JPS6354804A - Dielectric filter - Google Patents

Abstract

PURPOSE:To obtain a filter having a desired frequency characteristic with high accuracy and low cost simply without changing the length of each dielectric resonator by providing a non metalized face to side faces of a dielectric so as to reduce the presence of parasitic capacitance disabling of the consideration at the design. CONSTITUTION:The nonmetaized faces 11C, 11D are provided to, right left side faces 10C, 10D of the dielectric 10. The distance between the metalized layer formed to the left side face 10C and an input pattern 12A and the distance between the metalized layer formed to the right side face 10D and an output pattern 12B are made longer respectively and the capacitance C is decreased. That is, the parasitic capacitance is reduced. Thus, the presence of parasitic capacitance not taking into account at the design is less and only the cylindrical or hollowed-cylindrical center conductor has only to be processed to integral structure of the dielectric 10. Thus, the high frequency dielectric filter with low cost and high accuracy is obtained simply.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a dielectric filter for microwaves and the like having a dielectric resonator.

(Prior Art) Conventionally, dielectric filters for high frequencies such as microwaves using a dielectric resonator, that is, a dielectric material having a high dielectric constant, have been proposed. A dielectric resonator can realize a resonator with the same size as a stripline resonator, and also has an unloaded Q that is comparable to that of a waveguide resonator. Although the machining work required to do so is more complicated than that of a stripline resonator, it has the advantage of being easier than that of a waveguide resonator. However, dielectric resonators have the disadvantage of fatally poor temperature characteristics, so
However, with the progress of dielectric materials engineering, these limitations are gradually being resolved. Therefore, dielectric filters using such dielectric filters are being used in various high frequency circuits.

Conventionally, this type of dielectric filter has been disclosed in Japanese Patent Application Laid-open No. 54-3448 and Japanese Patent Application Laid-open No. 5
Some of these are described in JP-A No. 5-68702, JP-A-56-144802, and the like. The configuration will be explained below using figures. FIG. 2 is a block diagram of a conventional dielectric filter.

This dielectric filter has a metal case 1, and an input terminal 2 and an output terminal 3 are provided at both ends of the metal case 1, and transmission lines 4 and 5 are connected to the output terminals 2 and 3, respectively. has been done.

A plurality of cylindrical or prismatic dielectric resonators 6-1 to 6-4 are arranged on a single surface within the metal case 1, and are fixed between the transmission lines 4 and 5. .

To configure the dielectric filter, the transmission line 4 on the input and output side
．． 5 and the dielectric resonator 6-IJ-4 is set to a desired size. This coupling setting is for resonators e-1, 8-
This is done by changing the distance d between the transmission line 4.4 and the transmission line 4.5. That is, if the interval d is narrowed, the coupling will be increased, and if the interval d is widened, the coupling will be decreased. Further, the intervals between the dielectric resonances 1s-1 to 1s-4 must also be set to such an interval that the degree of coupling necessary for realizing the filter can be obtained.

FIG. 3 is a circuit diagram of a lumped constant equivalent circuit in the filter of FIG. 2.

In this circuit, the resonant circuit consisting of the inductor Ys L1 and the capacitance C1 corresponds to the input stage dielectric resonator 6-1, and similarly the resonant circuit L2.02. L3・0
3. L4・C4 is dielectric resonator 8-2.8-3.13-
4, respectively, and is realized by a semi-coaxial resonator having a length of input/4 (where input is the wavelength).

Input and output capacitance 001. CO4 is determined by the distance between the input and output stage dielectric resonators 8-1, 6-4 and the transmission line 4.5. In addition, capacitances 012.023 and C34 connected in series between capacitances COI and C:04 on the output side are connected to each dielectric resonator 6-
Determined by the interval between 1 and 6-4.

Usually, in this type of dielectric filter, Cot =
CO4, C12=C34, G1=C4, C2=C4, L
1=L4, L2=L3, (1) In addition, the resonance frequencies fl, f2 . f3. f4 is fl= −−211112πF ding Tπ 汀f2=□ 2πf 1 ding 1 cho■ f3−□ 2πF ding ru ding……(2), and between them, the following There is a relationship.

r1= f4>f2= F3 ・−・・−・(
3) In the dielectric filter shown in Fig. 2, there are inevitably parasitic capacitances 010 and C40 between the grounded metal case 1 and the input terminal 2, and between the metal case 1 and the output terminal 3, respectively, which are not considered at the time of design. exists in

In addition, in the dielectric resonators 8-1 to 6-4, the above (3)
In order to satisfy the formula, those dielectric resonators 8-1.
The length of the dielectric resonators 8-4 and the lengths of the dielectric resonators G-2 and 6-3 are made not to be equal.

