JPH0560682B2 - - Google Patents

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.

(Conventional technology) Conventionally, as a technology in this field,
There were some that were described in Publication No. 61-80901, etc.
The configuration will be explained below using figures.

FIG. 2 is a block diagram of a conventional dielectric filter.

This dielectric filter has a rectangular parallelepiped dielectric body 1 having an integral structure, and the dielectric body 1 is provided with a plurality of dielectric resonators 2-1 to 2-6 each having a cylindrical or cylindrical center conductor. Furthermore, frequency adjustment patterns 3-1 to 3-6 are extended to the center conductors of each of the dielectric resonators 2-1 to 2-6, and these are arranged on one side of the dielectric 1. There is. Gaps 4-1 to 4-5 are formed between each pattern 3-1 to 3-6. Furthermore, the input stage pattern 3-1 is provided with an input terminal 5, and the output stage pattern 3-6 is provided with an output terminal 6.

In the above configuration, an electric signal applied from the input terminal 5 generates an electromagnetic field by the dielectric resonator 2-1 of the input stage, and this electromagnetic field resonates with the adjacent interstage dielectric resonance through the gap 4-1. It is transmitted to the container 2-2. The electromagnetic field reaching the interstage dielectric resonator 2-2 passes through the gap 4-2 to the adjacent dielectric resonator 2-3.
will be communicated to. While repeating such operations, an electrical signal is transmitted to the output stage dielectric resonator 2-6, and electrical energy is supplied to the load connected to the output terminal 6.

In such a dielectric filter, each of the dielectric resonators 2-1 to 2-6 is controlled by the length of the dielectric resonators 2-1 to 2-6 and the frequency adjustment patterns 3-1 to 3-6.
The resonance frequency of 2-6 is determined, and the coupling capacitance is determined by the pitch between each dielectric resonator 2-1 to 2-6 and the shape of the frequency adjustment pattern.

In order to realize this type of dielectric filter, the resonance frequency and coupling capacitance are first given as design values. It is important how to realize the value of the coupling capacitance in this design value. This coupling capacitance is first determined by each frequency adjustment pattern 3-1 to 3-3.
-6 with a constant pitch between each dielectric resonator 2-
By changing the pitch between 1 and 2-6, the relationship with the coupling capacity is determined. From the relationship value, each dielectric resonator 2-
The pitch between 1 and 2-6 is determined to realize a filter having the desired coupling capacity.

(Problems to be Solved by the Invention) However, the dielectric filter having the above configuration has the following problems.

(a) Adjust the resonance frequency of each dielectric resonator 2-1 to 2-6 using frequency adjustment patterns 3-1 to 3-6.
It can be adjusted each time. However, at the same time, when trying to adjust the amount of coupling between the dielectric resonators 2-1 to 2-6, the amount of coupling and the resonance frequency influence each other, so both are set to the optimal value. Therefore, it is difficult to obtain the desired filter characteristics.

(b) Parasitic capacitance exists between pattern 3-1 in the input stage and ground, and between pattern 3-6 in the output stage and ground, which cannot be taken into account at the time of design, making it difficult to obtain the desired frequency characteristics. , performance is low.

(c) In the conventional dielectric filter, the pitch between each dielectric resonator 2-1 to 2-6 is changed while keeping the gap between each frequency adjustment pattern 3-1 to 3-6 constant to obtain the desired coupling capacitance. Therefore, when aiming for higher performance and miniaturization, each dielectric resonator 2-1 to 2-2-
Achieving a pitch of 6 is almost impossible in terms of manufacturing. This has been a problem in achieving higher performance, smaller size, and lower cost.

