JPS5827524Y2 - 1/4 wavelength coaxial resonator combination structure - Google Patents

Description

[Detailed description of the invention] This invention relates to a structure formed by joining two V4 wavelength coaxial resonators.

Conventionally, filters used in the VHF band or UHF band include those using an LC resonator and those using a coaxial resonator.

However, the former method does not provide sufficient selectivity characteristics, and the latter method has the disadvantage of being large in size.

In recent years, in the field of communication equipment, there has been a desire to make systems smaller and lighter.While other components are being made smaller and lighter, filters are still being used in large numbers due to their importance. Because it is difficult to make the system smaller and lighter, it has been delayed in making the system smaller and lighter.

Therefore, reducing the size and weight of filters has been a top priority for engineers in this field.

This is solved by providing a compact and high performance resonator.

Further, if such a small and high-performance resonator is provided, it can be said to be preferable for devices other than filters using the resonator.

By the way, as an earlier application by the present inventors, the patent application 1972-1
There is an application No. 5203.

That is, this prior invention comprises a plurality of quarter-wavelength coaxial TEM resonators each comprising an inner conductor, an outer conductor, and a dielectric material interposed between the inner conductor and the outer conductor;
and a cylindrical case housing the plurality of 1/4 wavelength coaxial TEM resonators in series, the open ends of each of the 1/4 wavelength coaxial TEM resonators are capacitively coupled to each other, and each of the 1/4 wavelength The short-circuited ends of the wavelength coaxial TEM resonator are inductively coupled filters.

Like this type of filter described above, the short-circuited ends of two 1/4 wavelength coaxial TEM resonators each consisting of an inner conductor, an outer conductor, and a dielectric material existing between the inner conductor and the outer conductor are connected to each other. In some cases, it is necessary to inductively couple the two resonators, so if the two resonators are joined and integrated in an inductively coupled state, handling is easy and it is preferable in terms of characteristics.

This invention was made primarily to produce this effect, and its gist is to bond both resonators together using a heat-resistant inorganic adhesive.

The above-mentioned objects and other objects and features of this invention will become clearer from the following detailed description of an embodiment applied to a filter with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing an example of a filter implementing this invention.

In the structure, the case 1 is made of a conductor such as duralumin and has a cylindrical shape, and has a plurality (six in this example) of 1/4 wavelength coaxial TEs inside.
M resonators 2, 2, . . . are housed in a line in the axial direction.

As shown in FIG. 2, each quarter-wavelength axis TEM resonator 2 has a dielectric material 23 such as a titanium oxide ceramic dielectric material between an inner conductor 21 and an outer conductor 22. being mediated.

That is, this "/4 wavelength coaxial TEM resonator 2 has an inner conductor formed by baking a material, for example, silver paste, which has excellent high frequency conductivity and good adhesion to the dielectric material, onto the inner wall and outer circumference of the cylindrical dielectric material 23. 21 and an outer conductor 22.

The 1/4 wavelength coaxial TEM resonator 2゜2... is 1/4 wavelength coaxial TEM resonator 2゜2...
Since it is a four-wavelength resonator, the minus end becomes the short-circuit side and the other end becomes the open side.

The short-circuit sides are coupled by a coupling electrode 7, which will be described in detail later, but in this case, the pair of resonators 2, 2 . The short-circuited ends of ... are bonded to each other with a glass glaze adhesive or a silica-based inorganic adhesive via the coupling electrode 7, and an outer conductor 22 is preferably provided integrally in view of the characteristics.

Moreover, each resonator 2, 2 . The inside of the dielectric body 23 and therefore the inner conductor 21 of . ...
is inserted.

Then, this pair of resonators 2, 2 . . . are connected to each other with a stray capacitance whose spacing is controlled by, for example, a dielectric spacer 8.

As shown in FIG. 3, the dielectric spacer 8 is formed into a ring shape with a width d made of a dielectric material having a low dielectric constant, such as forsterite. The degree of coupling between the resonators can be adjusted.

Further, the dielectric spacer 8 is not limited to such a ring shape, but may have any shape as long as it can maintain the resonators fixedly spaced apart from each other.

In addition, a small piece of dielectric material (the shape is arbitrary) is placed in a resonator 2°2,
It may be attached in advance to the open end of ....

Incidentally, the electrode 7 may have a structure as shown in FIG. 4.

flb5 Such an electrode 7 has, for example, a generally fan-shaped inductive coupling window 11 and a central hole 72 .

