JPH0823207A - Dielectric filter and multistage dielectric filter - Google Patents

Abstract

PURPOSE:To provide a dielectric filter which an improve its compactness in a simple structure and also can easily adjust its frequency. CONSTITUTION:A through hole 2 is drilled through a prism-shaped molded body 1 made of a dielectric material from its upper face to its lower face. A ground electrode 1a is formed on the outer circumferential surface of the body 1 excluding its upper face, and an inner circumferential electrode 2a is formed in the hole 2. Both electrodes 1a and 2a conduct on the lower face of the body 1. Then a deleted part 5 is secured at a part of the electrode 1a at a position near the edgeline set between the upper and lower faces of the body 1, and a coupling electrode 4 is formed in the part 5 to cover the upper and side faces of the body 1 and at a position near the edgeline. The electrode 4 is positioned opposite to the electrode 1a with no mutual contact. Then an open end electrode 3 is formed opposite to the electrode 4 with no mutual contact and in a capacitive coupling state. In such a constitution, a dielectric resonator 6 is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter used in, for example, a mobile phone and a multistage dielectric filter using the dielectric filter.

[0002]

2. Description of the Related Art In recent years, with respect to the dielectric filter, the practicality of the dielectric filter has been noticed as the size and cost of mobile phones have been reduced, and a small size, high performance and low price have been demanded.

A conventional dielectric filter will be described below with reference to the drawings. FIG. 10A shows a perspective view of a conventional dielectric filter. In FIG. 10A, the coupling electrodes 26a, 26b,
The combined substrate 24 having 26c and 26d is connected,
In addition, the dielectric resonators 22a and 22b are connected to the electrode patterns 26a and 26a through the coupling fittings 23a and 23b, respectively.
It is mounted so as to be connected to 26b. Figure 10 (b)
Shows an equivalent circuit of a conventional dielectric filter.
27a and 27b are dielectric resonators 22a and 22b, respectively.
28a is an input / output electrode 26c and an interstage electrode 26a.
, 28b is the capacitance of the inter-stage electrodes 26a and 26b,
Reference numeral 28c denotes a capacitance between the inter-stage electrode 26b and the input / output electrode 26d, which forms a dielectric filter, and the filter characteristic as shown in FIG. 10C is obtained.

[0004]

In the above structure, the dielectric filter has the mounting substrate 25 and the coupling substrate 24,
Since the number of parts is increased, the manufacturing process is complicated, downsizing is difficult, and it is difficult to adjust the frequency of the filter.

In order to solve the above problems, the present invention provides
It is an object of the present invention to provide a dielectric filter which does not require the mounting substrate 25 and the coupling substrate 24 and can be reduced in size with a simple structure and whose frequency can be easily adjusted.

[0006]

In order to solve the above problems, a dielectric filter of the present invention comprises a columnar molded body made of a dielectric material, a through hole penetrating the upper and lower surfaces of the molded body,
An inner peripheral electrode provided on the inner peripheral surface of the through hole, an outer peripheral electrode provided on the outer peripheral surface excluding the upper surface of the molded body, and an open electrode provided on the upper surface of the molded body, and the upper surface and side surfaces of the molded body. A coupling electrode is formed in the vicinity of the ridgeline formed on the above and extends over the same upper surface and side surface, and the coupling electrode is arranged to face the outer peripheral electrode and the open electrode in a non-contact state.

[0007]

With the above structure, the coupling electrode can be capacitively coupled to the outer peripheral electrode and the open electrode, and the mounting substrate and the coupling substrate are not required, and the frequency of the filter can be easily adjusted by cutting the coupling electrode. You can

[0008]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a perspective view of the first embodiment of the present invention. In FIG. 1, reference numeral 1 is a prismatic or cylindrical molded body made of a dielectric material, and a through hole 2 is provided from the upper surface to the lower surface thereof. Further, the ground electrode 1a is provided on the outer peripheral surface of the molded body 1 excluding the upper surface, and the inner peripheral electrode 2a is provided in the through hole 2.
The inner peripheral electrode 2a is electrically connected to the lower surface. Further, an open end electrode 3 is provided on the upper surface to shorten the resonator length. Further, one removal portion 5 is provided in a part of the ground electrode 1a near the ridgeline formed by the upper surface and the side surface of the molded body 1,
One coupling electrode 4 is provided in the vicinity of the ridgeline in the removal portion 5, and the ground electrode 1a and the coupling electrode 4 are opposed to each other in a non-contact manner. Then, the open-end electrode 3 and the coupling electrode 4 are capacitively coupled to form a dielectric resonator 6. The dielectric resonator 6 receives the coupling electrode 4 and serves as an output terminal 8 to form a one-stage band elimination type dielectric filter.

