JP3368386B2 - Dielectric filter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter,
Especially used for mobile communication, center frequency is 100MHz
To several GHz dielectric filter.

[0002]

2. Description of the Related Art First, the structure of a conventional dielectric filter will be outlined.

With reference to FIG. 7, here, for convenience of explanation, a dielectric filter using three two-layer plate resonators will be described. First, second and third two-layer plate resonator 1
a, 1b and 1c are each two rectangular dielectrics 11
And 12 are provided. A conductor plate 2 is sandwiched between the dielectrics 11 and 12 as shown in the figure, and the first, second and third two-layer plate resonators 1a, 1b and 1c are fixed to each other by, for example, soldering. Composed. First and second
In the two-layer plate resonators 1a and 1b, the dielectrics 11 and 12 are short-circuited to each other at the rear end face in the figure, and the third two-layer plate resonator 1c has the dielectric 11 at the front end face in the figure. And 12 are shorted together.

Further, as shown in the drawing, electrostatic couplings for input and output are respectively formed on a part of the side surfaces of the first and second two-layer plate type resonators 1a and 1b located at both ends. The dielectrics 3a and 3b are joined, and electrostatic coupling conductors 4a and 4b are formed on the surfaces of the input / output electrostatic coupling dielectrics 3a and 3b, respectively. Input / output terminals 6 and 7 are attached to the electrostatic coupling conductors 4a and 4b. The first, second and third two-layer plate type resonators 1a, 1b and 1c are grounding conductor plates 5a.
And 5b.

Here, referring to FIG. 8, a grounding conductor plate 5 is provided.
The flange portions a and 5b are joined to each other to form a rectangular tubular body. The first, second and third two-layer plate resonators 1a,
The upper and lower surfaces of 1b and 1c are in contact with the inner surfaces of the grounding conductor plates 5a and 5b, respectively. For example, first,
The second and third two-layer plate resonators 1a, 1b and 1c and the grounding conductor plates 5a and 5b are coupled by ohmic coupling.

In the illustrated dielectric filter, the electromagnetic fields leaking from the first, second and third two-layer plate type resonators 1a, 1b and 1c interfere with each other, whereby the first and second electromagnetic fields leak.
And the third two-layer plate resonators 1a, 1b and 1c are coupled to each other. The first and second two-layer plate type resonators 1a and 1b are respectively formed of the electrostatic coupling dielectric 3a.
And 3b and the electrostatic coupling conductors 4a and 4b are connected to the input / output terminals 6 and 7, so that the first, second, and third two-layer plate resonators are provided between the input / output terminals as a whole. 1
The vicinity of the resonance frequencies of a, 1b and 1c is the pass band.

FIG. 9 shows the characteristics of the dielectric filter having the above-mentioned structure. The dielectric filter used to obtain the characteristics shown in FIG. 9 has W = 1.4 mm, T = 2.8 mm, and L = W, T, L, and d in FIGS. 6 and 7, respectively.
7.0mm, d = 2.0mm, the dielectric constant of the dielectric is 9
It was set to 0.

In FIG. 9, the center frequency f ₀ is about 151.
0 MHz, 172 adjacent to the high frequency side of the pass band
There is a pole near 0 MHz. Also, f ₀ +150
The relative attenuation at MHz is about 45 dB.

[0009]

By the way, a large amount of attenuation is generally required near the pass band of the filter.
Since the rising characteristics of the filter are limited by the number of resonator elements and the Q value, it is difficult for the conventional dielectric filter to obtain a large amount of attenuation near the pass band.

An object of the present invention is to provide a dielectric filter capable of obtaining a large amount of attenuation near the pass band.

[0011]

According to the dielectric filter of the present invention, in a dielectric filter in which the lower surfaces of a plurality of resonators are connected to a ground conductor plate, the dielectric filters are arranged at a predetermined interval from each other, At least two resonators having the lower surface and the upper surface coupled to the ground conductor plate, and at least one resonator having the upper surface not coupled to the ground conductor plate connected to the lower surface A dielectric filter characterized by the above is obtained.

