JPH0426241B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a grounding structure for a dielectric coaxial resonator using a cylindrical dielectric.

(Prior art) A dielectric coaxial resonator, for example, a 1/4 wavelength coaxial TEM resonator 1 shown in FIG. More specifically, on the inner wall surface and outer wall surface of the thick pipe-shaped dielectric material 4,
The inner conductor 2 and the outer conductor 3 are made by baking a silver paste, for example, which has excellent high frequency dielectric properties and good adhesion to the dielectric 4. The inside of the inner conductor 2 is hollow, and a center rod 5 made of similar ceramic or the like and having an axial length longer than the dielectric 4 is fitted and fixed therein, and one end 6 of the center rod 5 is connected to a resonator 1. open end surface 7 of
It protrudes from the inner conductor 2 and is covered with an electrode film 8 extending from the inner conductor 2. 9 is an electrode that short-circuits the inner conductor 2 and the outer conductor 3.

FIG. 6 is a diagram showing only the essential parts of another resonator 11, in which the center rod 5 is not used. In this case, a terminal electrode 12 of an arbitrary shape is fitted into a hole surrounded by an inner conductor 2. , fixed with conductive adhesive, inner conductor 2
Connect with. On the other hand, 13 and 14 are chip-shaped capacitors, which are used when capacitively coupling the resonator 11 to other parts, such as another resonator or a connector. That is, the upper part of the terminal electrode 12 is shaped appropriately,
One electrode 15 of the chip-shaped capacitors 13, 14,
16, while chip-shaped capacitors 13,
Lead wires 19 and 20 are connected to the other electrodes 17 and 18 of 14.
One end of the lead wires 19 and 20 are connected to another resonator or connector, for example.

FIG. 7 shows a filter 21 constructed using the above-mentioned resonator, particularly the one shown in FIG. 6.

The same parts as in FIG. 6 are shown with the same numbers.

22 is a case. The case 22 is a rectangular parallelepiped made of a conductor, for example, duralumin, in which grooves 23, 24, 25, and 26 each having a semicircular cross section are formed in parallel at slight intervals. Moreover, the grooves 23 and 24,
Grooves 27, 28, and 29 each having a semicircular cross section are formed across the grooves 24 and 25 and the grooves 25 and 26. Further, the groove 31 extends between the groove 23 and the outside of the case 22, and the groove 3 extends between the groove 26 and the outside of the case 22.
2 is formed. Grooves 31, 27, 28, 29,
32 is in a straight line. After the case 22 is configured as described below, another case 33 having the same structure as the case 22 is placed over the case 22, as shown in FIG. 8, to complete the product. In other words, as shown in FIG. 8, the case 22 corresponds to one half of a rectangular case divided into two along the longitudinal section. Grooves 23, 24, 25, 26
Each half of the resonator 11 is fitted inside, and its outer conductor 3 is electrically connected and fixed to the case 22. This fixing is performed, for example, by using a dielectric adhesive or by screwing. 34 is an input coaxial connector that is half-fitted into the groove 31;
35 is an output coaxial connector which is half-fitted into the groove 32. Both connectors 34 and 35 are fixed to cases 22 and 33 by a conventionally known method. The center terminal of the input coaxial connector 34 and the capacitor 13 of the first stage resonator 11 are connected by a lead wire 36. The capacitor 14 of the first stage resonator 11 and the capacitor 13 of the second stage resonator 11 are connected by a lead wire 37 through the groove 27. The capacitor 14 of the second stage resonator 11 and the capacitor 13 of the third stage resonator 11 are connected to the groove 2.
8 and connected by a lead wire 38. Third
The capacitor 14 of the resonator 11 in the fourth stage and the capacitor 13 in the resonator 11 in the fourth stage are connected by a lead wire 39 through the groove 29. The capacitor 14 of the fourth stage resonator 11 and the center terminal of the output coaxial connector 35 are connected by a lead wire 40.

As is clear from the filter structure described above as an example, conventionally, as shown in FIG. Alternatively, as shown in FIG. 33 and fixed both together.

By the way, as described above, when the outer conductor 3 of the resonator 11 is grounded to the cases 22 and 33 using the leaf spring 42, the leaf spring 42 is interposed between the cases 22 and 33 and the resonator 11. Therefore, case 22,
33 needs to be thick enough to withstand the spring force of the leaf spring 42, which poses a problem in that the shape of a product such as a filter using the resonator 11 becomes large. On the other hand, when the outer conductor 3 of the resonator 11 is fixed to the cases 22 and 33 using the conductive adhesive 41, the linear expansion coefficient of the resonator 11 is
3 and the linear expansion coefficient of the adhesive, there was a problem that the outer conductor 3 would peel off due to sudden temperature changes. In addition, the work is troublesome and it takes a long time to harden, which is a factor in increasing costs.