An equivalent circuit is shown in FIG. Reference numeral 9 denotes a resonance portion of the dielectric resonator 6, and the coupling electrode 4 is provided from the upper surface to the side surface of the molded body 1 through the ridge line, so that 10 is a capacitance between the open end electrode 3 and the coupling electrode 4, and 11 Is the capacitance between the coupling electrode 4 and the ground electrode 1a.

The operation will be described below. By removing the trimming portion 7a of the coupling electrode 4 near the open end electrode 3 with a router or the like, the coupling capacitance 10 shown in FIG. 2 (a) is reduced, and as a result, the band characteristic is narrowed and the filter characteristic is easily adjusted. It becomes possible to do. Figure 2
A filter waveform is shown in (b). 12a is before adjustment, 12b
Shows the adjusted waveform with narrow band characteristics.

The earth electrode 1a near the coupling electrode 4 is also provided.
By similarly removing the trimming portion 7b of FIG.
The coupling capacitance 11 shown in (a) is reduced, and as a result, the filter characteristic behaves as if the coupling capacitance 10 were increased, the band characteristic is broadened, and the filter characteristic can be easily adjusted. FIG. 2C shows the filter waveform. 13a shows the waveform before adjustment, and 13b shows the waveform after adjustment, which broadens the band characteristic.

As described above, in the first embodiment, the one-stage band elimination filter does not require a mounting substrate, a coupling substrate, etc., and is small in size, and the frequency adjustment of the filter can be facilitated. In particular, since the coupling electrode 4 is provided from the upper surface to the side surface of the molded body 1 via the ridgeline, the band characteristic can be easily widened or narrowed.

(Embodiment 2) FIG. 3 is a perspective view of a second embodiment of the present invention. In FIG. 3, reference numeral 1 is a prismatic or cylindrical molded body made of a dielectric material, and a through hole 2 is provided from the upper surface to the lower surface thereof. Further, an earth electrode 1a is provided on the outer peripheral surface excluding the upper surface of the molded body 1, and an inner peripheral electrode 2a is provided in the through hole 2. These ground electrode 1a and inner peripheral electrode 2a are on the lower surface. There is continuity. Further, an open end electrode 3 is provided on the upper surface to shorten the resonator length. Further, the removing portion 5 is formed on a part of the ground electrode 1a near the ridgeline formed by the upper surface and the side surface of the molded body 1.
a and 5b are provided at two positions, and two coupling electrodes 4a and 4b are provided near the ridge lines in the removed portions 5a and 5b, and the ground electrode 1a and the coupling electrodes 4a and 4b are opposed to each other in a non-contact manner.
Then, the open-end electrode 3 and the coupling electrodes 4a and 4b are capacitively coupled to form the dielectric resonator 6.

The dielectric resonator 6 serves as a one-stage band elimination type dielectric filter using the coupling electrodes 4a and 4b as the input / output terminal 8 of FIG. 4 (a). An equivalent circuit is shown in FIG. 9
Reference numeral 10 is a resonance portion of the dielectric resonator 6, 10 is a capacitance between the open end electrode 3 and the coupling electrodes 4a and 4b, and 11 is a coupling electrode 4
It is the capacitance between a and 4b and the ground electrode 1a.

The operation will be described below. By removing the trimming portion 7a of the coupling electrode 4 near the open end electrode 3 with a router or the like, the coupling capacitance 10 shown in FIG. 4 (a) is reduced, and as a result, the band characteristic is narrowed and the filter characteristic is easily adjusted. It becomes possible to do. FIG.
A filter waveform is shown in (b). 14a is before adjustment, 14b
Shows the adjusted waveform with narrow band characteristics.

The earth electrode 1a near the coupling electrode 4 is also provided.
By similarly removing the trimming portion 7b of FIG.
The coupling capacitance 11 shown in (a) is reduced, and as a result, the filter characteristic behaves as if the coupling capacitance 10 were increased, the band characteristic is broadened, and the filter characteristic can be easily adjusted. FIG. 4C shows the filter waveform. Reference numeral 15a indicates a waveform before adjustment, and reference numeral 15b indicates a waveform after adjustment.

As described above, in the second embodiment, as in the first embodiment, the one-stage band elimination filter does not require a mounting substrate, a coupling substrate, etc., and is compact, and the frequency of the filter is adjusted. Can be facilitated.

