JP2000077916A - Dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide filter characteristics sufficient in high frequency bands and to provide the dielectric filter of high Q matched to miniaturizing and thinning requests by providing input/output electrodes composed of island-shaped conductor films on two adjacent surfaces of rectangular parallelopiped and chamfering edge side with no contact to two surfaces. SOLUTION: Island-shaped input/output electrodes 11 and 12 are formed at the central parts of adjacent surfaces, which have the same longitudinal and lateral sides and dimensions to the counter faces, of a rectangular parallelopiped dielectric 10, and a ground electrode 13 surrounding these electrodes while insulated is formed over almost all the surface. Then, this dielectric filter has a structure removing one part of the dielectric 10 on the edge side not contacted with the surfaces equipped with the input/output electrodes 11 and 12. Concerning such a dielectric filter, the resonance of TE mode, in which two resonance frequencies are equal, is mixed in a dielectric ceramic and by coupling these two resonances in the TE mode, the filter is constituted. Thus, the filter can be utilized in the high frequency bands of from 5 to 20 GHz and the miniaturized and thinned dielectric filter can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small-sized dielectric filter suitable for use in a high-frequency band of 5 GHz or more, comprising two resonators in one dielectric block,
A filter characteristic is obtained by combining them.

[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, and a filter combined with a dielectric coaxial resonator is generally used as a filter used in a mobile station.

[0003] However, when this dielectric coaxial resonator is used at a frequency of 5 GHz or more, it becomes difficult to obtain input / output coupling because the size defined by the frequency becomes thin.
Further, it is necessary to increase the outer diameter in order to secure a high Q. For example, an outer diameter of more than 10 millimeters is required to secure the required Q at a frequency of 5 GHz. This goes against the demand for miniaturization of electronic components and is not practical.
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 particular, an object of the present invention is to provide a very small dielectric filter which can be realized with a size of 5 mm or less.

[0005]

The present invention solves the above-mentioned problems by employing a structure completely different from that of the conventional dielectric filter.

That is, in a dielectric filter having input / output electrodes on a rectangular parallelepiped dielectric, input / output electrodes formed of island-shaped conductive films are provided on two adjacent surfaces of the rectangular parallelepiped, and at least an edge not in contact with the two surfaces is provided. The feature is that a part is chamfered. Alternatively, it is characterized in that at least a part of the edge not in contact with the two surfaces is provided with a stepped portion, or at least one of the edges of the edge not in contact with the two surfaces is chamfered.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An island-shaped input / output electrode is formed at the center of an adjacent surface of a rectangular parallelepiped dielectric having the same dimensions up to the vertical, horizontal, and opposing surfaces, and is insulated from and surrounds an earth electrode. Are formed on almost the entire surface. A structure is obtained in which a part of the dielectric on the edge that is not in contact with the surface provided with the input / output electrodes is removed.

In the dielectric filter according to the present invention, two TE-mode resonances having the same resonance frequency are mixed in the dielectric ceramic, and the two TE-mode resonances are combined to form a filter. .

[0009]

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

FIG. 1 is a perspective view of an example of a dielectric filter according to the present invention, wherein (a) and (b) show the same filter viewed from different angles. The rectangular parallelepiped dielectric 10 is 4.0 × 4.0 × 4.
The input / output electrodes 11 and 12 made of an island-shaped conductive film are formed on two adjacent surfaces having a size of 0 mm. The size of the input / output electrodes is 1.0 × 1.0 mm, and the periphery thereof is surrounded by a ground conductor 13 at intervals of 0.5 mm. The ground conductor 13 is formed on the entire other surface. A tapered portion 15 is formed at the edge of the rectangular parallelepiped dielectric that is not in contact with the surface on which the input / output electrodes are formed by cutting two surfaces at a position of 0.7 mm.

FIG. 2 is an explanatory diagram of the characteristics of the dielectric filter shown in FIG. 1, wherein the center frequency is 8.97 GHz and the 3 dB bandwidth is 17
At 0 MHz, the insertion loss was 0.61 dB. Note that poles are formed on both sides of the pass band.

FIG. 3 is a perspective view of another example of the dielectric filter according to the present invention, wherein (a) and (b) show the same filter viewed from different angles. The rectangular parallelepiped dielectric 30 is 6.0 × 4.0 ×
Input / output electrodes 31 and 32 of an island-shaped conductive film are formed on two adjacent surfaces having a size of 4.0 mm. The size of the input / output electrodes is 1.0 × 1.0 mm, and the periphery is surrounded by a ground conductor 33 at intervals of 0.5 mm. On the other surface, a ground conductor 33 is formed. A tapered portion 35 is formed at the edge of the rectangular parallelepiped dielectric that is not in contact with the surface on which the input / output electrodes are formed, with two surfaces cut off at 0.5 mm.

