an electrode that adjusts connection as necessary is formed at a part of it. The dielectrics 11 and 12 are united at planes where the dielectrics are exposed. The electrodes 13 and 14 are connected to input and output signal lines, the electrode 13 is connected to an input stripline and a signal line of a coaxial line and the conductor film that surrounds them is connected a ground line and this filter is configured in this way.

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 dimensions defined by the frequency become 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 smaller electronic components and is not practical.
Alternatively, although a TE mode resonator is used, the structure becomes large in size and the input / output coupling structure becomes complicated.

[0004]

SUMMARY OF THE INVENTION The present invention is to provide a dielectric filter which has sufficient filter characteristics in a high frequency band of 5 GHz to 30 GHz and which meets the demand for miniaturization and thinning.

[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, in a dielectric filter in which two rectangular parallelepiped dielectrics are joined, an input / output electrode formed of an island-shaped conductor film is provided on one surface of each dielectric, and is separated and insulated from the conductor film. The present invention is characterized in that a conductor film surrounding the conductor film is provided on the entire surface, and the conductor film is provided on the entire surface other than the joining surface.

In a dielectric filter in which two rectangular parallelepiped dielectrics are joined, one surface of each dielectric is provided with an input / output electrode of an island-shaped conductor film, and is isolated and insulated from the conductor film. A conductive film surrounding the conductive film is provided on the entire remaining surface, and a conductive film is provided on the entire surface other than the bonding surface, and a capacitance is formed between the input / output electrode and the conductive film surrounding the conductive film. It is characterized in that the dielectric is exposed at the joint surface of the two dielectrics and the resonators are coupled.

[0008]

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.

[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, in which (a) shows a state before assembly and (b) shows a state after assembly. 3.5 × 5.0 × 1.7 mm rectangular parallelepiped dielectric (dielectric constant 90) 11, 12 1.0 × 1.0 in the center of 3.5 × 5.0 mm surface
mm electrodes 13 and 14 are formed, and electrodes 15 and 16 of a conductor film surrounding the electrodes 13 and 14 are formed.

Conductive films are formed on the entire other surface except for the joint surface, and these conductive films are set to the same potential (earth potential) as the electrodes 15 and 16. The dielectric is exposed at the joint surface,
An electrode 18 for adjusting the coupling as required is formed on a part thereof. These dielectrics are joined at the exposed surface of the dielectric.

The 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. You.

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 5.64 GHz.
85MHz 3dB bandwidth, 4.2dB peak insertion loss
Had become. In this case, 4.2dB seems to be a large loss, but considering the extremely narrow bandwidth of 85MHz, it is considered to be low loss.

Hereinafter, another embodiment of the present invention will be described. The dielectric constant of each of the dielectrics used was 37. FIG.
Is formed in the same manner using a 6.0 × 6.0 × 1.7 mm dielectric, the input and output electrodes are formed to 1.2 × 1.2 mm, and a 2.0 mm wide coupling adjustment electrode is formed at the center of the joint surface. It is. FIG. 4 shows the characteristics in this case.
GHz, 3dB bandwidth 135MHz, peak insertion loss 1.
A result of 51dB was obtained.

FIG. 5 shows the same structure formed using a 5.0 × 8.0 × 1.7 mm dielectric. The input / output electrodes are formed to have a size of 1.2 × 1.2 mm. An electrode is formed. FIG. 6 shows the characteristics in this case.
The center frequency was 5.88 GHz, the 3 dB bandwidth was 153 MHz, and the insertion loss at the peak was 1.32 dB.

FIG. 7 shows a case in which a dielectric material of 8.0 × 5.0 × 1.7 mm is formed in the same manner. The input / output electrodes are formed in a size of 1.2 × 1.2 mm, and a 3.5 mm wide coupling adjusting member is formed at the center of the joint surface. An electrode is formed. FIG. 8 shows the characteristics in this case.
The center frequency was 5.89 GHz, the 3 dB bandwidth was 177 MHz, and the insertion loss at the peak was 1.62 dB.

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.

Further, the coupling state between the resonators changes depending on the conductive 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.

[0019]

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.

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

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram of characteristics of the dielectric filter of FIG.

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

FIG. 4 is an explanatory diagram of characteristics of the dielectric filter of FIG.

FIG. 5 is a perspective view of another embodiment of the present invention.

FIG. 6 is an explanatory diagram of characteristics of the dielectric filter of FIG.

FIG. 7 is a perspective view of another embodiment of the present invention.

FIG. 8 is an explanatory diagram of characteristics of the dielectric filter of FIG. 7;

[Explanation of symbols]

 11, 12: Dielectric 13, 14: I / O electrode

Claims (4)

[Claims] 1. A dielectric filter in which two rectangular parallelepiped dielectrics are joined to each other, comprising an input / output electrode formed of an island-shaped conductive film on one surface of each dielectric, and separated from the conductive film of the input / output electrode by insulation. A dielectric filter comprising: a conductive film formed on substantially the entire remaining surface of the conductive film; and a conductive film on the entire surface except for the joining 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 conductor film at a central portion of one surface thereof and is separated from the conductor film. And a conductor film surrounding the conductor film on the entire surface, and a conductor film on the entire surface except for the joint surface. 3. A dielectric filter comprising two rectangular parallelepiped dielectrics joined to each other, comprising an input / output electrode formed of an island-shaped conductor film at the center of one surface of each of the dielectrics, and separated and insulated from the conductor film. And a conductor film surrounding the conductor film on the entire surface, a conductor film on the entire surface other than the bonding surface, and an input / output electrode connected to the input / output signal line. Body filter. 4. A dielectric filter comprising two rectangular parallelepiped dielectrics joined to each other, comprising an input / output electrode formed of an island-shaped conductor film at the center of one surface of each of the dielectrics, wherein the input / output electrodes are separated and insulated from the conductor film. A conductive film surrounding the conductive film is provided on the entire surface, and a conductive film is provided on the entire surface other than the bonding surface, and the dielectric is exposed at the bonding surface of the two dielectrics, and the space between the resonators is formed. A dielectric filter characterized by being coupled.