(Problems to be Solved by the Invention) However, in the dielectric filter having the above configuration, the dielectric resonators 8-1 to B-4 do not all have the same length, making the manufacturing complicated and the manufacturing cost high. Become. Also, people
Since the parasitic capacitance CIO, C:40 exists between the output terminals 2, 3 and the metal case 1, it is difficult to obtain desired frequency characteristics, resulting in a problem of low performance.

The present invention provides a dielectric filter that solves the problems of the prior art, such as high cost due to complicated manufacturing and decreased performance due to parasitic capacitance.

(Means for Solving the Problems) In order to solve the above problems, the present invention consists of a homogeneous single dielectric material and a plurality of central conductors having a pattern and formed substantially parallel within the dielectric material. In a dielectric filter having an input stage, an interstage dielectric resonator, and an output stage dielectric resonator, on both sides of the dielectric corresponding to the formation positions of the input stage and output stage dielectric resonators, A non-metalized surface is provided for adjusting the resonance frequency in a dielectric resonator.

(Function) According to the present invention, since the dielectric filter is configured as described above, the non-metalized surface provided on the dielectric reduces the parasitic capacitance between the person, the output side, and the ground, and
It works to provide desired frequency characteristics without changing the length of each dielectric resonator, that is, to determine the resonant frequency. This makes it possible to simplify the structure, lower costs, and improve performance. Therefore, the above-mentioned problem can be eliminated.

(Example) FIG. 1 is a configuration diagram of a dielectric fill showing an example of the present invention.

This dielectric filter has a rectangular parallelepiped dielectric body 10 with an integral structure.
The dielectric 10 has a front surface 10A, a rear surface 10B, a left side surface 10C, a right side surface 10D, an upper surface 10E, and a lower surface 10F.
Among them, a metallized layer is formed on the entire front surface 10A, back surface 10B, and lower surface 10F, and a part of the left and right side surfaces 10C, 100, and a non-metalized surface 11c is formed on the upper part of the left and right side surfaces 10C and 100. , 110 are provided.

A conductive input cover turn 12A and an output cover turn 12B are formed on both ends of the upper surface 10E of the dielectric body 10, and a cylindrical or cylindrical conductive cover turn 12A and an output cover turn 12B are formed at both ends of the upper surface 10E. A plurality of dielectric resonators 13-1 to 13-4 each having a center conductor are buried therein. The center conductor of each dielectric resonator 13-1 to 13-4 has patterns 14-1 to 14 for adjusting the resonance frequency, respectively.
-4 are extended and arranged on the upper surface 10E of the dielectric IO. Between each pattern 14-1 to 14-4,
Conductive coupling amount adjustment patterns 15-1 at predetermined intervals
15-3 is formed.

Here, in order to configure a filter using dielectric resonators, the distance between each dielectric resonator 13-1 to 13-4 is set to a length that provides the degree of coupling necessary to realize the filter. In this embodiment, it is not necessary to process grooves or the like on the surface of the dielectric 10 in order to obtain the necessary degree of coupling.
The processing of dielectric resonator 1 consists of a central conductor of cylindrical shape, etc.
A filter is realized by providing 3-1 to 13-4, etc. In addition, inlet cover pattern 12A and pattern 14
There is a gap di between patterns 14-1 and 15-1.
1, a gap d3 between the pattern 15-1 and the dielectric front surface 10A, and a gap d3 between the pattern 15-1 and the dielectric front surface 10A.
A gap d4 is provided between the dielectric back surface 10B and the dielectric back surface 10B.

In the above configuration, the electric signal applied from the input cover turn 12A generates an electromagnetic field by the dielectric resonator 13-1 in the input stage, and this electromagnetic field is transmitted through the pattern 15-1 to the dielectric resonance between the adjacent legs. The signal is transmitted to the container 13-2. The electromagnetic field that has reached the interstage dielectric resonator 13-2 is pattern 15.
-2 to the a-contact interstage dielectric resonator 13-3. Similarly, the electric field reaching the crotch dielectric resonator 13-3 is transmitted to the adjacent output stage dielectric resonator 13-4 via the pattern 15-3, and the electric field is transferred to the load connected to the output cover turn 12B. supply.

FIG. 4 is a lumped constant equivalent circuit diagram for explaining the operating principle of FIG. 1, and has an equivalent relationship with the circuit of FIG. 3.