The present invention solves the problems of the prior art, such as the difficulty in simultaneously adjusting the resonant frequency and the amount of coupling, the deterioration of performance due to parasitic capacitance, and the precise connection between each dielectric resonator. The purpose of the present invention is to provide a dielectric filter that solves the problem that it is impossible to achieve sufficient performance, miniaturization, and cost reduction because it is impossible to realize the pitch.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides front 10A, back 10B, left side 10C, right side 10
D, a rectangular parallelepiped homogeneous single dielectric 10 having an upper surface 10E and a lower surface 10F, and a metallized layer formed on the front surface 10A, rear surface 10B, left side surface 10C, right side surface 10D, and lower surface 10F of the dielectric material 10; , the left side surface 10C of the upper surface 10E of the dielectric 10
A conductive input pattern 12A and an output pattern 12B formed on the side and right side 10D, and one end of which is connected to the input pattern 12A and the output pattern 12B.
a plurality of center conductors n (where n is 2
or more) dielectric resonators 13-n, and a plurality n of frequency adjustment devices extending from one end of the center conductor of each dielectric resonator 13-n and arranged on the upper surface 10E of the dielectric 10. In the dielectric filter provided with the pattern 14-n, the following measures are taken.

That is, a coupling amount adjustment pattern 15-m (where m is an integer of 1 or more) is arranged between each frequency adjustment pattern 14-n with a predetermined gap therebetween;
Left side 10C and right side 10D of the dielectric 10
Non-metalized surfaces 11C and 11D corresponding to the input pattern 12A and output pattern 12B are provided on the metallized layer formed on the metallized layer.

(Function) According to the present invention, since the dielectric filter is configured as described above, the frequency adjustment pattern 14-n
Therefore, the resonant frequency can be adjusted for each dielectric resonator 13-n, and the frequency adjustment pattern 1
The gap between the dielectric resonators 13-n and the coupling amount adjustment pattern 15-m allows the amount of coupling between the dielectric resonators 13-n to be adjusted, making it easier to obtain desired filter characteristics. Moreover, the non-metalized surfaces 11C and 11D provided on both sides of the dielectric 10 serve to determine the resonance frequency of the dielectric resonator 13-n, and one non-metalized surface 11C serves to determine the resonant frequency of the dielectric resonator 13-n. reduce the parasitic capacitance that occurs between
The other non-metallized surface 11D is the output pattern 1
This reduces the parasitic capacitance that occurs between 2B and ground, improving the performance of the filter. Therefore, the above-mentioned problems can be eliminated.

(Embodiment) FIG. 1 is a configuration diagram of a dielectric filter showing an embodiment of the present invention.

This dielectric filter has a length W, a width L, and a height H.
It has a rectangular parallelepiped dielectric body 10 with an integral structure,
The front surface 10A, the back surface 10B, the left side surface 10C, the right side surface 10D, the top surface 10E, and the bottom surface 1 of the dielectric 10
Of 0F, front 10A, back 10B and bottom 1
A metallized layer is formed on the entire surface of 0F and a part of the left and right side surfaces 10C and 10D, and the left and right side surfaces 10C and 10D are formed with metallized layers.
Non-metallized surfaces 11C, 1 on top of 0C, 10D
1D is provided.

The dielectric 10 has a dielectric input pattern 12A and an output pattern 12 at both ends of its upper surface 10E.
B is formed. Furthermore, between the input and output patterns 12A and 12B, there is a pattern approximately parallel to the height direction.
A plurality of n (n is an integer of 2 or more) dielectric resonators 1 each having a cylindrical or cylindrical center conductor.
3-n (for example, 13-1 to 13-4) are buried. A frequency adjustment pattern 14 is provided on the center conductor of each dielectric resonator 13-1 to 13-4.
-n (for example, 14-1 to 14-4) is extended,
These are arranged on the upper surface 10E of the dielectric 10. Conductive coupling amount adjusting patterns 15-m (where m is an integer of 1 or more), for example 15-1 to 15-3, are formed between the patterns 14-1 to 14-4.

Here, in order to configure a filter using dielectric resonators, each dielectric resonator 13-1 to 13-4
The distances (pitch) P1, P2, and P3 are set to lengths that provide the degree of coupling necessary to realize the filter. In this embodiment, in order to obtain the necessary degree of coupling, it is not necessary to process grooves or the like on the surface of the dielectric 10. 1 to 13-4, etc., a filter is realized.

