JPS58166803A - Dielectric filter - Google Patents

Abstract

PURPOSE:To realize a compact and light-weight structure of a microstrip line type dielectric filter, by adhering the rear sides of two dielectric plates to each other so that the resonator coupling windows overlap with each other. CONSTITUTION:A filter F1 consists of dielectric plates 22-1 and 22-2, and these plates are adhered to each other with their rear sides via a metallic supporting plate 21A. Thus the coupling windows 27-1 and 27-2 formed on the rear sides of the plates 22-1 and 22-2 overlap with each other via a through hole 28 drilled to the plate 21A. In such a way, 6 resonators 23-1-23-6 are connected successively. A compact and light-weight filter which excels in the electrical characteristics is obtained owing to application of a coupling system using the coupling windows that serve as nonmetallized regions.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a dielectric filter used in VHF band and UHF band wireless devices, and in particular to i-electronic filters! This relates to a line type dielectric filter.

(2) Background of the technology Dielectric filters are used as filters for VHF and UHF band radio equipment, but due to the nature of single-mounted radios and portable radio equipment called mobile radios, each component must be made smaller and lighter. Dielectric filters are also becoming smaller year by year, which is an important issue. However, conventional dielectric filters still have openings as described below, and countermeasures are desired.

(3) Prior art and one point Figure 1 is a partially cutaway view of a conventional general dielectric filter. A casing is shown in which a filter F is housed.

Filter F has a plurality of holes 3 (only some of which are shown in the figure) formed at predetermined intervals in a block 2 mainly made of barium titanate-based dielectric material, and holes 3 are formed on the side and bottom surfaces of each block 2 and on the inner surface of the holes 3. By forming a conductive film mainly made of silver-platinum material (partially shown by cross-hatching), a 174-wavelength half-coaxial resonant element with hole 3 short-circuited at one end and open at the other end. This is a dielectric filter configured to have the following structure. In addition, in FIG. 1, numeral 4 is an exciter, numeral 5 is a connector,
Reference numeral 6 indicates a frequency adjustment screw. However, although this 7-filter has very good electrical characteristics, it has the disadvantage of being large and heavy.

As a countermeasure to this problem, an example of a conventional dielectric filter is shown in FIG. 2, which is made smaller and lighter by sacrificing some electrical characteristics. In the figure, the reference numeral 11 indicates a housing, and the filter F is #! of the dielectric plate 12. A plurality of conductor films 13 (only one is shown in the figure) are formed on the surface at required intervals, and these are used as resonant elements,
A conductive film is also formed over the entire back surface of the dielectric plate 12 to serve as an external conductor, one end of the resonant element 13 is shorted to the external conductor, and the other end is opened to form 1/4 of the nine structure. This is a wavelength microstrip line type dielectric filter. Note that the reference numeral 14 indicates an excitation body made of a conductive film similar to that of the resonant element 13, and the reference numeral 16 indicates a connector.A filter with this structure can be made thinner than the filter shown in FIG.
Kana 9 can be made smaller and lighter. However, the length of the filter is not much different from before, and the space efficiency (space 7
Another problem is that the dielectric material is thin and elongated, so it tends to warp during firing of the material.

On the other hand, in radio equipment, when it is desired to improve the amount of attenuation only for a specific frequency outside the frequency band of the filter, a polarized filter having a pole outside the band may be used.

Figure 3 is a graph comparing the characteristics of the non-polar type and the polar type of a conventional four-stage filter. ), and non-polar filters are shown by dotted lines, and polar filters are shown by solid lines.In this way, polar filters can have a larger amount of attenuation than non-polar filters, so The number of stages can be reduced, which is very effective in reducing the size of the filter.Therefore, attempts have been made to further reduce the size of the filter by combining the above-mentioned microstrip line type and the above-mentioned polar type.

An example of this is shown in FIG. 4. This filter is basically the same microstrip line type four-stage polar dielectric filter as the filter shown in FIG. A polarized filter requires coupling not only between adjacent resonant elements but also between non-adjacent resonant elements (provided they are located symmetrically with respect to the center of the filter). Therefore, in the past, a structure was generally adopted in which the non-adjacent resonant elements 13-1 and 13-4, such as the fourth mesh, were coupled using a 16-fathom. However, in such a structure, cable 1
6C) It is necessary to increase the size of the dielectric plate 12 in order to secure the connection portion, and therefore it is necessary to increase the size of the casing 11, including an increase in the space for accommodating the cable 16. This tendency becomes more noticeable as the number of filter stages increases. Therefore, there is a problem in that there is no advantage in making the filter smaller by using the virtuous type.

(4) Purpose of the Invention In view of the above-mentioned actual state of the prior art, it is an object of the present invention to provide a dielectric filter that is significantly smaller and smaller in size than conventional filters.

(5) Structure of the Invention The dielectric filter according to the present invention generally consists of a resonant element formed by forming a plurality of conductive films at required intervals on the second peak of a dielectric plate, and A conductive film is formed on the surface in almost all directions except for the area that becomes the resonant element coupling window to constitute an external conductor, and the two dielectric plates are placed on the back side so that the resonant element coupling window overlaps. It has a structure in which the dense layer of copper is solidified.

(6) Practical Examples of the Invention Examples of the present invention will be described below with reference to the drawings.

Basic embodiment 'f of the dielectric filter according to the present invention: Shown in Figs. 5 to 7 ◇. This filter is a 1/4 wavelength microstriply type six-stage non-polar dielectric filter. In the figure, numeral 21 indicates a housing. As particularly shown in FIG. 7, the filter Fl is composed of two dielectric plates 22-1.
and 22-2. These dielectric plates 2
2(-1, -2) basically has the same structure as the dielectric plate 12 shown in FIG. 2 and FIG.
The dielectric plate 22-1 has three resonant elements 23 (-
1°-2,-3) and one exciter 24-1 is formed,
Furthermore, as shown by reference numeral 7A, an external conductor 26-1 is formed on almost the entire surface of the <m-plane.

On the other hand, the second dielectric plate 22-2 has three resonant elements 23 (-4°-5, -6) and one exciter 24-2 formed on its front surface, as shown by reference numeral 7B, and also has a back surface. An outer conductor 26-2 is formed over almost the entire surface. That is, the first and second sieve band plates 22 (-1, -2) are the conventional 1. A six-stage filter consisting of a dielectric plate of TK is cut into two at the center to have a configuration as shown in FIG.
is formed by fixing these two dielectric plates 22 (-1, -2) closely to each other on their back surfaces. In addition, in the illustrated example, the housing 2
1, both dielectric plates 22 (-1°-2) are bonded and fixed with a metal support plate 21 interposed between them. Then, in order to couple the third resonant element 23-3 and the fourth resonant element 23-4, a conductive film is placed on the back surface of the first ws electric board 22-1 at a position corresponding to the third resonant element 23-3. An unformed region (non-metalized region), that is, a bonding window 27-1 is formed, and a second electrical board 2 is formed.
A similar coupling window 27-2 is formed at a position corresponding to the fourth resonant element 23-4 on the back surface of 2-2, and these coupling windows 27-1 and 27-2 are opened in the support plate 21A. They are configured so that they are electrically connected to each other via the openings 28. As a result, a six-stage non-pole filter in which six resonant elements 23 (-1 to -6) are sequentially coupled is obtained. Input/output to the filter Fl is performed by connectors 25 (-1, -2) connected to the exciter 24 (-1, -2), respectively. By changing the position and shape of the coupling windows 27 (-1, -2), the coupling 11 between the resonant elements can be improved. 1ylJ and can prevent the coupling of unnecessary modes, and it is possible to improve the electrical characteristics of the filter, especially the deterioration of the attenuation outside the desired frequency band.

According to the configuration of the present invention as described above, although the filter F1 is twice as thick as the filter F shown in FIG. This is a significant downsizing. In addition, since the length of each dielectric plate is approximately half that of conventional plates, warping during firing is eliminated.
Manufacturing becomes very easy. Furthermore, as described above, the coupling method using the coupling window provides the additional advantage of improved filter characteristics.

FIGS. 8 and 9 show that the filter F
Although the structure itself is the same, the casing 21' has been improved. The housing 21' has a shape that can be easily press-molded, and is configured to be integrally connected with the filter support plate 21 sandwiched therebetween, and has a simple structure and is suitable for mass production. Further, as shown in FIG. 9, the lower part of the support plate 21 is connected to the housing 21
It protrudes from the top, making it easy to mount it on a glint board, etc.

Next, a second embodiment of the dielectric filter according to the present invention will be described.
This is shown in FIGS. 1 to 12. This filter is of the 174-wavelength microstripe line type similar to the basic embodiment, but is of the 4-stage polar type.
1 indicates a housing, and as particularly shown in FIG. 12, the filter F2 also includes two dielectric plates 32-1 and 32-2.
It consists of Two resonant elements 33 (-1, -2) and one exciter 3 are provided on the surface of the first # electric board 32 to 1.
4-1 is formed, and an external conductor 36-1 is formed on the back surface over almost the entire surface thereof, as shown by reference numeral 12. On the other hand, the second dielectric plate 32-2 has two resonant elements 33 (-3, -4) on its surface as shown by reference numeral 12B.
and one excitation body 34-2 are formed, and an external conductor 36-2 is formed on the back surface over almost the entire surface of the substrate.

Filter F2 consists of these two dielectric plates 32 (-1°-
2) between the surfaces! (b) It is something that can be determined.

Incidentally, in the illustrated example, like the above-mentioned filter it, the integral 31
A metal support plate 31A is interposed between both #electrical plates 32 (-1°-2) to provide support to the metal plates 32 (-1°-2), and the structure is such that they are in contact with each other. Then, the second resonant element 33-2 and the third resonant element 3
3-3, the first resonant element 33-1
and the fourth resonant element 33-4, the first resonant element 33-1 and the second resonant element 33-1 in the IIk direction of the first dielectric plate 32-1
Coupling windows 37-1 and 37-2, which are non-metallized regions, are formed at positions corresponding to the resonant element 33-2, respectively.
On the other hand, the third resonant element 33- on the back side of the second electrical board 32-2
Coupling windows 37-3 and 37-4 are formed at positions corresponding to the third and fourth resonant elements 33-4, respectively, and the coupling windows 37-1 and 3-hoo 2 of the first dielectric plate 32-1 It is configured to overlap with the coupling windows 37-4 and 37-3 of the second electric board 32-2 through the openings 38-1 and 38-2 of the support plate 31A, respectively. As a result, the four resonant elements 33 (-1 to -4) are coupled to the face, and the first resonant element 33-1 and the fourth resonant element 3 which are not adjacent to each other are connected to the face.
A 4-stage multipole filter in which 3-4 is also combined is obtained. Input/output to the filter r2 is performed by connectors 35 (-1, -2) connected to the exciter 34 (-1, -2), respectively. Furthermore, as mentioned above, the electrical characteristics of the filter can be improved by appropriately selecting the position and shape of the coupling windows 37 (-1 to -4).

As described above, according to the present invention, a multi-stage polarized filter can also be used as a conventional filter. There is no need for coupling by means of a filter, and therefore, it is possible to realize a compact filter on the same level as a non-pole type filter.

