JPH0419843Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a dielectric coaxial resonator used, for example, in a filter device.

<Prior art> In general, this type of dielectric coaxial resonator is
For example, as shown in FIG. 4, a rectangular parallelepiped dielectric block 2 made of dielectric material such as ceramic is provided, and a plurality of through holes 3 ₁ , 3 ₂ (in the figure, 2 A central conductor 4 ₁ , 4 ₂ is formed on the circumferential surface of each through hole 3 ₁ , 3 _{2 ,} and an outer conductor 5 is formed on the outer surface of the dielectric block 2 . ₂ and the outer conductor 5 are short-circuited via an electrode 7 formed on one end surface of the block 2, and a resonant element 1 ₁ , 1 ₂ is configured for each through hole 3 ₁ , 3 ₂ . Integrally molded resonators are known.

In the case of a resonator in which a plurality of resonant elements 1 ₁ and 1 ₂ are provided in one dielectric block 2 in this way, in order to capacitively couple adjacent resonant elements 1 ₁ and 1 ₂ to each other, Conventionally, for example, as shown in the same figure,
A square hole 20 for coupling is provided between both resonant elements 1 ₁ and 1 ₂ . In this case, the degree of coupling between the two resonant elements 1 ₁ and 1 ₂ is adjusted to a required coupling capacity by adjusting the size of the coupling hole 20 .

<Problems to be solved by the invention> By the way, the conventional dielectric coaxial resonator as described above is created by filling a mold with a dielectric material, compression molding it, and then firing it. In this case, first, the manufacturing cost of the mold is high, and the manufacturing process requires a lot of effort. Furthermore, even if the resonators have the same shape, the sizes of the coupling holes 20 differ between the resonators having different coupling capacitances, resulting in problems such as the inability to share a mold.

In order to improve such problems, in the past, for example, as shown in _{FIG .}
are made separately, and a coupling block 21 made of a dielectric material different from the dielectric material constituting the resonant elements 1 ₁ and 1 ₂ is interposed between the two resonant elements 1 ₁ and 1 ₂ , There is one in which this coupling block 21 and both resonant elements 1 ₁ and 1 ₂ are bonded with adhesive.

However, even in this case, there are problems in that the manufacturing process becomes complicated, and quality control becomes complicated, such as variations in the dielectric constant and bonding strength of the adhesive layer.

Furthermore, as a conventional improvement measure, a comline type one shown in FIG. 6 or FIG. 7, for example, has been proposed. Among these, in the resonator shown in FIG. 6, the two resonant elements 1 ₁ and 1 ₂ are constructed from one dielectric block 2 as in the first conventional example shown in FIG. 4 above. , the center conductors 4 ₁ , 4 ₂ and the outer conductor 5 are connected to the open end surface 8 of the dielectric block 2, respectively.
Both conductors 4 ₁ ,
By adjusting the formation area of the electrodes _4a , 5a on the open end surface 8 side of the resonant elements 1 ₁ , 1 2 of 4 2 , ₅
Adjusting the degree of connectivity between However, in this case as well, there is a problem that the Q value of the resonator decreases, and the capacitor electrodes 4a and 5
Since it is necessary to provide a, there is also the problem that additional work effort is required.

Furthermore, in the fourth conventional example shown in FIG.
The respective center conductors 4 ₁ , 4 2 of the two resonant elements 1 ₁ , 1 ₂ integrally formed with the dielectric blocks 2 are connected to metal posts 23 , ₂₃ provided on the lid 22 of a shielding case (not shown). The metal posts 23, 23 and the center conductors 4 ₁ , 4 ₂ are arranged to face each other to form a coupling capacitance. However, even in this conventional example, it is necessary to devise the shape of the shield case, and each metal post 2 for connection
There is a problem in that it is difficult to set the distance between 3 and 23 and the center conductors 4 ₁ and 4 ₂ .

In view of these conventional problems, the present invention adjusts the degree of coupling between each resonant element in the above-mentioned integrally molded dielectric coaxial resonator without changing the shape of the dielectric block or shield case. The object of the present invention is to facilitate the adjustment of coupling capacitance.

<Means for solving the problem> In order to achieve this purpose, this invention
A dielectric block having a plurality of through holes is provided, and a center conductor formed on the inner circumferential surface of each through hole and an outer conductor formed on the outer circumferential surface of the dielectric block are short-circuited to each other. In a dielectric coaxial resonator in which one end surface of the dielectric block in which the hole is opened is an open end surface in which the surface of the dielectric block is exposed, the dielectric block has an open end surface that extends over the entire circumference of the outer peripheral surface of the dielectric block that is continuous with the open end surface. The dielectric block is characterized in that the through hole has a constant length along the axial direction, and has an open surface where the surface of the dielectric block is exposed without the outer conductor formed thereon.

<Example> Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 is a partially cutaway perspective view of this embodiment.
FIG. 2 is its equivalent circuit diagram, and FIG. 3 is its central vertical sectional side view. In these figures, the dielectric coaxial resonator of this embodiment is, for example, a two-stage combline type filter that is used while being electrically connected to a shield case (not shown), and has the same specifications. The first and second resonant elements 1 ₁ and 1 ₂ are integrally molded with one ceramic dielectric block 2 arranged on the left and right sides.