A gap g1 is provided between the input pattern 12A and the input stage frequency adjustment pattern 14-1. Similarly, patterns 14-1 and 15-1
Gap g2 between patterns 15-1 and 14-
Gap g3 between 2, patterns 14-2 and 15
Gap g4 between -2, pattern 15-2 and 1
Gap g5 between patterns 4-3, gap g6 between patterns 14-3 and 15-3, pattern 15-3
Gap g7 between and 14-4, and pattern 1
A gap g8 is provided between 4-4 and 12B, respectively. Furthermore, there is a gap d1 between the pattern 15-1 and the dielectric front surface 10A, and a gap d1 between the pattern 15-1 and the dielectric front surface 10A.
Gap d2 between 5-1 and dielectric back surface 10B
are provided for each.

In the above configuration, the electrical signal applied from the input pattern 12A is transmitted to the dielectric resonator 13 at the input stage.
-1 generates an electromagnetic field, and this electromagnetic field is transmitted to the dielectric resonator 13-2 between adjacent stages via the pattern 15-1. Dielectric resonator 13 between stages
The electromagnetic field that has reached −2 is transmitted to the adjacent interstage dielectric resonator 13-3 via the pattern 15-2.
Similarly, the electric field reaching the interstage dielectric resonator 13-3 is transmitted to the adjacent output stage dielectric resonator 13-4 via the pattern 15-3, and
Supply electrical energy to the load connected to B.

In this embodiment, each frequency adjustment pattern 14-
Coupling amount adjustment pattern 15-1 between 1 and 14-4
15-3, the frequency adjustment patterns 14-1 to 14-4 not only allow the resonance frequency to be adjusted for each dielectric resonator 13-1 to 13-4, but also simultaneously. The gap between the frequency adjustment patterns 14-1 to 14-4 and the coupling amount adjustment patterns 15-1 to 15-3 allows adjustment of the amount of coupling between the dielectric resonators. Therefore, desired filter characteristics can be easily obtained by adjusting both the resonance frequency and the amount of coupling at the same time.

Next, (1) the functions of the non-metallized surfaces 11C and 11D, and (2) the method of setting the coupling capacitance will be explained.

(1) Functions of non-metallized surfaces 11C and 11D Figure 3 shows the non-metalized surfaces 11C and 1 in Figure 1.
FIG. 3 is a lumped constant equivalent circuit diagram for explaining the function of 1D.

The circuit shown in FIG. 3 includes a plurality of coupling capacitors C1, C2a, C2c, C3a,
It has C3c, C4a, C4c, and C5. Furthermore, there is an inductance L1 between the input and output.
1, L12, L13, L14 and capacity C11, C
12, C13, and C14, and capacitors C2b, C3b, and C4b are branch-connected, respectively.

Here, the coupling capacitance C1 is the gap g1 in FIG.
corresponds to Similarly, each coupling capacitance C2a, C2
c, C3a, C3c, C4a, C4c, C5 are
Gap g2, g3, g4, g5, g respectively
It corresponds to 6, g7, and g8. The capacity C26 is
This corresponds to gaps d1 and d2. Capacity C3b,C
4b also corresponds to the gap between the front surface 10A and the rear surface 10B in patterns 15-2 and 15-3. Furthermore, the resonant circuits L11 and C11 correspond to the input stage dielectric resonator 13-1. Similarly, resonant circuits L12, C12, L13, C13, L14, C1
4 is a dielectric resonator 13-2, 13-3, 13-
4 respectively.

The correspondence between FIG. 1 and FIG. 4 is approximately as follows. Generally, the capacitance C of a parallel plane plate is calculated by the following formula:
It is given by (1).

