JPH063842B2 - Microwave filter - Google Patents

Description

The present invention relates to an improvement of a microwave filter having a structure in which a plurality of dielectric resonators are mounted on a substrate.

[Prior Art] FIG. 2 is a circuit diagram of a bandpass filter using a dielectric coaxial resonator. Multiple dielectric resonators 1 between input and output
4 to 5 are connected in parallel, and capacitors 5 to 9 are connected in series. Specifically, such a bandpass filter is
It was constructed as shown in FIG. 3 or FIG.

That is, in the example of FIG. 3, the plurality of coaxial resonators 11 to 14 are arranged in the metal case 10 so as to be in contact with each other. Electrodes 2 having coupling rods 15-18 connected to the inner conductors of the respective dielectric resonators 11-14 formed on a coupling substrate 19
1 to 24 are electrically connected. Electrodes 25 and 26 are formed on the combined substrate 19 outside the electrodes 21 and 24, respectively. The electrodes 25 and 26 form an extraction electrode on the input side or the output side. Each electrode 21-24 is
On one surface of the coupling substrate 19 made of a dielectric material, they are opposed to each other at a predetermined distance and are capacitively coupled to each other.

On the other hand, in the example of FIG. 4, the ground electrode 31 is formed on the dielectric substrate 30. Coaxial resonators 32 to 35 are fixed on the ground electrode 31. Coaxial resonator 32
The inner conductors 35 to 35 are electrically connected to the electrodes 41 to 44 formed on the substrate 30 by the connecting rods 36 to 39. The electrodes 41 to 44 are the electrodes 21 to 2 of the example of FIG.
It is equivalent to 4. Therefore, a capacitance based on the substrate 30 made of a dielectric material is formed between the electrodes 41 to 44. Note that reference numerals 45 and 46 denote electrode patterns for input / output extraction.

[Problems to be solved by the invention]

In the example of FIG. 3, a plurality of coaxial resonators 11 to 14 are housed in the metal case 10, and a coupling substrate 19 is prepared separately from the coaxial resonators 11 to 14 and housed in the metal case 10 as well. Therefore, there is a problem that the whole shape becomes considerably large and the assembling work is complicated.

On the other hand, in the example of FIG. 4, the coaxial resonators 32 to 35 are collectively arranged on one substrate 30, and the coaxial resonators 32 to 35 are formed by using the electrode pattern formed on the substrate 30.
Is to combine. Therefore, the overall shape can be made smaller than that of the example of FIG. 3, and it can be said that the configuration is suitable for the microwave IC. However, smaller ones are desired. Further, in order to obtain various filter characteristics, it is necessary to form various conductive patterns and the like on the substrate 30, and in some cases a larger substrate 30 is required.

Therefore, an object of the present invention is to provide a microwave filter which is smaller in size and excellent in designability.

[Means for solving problems]

The microwave filter of the present invention comprises a dielectric substrate, an electrode formed on the dielectric substrate and having a plurality of electrode missing portions, and a coupling missing portion formed in a part of the outer conductor. And a plurality of coaxial resonators arranged on the substrate, and the plurality of coaxial resonators are closely fixed on the substrate so that the coupling missing portions overlap the electrode missing portions on the substrate. It is characterized by.

[Action]

In the present invention, a coupling missing portion is provided in a part of the portion where the outer conductor of the coaxial resonator is formed, and adjacent coaxial resonators are formed by utilizing the coupling missing portion and the electrode missing portion on the substrate. Be combined. Therefore, the coaxial resonators can be coupled to each other within the mounting region of the plurality of assembled coaxial resonators on the dielectric substrate.

Therefore, a coaxial resonator can be coupled on a dielectric substrate using a relatively small dielectric substrate.

[Explanation of Examples]

1 and 5 are a front sectional view and a plan view of an embodiment of the present invention. A ground electrode 52 is formed on the upper surface of the dielectric substrate 51. Electrode missing parts 53 and 54 are formed in the ground electrode 52. Electrode missing portion 53,
54 is provided so that the ground electrode 52 is not formed in that portion.

Two prismatic dielectric coaxial resonators 55 and 56 are fixed to the upper surface of the dielectric substrate 51. Each coaxial resonator 5
Reference numerals 5 and 56 have inner conductors 55a and 56a formed on the peripheral surface of the through hole extending in the axial direction, and outer conductors 55c and 56c formed on the outer peripheral surface except the voltage open end surface. Further, a part of the outer conductors 55c, 56c is provided with a connecting missing portion 57, 58.
Are formed. As is apparent from FIG. 1, the connecting missing portions 57 and 58 are formed so as to overlap the electrode missing portions 53 and 54. In this embodiment, the coaxial resonators 55 and 56 are coupled to each other by the coupling missing portions 57 and 58 and the electrode missing portions 53 and 54.
That is, the lines of electric force or the lines of magnetic force extend as shown by the arrows in FIG. 1, so that the lines of electric force and the lines of magnetic force move back and forth between the resonators 55 and 56, and are thereby coupled to each other.

The inner conductors 55a and 56a of the two coaxial resonators 55 and 56 are
Although not shown in the drawings, connection between the outside and the outside can be performed using a known electrical or magnetic coupling means.

As is clear from FIG. 1 and FIG. 5, in the microwave filter of the present embodiment, the coupling between the coaxial resonators 55 and 56 is the coupling lacking portions 57 and 5 formed in a part of the outer conductor.
8 and the electrode missing portions 53 and 54 on the dielectric substrate 51. Therefore, since the coupling is achieved in the space where the coaxial resonators 55 and 56 are placed,
Unlike the conventional example shown in FIG. 3 or 4, a space for coupling is not required outside the area where the coaxial resonator is mounted. Therefore, it can be seen that the overall size can be dramatically reduced.

