JPH11308012A - Waveguide type filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waveguide type filter which is made small-sized and light in weight by directly connecting a coaxial connector to a waveguide type filter, without using a waveguide coaxial converter. SOLUTION: The inside of a waveguide 1 is divided by iris type reactance elements 21 to 23 to form one or plural pieces of cavity resonators 51 to 54, at least one (both in the example shown in the diagram) of the reactance elements on the input and output sides of the one or plural pieces of the resonators 51 to 54 is formed by short-circuit plates 31 and 32 and central conductors 41a and 42a of coaxial connectors 41 and 42 for input-output are connected to the cavity resonators 51 and 54 adjacent to the plates 31 and 32 so as to obtain a desired passband.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide filter used in a high frequency band such as a UHF band, a microwave band, and a millimeter wave band. More specifically, the present invention relates to a waveguide type filter that can be downsized by improving the mounting structure of the input / output coaxial connector of the waveguide type filter in which at least one of input and output is performed via a coaxial type connector.

[0002]

2. Description of the Related Art A conventional waveguide filter has a structure as shown in, for example, a perspective view in FIG. 5 (a) and FIG. That is, the iris-type reactance elements 21 to 2 are provided inside the waveguide 1.
5 are formed by forming the resonators 51 to 54, respectively, and coupling them so as to obtain desired band characteristics between adjacent resonators. The irises of the reactance elements 21 to 25 are set so as to obtain a weak coupling degree that allows only a signal of a predetermined bandwidth to pass. Therefore, input and output to and from the waveguide filter are performed by connection of the waveguide, and even when input and output are performed through a coaxial connector, as shown in FIG. Flange 11 at the input / output end of
The waveguide coaxial converters 45 and 46 are connected to the coaxial connector 12 and the coaxial connector 4 provided on the waveguide coaxial converters 45 and 46.
1 and 42.

[0003]

In a conventional waveguide filter having a structure in which input and output are performed by a conventional coaxial connector, the waveguide filter is once converted into a waveguide using a waveguide coaxial converter as described above.
The electromagnetic wave in the waveguide is coupled to a cavity resonator forming a filter via an iris whose coupling degree is adjusted.
However, this waveguide coaxial converter is usually formed to have a size equal to or larger than one resonator of the waveguide type filter, and the central conductor of the connector propagates through the waveguide on its wide surface. Because it is inserted to combine in a wide band to get
There is a problem that the overall size is large, the weight is heavy, and the cost is high. This structure contradicts recent demands for smaller and lighter electronic devices.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a small and lightweight coaxial connector is directly connected to a waveguide filter without using a waveguide coaxial converter. It is an object of the present invention to provide a waveguide type filter having a simplified structure.

[0005]

SUMMARY OF THE INVENTION The present invention does not use a waveguide coaxial converter, but rather coaxially vertically with an electric field in the waveguide which is not normally conceivable for coupling a coaxial connector to a waveguide. Insert the center conductor of the mold connector and widen its tip if necessary, provide a metal plate shaped along the direction of the electric field, or insert it in the direction parallel to the electric field. By adjusting the degree of coupling such as, for example, positioning it outside the inner surface of the waveguide wall, it is possible to couple so that a desired band characteristic is obtained,
It is characterized in that a waveguide filter having desired band characteristics can be obtained.

In the waveguide type filter according to the present invention, one or a plurality of cavity resonators are formed by partitioning the inside of the waveguide with a reactance element such as an iris type or a post type. The reactance element on at least one of the input side and the output side of the device is formed of a short-circuit plate, and the connector pin (center conductor) of the coaxial connector for input / output passes through a desired passage in the cavity resonator near the short-circuit plate. They are electrically coupled to obtain a band.

With this configuration, it is possible to form a desired bandpass filter while directly coupling the coaxial connector and the cavity resonator forming the waveguide type filter. Since it can be eliminated, the size and weight can be reduced at a very low cost.

[0008] The coaxial connector may be provided on the short-circuit plate, and a connector pin may be inserted in a direction perpendicular to the short-circuit plate, or may be provided on a narrow side surface of the waveguide, and the connector pin may be connected to the narrow side surface. It is formed by being inserted in a vertical direction, or provided on a wide side surface of the waveguide, and a connector pin is inserted in a direction perpendicular to the wide side surface.

[0009]

Next, a waveguide type filter according to the present invention will be described with reference to the drawings.