C=0.0855・εr・A/t...(1) However, εr: relative dielectric constant of dielectric material A: area of one side of one flat plate (cm ² ) t: thickness of dielectric material (cm) And this example Now, non-metalized surfaces 11C and 11D are formed on the left and right side surfaces 10C and 10D of the dielectric 10.
Since this is provided, the following functions and effects can be achieved.

(a) Distance between the metallized layer formed on the left side surface 10C and the input pattern 12A, and the right side surface 10D
The metallized layer and output pattern 12 formed on
The distance to B becomes longer, and the capacitance C shown in equation (1) becomes smaller. That is, the parasitic capacitance generated between the conventional input stage pattern 3-1 and the ground and between the output stage pattern 3-6 and the ground in FIG. 2 is reduced.

(b) By providing the non-metalized surfaces 11C and 11D, the center frequency of the dielectric filter can be changed.

Therefore, the dielectric filter of this embodiment has a small parasitic capacitance on the input/output side that cannot be taken into account at the time of design, and moreover, only a cylindrical or cylindrical center conductor is processed on the dielectric 10 having an integral structure. It is possible to easily manufacture a high-precision dielectric filter for high frequencies at low cost. In particular, in the configuration of this type of filter, the pitches P1, P2 between the center conductors, which have the largest characteristic variation,
P3 also does not fluctuate during assembly, resulting in higher precision.Furthermore, since the dielectric 10 has an integral structure, assembly is easy.

(2) How to set the coupling capacitance In Figure 1, the pitches g2 to g7 are set as g2=g
3, g4=g5, g6=g7, the lumped constant equivalent circuit can be expressed as shown in FIG.

In this circuit, the coupling capacitance C2 corresponds to the coupling capacitances C2a and C2c in FIG. Similarly,
The coupling capacitance C3 is connected to C3a and C3c, and the coupling capacitance C4
is C4a, C4c, and the coupling capacitance C5 is C5a, C4c.
5c, respectively. Note that the capacitors C2b, C3b, and C4b in FIG. 3 are omitted in FIG. 4.

The relationships among the elements shown in FIG. 4 are as shown in the following equations (2) and (3).

Coupling capacitance C11=C0−C1−C2 C12=C0−C2−C3 C13=C0−C3−C4 C14=C0−C4−C5 ……(2) However, angular frequency ω0=1/√L0・C0 C0=1 /80・Z0 L0=2・Z0/π ²・0 0; Resonant frequency Z0; Characteristic impedance Coupling amount K12=C2/C0 K23=C3/C0 K34=C4/C0 ……(3) Usually, this type of dielectric In order to realize the field filter, the element values of the circuit shown in FIG. 4 are first given at the time of design. At this element value, the coupling capacitance C2, C
The key is how to achieve the value of 3.C4.

Let us consider a case where a method similar to the prior art is adopted as a method for realizing the coupling capacitances C2, C3, and C4. First, gap g2=g3, g4=
With g5, g6=g7 constant, each dielectric resonator 1
3-1 to 13-4 by changing the pitches P1, P2, and P3 to find the relationship with the coupling amounts k12, k23, and k34. An example of this is shown in FIG. The pitches P1, P2, and P3 are determined from FIG. 5 to realize a dielectric filter. However, the exact pitch P1,
Achieving P2 and P3 is almost impossible in terms of manufacturing.

Therefore, in this embodiment, the pitches P1, P2, P3
Assuming constant, the gap g2=g3, g4=g5,
By changing g6=g7, desired coupling capacitances C2, C3, and C4 are obtained. That is,
Generally, the capacitance C of a parallel plane plate is given by the above equation (1). And gap g2=g3, g4=g
Changing 5, g6=g7 means changing the thickness t in equation (1) above to realize the coupling capacitances C2, C3, and C4. In this case, each dielectric resonator 1
The pitches P1, P2, and P3 between 3-1 and 13-4 can be constant.

In this embodiment, the pitches P1, P2, and P3 are fixed and the gaps g2=g3, g4=g5, and g6=g.
7, it has the following advantages.