FIG. 4 is an explanatory diagram of the characteristics of the dielectric filter shown in FIG. 3, in which the center frequency is 7.55 GHz and the 3 dB bandwidth is 99.
MHz and the insertion loss were 0.84 dB. Note that poles are formed on both sides of the pass band.

FIG. 5 is a perspective view of another example of the dielectric filter according to the present invention. FIGS. 5A and 5B show the same filter viewed from different angles. The rectangular parallelepiped dielectric 50 is 4.0 × 4.0 ×
The input / output electrodes 51 and 52 are formed of an island-shaped conductive film on two adjacent surfaces having a size of 4.0 mm. The size of the input / output electrodes is 1.0 × 1.0 mm, and the periphery is surrounded by a ground conductor 53 at intervals of 0.5 mm. A ground conductor 53 is formed on the other surface. A step 56 is formed at the edge of the rectangular parallelepiped dielectric that is not in contact with the surface on which the input / output electrodes are formed, with two surfaces cut off at a right angle at 0.5 mm from the edge.

FIG. 6 is an explanatory diagram of the characteristics of the dielectric filter shown in FIG. 5, in which the center frequency is 8.97 GHz and the 3 dB bandwidth is 18
At 2 MHz, the insertion loss was 0.60 dB. Note that poles are formed on both sides of the pass band.

FIGS. 7A and 7B are perspective views of another example of the dielectric filter according to the present invention. FIGS. 7A and 7B show the same filter viewed from different angles. The rectangular parallelepiped dielectric 70 is 4.0 × 4.0 ×
The input / output electrodes 71 and 72 are formed of an island-shaped conductive film on two adjacent surfaces having a size of 4.0 mm. The size of the input / output electrodes is 1.6 × 1.6 mm, and the periphery is surrounded by a ground conductor 73 at intervals of 0.5 mm. A ground conductor is formed on the surface without the input / output electrodes. A tapered portion 77 is formed at the end of the edge of the rectangular parallelepiped dielectric that is not in contact with the surface on which the input / output electrodes are formed, cut off at a position of 1.0 mm.

FIGS. 8A and 8B are explanatory diagrams of the characteristics of the dielectric filter shown in FIG. 7, in which FIG. 8A shows a tapered portion 77 covered with a metal film, and FIG. 8B shows an exposed dielectric. It is. The former has a center frequency of 9.01 GHz and a 3 dB bandwidth of 161 MHz.
z, the insertion loss was 0.65 dB, and the latter had a center frequency of 9.00 GHz, a 3 dB bandwidth of 168 MHz, and an insertion loss of 0.66 dB. Note that a pole is formed on the lower side of the pass band.

FIG. 9 shows an example similar to FIG. 7, except that tapered portions are formed at both ends. As shown in FIG. 10, the characteristics were as follows: the center frequency was 9.01 GHz, the 3 dB bandwidth was 156 MHz, and the insertion loss was 0.65 dB.

FIG. 11 shows an example similar to that of FIG. 7, except that step portions are formed at both ends in place of the tapered portions. Its characteristic is that the center frequency is 9.01 as shown in FIG.
GHz, 3dB bandwidth was 159MHz, and insertion loss was 0.65dB.

[0020]

According to the present invention, a small and thin dielectric filter which can be used in a high frequency band can be obtained. In particular, since the filter is composed of only a dielectric material of 5 mm or less, an extremely small and lightweight dielectric filter is realized.

[Brief description of the drawings]

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

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

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

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

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

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

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

FIG. 8 is an explanatory diagram of characteristics of the dielectric filter of the embodiment shown in FIG.

FIG. 9 is a perspective view showing another embodiment of the present invention.

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

FIG. 11 is a perspective view showing another embodiment of the present invention.

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

[Explanation of symbols]

 10, 30, 50, 70: dielectric 11, 12, 31, 32, 51, 52, 71, 72: input / output electrode 13, 33, 53, 73: ground electrode 15, 35: taper portion 56: step portion 77 ： Tapered part

Claims (3)

[Claims] 1. A dielectric filter having input / output electrodes on a rectangular parallelepiped dielectric, comprising input / output electrodes formed of an island-shaped conductive film on two adjacent surfaces of the rectangular parallelepiped and having at least an edge not in contact with the two surfaces. A dielectric filter partially chamfered. 2. A dielectric filter comprising input / output electrodes on a rectangular parallelepiped dielectric, comprising input / output electrodes formed of an island-shaped conductive film on two adjacent surfaces of the rectangular parallelepiped and having at least an edge not in contact with the two surfaces. A dielectric filter comprising a step portion in a part thereof. 3. A dielectric filter provided with input / output electrodes on a rectangular parallelepiped dielectric, comprising input / output electrodes formed of island-shaped conductive films on two adjacent surfaces of the rectangular parallelepiped, and edges of edges not in contact with the two surfaces. A dielectric filter, wherein at least one of the portions is chamfered.