The circuit of FIG. 4 consists of a plurality of capacitors 0101. ClO2,0105,ill:
107°0108.0110. C11l, and an inductance L110. between its input and output. L200.
L300. LaO2 and capacitance C100,02
00,0300,C:400, and a capacitance of 0103. C:1013. C109
are branched and connected to each other. Here, the capacitance C101 is the capacitance of the gap di in FIG. 1, the capacitance ClO2 is the capacitance of the gap d2, and the capacitance 0103 is the capacitance of the gap d3. This is the capacity of d4.

Part A1 consisting of resonant circuits L1/C1, L2/C2 and capacitance C12 in FIG. 3, and resonant circuits L100/0100, L200/C200 in FIG.
and capacitance 0102. C:103. G, 104
There is a relationship as shown in the following equation with the part A2 consisting of .

Therefore, there is a relationship similar to that described above between the capacitance in FIG. 3 and the capacitance in FIG. 4, and the center frequency fO of the dielectric filter in FIG. 3 has a relationship as shown in the following equation.

fol =□ 2π ``■ (Menkoshi T Hikinori edition■ f02 =□ 2π + 1+3 f03 =□ 2π 3 + 023-Hll:34)...
・(5) Furthermore, the correspondence between FIG. 1 and FIG. 4 is approximated as follows. In general, the capacitance C of a engineered flat plate is calculated using the following formula (%). However, ε-; Specific electric constant A of the dielectric; Surface area of one side of one flat plate (am2); d; Thickness of the dielectric (am); In the example, the left and right sides 10C of the dielectric IO:
, 100 are provided with non-metalized surfaces 110, 110, which has the following advantages.

■ The distance between the metallized layer formed on the left side surface 10C and the input cover turn 12A and the distance between the metallized layer formed on the right side surface 100 and the output cover turn 12B become longer, and the capacitance C shown in the above equation (6) increases. becomes smaller. That is, the parasitic capacitance c in FIG.
to and cao become smaller.

■ Conventionally, it was necessary to change the length of the dielectric resonators 6-1 to B-4 in order to satisfy the condition of formula (3), but in this embodiment, non-metalized surfaces 110 and 110 are provided. By doing so, it is possible to satisfy not only equation (2) but also equation (5) without changing the lengths of the dielectrics 13-1 to 13-4.

Therefore, the dielectric filter of this embodiment has less parasitic capacitances 010 and C40 that cannot be taken into consideration at the time of design, and is easy to use by simply processing only a cylindrical or cylindrical center conductor on the dielectric 10 having an integral structure. It is possible to manufacture high-frequency dielectric filters at low cost and with high precision. In particular, the distance between the center conductors, which has the largest characteristic variation in the configuration of this type of filter, does not change during assembly, resulting in higher precision.Furthermore, the dielectric 10 is integrated into the assembly. Therefore, it has advantages such as easy installation.

In addition, in the above embodiment, four dielectric resonators 13-1 to 1
3-4 is shown, but five or more of them may be provided, and 101 dielectrics, 12 A, 1
2B, center conductor, and patterns 14-1 to 14-4
, 15-1 to 15-3, their arrangement positions, etc. may be modified to those other than those shown.

(Effects of the Invention) As described in detail above, according to the present invention, since the non-metalized side surfaces of the dielectric are provided, the presence of parasitic capacitance that cannot be considered during design can be reduced, and each dielectric resonator Even without changing the length of the filter, a filter with desired frequency characteristics can be manufactured simply, with high precision, and at low cost.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a dielectric filter showing an embodiment of the present invention, Fig. 2 is a block diagram of a conventional dielectric filter, Fig. 3 is a lumped constant equivalent circuit diagram of Fig. 2, and Fig. 4 is a block diagram of a conventional dielectric filter. FIG. 1 is a lumped constant equivalent circuit diagram of FIG. 10...Dielectric, IIC:, 110...
・Non-metallized surface, 12A... Inner cover turn,
12B... Output turn, 13-1 to 13-4
...Dielectric resonance, 14-1 to 14-4...
... Resonance frequency adjustment pattern, 15-1 to 15-3
・・・・・・Pattern for adjusting the amount of binding.

Claims (1)

[Claims] Input stage, interstage and output stage dielectric resonators each comprising a homogeneous single dielectric body and a plurality of central conductors having a pattern and formed substantially parallel within the dielectric body. In the dielectric filter, non-metalized surfaces for adjusting resonance frequencies of the dielectric resonators of the input and output stages are provided on both sides of the dielectric corresponding to the formation positions of the dielectric resonators of the input stage and the output stage. A dielectric filter characterized by: