JPS58111404A - Coaxial filter - Google Patents

Abstract

PURPOSE:To attain easy adjustment of coupling capacitance and to prevent the destruction by a large power input signal, by loading a dielectric base which is held a metallic conductor region with a dielectric member at an open end of an inner conductor of each resonator. CONSTITUTION:A dielectric base 9 is fixed to a conductive retainer plate 8 at the tip of an inner conductor 1. In this case, the tip of the conductor 1 and the retainer 8 are fixed to be the same potential and the retainer is removable. In the base 9, a metallic conductor 20 is formed on a dielectric 14 having partial projections with etching or printing and a dielectric plate 15 is laminated on the conductor 20 with thermal pressing. The terminal of the conductor 20 is formed on the projection of the dielectric 14. The base 9 is connected with a metallic conductor line 10 having a low loss, and the capacitance is controlled with the area of the conductor 20 at the inside of the dielectric base and the thickness of the base plate 15.

Description

[Detailed Description of the Invention] The present invention relates to a coaxial filter, and provides a coaxial filter that provides a coupling circuit with a new structure between resonators, facilitates adjustment of coupling capacitance, and is excellent in mass production. It is something.

Conventionally, when constructing a filter using a coaxial resonator,
As shown in Fig. 1, there is a method using a specific wavelength resonator filled with a dielectric material 3, and coupling between each resonator using a dielectric rod 7 (for details, refer to Japanese Patent Laid-Open No. 56-3267). . In the figure, 1 is an internal conductor, 2 is an external conductor, 6 is a housing, 6 is an input/output terminal, and 19 is a metal rice layer provided so as to sandwich the dielectric rod 7. In this configuration, the dielectric rod 7
It is difficult to control the capacitance value of the dielectric rod 7 having the shape of
The coupling is strong, and in the case of a narrowband filter, one coupling is weak.) This is very difficult and is not suitable for mass production. Furthermore, there is a drawback that the electric field at the tip of the resonator is easily disturbed and the no-load Q of the resonator is deteriorated.

FIG. 2 shows a conventional example of a filter using a coaxial resonator. In the figure, 1 is an internal conductor, 2 is an external conductor, 4 is an electrode provided on the dielectric substrate 13, 6 is a housing, 6 is an input/output terminal, and 8 is fixed to the tip of the internal conductor 1 by screwing. It is a holding plate, and 12 is a tuning screw. FIG. 3 shows an enlarged explanatory view of the electrode 4 provided on the dielectric substrate 13 (FIG. 3 shows a sectional view taken along line X in the drawing (&) in FIG. 3). In this configuration, resonators with different characteristic impedances are used, and coupling between the resonators, including coupling between input and output terminals, is determined by the size of the electrodes 4 or the mutual gap formed on one dielectric substrate 13. This method uses gap capacitance, but if the input/output terminal coupling portion or the middle of the band is large, the coupling capacitance becomes large and the electrode gap on the dielectric substrate 13 becomes small. It had the disadvantage of being destroyed by electrical discharge between the electrodes. Furthermore, it was difficult to modify individual capacitance values. The present invention has been made in order to eliminate these drawbacks, and is suitable for mass production.
A coaxial filter having a capacitive coupling circuit with a new structure is provided.

FIG. 4 shows a first embodiment of the present invention. In this embodiment, resonators with different characteristic impedances are used, and coupling between the resonators, including coupling between input and output terminals, is performed by a ring-shaped dielectric substrate 9 attached to the tip of the internal conductor 1 of the resonator. It is a coaxial type filter. In the figure, a dielectric substrate 9, which is part of the features of the present invention, is fixed to the tip of an internal conductor 1 with a conductive holding plate 8. In this case, the tip of the internal conductor 1 and the holding plate 8 are fixed to have the same potential, and the holding plate 8 can be removed as necessary. Outer conductor 2. Housing 5. The input/output terminal 6° tuning screw 12 is provided as in the conventional case.

The detailed structure of the ring-shaped dielectric substrate 9 is shown in FIG.

(&) is a plan view, and (b) is a cross-sectional view in the muum of figure (a). The present dielectric substrate 9 includes a first dielectric plate 14 (for example, ceramic, Teflon,
Metal conductor 2 is formed by etching, printing, etc. on glass, etc.)
The shape of the metal conductor 20 is arbitrarily selected based on design values. ), and a second dielectric plate 15 is further laminated thereon by thermocompression bonding or the like. Terminals of the metal conductor 20 are formed on the protrusion of the first dielectric 14 . In the present invention, the protrusion may have any shape as long as the terminal of the metal conductor 20 can be taken out. For example, the first dielectric plate 14 may
A disk having a diameter larger than 6 may also be used. Coupling between each resonator, including coupling between input and output terminals, is performed by the capacitance between the metal conductor 20 inside the dielectric substrate, the tip of the internal conductor 1, and the holding plate 8, and each dielectric substrate 9 The capacitance value is controlled by the area of the metal conductor 20 inside the dielectric substrate and the thickness of the substrate 15. 6th
The figure shows the electrical equivalent circuit of this coaxial filter.