Further, according to the dielectric filter of the present invention, the conductor plate is sandwiched between the two ground conductor plates facing each other and the conductor plate is sandwiched between the two dielectric bodies having a rectangular prism shape. A two-layer plate resonator having a plurality of two-layer plate resonators arranged at a predetermined distance from each other, and each of the two two-layer plate resonators having a coupling means between an input terminal and an output terminal. The dielectric filter according to claim 1, wherein at least one two-layer plate resonator is arranged between the two two-layer plate resonators in a state where only the lower surface thereof is connected to the ground conductor plate. Is obtained.

Further, according to the dielectric filter of the present invention, the conductor plate is sandwiched between the two ground conductor plates facing each other, and the conductor plate is sandwiched between the two dielectric bodies having a rectangular prism shape. A two-layer plate resonator having a plurality of two-layer plate resonators arranged at a predetermined distance from each other, and each of the two two-layer plate resonators having a coupling means between an input terminal and an output terminal. The single-plate resonator in which an electrode is formed between one of the upper surface, the lower surface and the end surface of at least one dielectric between the two two-layer plate resonators, and only the lower surface is the ground conductor. A dielectric filter is obtained which is arranged in a state of being connected to a plate.

Further, according to the dielectric filter of the present invention, the conductor plate is sandwiched between the two ground conductor plates facing each other, and the conductor plate is sandwiched between the two dielectric bodies having a rectangular prism shape. A two-layer plate resonator having a plurality of two-layer plate resonators arranged at a predetermined distance from each other, and each of the two two-layer plate resonators having a coupling means between an input terminal and an output terminal. In two, two or more two-layer plate resonators arranged side by side between the two two-layer plate resonators are connected to the ground conductor plate only at their lower surfaces,
Further, there is obtained a dielectric filter characterized in that the upper surfaces thereof are arranged electrically independent of each other and connected to each other by the conductor plates.

[0015]

In the present invention, the pole existing adjacent to the high frequency side of the pass band can be further shifted to the pass band side, the rising characteristic on the high frequency side of the pass band is improved, and a large amount of attenuation is secured. You can

[0016]

EXAMPLES The present invention will be described below with reference to examples.

A dielectric filter according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. Here, the same components as those of the dielectric filter shown in FIG. 6 are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 1, the structure and arrangement of the two-layer plate resonator are the same as those of the dielectric filter shown in FIG.

The difference from the dielectric filter shown in FIG. 7 is that
In the dielectric filter of this embodiment, one ground conductor plate 5a is used.
Instead of the above, the ground conductor plate 5c divided into two pieces is used. One of the ground conductor plates 5c is electrically connected to the first two-layer plate resonator 1a, and the ground conductor plate 5c
The other of the two is electrically connected to the second two-layer plate resonator 1b. That is, the third two-layer plate resonator 1c is not electrically connected to either of the two ground conductor plates 5c.

Here, in FIG. 1, the outer dimensions of the first and second two-layer plate resonators 1a and 1b located at both ends are W = 1.4 mm, T = 2.8 mm, L = 7. 0 mm
And that of the third two-layer plate resonator 1c located at the center has W = 1.4 mm, T = 2.8 mm, L = 7.5 m.
m. The distance between the first, second and third two-layer plate resonators 1a, 1b and 1c is d = 2.0 mm.
And the dielectric constant of those dielectrics is 90. The measurement of the filter characteristics of the dielectric filter thus created is shown in FIG.

As shown in FIG. 3, the center frequency f ₀ is about 1
503 MHz, which is adjacent to the high frequency side of the pass band and is 1
There is a pole near 570 MHz. Also, f ₀ +1
The relative attenuation amount at 50 MHz is about 55 dB.