(i) Each allowable dielectric resonator 13-1 to 13-
The error in the pitch P1=P2=P3 between 4 is greatly reduced, and the performance of the dielectric filter can be improved and the cost reduced.

(ii) Gap between frequency adjustment patterns 14-1 to 14-4 and coupling amount adjustment patterns 15-1 to 15-3 g2=g3, g4=g5, g6=g7
By changing the coupling capacitances C2, C3, and C4, it becomes possible to significantly reduce the size. for example,
In order to obtain the coupling amounts k12, k23, and k34 of 0.03, the conventional method required a pitch of 6.8 mm and a gap of 0.4 mm, but in this embodiment, a pitch of 4.5 mm and a gap of 0.2 mm are sufficient.

In addition, in the above embodiment, four dielectric resonators 13
-1 to 13-4 have been shown, but two or three of them may be provided, or five or more of them may be provided.
2A, 12B, center conductor, and pattern 14-1
The shapes of ~14-4, 15-1~15-3, their arrangement positions, etc. may be modified to those other than those shown in the drawings.

(Effects of the Invention) As explained in detail above, according to the present invention,
Since the coupling amount adjustment pattern 15-m is provided between each frequency adjustment pattern 14-n, each dielectric resonator 13
Not only can the resonant frequency be adjusted for each dielectric resonator 13-n, but also the cap between the frequency adjustment pattern 14-n and the coupling amount adjustment pattern 15-m allows coupling between the dielectric resonators 13-n. You can also adjust the amount. Therefore, desired filter characteristics can be easily obtained by adjusting both the resonance frequency and the amount of coupling at the same time. Furthermore, non-metalized surfaces 1 are provided on both sides 10C and 10D of the dielectric 10.
Since 1C and 11D are provided, the parasitic capacitance on the input/output side that cannot be taken into account during design can be reduced, the desired frequency characteristics can be easily obtained, and the performance of the filter can be improved.

[Brief explanation of drawings]

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. 1, and Fig. 4 is a block diagram of a dielectric filter showing an embodiment of the invention.
This figure is another lumped constant equivalent circuit diagram of FIG. 1, and FIG. 5 is a diagram showing the relationship between the pitch between dielectric resonators and the amount of coupling. 10... Dielectric, 11C, 11D... Non-metallized surface, 12A... Input pattern, 12B... Output pattern, 13-1 to 13-4... Dielectric resonator, 14-1 to 14-4... Frequency adjustment pattern, 15-1 to 15-3...coupling amount adjustment pattern, d1, d2, g1 to g8...gap, P1
~P3... Pitch.

Claims (1)

[Scope of Claims] 1. A rectangular parallelepiped-shaped homogeneous single dielectric material 10 having a front surface 10A, a back surface 10B, a left side surface 10C, a right side surface 10D, an upper surface 10E, and a lower surface 10F; a front surface 10A and a rear surface of the dielectric material 10; 10B, a metallized layer formed on the left side 10C, right side 10D, and bottom surface 10F, and conductive input patterns 12A and output patterns formed on the left side 10C and right side 10D of the upper surface 10E of the dielectric 10. 12B, and a plurality of central conductors formed substantially parallel in the dielectric 10, one end of which is located between the input pattern 12A and the output pattern 12B, the other end of which is electrically connected to the metallized layer on the lower surface 10F. (however,
a dielectric resonator 13-n (n is an integer of 2 or more); and a plurality of n dielectric resonators 13-n extending from one end of the center conductor of each dielectric resonator 13-n and arranged on the upper surface 10E of the dielectric 10. Frequency adjustment pattern 14
-n, the coupling amount adjustment pattern 15-n is provided with a predetermined gap between each of the frequency integer patterns 14-n.
m (where m is an integer of 1 or more), and the left side surface 10C and the right side surface 10 of the dielectric 10
A dielectric filter characterized in that non-metalized surfaces 11C and 11D corresponding to the input pattern 12A and output pattern 12B are provided on the metallized layer formed in D.