JPH11220307A - Dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sufficient filter characteristic in a high frequency band by providing a blind hole positioned between input/output electrodes and extending to a surface forming the input/output electrodes from a surface opposed to the surface forming the input/output electrodes and filling this blind hole with a conductor. SOLUTION: Input/output electrodes 11 and 12 consisting of conductor films like an island are formed on the widest surface of a rectangular-parallelopiped dielectric block 10 at an interval and a conductor film 13 is formed surrounding these electrodes on nearly the whole remaining surface of this surface. Conductor films are formed also on all of the other surfaces than the surface forming the electrodes 11 and 12 to continue with the film 13 surrounding the electrodes 11 and 12 to make the whole of them a grounding electrode. Then, the electrodes 11 and 12 are connected to an input/output signal line. Here, a blind hole 15 extending from the surface of not forming the input/output electrodes to the surface opposed to it is formed and a conductor material 16 is filled into this hole 15 to arrange a conductor layer between resonators.

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. Conventional mobile communication uses frequencies up to about 2 GHz band, and as a filter used in a mobile station, a combination of a dielectric coaxial resonator and a filter is mainly used.

However, when an attempt is made to use a dielectric coaxial resonator at a higher frequency, the size defined by the frequency becomes thin, so that it is difficult to obtain input / output coupling, and high Q
It is necessary to increase the outer diameter in order to maintain For example,
To ensure the required Q at a frequency of 5 GHz, 10
An outer diameter of several millimeters is required. Alternatively, a TE mode resonator is used, but the structure becomes large,
The input / output coupling structure is also 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.

It is another object of the present invention to provide a dielectric filter whose pass band characteristics can be easily adjusted. Further, the present invention provides a dielectric filter having an attenuation pole.

[0006]

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 integrally formed with a rectangular parallelepiped dielectric block, an input / output electrode made of an island-shaped conductive film formed on a surface having the largest area of the dielectric block at intervals in the longitudinal direction. And a ground electrode formed of a conductive film which is insulated and insulated from the conductive film of the input / output electrode and is formed on substantially the entire remaining surface and the entire surface of the other surface. A blind hole extending from a surface facing the surface on which the I / O electrodes are formed to a surface on which the input / output electrodes are formed, and the blind hole is filled with a conductor.

In a dielectric filter integrally formed with a rectangular parallelepiped dielectric block, an input / output electrode formed by an island-shaped conductive film formed on a surface having the largest area of the dielectric block at intervals in a longitudinal direction. And a ground electrode formed of a conductive film which is insulated and insulated from the conductive film of the input / output electrode and is formed on substantially the entire remaining surface and the entire surface of the other surface. It has a blind hole extending from the surface opposite to the surface where the is formed to the surface where the input / output electrode is formed, and the coupling between the resonators is adjusted by filling the blind hole with a conductor. Things.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Although the resonance mode of a dielectric filter according to the present invention has not been completely analyzed, it has the same function as a waveguide, and has a structure in which a dielectric is filled inside the waveguide. It is considered that It is considered that a resonator is formed by the input and output electrode portions, and a filter characteristic can be obtained by the combination of these resonators.

In the present invention, the conductor connected to the ground potential is arranged between the resonators, whereby the coupling of the resonators is adjusted to form an attenuation pole having a predetermined frequency. That is, the frequency of the attenuation pole is adjusted by the inductance and the capacitance of the conductor.

[0011]

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 front view and FIG. 1B is a bottom view. I / O electrodes 11 and 12 of island-shaped conductive film are formed at intervals on the widest surface of the area of a rectangular parallelepiped dielectric block 10 of 12.0 × 6.0 × 2.5 mm,
These are input / output electrodes. The dimensions of the input and output electrodes are 1.4 ×
It is 1.4 mm.

A conductor film 13 surrounding the input / output electrodes 11 and 12 is formed on almost the entire remaining surface of the surface at intervals of 0.5 mm. In addition, a conductor film is formed on all surfaces other than the surface on which the input / output electrodes 11 and 12 are formed, and
Conduction is made with the conductor film 13 surrounding 1 and 12, and the whole becomes a ground electrode. The input / output electrodes 11 and 12 are connected to input / output signal lines.

In the present invention, a blind hole 15 is formed between the input / output electrodes 11 and 12 and extends from the surface where the input / output electrodes are not formed to the opposite surface. In this example, the size of the through hole 15 is 0.3 × 0.5 mm and the depth is 2.3 mm. The conductor material 16 is filled in the blind hole 15, and the conductor layer is arranged between the resonators.

FIG. 2 shows the bandpass characteristics of the dielectric filter manufactured using the dielectric having a relative permittivity of 37 according to the embodiment shown in FIG. Center frequency is 6.03GHz, 3dB bandwidth is
At 174 MHz, the insertion loss at the peak was 0.89 dB, and it was confirmed that it could be used as a band-pass filter in the 6 GHz band. And 5.45 on the lower side of the pass band
An attenuation pole was obtained near GHz.

3A and 3B show another embodiment of the present invention, wherein FIG. 3A is a front view and FIG. 3B is a bottom view. The size of the dielectric block is the same as that of FIG. 1, and the input / output electrodes 31 and 32 have the same size. The size of the blind hole 35 between the input and output electrodes is changed, and is 1.4 × 0.3 mm and the depth is 2.1 mm.

The characteristics shown in FIG. 4 show the bandpass characteristics of the dielectric filter shown in FIG. The center frequency was 6.12 GHz, the 3 dB bandwidth was 179 MHz, and the insertion loss at the peak was 0.91 dB, confirming that the filter can be similarly used as a 6 GHz band band pass filter. In this example, an attenuation pole was obtained around 6.87 GHz on the higher side of the passband.

As described above, according to the present invention, by utilizing the fact that the passband characteristics change depending on the size of the blind hole and the width, thickness, depth and the like of the conductor filled therein, the characteristics such as the bandwidth are utilized. Can be adjusted. In the example of FIG. 1, an attenuation pole was obtained on the lower side of the pass band, but in the example of FIG. 3, an attenuation pole was obtained on the higher side of the pass band.

The conductor filled in the blind hole between the input and output electrodes is
This means that the inductance and the capacitance of the conductor are added from the surface opposite to the surface where the input / output electrodes are formed to the surface where the input / output electrodes are formed. By selecting the inductance and the capacitance value, the frequency of the attenuation pole can be adjusted.

[0020]

According to the present invention, it is possible to obtain a dielectric filter which can be used in a frequency band of 5 GHz or more and whose characteristics can be easily adjusted. An attenuation characteristic can be added to the filter characteristic by the conductor between the resonators.

Further, not only the size and thickness can be reduced, but also the dielectric filter can be manufactured only by forming a conductor 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. 1A is a front view showing an embodiment of the present invention, and FIG.
Bottom view

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

3 (a) is a front view and FIG. 3 (b) is a bottom view showing another embodiment of the present invention.

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

[Explanation of symbols]

 10: Dielectric block 11, 12, 31, 32: I / O electrode 13: Conductor film (earth electrode) 15, 35: Blind hole 16, 36: Conductor

Claims (3)

[Claims] 1. A dielectric filter integrally formed with a rectangular parallelepiped dielectric block, wherein the input / output electrodes are formed by island-shaped conductive films formed at intervals in the longitudinal direction on the surface of the dielectric block having the largest area. And a ground electrode formed of a conductive film which is insulated and insulated from the conductive film of the input / output electrode and is formed on substantially the entire remaining surface and the entire surface of the other surface. A dielectric filter, comprising: a blind hole extending from a surface opposite to a surface on which an I / O electrode is formed to a surface on which an input / output electrode is formed, wherein the blind hole is filled with a conductor. 2. A dielectric filter integrally formed on a rectangular parallelepiped dielectric block, wherein the input / output electrodes are formed by island-shaped conductor films formed at intervals in the longitudinal direction on the surface of the dielectric block having the largest area. And a grounding electrode formed of a conductive film which is separated and insulated from the conductive film of the input / output electrode and is formed on almost the entire remaining surface and the entire surface of the other surface, and the input / output electrode is connected to the signal input / output line. A blind hole extending between a surface facing the surface where the input / output electrode is formed and located between the input / output electrode and extending from the surface facing the surface where the input / output electrode is formed, and the blind hole is filled with a conductor. Dielectric filter. 3. A dielectric filter integrally formed on a rectangular parallelepiped dielectric block, wherein the input / output electrodes are formed by island-shaped conductive films formed at intervals in the longitudinal direction on a surface having the largest area of the dielectric block. And a ground electrode formed of a conductive film which is insulated and insulated from the conductive film of the input / output electrode and is formed on substantially the entire remaining surface and the entire surface of the other surface. A blind hole extending from a surface facing the surface on which the I / O electrodes are formed to a surface on which the input / output electrode is formed, and the coupling between the resonators is adjusted by filling the blind hole with a conductor. Dielectric filter.