JPH0744083Y2 - Dielectric filter - Google Patents

Description

[Detailed Description of the Invention] [Industrial application] The present invention relates to a dielectric filter used in a high frequency band such as a VHF band, a UHF band, and a microwave band. More specifically, the resonance frequency can be easily adjusted. Dielectric filter.

[Prior Art] It is publicly known that a bandpass filter used for an ultra-high-frequency communication device such as a car phone, a personal radio, a cordless phone, and a BS converter is composed of a dielectric filter including a distributed constant dielectric resonator. Is. FIG. 7 shows an example of a conventional dielectric filter. This dielectric filter is a microstrip line type, and the first and second strip conductors (2) (3) are formed on one main surface (upper surface) of a dielectric plate (1) made of, for example, barium titanate-based porcelain. )When,
It is provided with first and second coupling electrodes (4) and (5), and an input terminal (6) and an output terminal (7) which are continuous with the first and second coupling electrodes (4) and (5). The ground conductor (8) is provided on the other main surface (lower surface). The first and second strip conductors (2) and (3) are linearly extended from one end surface to the other end surface of the dielectric plate (1) and arranged in parallel with each other, and are distributed constant type of 1/4 wavelength. In order to form the first and the second resonant circuit, the one end of these is open and the other end is connected to the ground conductor (8). The first and second strip conductors (2) and (3), the first and second coupling electrodes (4) and (5), the input terminal (6), the output terminal (7), and the ground conductor (8) are , A conductive film formed by applying, for example, a silver paste on the dielectric plate (1) and baking it.

FIG. 4 shows an equivalent circuit of the dielectric filter of FIG. The input coupling capacitance C1 is obtained between the first coupling electrode (4) and the first strip conductor (2), and the first resonance circuit composed of the capacitance C3 and the inductance L1 is the first strip conductor. Obtained based on (2), capacitance C4 and inductance L2
A second resonant circuit consisting of and is obtained on the basis of the second strip conductor 3, and the capacitance C5 coupling the first and second resonant circuits to each other is defined by the first and second strip conductors (2).
The output coupling capacitance C2 is obtained based on the capacitance between (3) and between the second strip conductor (3) and the second coupling electrode (5). It should be noted that the first and second strip conductors (2) and (3) are coupled by both capacitance and induction, but the ratio of capacitive coupling is higher than the ratio of inductive coupling. Therefore, the coupling is indicated by the capacitance C5 in the equivalent circuit of FIG.

[Problems to be Solved by the Invention] Since the microstrip line type dielectric filter uses a dielectric as a substrate, it has an advantage that the wavelength shortening rate is large and the size can be reduced, but the dielectric is There is a disadvantage that it is difficult to obtain a predetermined resonance frequency and pass band width due to variations in the dimensions of the plate, variations in the relative dielectric constant, variations in the dimensions of the strip conductor, and the like. That is, conventionally, when the predetermined resonance frequency cannot be obtained, the open ends (2) of the strip conductors (2) and (3) are
a) The resonance frequency was adjusted by mechanically or laser shaving (3a), but the resonance frequency was significantly changed by a slight change in the area to be scraped off. ) It was necessary to bring the resonance frequency close to the target value while repeating the cutting of (3), and the adjustment work was troublesome. In addition, it was practically impossible to return the strip conductors (2) and (3) to their original positions when they were scraped off too much. Also, strip conductors (2) (3)
It was difficult to adjust the degree of coupling between them.

In order to solve the above-mentioned problems, it is described in Japanese Utility Model Publication No. 56-96708 that a dielectric chip is arranged between or on the strip lines of a strip line type dielectric filter. . However, in this structure, since the arrangement position of the dielectric chip is not specified, the adjustment work for obtaining desired filter characteristics becomes complicated. Moreover, since the dielectric chip is arranged on the strip conductor, the dielectric filter becomes thick. Further, since the dielectric chip is arranged so as to partially overlap the strip conductor, the Q of the resonator is deteriorated and the insertion loss of the filter is increased.

Therefore, an object of the present invention is to provide a dielectric filter that can suppress the increase in thickness and obtain desired filter characteristics accurately and easily.

[Means for Solving the Problems] The present invention for achieving the above object will be described with reference to the reference numerals of the drawings showing an embodiment. A dielectric plate (1) and the dielectric plate (1). A plurality of strip conductors (2) and (3) which are provided on one surface and are arranged parallel to each other;
In a dielectric filter having a ground conductor (8) provided on the other surface of the dielectric plate (1), the plurality of strip conductors (2) on one surface of the dielectric plate (1). ) A plurality of adjustment holes (9a) to (9
i) are provided, and the plurality of adjustment holes (9a) to (9
i) are arranged in the same direction as the extending direction of the strip conductors (2) and (3), and the plurality of adjusting holes (9a) to
The present invention relates to a dielectric filter in which a dielectric piece (10) is inserted in a material selected from (9i).

[Operation and Effect of Invention] The present invention has the following operation and effect.