As shown in FIG. 5, this inductive coupling window 71 has an opening degree θ
The coupling state between the resonators can be adjusted by the opening degree determined by the radial direction length d and the center hole 72, and the center rod 3 is inserted through the center hole 72.

This center hole 12 is not necessarily required.

The coaxial TEM mode is a point-symmetric mode, and higher-order modes that break the symmetry will cause deterioration of spurious characteristics. It is desired that it be formed into a pattern.

In this respect, although the mutual positional relationship of the generally fan-shaped inductive coupling windows 71 is excellent in symmetry, it goes without saying that it is not limited to the generally fan shape.

Further, since the position and opening area of the coupling window 71 can be described in a cylindrical coordinate system centered on the coaxial central axis, there is an advantage that the degree of coupling can be easily designed.

Such an electrode 7 can be formed, for example, by baking a silver paste, by fault etching, or by using a thin silver plate or a solid white plate.

Resonators 2, 2 .・
An input coupling capacitor 61 is coupled to the input side of . . . , and an output coupling capacitor 62 is coupled to the output side thereof.

These coupling capacitors 6L62 are formed by, for example, providing electrodes on both end faces of a cylindrical dielectric body, one electrode of which is connected to the inner conductor 21 of the resonator 2, and the other electrode of the input matching connection terminal 51. It is connected to the output matching connection terminal 52.

The input matching connection terminal 51 is connected to the input coaxial connector 41, and the output matching connection terminal 52 is connected to the output coaxial connector 42.

For example, such a filter is assembled as follows.

A plurality of pairs (three in the illustrated example) of 1/4 in case 1
Wavelength coaxial TEM resonators 2, 2J, . . . are housed in series via dielectric spacers 8 for coupling, respectively.

The outer conductor 22 of each resonator 2 is fixed to the inner wall of the case 1 with a conductive adhesive injected through a hole provided in the case for fixation and electrical connection.

In this case, it is advantageous in terms of loss etc. to provide the holes near both ends of each resonator 20.

Alternatively, this may be fixed using screws, but each resonator 2, 2. . . are preferably stored in close contact with the inner wall of the case 1.

A pair of multiple resonators 2, 2° arranged in this way...
・Input coupling capacitor 61. Input junction terminal 51. The input coaxial connectors 41 are fixed in contact with each other.

An output coupling capacitor 62 is provided on the other end face. The output joint terminal 52 and the output coaxial connector 42 are brought into contact and fixed, respectively.

Both end surfaces of the case 10 may be configured with screw caps, or may be fixed with bolts or the like.

Alternatively, the coaxial connectors 41 and 42 may form both end surfaces thereof.

As is clear from the above embodiments, according to this invention, two wavelength-coaxial TEM resonators each consisting of an inner conductor, an outer conductor, and a dielectric material present between the inner conductor and the outer conductor are short-circuited. In a resonator combination structure in which the ends are mutually inductively coupled, it is possible to obtain a combination structure of IA wavelength coaxial resonators bonded with the heat-resistant inorganic adhesive of the image resonator, making it easy to handle the resonators. This improves the efficiency of filter manufacturing, for example.

Note that since the short-circuited ends are bonded to each other where the electric field is minimum, the dielectric loss caused by the adhesive is small and practical.

In addition, since an inorganic material is used, the adhesive layer has good chemical stability and is stable against external environmental factors such as temperature and humidity, and can also be used during the firing process to form internal and external conductors on the ceramic dielectric. This is a practically useful idea that does not cause any change in adhesive strength.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing a filter using an embodiment of this invention. FIG. 2 is a perspective view showing an example of a four-wavelength coaxial TEM resonator 2. FIG. 3 is a perspective view showing a specific example of the dielectric spacer 8. FIG. FIG. 4 is a schematic plan view showing a specific example of the electrode 7. FIG. 5 is an enlarged explanatory diagram of the inductive coupling window 71.

Claims (2)

[Scope of utility model registration request] (1) 174-wavelength coaxial TEM consisting of an inner conductor, an outer conductor, and a dielectric material between the inner conductor and the outer conductor
The short-circuit ends of two resonators are bonded to each other with a heat-resistant inorganic adhesive via an electrode having an inductive coupling window.
4-wavelength coaxial resonator combination structure. (2) A 1/4 wavelength coaxial resonator combination structure according to claim (1), in which the external conductor of the picture frame resonator is integrated.