(Embodiment 3) FIG. 5 shows a perspective view of a third embodiment of the present invention. 6 (a) and 6 (b) are front and side perspective views of a dielectric resonator forming the filter, respectively. In FIGS. 6A and 6B, reference numeral 1 denotes a prismatic or cylindrical molded body made of a dielectric material, and a through hole 2 is provided from the upper surface to the lower surface thereof. Further, an earth electrode 1a is provided on the outer peripheral surface excluding the upper surface of the molded body 1, and an inner peripheral electrode 2a is provided in the through hole 2. These ground electrode 1a and inner peripheral electrode 2a are on the lower surface. There is continuity. Further, an open end electrode 3 is provided on the upper surface to shorten the resonator length. Further, the removing portion 5 is provided in a part of the earth electrode 1a near the ridgeline formed by the upper surface and the side surface of the molded body 1, and the coupling electrode 4 is provided in the vicinity of the ridgeline in the removing portion 5, and the ground electrode 1a is provided. And the coupling electrode 4 are opposed to each other in a non-contact manner. The open end electrode 3 and the coupling electrode 4 are capacitively coupled. In addition, the removing portion 17 is provided at one place in a part of the ground electrode 1a, and the coupling electrode 16 is provided in the removing portion 17, and the inner peripheral electrode 2a and the coupling electrode 16 are capacitively coupled to each other to form the dielectric resonator 6. Are configured. FIG. 5 shows a filter using two of the dielectric resonators 6. The two dielectric resonators 6a and 6b are coupled via the respective coupling electrodes 4. Further, the other coupling electrode 16 is capacitively coupled to the respective dielectric resonators 6a and 6b and functions as an input / output terminal to form a two-stage filter as a whole. 7B is an equivalent circuit of the dielectric resonator 6 shown in FIGS. 6A and 6B, and 9 is a resonance portion of the dielectric resonator 6.
10a is a capacitance between the inner peripheral electrode 2a and the coupling electrode 16,
10b is a capacitance between the open end electrode 3 and the coupling electrode 4, and
1a and 11b are capacitors between the coupling electrodes 4 and 16 and the ground electrode 1a.

FIG. 7A is an equivalent circuit of the dielectric filter shown in FIG. 5, in which 9a and 9b are dielectric resonators 6a and 6a, respectively.
In the resonance part of 6b, 10a and 10d are the capacitances of the inner peripheral electrode 2a and the coupling electrode 16, 10b and 10c are the capacitances of the open end electrode 3, 11a and 11d are the capacitances between the coupling electrode 16 and the ground electrode 1a, and 11b. , 11c are capacitances between the coupling electrode 4 and the ground electrode 1a. When the coupling electrodes 4 are brought into contact with each other, the coupling capacitors 10b and 10c are coupled in series, so that a two-stage filter is formed.

The operation will be described below. In FIG. 5, by removing the trimming portion 7a of the coupling electrode 4 near the open end electrode 3 with a luter or the like, the coupling capacitances 10b and 10c shown in FIG. 7A are reduced, and as a result,
The band characteristic is narrowed, and the filter characteristic can be easily adjusted. FIG. 7C shows the filter waveform. 18
A is a waveform before adjustment and 18b is a waveform after adjustment, and the band characteristic is narrowed.

Further, the earth electrode 1a near the coupling electrode 4
By removing the trimming portion 7b of FIG.
The capacities 11b and 11c shown in (a) are reduced, and as a result, the filter characteristic is as if the band characteristic is widened, and the filter characteristic can be easily adjusted. Figure 7 (d)
Shows the filter waveform. 19a shows a waveform before adjustment, and 19b shows a waveform after adjustment, which broadens the band characteristic.

As described above, in the third embodiment, the two-stage band elimination filter does not require a mounting substrate, a coupling substrate, or the like, and it is easy to adjust the frequency of the filter.

(Fourth Embodiment) FIG. 8 shows a perspective view of a fourth embodiment of the present invention. As shown in FIG. 8, the dielectric filter according to the fourth embodiment is the same as that used in the second and third embodiments.
It is a dielectric filter using one and two dielectric resonators 6 shown in (a) and (b), respectively. The three dielectric resonators 6a, 6b, 6c are coupled to each other via the coupling electrodes 4. The other coupling electrode 16 of each of the dielectric resonators 6a and 6c is capacitively coupled to each of the dielectric resonators 6a and 6c, and functions as an input / output terminal to form a three-stage filter as a whole.

FIG. 9A shows an equivalent circuit. 9a, 9
Reference numerals b and 9c are resonance portions of the dielectric resonators 6a, 6b and 6c, and 10a and 10f are inner peripheral electrodes 2a and coupling electrodes 1.
6, 10b, 10c, 10d and 10e are capacitances between the open end electrode 3 and the coupling electrode 4, and 11a and 11f are capacitances between the coupling electrode 16 and the ground electrode 1a. Also, 1
1b, 11c, 11d and 11e are capacitors between the coupling electrode 4 and the ground electrode 1a. When the coupling electrodes 4 are brought into contact with each other, the coupling capacitances 10b, 10c, 10d and 10e are respectively generated.
Are connected in series to form a three-stage filter.