(A) When the dielectric piece (10) is inserted into the adjustment holes (9g) to (9i) of the dielectric plate (1), an effect equivalent to changing the relative permittivity of the dielectric plate (1) is obtained, Strip conductor (2)
The effective dielectric constant between (3) changes, and the degree of mutual coupling and the resonance frequency change. Multiple adjustment holes (9g) ~
Since (9i) is arranged at a predetermined position, the coupling degree and the resonance frequency when the dielectric piece (10) is selectively inserted into the plurality of adjustment holes (9g) to (9i) The change can be grasped in advance. Therefore, adjusting hole (9g) ~
A filter having desired characteristics can be accurately and easily obtained by using (9i) and the dielectric piece (10).

(B) Since the dielectric piece (10) is inserted into the adjustment holes (9g) to (9i), the thickness of the filter is increased as compared with the conventional filter in which the dielectric chip is arranged on the strip conductor. Can be suppressed.

(C) Since the dielectric piece (10) is inserted into the adjustment holes (9g) to (9i) without being arranged on the strip conductors (2) and (3), the dielectric piece (10) is Q based on setting
It is possible to provide a filter having a small insertion loss without causing a decrease in

[First Embodiment] Next, a dielectric filter according to a first embodiment of the present invention will be described with reference to FIGS. However, in FIGS. 1 and 2 showing the first embodiment and FIG. 5 showing the second embodiment, the same parts as those in FIG. To do.

As is clear from FIG. 1 showing the state before adjusting the resonance frequency, three adjusting holes (9a) are provided at predetermined positions on the left side in the vicinity of the open end of the first strip conductor (2) in the dielectric plate (1). ) (9b) (9c) are provided, and three adjustment holes (9d) (9e) (9f) are also provided at predetermined positions on the right side near the open end of the second strip conductor (3). Also, three adjustment holes (9g) (9h) (9i) are provided at predetermined positions between the second strip conductors (2) and (3). The adjustment holes (9a) to (9i) are for selectively inserting a cylindrical dielectric piece (10), and are directed from one main surface of the dielectric plate (1) to the other main surface. The strip conductors are formed so as to extend and are arranged so as to match the extending directions of the first and second strip conductors (2) and (3).

FIG. 2 shows the dielectric filter after the resonance frequency adjustment.
In this example, 6 adjustment holes (9a) (9b) (9d) (9e)
The dielectric piece (10) is inserted into (9g) and (9h).

The size of the dielectric plate (1) of this dielectric filter is 9m in width.
m, depth 13 mm, thickness 3.5 mm, and the dimensions of the dielectric piece (10) are diameter 0.5 mm and length 1 mm.

FIG. 3 shows changes in the resonance frequency with respect to the position and number of the dielectric pieces (10) inserted in the holes (9a) to (9i). In addition, line A
The upper points show the case where the relative permittivity εr of the dielectric piece (10) is set to 10, and the points on the line B indicate the relative permittivity εr of the dielectric piece (10).
The figure shows the case of 50. (A) (b) (c) (d) on the horizontal axis
Indicates the insertion position and number of the dielectric pieces (10), and (a) indicates 9
Dielectric piece (10) in each of the adjustment holes (9a) to (9i)
Shows the state where is not inserted. The resonance frequency fo in this case is 90
It is 0 MHz, and the change in resonance frequency on the vertical axis of FIG. 3 is shown with reference to this. (B) shows a state in which the dielectric pieces (10) are inserted into the innermost adjustment holes (9a) (9d) (9g) of each row. (C) is the second adjustment hole (9a) from the back of each row
(9b) (9d) (9e) (9g) (9h) shows a state in which the dielectric piece (10) is inserted. (D) is all adjustment holes (9a) to (9
The state in which the dielectric piece (10) is inserted in i) is shown. The target resonance frequency is set lower than the resonance frequency in the unadjusted state, that is, the state of (a) in FIG. When mass-producing the dielectric filter, the data shown in FIG. 3 is obtained in advance.

When adjusting the resonance frequency of the manufactured dielectric filter, first measure the resonance frequency in the unadjusted state without inserting the dielectric piece (10) into any of the adjustment holes (9a) to (9i). Know the difference Δf from the target resonance frequency. Then, based on FIG. 3, the most suitable insertion position and number of the dielectric pieces (10) for eliminating the frequency difference Δf are determined,
The dielectric piece (10) is inserted into one selected from the adjustment holes (9a) to (9i). After that, the resonance frequency is measured and it is checked whether or not the target value is obtained. If the target value cannot be obtained, the insertion position of the dielectric piece (10) and / or
Alternatively, it may be readjusted by changing the number, or the relative permittivity of the dielectric piece (10) as necessary. After the adjustment of the resonance frequency is completed, the dielectric piece (10) is fixed to the dielectric plate (1) with an adhesive so that the dielectric piece (10) does not separate from the adjustment holes (9a) to (9i). In addition,
If the dielectric pieces (10) are fitted into the adjustment holes (9a) to (9i) in a good fitted state, the fixing with an adhesive may be omitted. First based on first and second strip conductors (2) (3)
And when adjusting the passband width by changing the coupling degree of the second resonator, the first and second strip conductors (2)
The selective insertion state of the dielectric piece (10) into the adjustment holes (9g) to (9i) between (3) is changed.