This dielectric block 2 is formed in the shape of a rectangular parallelepiped,
A pair of circular through holes 3 ₁ and 3 ₂ are formed in the axial direction. Center conductors 4 ₁ , 4 ₂ are formed on the inner peripheral surface of each through hole 3 ₁ , 3 ₂ , while an outer conductor 5 is formed on the outer peripheral surface 2 a of the dielectric block ₂ . , 4 ₂ and the outer conductor 5 are both through holes 3 ₁ ,
3 ₂ is electrically short-circuited by an electrode 7 formed on one opening side end surface 6 . Further, the other opening side end surface 8 opposite to this short circuit end surface 6 is an open end surface in which the surface of the dielectric block 2 is exposed.
The through holes 3 ₁ , _{3 2} of each resonant element 1 1 , 1 ₂ have inlet and
Insulating bushing 11 _{1 .} into which output pin terminals 10 ₁ , 10 ₂ are press-fitted. 11 ₂ is fitted. Each insulating bushing 11 ₁ , 11 ₂ has a pin terminal 10 ₁ , 1
0 ₂ and ensure coupling capacitance between the center conductors 4 ₁ , 4 ₂ and the pin terminals 10 ₁ , 10 ₂ .

The first and second resonant elements 1 ₁ which are configured by sharing one dielectric block 2 in this way,
1 ₂ are electrostatically and capacitively coupled by the following configuration.

Further, the entire circumference of the outer circumferential surface 2a continuous with the open end surface 8, which is the open end surface of the dielectric block 2, has a constant length along the axial direction of the through holes 3 ₁ and 3 ₂ , and An open surface 12 is provided in which the surface of the dielectric block 2 is exposed without forming an outer conductor. Therefore, in this open surface portion a, electrostatic capacitance is generated between the first and second resonant elements 1 ₁ and 1 ₂ , and thereby both the resonant elements 1 ₁ and 1 ₂ are electrostatically coupled. Ru. Further, the outer conductor portion b acts as a resonant line.

Therefore, a dielectric block 2 in which the dimensions and shape of each part are set in advance is prepared, and this dielectric block 2 is
When forming the outer conductor 5 on the outer circumferential surface 2a, an arbitrary coupling capacity can be obtained by adjusting the dimensional ratio (a:b) between the open surface portion a and the outer conductor portion b.

This outer conductor 5 is formed, for example, by dipping the dielectric block 2 into an electrode material bath (not shown). In this case, if the immersion depth of the block 2 is set in advance, the dimensional ratio can be easily selected.

In the filter configured in this way, for example, when a high frequency signal is input to the pin terminal 10 ₁ of the first resonant element _{1 1} , this signal is transmitted to the pin terminal 1
0 ₁ and the first central conductor 4 ₁ through the coupling capacitance generated between the first central conductor 4 1 and the first resonant element 1 1 , this signal is then applied to the first resonant element 1 ₁ due to the dimensions of the open surface portion a and the outer conductor portion b After being propagated to the second resonant element 1 ₂ with a predetermined coupling degree determined by the ratio, the second central conductor 4 ₂
The signal is sent to the output pin terminal 10 _{2 via the coupling capacitance generated between the output pin terminal 10 2} and the output pin terminal 10 ₂ .

The outer conductor 5 may be formed in advance on the front surface of the outer circumferential surface 2a of the dielectric block 2, and then removed by a method such as polishing to a required size.

Furthermore, although the present invention was applied to a two-stage filter in the above embodiment, it is of course applicable to a multi-stage filter.

<Effects of the invention> As described above, according to the invention, an open surface on which no outer conductor is formed is formed in the portion of the outer peripheral surface of the dielectric block that is continuous with the open end surface. By appropriately setting the dimensional ratio between the outer conductor portion and the outer conductor portion, the degree of coupling between each resonant element can be arbitrarily adjusted. Therefore, the same dielectric block can be used with various types of filters with different degrees of coupling between resonant elements without changing the shape of the block or shield case, and the degree of coupling can also be adjusted. Easy to do.

[Brief explanation of the drawing]

1 to 3 show embodiments of the present invention,
Fig. 1 is a partially cutaway perspective view of this embodiment, Fig. 2 is its circuit configuration diagram, and Fig. 3 is its central vertical sectional side view.
Fig. 4 is a central longitudinal sectional side view of the first conventional example, Fig. 5 is a central longitudinal sectional side view of the second conventional example, and Fig. 6 is a central longitudinal sectional side view of the first conventional example.
FIG. 7 is a perspective view of the fourth conventional example, and FIG. 7 is a central longitudinal sectional side view of the fourth conventional example. 2...Dielectric block, 2a...Outer peripheral surface of dielectric block, ₃₁ , ₃₂ ...Through hole, ₄₁ , ₄₂ ...
Center conductor, 5...Outer conductor, 6...Short-circuited end surface, 8...
...Open end surface, 12...Open surface.

Claims (1)

[Claims for Utility Model Registration] A dielectric block having a plurality of through holes formed therein, a center conductor formed on the inner peripheral surface of each through hole, and an outer conductor formed on the outer peripheral surface of the dielectric block. In a dielectric coaxial resonator in which one end surface of the dielectric block in which the through hole is opened is an open end surface in which a surface of the dielectric block is exposed, one end surface of the dielectric block that is continuous with the open end surface is short-circuited to each other. The entire circumference of the outer peripheral surface has a constant length along the axial direction of the through hole, and an open surface is provided where the surface of the dielectric block is exposed without the outer conductor formed thereon. Features dielectric coaxial resonator.