The operation will be described below. By removing the trimming portion 7a of the coupling electrode 4 near the open end electrode 3 with a router or the like, the coupling capacitances 10b, 10c, 10d, 10e shown in FIG. 9A are reduced, and as a result, the band characteristic is narrowed, It is possible to easily adjust the filter characteristics. FIG. 9B shows the filter waveform.
20a is a waveform before adjustment and 20b is a waveform after adjustment, and the band characteristic is narrowed.

The earth electrode 1a near the coupling electrode 4
Similarly, by removing the trimming portion 7b of FIG.
The capacities 11b, 11c, 11d, and 11e shown in (a) are reduced, and as a result, the filter characteristic is widened as if it were a band characteristic, and the filter characteristic can be easily adjusted. FIG. 9C shows the filter waveform. Reference numeral 21a indicates a waveform before adjustment, and reference numeral 21b indicates a waveform after adjustment.

Although the dielectric resonators are contacted and connected in the third and fourth embodiments, the same effect can be obtained by using a substrate and connecting the wirings on the substrate.

As described above, in the fourth embodiment, the three-stage band elimination filter does not require a mounting substrate, a coupling substrate, etc., and is small in size, and the frequency adjustment of the filter can be facilitated.

[0030]

As described above, according to the present invention, the coupling electrode is provided near the ridgeline formed by the upper surface and the side surface of the molded body, and the coupling electrode is electrically connected to the outer peripheral electrode and the open electrode. Therefore, capacitive coupling can be performed, a mounting substrate and a coupling substrate are not required, and the frequency of the filter can be easily adjusted by cutting the coupling electrode.

As a result, it is possible to provide a compact dielectric filter whose frequency can be easily adjusted.

[Brief description of drawings]

FIG. 1 is a perspective view of a dielectric filter according to a first embodiment of the present invention.

2A is an equivalent circuit diagram of the same dielectric filter, FIG. 2B is a waveform diagram of the same dielectric filter, and FIG. 2C is a waveform diagram of the same dielectric filter.

FIG. 3 is a perspective view of a dielectric filter according to a second embodiment of the present invention.

4A is an equivalent circuit diagram of the same dielectric filter, FIG. 4B is a waveform diagram of the same dielectric filter, and FIG. 4C is a waveform diagram of the same dielectric filter.

FIG. 5 is a perspective view of a dielectric filter according to a third embodiment of the present invention.

FIG. 6A is a perspective view of a dielectric resonator used in the same dielectric filter. FIG. 6B is a perspective view of another dielectric resonator used in the same dielectric filter.

7A is an equivalent circuit diagram of the same dielectric filter, FIG. 7B is an equivalent circuit diagram of a dielectric resonator of the same dielectric filter, and FIG. 7C is a waveform diagram of the same dielectric filter. Figure

FIG. 8 is a perspective view of a dielectric filter according to a fourth embodiment of the present invention.

9A is an equivalent circuit diagram of the dielectric filter, FIG. 9B is a waveform diagram of the dielectric filter, and FIG. 9C is a waveform diagram of the dielectric filter.

10A is a perspective view of a dielectric filter of a conventional example, FIG. 10B is an equivalent circuit diagram of the dielectric filter, and FIG. 10C is a waveform diagram of the dielectric filter.

[Explanation of symbols]

 1 Molded Body 1a Ground Electrode 2 Through Hole 2a Inner Circumferential Electrode 3 Open End Electrode 4 Coupling Electrode 5 Removal Section 6 Dielectric Resonator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideyuki Miyake 55-12 Hama Ozumi, Tanabe-cho, Tsuzuki-gun, Kyoto Pref. 55-12 Matsushita Nitto Electric Co., Ltd.

Claims (2)

[Claims] 1. A columnar molded body made of a dielectric material, a through hole penetrating the upper and lower surfaces of the molded body, an inner peripheral electrode provided on an inner peripheral surface of the through hole, and an upper surface of the molded body. A coupling electrode that includes an outer peripheral electrode provided on the outer peripheral surface excluding the above and an open-end electrode provided on the upper surface of the molded body, and extends over the upper surface and the side surface near the ridgeline formed by the upper surface and the side surface of the molded body. And the coupling electrode is opposed to the outer peripheral electrode and the open end electrode in a non-contact state. 2. A multistage dielectric filter comprising a plurality of dielectric filters according to claim 1, wherein adjacent dielectric filters are electrically connected by a coupling electrode.