FIG. 1 is a perspective explanatory view of one embodiment of a waveguide type filter according to the present invention, and FIG.
As shown in (a) and (b), the inside of the waveguide 1 is partitioned by iris-type reactance elements 21 to 23 to form one or a plurality of cavity resonators 51 to 54, and one or a plurality of cavity resonators 51 to 54 are formed. The reactance elements on at least one of the input side and the output side (both in the example shown in FIG. 1) of the cavity resonators 51 to 54 are formed by the short-circuit plates 31 and 32, and the cavity resonators near the short-circuit plates 31 and 32 The central conductors (connector pins) 41a and 42a of the coaxial connectors 41 and 42 for input and output are electrically coupled in 51 and 54 so that a desired pass band is obtained.

The waveguide 1 is usually made of a metal such as aluminum, brass, and invar. A waveguide having a normal size corresponding to the frequency is used. Although a rectangular waveguide is shown in the figure, other shapes such as a circle and a square may be used. Reactance elements 21 to 23
Is similarly formed of a metal plate or a metal rod. For example, as shown in FIG. 1C, a portion of one cavity resonator 52 is partially broken, and irises 21a and 22a are formed at the center thereof. The width W of the iris 21a is set so as to obtain a degree of coupling that can realize a filter having a predetermined bandwidth, and the interval L between the reactance elements 21 and 22 resonates according to the frequency. It is set as follows.

In the present invention, the input-side reactance element forming the input-side cavity resonator 51 and the output-side reactance element forming the output-side cavity resonator 54 are formed by the short-circuit plates 31 and 32, respectively. The short-circuit plates 31, 3
2 has a coaxial connector 41, 42 and a central conductor 41 thereof.
a, 42a are provided so as to be coupled to the cavity resonators 51, 54, respectively. The coupling between the center conductor of the coaxial connector and the waveguide is usually performed by inserting the center conductor to a certain depth in parallel with the electric field, as described above. That is, as shown in FIG. 1, even when a conductor such as a thin metal plate is inserted perpendicularly to the electric field, the electromagnetic field is not affected by the electric field. . However, as described above, the present inventors have found, after intensive studies, in such rectangular TE ₁₀ mode of the filter shown in FIG. 1, a metal rod having a constant diameter, such as the center conductor of the coaxial connector Is inserted in the direction perpendicular to the electric field as shown in FIG. 1, a small amount of coupling occurs. By adjusting the insertion length and the diameter of the metal rod, optimal coupling for obtaining narrow-band filter characteristics can be obtained. It has been found that the coaxial connector and the waveguide filter can be directly coupled.

As a result of further diligent studies by the present inventors, if a broadband filter is desired, the diameter of the center conductor tip of the coaxial connector may be increased, or the tip may be extended along the direction of the electric field. It has been found that a larger degree of coupling can be obtained by attaching a conductor such as a metal plate having a shape, and a desired broadband filter can be formed.

As a result, as described above, of the cavity resonators constituting the waveguide filter, the reactance element on the input side or output side of the cavity resonator at the end is short-circuited and short-circuited. Coaxial connectors 41, 31 and 32,
Thus, a compact waveguide type filter which can be directly connected to a coaxial connector without using a waveguide coaxial converter can be constructed by providing 42.

FIG. 2 is a perspective explanatory view similar to FIG. 1A of another embodiment of the waveguide filter of the present invention. In this example, as in the case of FIG. 1, the input and output reactance elements at both ends of the cavity resonator are formed by short-circuit plates 31 and 32, and the coaxial connectors 41 and 42 are formed by narrowing the width of the waveguide 1. Side 1
4 and the center conductor is coupled from the narrow side surface 14 side of the waveguide 1. Reference numeral 13 denotes a wide side surface of the waveguide 1. Also in this example, the center conductors of the coaxial connectors 41 and 42 are perpendicular to the direction of the electric field, as in the example shown in FIG. By increasing the diameter of the distal end of the center conductor or attaching a metal plate or the like along the direction of the electric field to the distal end, a waveguide filter having desired band characteristics can be obtained. The functions of the other parts such as the reactance elements 21 to 23 are the same as those in the example shown in FIG. 1, and the same parts as those in FIG. In the example shown in FIG. 2, the coaxial connectors 41 and 42 on the input side and the output side have the same narrow side surface 1.
4, but it is needless to say that they may be separately provided on the opposed narrow side surfaces.

FIG. 3 is an explanatory view similar to FIG. 1 of still another embodiment of the waveguide type filter of the present invention. In this example, the center conductors 41a, 42 of the coaxial connectors 41, 42
Since the tip of a is inserted parallel to the direction of the electric field,
The coupling with the cavity resonators 51 and 54 is strong, and the insertion length is shortened for coupling. In particular, in order to obtain a narrow band filter characteristic, it is necessary to weaken the degree of coupling. The distal ends of the center conductors 41a, 42a of the coaxial connectors 41, 42 are further pulled up from the inner wall surfaces of the cavity resonators 51, 54. In some cases, it may be preferable to couple with the cavity resonators 51 and 54 in the inserted state. That is, the coupling between a conventional coaxial connector such as a waveguide coaxial converter and a waveguide is coupled by a considerable insertion length into the waveguide, but when directly coupled to the waveguide filter of the present invention. In general, a waveguide type filter having a desired band characteristic can be obtained by coupling the center conductor with its tip portion being very shallow or recessed. In FIG. 3, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted.