In this embodiment, the coupling lacking portions 57 and 58 are formed to have a shape and size that completely overlap with the electrode missing portions 53 and 54, but they are not necessarily formed to have exactly the same size and shape. There is no.

Further, as is clear from FIG. 5, the connecting missing portion 57,
58 and the electrode missing parts 53, 54 are coaxial resonators 55, 5
6 is formed close to the voltage open end face side. Therefore,
In this embodiment, both coaxial resonators 55 and 56 are capacitively coupled, but if the electrode missing portion and the coupling missing portion are formed close to the short-side end face, both coaxial resonators 55 and 56 are inductively coupled. be able to.

6 to 8 are views for explaining the second embodiment of the present invention, and FIG. 9 is an equivalent circuit diagram of the embodiment. Here, the hot side electrode 6 is formed on the upper surface of the combined substrate 61.
2, the ground side electrode 63 is formed on the lower surface. As shown in FIG. 10, the hot side electrode 62 has slots 64, 65, 66 and electrode missing portions 67, 68, 69,
70, 71-76 are formed. Returning to FIGS. 6 to 8, the dielectric coaxial resonators 81 to 86 are arranged on the hot side electrode 62. Each dielectric coaxial resonator 81
The structures of ~ 86 are the coaxial resonators 55 and 56 of the embodiment of FIG.
Is almost the same as. The difference is that each coaxial resonator 81
To 86, the coupling missing portions 87 to 92 are formed by the surface on the short-circuit side, and the coaxial resonators 81, 82, 85, 8 are formed.
In No. 6, the connection missing portions 93, 94,
95 and 96 are formed.

In this embodiment, as is clear from FIGS. 6 and 8, the simultaneous resonators 81 to 86 are inductively coupled to each other via the coupling missing portions 87 to 92 formed near the end face on the short-circuit side. .

Further, as is clear from FIG. 7, the coaxial resonators 81, 8
6. The coupling lacking portions 93, 9 formed on the voltage open end face side of 6
6 is capacitively coupled to the slots 64 and 66.

Further, in the coaxial resonators 82-85, the circuit portion shown in the upper part of FIG. 9 is formed by the coupling missing portion 94, the slot 65 and the coupling missing portion 95 on the voltage open end face side. Therefore, if the size and position of the slot 65 and the coupling lacking portions 94 and 95 are not adjusted, between the coaxial resonator 82 and the coaxial resonator 85,
A signal transmitted through the inductively coupled line and a signal that is 180 degrees out of phase at a specific frequency can be propagated to the voltage open end face side and combined. As a result, the filter is a polar filter having an attenuation pole at a specific frequency.

In each of the above-described embodiments, the shapes of the coupling lacking portion and the electrode lacking portion are rectangular, but needless to say, the shape is not limited to a rectangular shape and may be an elliptical shape or any other shape.

Regarding the coupling between the coaxial resonator and the input / output terminal, the sixth
Not only the slot line using the slots 64 and 66 shown in the drawing can be used, but also various electrical or magnetic coupling means can be used for coupling.

[Advantages of the Invention] As described above, according to the present invention, the coupling missing portion is formed in a part of the outer conductor of the coaxial resonator, and the electrode missing portion is formed in the electrode formed on the substrate. By disposing the coaxial resonator on the substrate so that the coupling missing portion overlaps the electrode missing portion, the plurality of coaxial resonators are electrically or magnetically coupled to each other. Therefore, since the coupling between the coaxial resonators is performed in the region where the coaxial resonators are arranged, it is possible to dramatically reduce the size of the entire microwave filter. Also, for microwave filters with various characteristics such as filters with attenuation poles, it is easy to change the coupling method between coaxial resonators by changing the pattern in the area where the coaxial resonators are mounted. Therefore, the microwave filter having excellent designability can be realized.

Since the microwave filter of the present invention has the above-mentioned excellent effects, it is required to be downsized in the microwave IC.
It should be pointed out that it is the best one.

[Brief description of drawings]

FIG. 1 is a front sectional view of an embodiment of the present invention, FIG. 2 is a circuit diagram showing an example of a bandpass filter, FIG. 3 is a sectional view showing a first example of a conventional microwave filter, and FIG. FIG. 5 is a plan view showing a second example of the conventional microwave filter, FIG. 5 is a plan view of the embodiment shown in FIG. 1, FIG. 6 is a plan view showing the second embodiment of the present invention, and FIG. Is VII-VII in FIG.
8 is a sectional view taken along line VIII-VIII in FIG. 6, FIG. 9 is a diagram showing an equivalent circuit of the embodiment shown in FIG. 6, and FIG. 10 is a substrate shown in FIG. It is a top view which shows the electrode pattern formed above. In the figure, 51 is a substrate, 52 is an electrode formed on the substrate, 53 and 54 are electrode missing portions, 55 and 56 are coaxial resonators, 55c and 56c are outer conductors, and 57 and 58 are coupling missing portions. .

Claims (1)

[Claims] 1. A dielectric substrate, an electrode formed on the dielectric substrate and having a plurality of electrode missing portions, a coupling missing portion formed in a part of an outer conductor, and A plurality of dielectric coaxial resonators arranged on the substrate, wherein the plurality of coaxial resonators are closely fixed to the substrate such that the coupling lacking portions overlap the electrode missing portions on the substrate. , Microwave filter.