JPH0543521Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a waveguide type dielectric filter that utilizes the TM mode, and particularly relates to one in which the support structure of the dielectric pillars is improved.

[Prior Art] FIGS. 2 and 3 show conventional examples of TM mode dielectric filters. A plurality of dielectric columns 2 shown in FIG. 3 are fixedly arranged inside the metal case 1, and each dielectric column cooperates with the metal case 1 to form a dielectric resonator. In FIG. 2, numeral 3 indicates a coaxial connector, which is coupled to a dielectric pillar constituting an input stage or an output stage. Also,
4 indicates a metal screw for frequency adjustment.
As shown in FIG. 3, each dielectric column 2 is fixed to the inner surface of the metal case 1 via electrodes 5 and 6 formed at both ends.

[Problem that the invention attempts to solve]

In the conventional example described above, the dielectric column 2 is fixed to the metal case 1, but the dielectric ceramic and the metal have considerably different coefficients of linear expansion. Therefore, even if the dielectric column is fixed as shown in Figure 3, if the operating temperature changes, the dielectric column 2 will change as shown in Figure 4.
One end of the metal case 1 may separate from the inner surface of the metal case 1, and a gap l may occur. As a result, there was a problem in that the effective dielectric constant of the dielectric filter decreased and the center frequency varied.

Therefore, an object of the present invention is to provide a dielectric filter that exhibits stable filter characteristics against temperature changes.

[Means for solving problems]

The dielectric filter of the present invention utilizes the TM mode, and has a pair of opposing surfaces as open surfaces, and a frame made of dielectric ceramics with electrodes formed on the outer surfaces. and a dielectric column that is integrally provided with the frame and is made of the same material as the frame so as to be located in the frame from at least one of the opening surfaces. Equipped with multiple vessels. The plurality of dielectric resonators are assembled so that the openings of their respective frames overlap. and,
The assembled dielectric resonators are housed and held in a metal case in an assembled state.

[Effect]

In this invention, the frame body is installed integrally with the dielectric column and made of the same material as the dielectric column and is used as the filter case, so even if the ambient temperature changes, the dielectric column remains in the filter case. It cannot be separated from. Note that the metal case in the present invention does not constitute a part of each dielectric resonator, but is provided to hold a group of dielectric resonators.

In addition, in the present invention, in each dielectric resonator, the dielectric column is surrounded by a frame body except for the aperture side, so the aperture surfaces of multiple dielectric resonators are The main body of the dielectric filter, excluding the metal case, can be assembled by simply stacking and assembling the parts.

[Explanation of Examples]

FIG. 1 is a perspective view showing the main parts of an embodiment of the present invention. A plurality of dielectric resonators 12 to 14 assembled in a metal case 11 are held and fixed in an assembled state. In this embodiment, the dielectric resonator 12 is the first stage dielectric resonator, the dielectric resonator 13 is the last stage dielectric resonator, and the dielectric resonator 1 is the first stage dielectric resonator.
4 constitutes second and third stage dielectric resonators.

As shown in FIG. 5, the dielectric resonator 12 constituting the first stage has a frame 1 made of dielectric ceramics.
A dielectric column 1 integrally made of the same material is disposed within 2a.
2b. As shown in the figure, the frame body 12a has a pair of opposing side surfaces each serving as an opening surface, and the dielectric column 12b is arranged at a position recessed from the opening surface. In addition,
The width of the dielectric pillar 12b is approximately 1/1 of the thickness of the frame 12a.
It is set to 2. Further, an electrode 12c shown by hatching is formed on the outer surface of the frame 12a. The dielectric pillar 12b and the electrode 12c cooperate to form one dielectric resonator.

Note that since the dielectric resonator 12 constitutes the first stage, the hole 12d for coupling with the outside is located in the frame 12.
It is formed in a part of a. A center conductor such as a coaxial connector is inserted through this hole 12d and coupled to the dielectric column 12b.

As shown in FIG. 6, the dielectric resonator 13 constituting the final stage has a structure in which dielectric columns 13b are integrally provided within a frame 13a made of dielectric ceramics, and the outer periphery of the frame 13a is An electrode 13c is formed on the surface. Moreover, since it constitutes the final stage, a hole 13d for coupling with the outside is formed in a part of the frame 13a. As is clear from FIG. 1, the dielectric resonator 13 is in the state shown in FIG.
The dielectric resonators 12 and the frame bodies are assembled so that their openings overlap with each other when rotated by 90 degrees.

The dielectric resonator 14 constitutes the second stage and the third stage, and as shown in FIG. There is. An electrode 1 is provided on the outer peripheral surface of the frame 17.
7c is formed. These dielectric pillars 15, 16
cooperates with the electrode 17c to form a two-stage dielectric resonator. The dielectric pillar 15 constituting the second stage resonator is arranged in parallel with the dielectric pillar 12b of the dielectric resonator 12 constituting the first stage. On the other hand, 3
The dielectric pillars 16 constituting the resonators in the second stage are arranged in parallel with the dielectric pillars 13b of the dielectric resonators 13 constituting the final stage. Therefore, the first-stage dielectric resonator 12 and the second-stage dielectric resonator are electromagnetically coupled, and similarly, the dielectric column 16 constituting the third-stage dielectric resonator and the final-stage dielectric resonator are coupled electromagnetically. The dielectric resonator 13 is electromagnetically coupled.

As is clear from FIG. 7, the dielectric pillars 1 constituting the second and third stage dielectric resonators
Cut portions 18 and 19 are formed at opposing diagonal corners at the intersection of portions 5 and 16. The notches 18 and 19 are formed to couple the second and third stage resonators.

In this embodiment, the dielectric resonators constituting the second and third stages are dielectric columns 15 and 1 shown in FIG.
6, the size of the filter device can be effectively reduced compared to the case where separate dielectric resonators are used. There is.

Returning to FIG. 1, each dielectric resonator 12 to 14 is
They are assembled in the above-mentioned direction and held within the metal case 11. Here, slits 11a to 11d are formed in the metal case 11. The slits 11a to 11d are provided for pouring solder into the slits 11a to 11d.
The metal case 1 is assembled with each dielectric resonator 12 to 14 assembled by pouring solder from 1d.
Fixed to 1. At the same time, each dielectric resonator 12~
Electrodes 12c to 17c formed on the outer surface of 14
(FIGS. 5 to 7) are electrically connected to the metal case 11.

Further, the metal case 11 has through holes 11e, 1
1f is formed. These through holes 11e, 11
f is provided for coupling with the outside, and is similar to the hole 12 of the dielectric resonator 12 in FIG.
d and at a position that coincides with the hole 13d of the dielectric resonator 13 in FIG.

The filter of the embodiment shown in FIG. 1 can be connected to the outside by using the above-mentioned connecting holes 12d, 13d and through holes 11e, 11f. For example, as shown in the cross-sectional view in FIG. 8, the center conductor 21a of the coaxial connector 21 is inserted through the hole 12d, an electrode 12e is formed on the side surface of the dielectric column 12b, and the electrode 12e and the center conductor 21a are connected. All you have to do is connect. In this case, the coaxial connector 21 itself is fixed to the metal case 11 by soldering. Note that FIG. 8 shows an example of a coupling structure with the outside for input/output, and various other electrical or magnetic coupling structures may be used.

Although not shown in FIG. 1 for ease of understanding, shorting plates made of the same material as the metal case 11 are usually arranged on the front and rear end surfaces of the metal case 11. The openings at both ends of the metal case 11 are closed. In this case, a hole or screw hole for incorporating a frequency adjustment or coupling adjustment mechanism may be formed in the short circuit plate. The shorting plate can be easily fixed by soldering to the metal case.

Further, in the above embodiment, the dielectric resonators 12 to 1
4 are assembled so as to be in contact with each other, and the metal case 11
However, as shown in FIG. 9 with the metal case removed, the metal plates 22 and 23 are sandwiched between the dielectric resonators 12 to 14.
If a coupling window is formed in 3, the degree of coupling between each dielectric resonator can be adjusted by adjusting the size of the coupling window. Therefore, a bandpass filter with a narrower band can be constructed.

In the illustrated embodiment, a dielectric resonator in which prismatic dielectric pillars are arranged within a rectangular frame is used, but the shapes of the frame and dielectric pillars are not particularly limited; A configuration in which columnar or prismatic dielectric columns are arranged may also be used.

[Effect of idea]

According to the present invention, a plurality of dielectric resonators each having a frame made of ceramics with electrodes formed on the outer surface and dielectric pillars made of the same material as the frame are integrally provided inside the frame. Because it has a structure in which the dielectric pillars are gathered together and held in a metal case, even if the ambient temperature changes, the dielectric pillars will not separate from the case as in conventional examples, and therefore the effective fluctuation of the center frequency and the effective dielectric A filter device that can effectively prevent a decrease in the rate and exhibit a stable Q can be realized. In addition, each dielectric resonator is
It is constructed using a frame made of ceramics and dielectric pillars that are integrated with the frame.
By simply assembling a plurality of dielectric resonators so that their apertures overlap each other, the main body of the dielectric filter excluding the metal case can be easily constructed.
Furthermore, since it is only necessary to assemble a plurality of dielectric resonators as described above, the degree of coupling between each resonator can also be surely set to a desired value. Then,
Since there is no variation in coupling due to positional shift that occurs when a dielectric resonator is placed in a metal case as in the past, it is easy to obtain a filter with the desired amount of coupling, and the amount of adjustment of the amount of coupling is also effective. can be reduced to

Additionally, if a narrowband filter is required, a conductive member such as a metal plate is sandwiched between each dielectric resonator, and a coupling window is provided in the dielectric member to adjust the size of the window. You can easily obtain a narrowband filter by simply doing the following:

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the main parts of an embodiment of the present invention, Fig. 2 is a perspective view showing an example of a conventional dielectric filter, and Fig. 3 shows the relationship between the dielectric column and the metal case in the conventional example. 4 is a sectional view for explaining the problems of the conventional example, FIGS. 5 to 7 are perspective views for explaining each dielectric resonator used in the embodiment, and FIG. 8 is a sectional view for explaining the problems of the conventional example. 9 is a cross-sectional view showing an example of a coupling structure with the outside in the embodiment, and FIG. 9 is a schematic cross-sectional view showing another embodiment of the present invention. In the figure, 11 is a metal case, 12 to 14 are dielectric resonators, 12a, 13a, and 17 are frame bodies, and 1
2b, 13b, 15, 16 are dielectric pillars, 12c,
13c and 17c indicate electrodes.

Claims (1)

[Claims for Utility Model Registration] A frame body made of dielectric ceramics, a pair of opposing surfaces each of which is an opening surface, and an electrode is formed on the outer surface; is provided integrally with the frame so as to be located at the back from at least one of the
and a plurality of dielectric resonators each having a frame and a dielectric column made of the same material, the plurality of dielectric resonators being grouped together such that the opening surfaces of the respective frames overlap, A dielectric filter further comprising a metal case housing the assembled dielectric resonators to hold the assembled dielectric resonators.