JPH0644201U - Dielectric filter - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a dielectric filter adapted to be coupled with an external circuit without lowering the unloaded Q. [Structure] Columnar dielectrics 3, 4 and the columnar dielectrics 3, 4
Is a multistage dielectric filter composed of TM mode resonators 11 and 12 each including a conductor cavity 2 surrounding the. The TEM mode or quasi-TEM mode resonators 24 and 25 connected to the external circuits 22 and 23 are connected to the conductor cavities 2 of the resonators of the resonators 11 and 12 which are coupled to the external circuits 22 and 23. The outer conductor 26 is in contact with and arranged outside thereof. The resonators 11 and 12 coupled to the external circuits 22 and 23 and the resonators 24 and 25 in the TEM mode or the quasi-TEM mode are coupled holes 36 and 37 in the conductor cavity 2 and the external conductor at the opposing portions thereof, respectively. Equipped with
The two are electromagnetically coupled through these coupling holes 36 and 37.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a multistage dielectric filter composed of a dielectric resonator using a TM mode of electromagnetic waves, and more particularly to a coupling structure between a dielectric resonator forming a dielectric filter and an external circuit.

[0002]

[Prior art]

 FIG. 4 shows an example of the configuration of a conventional dielectric filter of this type. The dielectric filter 1 is formed by arranging cylindrical columnar dielectrics 3 and 4 inside a conductor cavity 2 which is entirely made of metal. The columnar dielectrics 3 and 4 are arranged in parallel between both ends of the rectangular parallelepiped conductor cavity 2.

At both ends of the conductor cavity 2, an input coaxial connector 5 and an output coaxial connector for connecting the dielectric filter 1 to an external circuit (not shown) by a coaxial cable (not shown). 6 are attached respectively. The input coaxial connector 5 and the output coaxial connector 6 are connected to their respective center conductors 7 at one end of each probe loop 8 which is coupled to the magnetic field inside the conductor cavity 2. The other end of the probe loop 8 is soldered to the inner wall surface of the conductor cavity 2.

An input-stage dielectric resonator 11 composed of a columnar dielectric 3 and a conductor cavity 2 surrounding the columnar dielectric 3, another columnar dielectric 4 and a conductor cavity 2 surrounding it. The two-stage dielectric resonator 12 is electromagnetically coupled to each other to form a two-stage dielectric filter 1.

The dielectric filter 1 having the structure as shown in FIG. 4 generally has an equivalent circuit structure as shown in FIG. 5 in the case of n stages. 5, K ₁ , K ₂ , ... Are coupling coefficients between adjacent dielectric resonators, E ₁ is a coupling coefficient between the probe loop 8 and the dielectric resonator 11 at the input stage, E ₂ is a coupling coefficient between the probe loop 8 and the dielectric resonator 12 in the output stage.

[0006]

[Problems to be solved by the device]

 By the way, in the above-mentioned conventional dielectric filter 1, there is a problem that the no-load Q is significantly reduced by the probe loop 8 in the dielectric resonator 11 in the input stage and the dielectric resonator 12 in the output stage. there were. The decrease in the unloaded Q is due to the insertion of the metal (the probe loop 8) into the resonance system.

An object of the present invention is to provide a dielectric filter adapted to be coupled with an external circuit without lowering the unloaded Q.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a multi-stage dielectric filter comprising a TM mode resonator comprising a columnar dielectric and a conductor cavity surrounding the columnar dielectric. A resonator of a TEM mode or a quasi-TEM mode, which is arranged outside the outer conductor in contact with the conductor cavity of the resonator coupled to the external circuit, is connected to the external circuit. The resonator and the TEM mode or quasi-TEM mode resonator, which are provided with the external cavity and the external circuit, are provided with coupling holes in the conductor cavity and the external conductor, respectively, which face each other. It is characterized by being combined.

[0009]

[Action]

 The resonator coupled to the external circuit and the TEM mode or quasi-TEM mode resonator are electromagnetically coupled through the coupling hole.

[0010]

[Effect of device]

 According to the present invention, the resonator coupled to the external circuit and the resonator of the TEM mode or the quasi-TEM mode are electromagnetically coupled through the coupling hole, so that the resonator is coupled to the external circuit to couple with the external circuit. No metal is inserted in the resonator, and therefore no drop in unloaded Q due to the insertion of metal into the resonance system is obtained, and a dielectric filter with high unloaded Q and good characteristics is obtained. You can

[0011]

【Example】

 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The construction of one embodiment of the dielectric filter according to the present invention is shown in FIGS.

The dielectric filter 21 shown in FIGS. 1 and 2 has cylindrical columnar dielectrics 3 and 4 arranged in parallel between both ends of a rectangular parallelepiped conductor cavity 2 formed of metal. The present invention is applied to the dielectric filter 1 described in FIG. 4, which utilizes the TM mode of electromagnetic waves. 1 and 2, the parts corresponding to those in FIG. 4 are denoted by the corresponding reference numerals, and the duplicated description will be omitted.

The dielectric filter 21 uses quarter wavelength dielectric coaxial resonators 24 and 25 that utilize the TEM mode of electromagnetic waves for coupling with the external circuits 22 and 23. That is, the dielectric coaxial resonator 24 for input coupling has the outer conductor 26 in contact with the conductor cavity 2 of the resonator 11 at the input stage, which is coupled to the outer circuit 22 of the dielectric filter 21. Placed outside of. Similarly, in the dielectric coaxial resonator 25 for output coupling, the outer conductor 26 is in contact with the conductor cavity 2 of the resonator 12 in the output stage, which is coupled to the outer circuit 23 of the dielectric filter 21, and the outer side of the outer cavity 26 is in contact therewith. Will be placed.

The dielectric coaxial resonators 24 and 25 on the input side and the output side have the same configuration. Each of the dielectric coaxial resonators 24 and 25 is formed on a dielectric block 28 made of a dielectric material having a through hole 27 in the shaft core and four side surfaces surrounding the through hole 27 of the dielectric block 28. The outer conductor 26, the inner conductor 31 formed on the inner peripheral surface of the through hole 27, and the short-circuit conductor 29 that short-circuits the outer conductor 26 and the inner conductor 31 at one end surface of the dielectric block 28. Become.

In each of the dielectric coaxial resonators 24 and 25, a pin 33 having a resin 32 attached to the outer periphery is fitted into the through hole 27 from each open end side thereof, and each pin 33 is attached to the outside. It is connected to the circuits 22 and 23.

The dielectric coaxial resonator 24 and the resonator 11 at the input stage of the dielectric filter 21 are arranged such that the conductor cavity 2 of the dielectric filter 21 and the outer conductor of the dielectric coaxial resonator 24 are opposed to each other. 26 is provided with coupling holes 36 and 37, respectively, and through the coupling holes 36 and 37, the dielectric coaxial resonator 24 and the resonator 11 at the input stage of the dielectric filter 21 are electromagnetically coupled. Similarly, the dielectric coaxial resonator 25 and the output-stage resonator 12 of the dielectric filter 21 are arranged such that the conductor cavity 2 of the dielectric filter 21 and the outer conductor of the dielectric coaxial resonator 25 in the opposing portion thereof. 26 is provided with coupling holes 36 and 37, respectively, and through the coupling holes 36 and 37, the dielectric coaxial resonator 25 and the resonator 25 at the output stage of the dielectric filter 21 are electromagnetically coupled.

With such a configuration, metal is inserted in the resonators 11 and 12 of the input stage and the output stage, which are coupled to the external circuits 22 and 23 to couple with the external circuits 22 and 23. Therefore, there is no decrease in unloaded Q due to the insertion of metal into the resonance system, and a dielectric filter having excellent unloaded Q and good characteristics can be obtained.

In the above embodiment, the conductor cavity 2 of the dielectric filter 21 is made of metal, but the conductor cavity 2 of the dielectric filter 21 is made of ceramic, as shown in FIG. 3, for example. It is also possible to use a case 39 in which the outer peripheral surface is metalized with a metal plating film 40 or the like. The case 39 and the metal plating film 40 are also provided with coupling holes 36 and 38 for coupling with the dielectric coaxial resonators 24 and 25.

Further, the coupling between the dielectric coaxial resonators 24 and 25 and the external circuits 22 and 23 is not limited to the pin 33 in which the resin 32 is attached to the outer peripheral surface as described above. Although not shown, for example, a capacitor connected to the internal conductor 31 can be used to connect to the external circuits 22 and 23.

Further, instead of the dielectric coaxial resonators 24 and 25, a so-called semi-coaxial resonator in which a center conductor is provided in the conductor cavity can be used.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of a dielectric filter according to the present invention.

FIG. 2 is a sectional view taken along line III-III of the dielectric filter of FIG.

FIG. 3 is a vertical cross-sectional view of another embodiment of the dielectric filter according to the present invention.

FIG. 4 is a vertical sectional view of an example of a conventional dielectric filter.

5 is an equivalent circuit diagram of a dielectric filter having the structure of the dielectric filter of FIG.

[Explanation of symbols]

 2 Conductor Cavity 3 Columnar Dielectric 4 Columnar Dielectric 11 Dielectric Resonator 12 Dielectric Resonator 21 Dielectric Filter 22 External Circuit 23 External Circuit 24 Dielectric Coaxial Resonator 25 Dielectric Coaxial Resonator 26 External Conductor 27 Through Hole 29 Short-circuit conductor 31 Internal conductor 36 Coupling hole 37 Coupling hole 38 Coupling hole 39 Ceramic case 40 Plating film 41 Dielectric filter

Claims (1)

[Scope of utility model registration request] 1. A multistage dielectric filter comprising a TM-mode resonator comprising a columnar dielectric and a conductor cavity surrounding the columnar dielectric, wherein an external circuit of the resonator is provided. An external conductor is placed in contact with a conductor cavity of a resonator to be coupled and arranged outside thereof, and a resonator of a TEM mode or a quasi-TEM mode connected to the external circuit is provided, and the resonator is coupled to the external circuit. A dielectric material characterized in that a resonator and a resonator of a TEM mode or a quasi-TEM mode are provided with coupling holes respectively in the conductor cavity and the outer conductor of the opposing portions, and are electromagnetically coupled through these coupling holes. filter.