FIG. 4 is an explanatory view similar to FIG. 1 of still another embodiment of the present invention. In this example, one end, for example, the output side is not a coaxial connector, but a waveguide circuit 6 is connected. It was done. On the side to which the waveguide circuit 6 is connected, the reactance element 24 at the end is formed of an iris-type reactance element as in the conventional case. In this structure, the waveguide circuit 6 is connected to the output side. On the input side, a reactance element at the end is formed by the short-circuit plate 31, and the coaxial connector 41 is directly connected to the cavity resonator 51 at the end. As a result, a compact, lightweight and low-cost waveguide filter can be obtained. That is, in each of the above-described examples, the reactance elements at both ends of the input and output are short-circuited, and the coaxial connector is provided in the vicinity of the short plate. can do. In FIG. 4, the same portions as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

According to the present invention, since the center conductor of the coaxial connector is electrically coupled directly to the cavity resonator constituting the filter, the waveguide coaxial converter is not required,
It can be directly coupled to a waveguide filter via a coaxial connector. On the other hand, the coupling between the cavity resonator and the center conductor of the coaxial connector is such that the center conductor is inserted in the direction perpendicular to the electric field, or when inserted in the direction parallel to the electric field, the center conductor is pulled in from the inner wall of the waveguide. Since the coupling method is set including the state where the signal is kept in a closed state, the degree of coupling can be adjusted so as to obtain a desired bandwidth. As a result, a waveguide coaxial converter becomes unnecessary, and a very small and lightweight waveguide filter can be obtained.

In each of the above examples, a rectangular waveguide has been described, but a circular waveguide, a waveguide having a square cross section, etc.
The same applies to other shapes. In addition, in the examples shown in FIGS. 1 to 3, the mounting surfaces of the coaxial connectors 41 and 42 on the input / output side are configured to be mounted on the same wall surface or the opposite wall surface. However, the mounting surface is not limited. For example, another combination such as providing the input side and output side coaxial connectors separately on different wall surfaces such as the short-circuit plate 31 and the narrow side surface 14 can be used. For example, as is well known, a post provided using a rod-shaped metal or the like is provided between resonators such as the iris-type reactance elements 21, 22, and 23 shown in FIG. The effect of the present invention is exactly the same even when a type reactance element is used, and such a waveguide type filter also satisfies the object of the present invention.

[0020]

According to the present invention, it is possible to form a very small and lightweight waveguide filter, which does not require a waveguide coaxial converter, even with a waveguide filter that inputs and outputs with a coaxial connector. It is possible to meet the demand for lightness and shortness. Moreover, the degree of coupling can be adjusted much more easily than the adjustment of the degree of coupling using the iris-type reactance element, and a significant cost reduction can be achieved in combination with the reduction in the number of components.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of a waveguide filter of the present invention.

FIG. 2 is an explanatory diagram of another embodiment of the waveguide filter of the present invention.

FIG. 3 is an explanatory view of still another embodiment of the waveguide filter of the present invention.

FIG. 4 is an explanatory view of still another embodiment of the waveguide filter of the present invention.

FIG. 5 is an explanatory diagram of an example of a conventional waveguide filter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Waveguide 21-23 Iris type reactance element 31, 32 Short circuit board 41, 42 Coaxial connector 51-54 Cavity resonator

Claims (4)

[Claims] 1. The waveguide is partitioned by an iris-type or post-type reactance element to form one or more cavity resonators, and at least an input side and an output side of the one or more cavity resonators are formed. A waveguide in which one of the reactance elements is formed by a short-circuit plate, and a connector pin of an input / output coaxial connector is coupled in a cavity resonator near the short-circuit plate so as to obtain a desired pass band. Type filter. 2. The waveguide filter according to claim 1, wherein the coaxial connector is provided on the short-circuit plate, and a connector pin of the coaxial connector is inserted in a direction perpendicular to the short-circuit plate. 3. The waveguide according to claim 1, wherein the coaxial connector is provided on a narrow side surface of the waveguide, and a connector pin of the coaxial connector is inserted in a direction perpendicular to the narrow side surface. Type filter. 4. The waveguide filter according to claim 1, wherein the coaxial connector is provided on a wide side surface of the waveguide, and a connector pin of the coaxial connector is inserted in a direction perpendicular to the wide side surface. .