In this embodiment, since the dielectric piece (10) is inserted into the adjustment holes (9a) to (9i), it is possible to suppress the increase in the thickness of the dielectric filter. Further, since the dielectric piece is not arranged on the first and second strip conductors (2) and (3), the Q of the resonator is not lowered.

[Second Embodiment] FIGS. 5 and 6 show a dielectric filter according to a second embodiment of the present invention. The dielectric filter of FIG. 5 is the same as that of FIG. 1 in principle, but the formation positions of the first and second strip conductors (2) and (3) and the equivalent circuit of FIG. The method for forming the input coupling capacitance C1, the output coupling capacitance C2, and the coupling capacitance C5 between the two resonance circuits is different from that in FIG. That is, the first and second strip conductors (2) (3) are formed in the first and second grooves (11) (12) provided on the main surface of the dielectric plate (1), The input coupling capacitor C1 is composed of a first insulating rod (1) made of a fluorine-based resin dielectric in which a part (13a) of the first conductive rod (13) is embedded.
4) is inserted into the first groove (11),
The output coupling capacitance C2 is a part (15) of the second conductor rod (15).
a) is formed by inserting a second insulating rod (16) made of a fluorine-based resin dielectric in which is embedded in the second groove (12), and the coupling capacitance C5 is the first and second strip conductors. (2) The dielectric substrate (19) is arranged on the pair of conductor films (17) and (18) connected to (3). Explaining the correspondence between FIG. 1 and FIG. 5, the protruding portions (13b) (15b) of the first and second conductor rods (13) (15)
Correspond to the input terminal (6) and the output terminal (7), and the embedded portions (13a) (15a) of the first and second conductor rods (13) (15) are connected to the first and second coupling electrodes (4). ) (5).
The first insulating rod (14) is independently formed as shown in FIG. 6 and then inserted into the groove (11). The second insulating rod (16) has the same structure as the first insulating rod (14) and is similarly inserted into the groove (12).

In order to adjust the resonance frequency, nine adjustment holes (9a) to (9) are arranged on one main surface of the dielectric plate (1) in the same arrangement as in FIG.
i) is provided and two adjustment holes (9j) (9k) are provided on the side surface.
Is provided.

Also in this embodiment, the resonance frequency can be adjusted by selectively inserting the dielectric adjusting piece (10) similar to that shown in FIG. 1 into the adjusting holes (9a) to (9k).

[Modification] The present invention is not limited to the above-mentioned embodiment, but can be modified. For example, in the dielectric filter of FIGS. 1 and 5, the first and second strip conductors (2)
A groove can be provided between (3). It is also possible to couple the two resonant circuits both by capacitance and by induction.
Further, the dielectric piece (10) is not limited to a cylindrical shape, but a prismatic shape,
Another shape such as a groove shape may be used, and the adjustment holes (9a) to (9k) may also have a shape corresponding thereto. Further, although a dielectric filter having a two-stage resonant circuit is shown in the embodiment, the present invention can be applied to a dielectric filter having a different number of stages.

[Brief description of drawings]

FIG. 1 is a perspective view showing an unadjusted state of the dielectric filter according to the first embodiment of the present invention, FIG. 2 is a perspective view showing the state of the dielectric filter of FIG. 1 after adjustment, and FIG. FIG. 4 is a diagram showing the relationship between changes in the insertion position and number of dielectric pieces with respect to the adjustment holes in the dielectric filter of FIG. 1 and changes in resonance frequency, FIG. 4 is an equivalent circuit diagram of the dielectric filter, and FIG. FIG. 6 is a perspective view showing a dielectric filter according to a second embodiment of the present invention, FIG. 6 is a perspective view showing the first insulating rod of FIG. 5, and FIG. 7 is a perspective view showing a conventional dielectric filter. is there. (1) ... dielectric plate, (2) ... first strip conductor, (3) ... second strip conductor, (4) ... first
Coupling electrode, (5) ... second coupling electrode, (6) ... input terminal, (7) ... output terminal, (8) ... ground electrode,
(9a) (9i) …… Adjustment hole, (10) …… Dielectric piece.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Susumu Hirooka 1-22-1 Ueno, Taito-ku, Tokyo Within Taiyo Denki Co., Ltd. (56) Reference JP 54-14655 (JP, A) 56-96708 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A dielectric plate (1), a plurality of strip conductors (2) (3) provided on one surface of the dielectric plate (1) and arranged parallel to each other, and the dielectric body. A dielectric filter having a ground conductor (8) provided on the other surface of the plate (1), the plurality of strip conductors (2) (3) on one surface of the dielectric plate (1). ) Between the adjustment holes (9a) ~
(9i) is provided, and the plurality of adjustment holes (9a) to (9i) are arranged in the same direction as the extending direction of the strip conductors (2) and (3). ) To (9i), the dielectric filter (10) is inserted in the selected one.