(Object of the Invention) The present invention has been made to solve the above-mentioned problems in the conventional grounding structure of a dielectric coaxial resonator. The object of the present invention is to provide a grounding structure for a dielectric coaxial resonator that does not cause peeling of the outer conductor, etc., and allows for the compactness of a product incorporating the dielectric coaxial resonator.

(Structure of the Invention) Therefore, the present invention provides a dielectric coaxial resonator that is housed in a metal case made of a thin metal plate having spring properties, and a spring piece that is formed by cutting and raising a part of the metal case. is in pressure contact with the outer conductor of the dielectric coaxial resonator, and a shield plate is electrically conductively adhered to the surface of the metal case from which the spring piece is cut and raised.

That is, in the present invention, a spring piece is formed by cutting and raising a part of a metal case made of a thin metal plate having spring properties, and this spring piece is pressed against the outer conductor of a dielectric coaxial resonator to form a dielectric coaxial resonator. The resonator is fixed in the metal case and the outer conductor is electrically connected to the metal case.The hole formed in the cut and raised part of the spring piece is conductively bonded to the metal case. It is closed by a shield plate.

(Effects of the Invention) According to the present invention, since the dielectric coaxial resonator is fixed and the outer conductor is connected to the ground using the spring piece formed in a part of the metal case, the dielectric coaxial resonator Dimensional changes due to thermal expansion of the metal case are absorbed by the spring piece, preventing the outer conductor from peeling off. Also, since the spring piece is formed on a part of the metal case, an independent spring member can be used. Compared to the case where a dielectric coaxial resonator is fixed to a metal case, the thickness of the metal case can be made thinner, and the shape of products such as microwave filters using a dielectric coaxial resonator can be made smaller. It is possible to aim for

(Example) Hereinafter, the present invention will be specifically described with reference to the accompanying drawings regarding an example in which the present invention is applied to a microwave filter.

In FIG. 1, inside a rectangular parallelepiped-shaped metal case 51 made of a thin metal plate having spring properties such as brass, there are 1/4 wavelength coaxial TEM resonators 1-1, 1-2, and 1 described in FIG. -3 and 1-4 are accommodated. These 1/4 wavelength coaxial TEM resonators 1-
1, 1-2, 1-3, and 1-4 are arranged in parallel in the metal case 51 with their respective axial directions aligned.

The above 1/4 wavelength coaxial TEM resonator 1-1, 1-2,
An electrode film 8 (see FIG. 5) extending from the inner conductor 2 of the dielectric 4 of each center rod 5 of 1-3 and 1-4 is soldered to an electrode 53 formed on a bonding substrate 52. This bonding substrate 52 is made by forming the electrodes 53, 53, .
Due to the capacitance formed between adjacent electrodes 53, 53, the center rods 5, 5 are connected to these electrodes 53, 53.
Adjacent resonators 1-1 and 1-2, resonators 1-2 and 1-3, and resonators 1-3 and 1-4 to which electrode films 8 and 8 are soldered are electrostatically coupled, respectively. Ru.
Further, electrodes 55,
55 (one of the electrodes 55, 55 is not shown in FIG. 1) is formed, and these electrodes 55, 55
are the center conductor 56a of the input coaxial connector 56 attached to the metal case 51, and the output coaxial connector 5
It is soldered to the center conductor 57a of No.7.

On the other hand, as shown in FIG.
Spring pieces 58a, 58a, . . . and 59a, 59a, . Spring pieces 58b, 58b, . . . and 59b, 5
9b, . . . are formed.

The spring pieces 58a, 58a, ... and 59a,
59a,... are the side plates 51a of the metal case 51,
Resonator 1-1, 1 housed in metal case 51
-2, 1-3 and 1-4, they are cut and raised diagonally inward. Also, spring piece 5
8b, 58b, ... and 59b, 59b, ... also,
Similarly to the above, the side plate 51b of the metal case 51 is
Resonator 1-1, 1 housed in metal case 51
-2, 1-3 and 1-4, they are cut and raised diagonally inward.

The resonators 1-1, 1-2, 1-3, and 1-4 are all arranged in the metal case 51 between the spring pieces 58a and 58b and between the spring pieces 59a and 59b due to their spring force. being held in place.