In the case of this embodiment, since the metal conductor 2o is sandwiched between the first and second dielectric plates 14 and 15, it has the advantage that it will not be destroyed even by input signals of high power. Furthermore, the pattern of the metal conductor 2° can be precisely controlled by etching or the like, and a desired coupling capacity can be easily obtained. Furthermore, since the dielectric substrate 9 is removable, there is an advantage that the coupling capacitance can be modified.

FIG. 7 shows a second embodiment of the invention. This example uses a dielectric-mounted coaxial resonator in which a dielectric is mounted on the open end of the resonator, and coupling between each resonator, including coupling between input and output terminals, is performed by a dielectric substrate 9. This is an example of a coaxial type filter. The open end of the internal conductor 1 is made thinner, and a ring-shaped capacitive element having a conductor part 16 inside and a dielectric 17 outside is inserted therein, and a ring-shaped dielectric substrate 9 shown in FIG. 6 is inserted therein. death,
It is screwed with a presser plate 8. Note that the dielectric 17 is connected to the conductor portion 16 and the external conductor 6 through a metallized layer 18. This embodiment is the same as the first embodiment except that the resonator is of the dielectric mounted type, and has all the advantages described in the first embodiment.

FIG. 8 shows a third embodiment of the present invention, which is applied to a band rejection filter. FIG. 9 shows the structure of a dielectric substrate 9' used for coupling the band-stop filter. Metal conductor 20'
is sandwiched between a first dielectric plate 14' and a second dielectric plate 16'. Dielectric substrate 9 with such a structure
' is attached to the tip of the internal conductor 1 as shown in FIG. 8, and the metal conductor 20' between each resonator is connected by a false wavelength line 11.

In this embodiment, the coupling between the respective resonators, including the coupling between the input and output terminals, is achieved by the capacitance between the metal conductor 20' inside the dielectric substrate, the tip end surface of the internal conductor 1, and the holding plate 8. FIG. 10 shows an electrical equivalent circuit of this embodiment. This embodiment also has the advantage that it is not destroyed by a high power input signal and the coupling circuit can be easily finely adjusted.

FIG. 11 shows a fourth block diagram of an electromagnetic coupling band-pass filter as an embodiment of the present invention shown in FIG. 4. This example uses a dielectric-mounted coaxial resonator similar to the second example, and connects the input/output coupling between the metal conductor 4 inside the dielectric substrate 9 and the input/output terminal 6.
This is done by connecting them with a metal conductor wire 10 with low loss. The dielectric substrate 9 is screwed to the tip of the internal conductor 1 by a holding plate 8. In this embodiment, it is possible to accurately control the degree of coupling between input and output terminals, which has been difficult in the past, and it is possible to realize filter characteristics faithfully to the designed values.

As described above, in the present invention, by using a dielectric substrate having a metal conductor inside the filter coupling circuit, it is possible to prevent damage caused by high-power input signals, and further, by patterning the metal conductor, coupling capacitance can be prevented. can be achieved as designed. In addition, the dielectric substrates are individually removable and can easily modify the coupling capacitance, making it possible to fine-tune the coupling circuit of the filter, making it possible to provide a coaxial filter with excellent mass productivity.

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing a conventional coaxial filter, and FIG.
4 is a sectional view showing the first embodiment of the coaxial filter according to the present invention, ljs (a) is a plan view of the bonded substrate used in FIG. 4, and (b) is a sectional view of the same. 6 is an equivalent circuit diagram of the embodiment of FIG. 4, and FIG. 7 is an equivalent circuit diagram of the embodiment of the present invention.
FIG. 8 is a cross-sectional view showing a band rejection filter according to the third embodiment of the present invention. FIG. 9 (IL) is a plan view of the bonded substrate used in FIG. b) is the same cross-sectional view,
FIG. 10 is an equivalent circuit diagram of the embodiment shown in FIG. 8, and FIG. 11 is a sectional view of the electromagnetic field coupling bandpass filter. 1...Inner conductor, 2...Outer conductor, 5
...Housing, 6...Input/output terminal, 8...
... Pressing plate, 9 ... Dielectric substrate, 10 ...
...Metal conductor wire, 11...False wavelength line, 1
2... Tuning screw, 14... First dielectric plate, 15... Second dielectric plate, 20...
...Metal conductor. Name of agent: Patent attorney Toshio Nakao and 1 other person
Figure 1 - Figure 2 Figure 1ri Figure 4 Figure 7 Figure 10 Figure 11

Claims (3)

[Claims] (1) λ is constructed by arranging a plurality of coaxial resonators each having an outer conductor and an inner conductor, one end open and the other end short-circuited. A coaxial type filter characterized in that a dielectric substrate having a metal conductor region sandwiched between dielectric materials is mounted on the open end of the internal conductor of each of the resonators. (2) The internal conductor of each resonator has a protrusion on the open end side, a dielectric substrate having a metal conductor region sandwiched between dielectric materials is attached to the protrusion, and a conductive holding plate is attached to the protrusion. The coaxial filter according to claim 1, wherein the coaxial filter is detachably attached. (3) Control of coupling between resonators, including input/output coupling,
3. The coaxial type filter according to claim 1, wherein the configuration is determined by the shape of the metal conductor region of the dielectric substrate and the thickness of the dielectric material.