As is clear from the comparison between FIG. 3 and FIG.
The dielectric filter of this embodiment has a
The pole shifts to the pass band side by about 150MHz, and about 10d
It can be seen that B also has a large amount of attenuation.

FIG. 4 shows a dielectric filter according to the second embodiment of the present invention. Here, the same components as those of the dielectric filter shown in FIG. 7 are designated by the same reference numerals, and the description thereof will be omitted. The dielectric filter of this embodiment is the same as the dielectric filter shown in FIG. 7 except that a single plate resonator 1d is used instead of the third two-layer plate resonator 1c.

The single-plate resonator 1d is one in which an electrode is formed by metal plating or the like on one of the upper surface, the lower surface and the end surface of the dielectric. In FIG. 4, the rear side of the single plate resonator 1d is the open end. As shown in FIG. 4, the single plate resonator 1d
Are electrically connected to the ground conductor plate 5a, but are not electrically connected to the ground conductor plate 5b.

Even with the dielectric filter having such a structure, the rising characteristics on the high frequency side of the pass band can be improved as compared with the conventional filter shown in FIG. 6, and a large amount of attenuation can be secured near the pass band. can do.

Referring to FIG. 5, the dielectric filter according to the third embodiment of the present invention has first, second, third and fourth two-layer plate resonators 1a, 1b, 1e and 1f. . These resonators 1a, 1b, 1e and 1f are connected to the ground conductor 5d with a space d so that the short-circuited end and the open end are staggered. In FIG. 5, the front sides of the first and fourth two-layer plate resonators 1a and 1f are open ends, and the second and third two-layer plate resonators 1b and 1e are open ends.
In addition, the first and second double-layer plate resonators 1 located at both ends
Input / output terminals 6 and 7 are connected to a and 1b via electrostatic coupling dielectrics 3a and 3b and electrostatic coupling conductors 4a and 4b, respectively. A ground conductor plate 5c is connected to the upper surfaces of the first and second two-layer plate resonators 1a and 1b located at both ends. Third and fourth centrally located
The two-layer plate resonators 1e and 1f of FIG.
Electrically independent of c, they are electrically connected by the conductor plate 8.

Even with the dielectric filter having such a structure, the rising characteristics on the high frequency side of the pass band side can be improved as compared with the conventional filter shown in FIG. 7, and a large amount of attenuation is secured near the pass band. can do.

FIG. 6 shows a dielectric filter according to the fourth embodiment of the present invention. The dielectric of this example is shown. In this embodiment, the same components as those of the dielectric filter shown in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted.

Referring to FIG. 6, the dielectric filter according to the fourth embodiment of the present invention has first, second and fourth two-layer plate resonators 1a, 1b and 1f. These resonators 1a, 1b, and 1f are connected to the ground conductors 5a and 5b. In FIG. 6, the first and fourth two-layer plate resonators 1a and 1f have an open end on the front side, and the second two-layer plate resonator 1b has an open end on the rear side. In addition, the first and second two-layer plate resonators 1a and 1b located at both ends are inserted via the electrostatic coupling dielectrics 3a and 3b and the electrostatic coupling conductors 4a and 4b, respectively. The output terminals 6 and 7 are connected. First and fourth two-layer plate resonators 1a and 1
Between f, the first single-plate resonator 1d is connected with its lower surface connected to the ground conductor 5d. Second and fourth
A second single plate resonator 1g is connected between the two-layer plate resonators 1b and 1f with the lower surface thereof being connected to the ground conductor 5d. First and second single-plate type resonators 1d and 1g
May be a two-layer plate resonator, and in the case of a two-layer plate resonator, the rear side of these is the open end. The first and second single-plate type resonators 1d and 1g are electrically connected to the ground conductor plate 5d, but are not electrically connected to the ground conductor plate 5c.

Even with the dielectric filter having such a structure, the rising characteristic on the high frequency side of the pass band side can be improved as compared with the conventional filter shown in FIG. 7, and a large amount of attenuation is secured near the pass band. can do.