The spring pieces 58a and 58b are connected to the resonators 1-1, 1-2, 1- through which a large high-frequency current flows.
It is preferable that the outer conductor 3 be brought into pressure contact with the outer conductor 3 near each of the open ends 3 and 1-4.

The metal case 51 has side plates 51a and 51.
An opening 62 into which a lid member 61 is fitted and fixed is provided between the resonator 1-1 and the resonator 1-1 through this opening.
1-2, 1-3 and 1-4 are accommodated.

Side plates 51a and 51b of the metal case 51
includes spring pieces 58a, 59a and spring piece 58.
In order to prevent electromagnetic waves from leaking from the opening formed by b and 59b, a thin shield plate 6 is provided.
3a and 63b are electrically conductively bonded.

With the above configuration, the resonator 1-1,
1-2, 1-3 and 1-4 are the spring pieces 58a.
58b and the spring pieces 59a and 59b, the resonators 1-1, 1-
The high frequency current of each outer conductor 3 of 2, 1-3 and 1-4 is transmitted by the spring pieces 58a, 58b, 59a and 59b, especially the resonators 1-1, 1-2, 1-3 and 1-4. Spring pieces 58a, 58 near each open end
b, and is bypassed to the metal case 51.

The microwave filter shown in FIG. 1 includes a metal case 51, resonators 1-1, 1-2, 1-3 and 1-
Even if the dimensions of resonator 1 change due to thermal expansion, etc.
The outer conductors 3 of -1, 1-2, 1-3 and 1-4 do not peel off from the dielectric 4.

In addition, a resonator 1-1 is provided in a part of the metal case 51.
Spring pieces 5 that hold 1-2, 1-3 and 1-4
8a and 58b and spring pieces 59a and 59b are formed, so that the resonators 1-1, 1-2, 1-3
and 1-4 within the metal case 51 does not require any special member or dielectric adhesive. Furthermore, the force applied to the metal case 51 is small, and the metal case 5
The thickness of the material No. 1 also becomes thinner, and the shape of the microwave filter becomes smaller.

In addition, in the above embodiment, the spring pieces 58a, 5
The tips 9a, 58b, and 59b may be bent toward the outside of the metal case 51, as shown in FIG.

Further, as shown in FIG. 4, the side plate 51b side of the metal case 51 is extruded so that the metal case 5
1, and the resonator 1-
1, 1-2, 1-3 and 1-4 may be positioned.

The present invention can be applied not only to microwave filters but also to devices such as duplexers.

Further, the present invention can be applied to the grounding structure of the 1/4 wavelength dielectric coaxial resonator and the 1/2 wavelength dielectric coaxial resonator described in FIG.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of a microwave filter to which the present invention is applied, FIG. 2 is a sectional view showing the internal structure of the microwave filter of FIG. 1, and FIG.
A cross-sectional view showing the internal structure of a microwave filter having spring pieces different from the spring pieces of the microwave filter shown in the figure, and Fig. 4 is an implementation of the microwave filter shown in Fig. 1 in which some of the spring pieces are replaced with protrusions. An explanatory diagram of an example, Figure 5 is a cross-sectional view of an example of a 1/4 wavelength coaxial TEM resonator, and Figure 6 is a different 1/4 wavelength coaxial TEM.
A sectional view showing the main parts of a resonator, FIG. 7 is an internal explanatory diagram of a filter having a conventional dielectric coaxial resonator grounding structure, and FIG. 8 is a top view of the filter in FIG. 7.
9 and 10 are sectional views taken along the line A--B in FIG. 7, respectively, and show the conventional structure. 1-1 to 1-4...1/4 wavelength coaxial TEM resonator,
2...Inner conductor, 3...Outer conductor, 4...Dielectric, 5
... Center rod, 7 ... Open end surface, 51 ... Metal case, 58a, 58b, 59a, 59b ... Spring piece, 63a, 63b ... Shield plate, 65a, 6
5b... Protrusion.

Claims (1)

[Claims] 1. An inner conductor and an outer conductor are formed on the inner and outer peripheral surfaces of a cylindrical dielectric, respectively, and these inner and outer conductors are short-circuited by a short-circuiting conductor formed on one end surface of the dielectric. The dielectric coaxial resonator is housed in a metal case made of a thin metal plate with spring properties, and a spring piece formed by cutting and raising a part of the metal case is pressed against the outer conductor of the dielectric coaxial resonator. A grounding structure for a dielectric coaxial resonator, characterized in that a shield plate is dielectrically adhered to the surface of the metal case from which the spring piece is cut and raised.