Although the dielectric filter having 3 to 5 resonators has been described in the above embodiment, a dielectric filter having 6 or more resonators can be similarly constructed. In this case, the resonators are arranged at a predetermined interval from each other, and the resonators located at both ends are respectively formed with input / output terminals.

[0031]

As described above, according to the present invention, the rising characteristic on the high frequency side of the pass band can be improved, and as a result, a large amount of attenuation can be secured near the pass band.

[Brief description of drawings]

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

FIG. 2 is a front view of the dielectric filter shown in FIG.

FIG. 3 is a frequency characteristic diagram showing filter characteristics of the dielectric filter shown in FIG.

FIG. 4 is a front view showing a dielectric filter according to a second embodiment of the present invention.

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

FIG. 6 is a front view showing a dielectric filter according to a fourth embodiment of the present invention.

FIG. 7 is an exploded perspective view showing a conventional dielectric filter.

FIG. 8 is a front view of the dielectric filter shown in FIG.

9 is a frequency characteristic diagram showing filter characteristics of the dielectric filter shown in FIG.

[Explanation of symbols]

1a, 1b, 1c, 1d, 1e, 1f, 1g Resonator 11,12 Dielectric 2,8 conductor plate 3a, 3b Input / output electrostatic coupling dielectric 4a, 4b Electrostatic coupling conductor 5a, 5b, 5c, 5d Grounding conductor plate 6,7 Input / output terminals

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Ken Yano Ken 398 Kokomoguchi, Takatsu-ku, Kawasaki City, Kanagawa Tokin Co., Ltd. (56) Reference JP-A-64-37101 (JP, A) (58) Fields investigated (58 Int.Cl. ⁷ , DB name) H01P 1/205 H01P 1/203 H01P 7/08

Claims (4)

(57) [Claims] 1. A dielectric filter in which the lower surfaces of a plurality of resonators are connected to a ground conductor plate at a predetermined distance from each other, and at least the lower surface and the upper surface of the resonator are coupled to the ground conductor plate. A dielectric filter comprising: two resonators; and at least one resonator in which the ground conductor plate connected to the lower surface and the upper surface are not coupled. 2. Two two-layer plate resonators, which are formed by sandwiching a conductor plate between two ground conductor plates facing each other and sandwiching the conductor plate in the middle of two dielectrics having a rectangular prism shape, In the dielectric filter, which is arranged at a predetermined interval, and wherein the two two-layer plate resonators are provided with coupling means between the input terminal and the output terminal, the two two-layer plate resonators are provided. At least one two-layer plate resonator between the resonators,
A dielectric filter characterized in that it is arranged with only its lower surface connected to the ground conductor plate. 3. Two two-layer plate type resonators, which are formed by sandwiching a conductor plate between two grounding conductor plates facing each other and sandwiching the conductor plate in the middle of two dielectrics having a rectangular prism shape. A dielectric filter comprising two two-layer plate resonators arranged at a predetermined interval, each of which is provided with a coupling means between an input terminal and an output terminal of the two two-layer plate resonators. Characterized in that a single-plate type resonator having electrodes formed on at least one of an upper surface, a lower surface and an end surface of a dielectric is arranged in a state where only the lower surface is connected to the ground conductor plate. And a dielectric filter. 4. Two two-layer plate resonators, which are formed by sandwiching a conductor plate between two ground conductor plates facing each other and sandwiching the conductor plate between two dielectric bodies having a rectangular prism shape, A dielectric filter comprising two two-layer plate resonators arranged at a predetermined interval, each of which is provided with a coupling means between an input terminal and an output terminal of the two two-layer plate resonators. Between two or more vessels
A state in which the two-layer plate type resonators arranged in a staggered manner are connected to the ground conductor plate only at their lower surfaces, and are electrically connected to the ground conductor plates at their upper surfaces by conductor plates independently of each other. A dielectric filter characterized by being arranged in.