In addition, when configuring a virtuous filter of 41R or more according to the present invention, if it is an even number attack, the above-mentioned four-stage filter i
It is sufficient to simply increase the number of resonance elements and coupling windows of each dielectric plate based on F2. On the other hand, as an example of an odd number of stages, a five stage filter F3 is shown in FIG. In this case, three resonant elements 43 are installed on the first #electrical board 42-1.
(-1, -2°-3), and the second dielectric plate 42-2
Two resonant elements 43 (-4, -5) i- are formed in the. However, in the case of an odd number of stages, the middle resonant element 43-3, that is, in the case of 5 stages, the resonant element 43-3 of I3 is the second adjacent resonant element.
and 1g4 resonant element 43-2.43-4; on the other hand, the first resonant element 43 which is not connected to lI4
-1, the fifth resonant element 43-5, and the second resonant element 43-
2 and the fourth resonant element 43-4'j- because it is necessary to couple them respectively, the first and second resonant element 43-1
．． 43-2t-An external conductor 46-1 and a coupling window 47 formed on the surface of the first il electric board 42-1 and corresponding thereto.
-1.47-2t- Formed on the base surface of the first #electric body plate 42-1, and also ag4 and ag5 resonant elements 43-4.43-5
are formed on the surface of the tuna 2 sieve housing plate 42-2, and the corresponding outer conductor 46-2 and coupling window 47-3 and 47-4 are formed.
is formed on the back surface of the second Fflj electric body 42-2, and the a11 resonant element 43 -1 is coupled to the fifth resonant element 43-5 through the coupling window 47"1, the opening 48-1 of the support plate 41A, and the coupling window 47-4, and the second resonant element 43-2 47-2, a through the opening 48-2 of the support plate 41, and the connecting window 47-3.
ll! On the other hand, the third resonant element 43-3 and its corresponding external conductor 46-1' are connected to the back and front surfaces of the 111th electric board 42-1, respectively. The second resonant element 43-2 and [
4 resonant element 43-4 through a dielectric plate. In addition to this, 19.5 resonant elements 43 (-1 to -
5) are coupled in order, and the first resonant element 43-1 and the fifth resonant element 43-5, and the second resonant element 43-2 and the fourth resonant element 43-4, which are not adjacent, are coupled respectively. A five-stage polarized filter is obtained.

(7) Effects of the Invention As described above, according to the present invention, in a MyFrostrilagline type dielectric filter, by adopting a coupling method using a coupling window which is a non-metalized region, p1 can be made non-polar or polar. Regardless of its shape, it is much smaller in size than conventional filters, has a simple structure, is easy to manufacture, and moreover, can centrally produce a dielectric filter with good electrical characteristics.

All of the embodiments being described are filters composed of quarter-wave resonant elements with one end open and the other end short-circuited; The present invention is also applicable to filters made up of resonant elements.

[Brief explanation of the drawings] Figure 1 is a partially cutaway perspective view of a conventional general dielectric filter.
Figure 2 is a partially cutaway perspective view of a conventional Myfrost Rilla line dielectric filter, Figure 3 is a diagram showing the characteristics of a non-polar filter and a polar filter, and Figure 4 is a conventional polar dielectric filter. A vertical cross-sectional view of the filter, FIG. 5 is a partial cross-sectional view of a basic embodiment of the dielectric filter according to the present invention, and FIG. 6 is a cross-sectional view taken along arrow Vl-11 of the embodiment of FIG. FIG. 7 is an exploded and developed perspective view of the main parts of the embodiment shown in FIG.
Figures 1g9 and 1g9 are plan sectional views and side views, respectively, of page break examples of the above basic embodiment, and Figures 1θ, 11, and 12 are longitudinal sectional views, respectively, of the second embodiment of the galvanic filter of the present invention. , a plan sectional view and an exploded and developed perspective view of the main lk part,
FIG. 13 is an exploded and developed perspective view of the main parts of a modification of the second embodiment. Fl, F2, F3...dielectric filter, 21゜2
1', 31...Case, 21A, 31A, 41m...
Support plate, 22 (-1, -2), 32 (-1, -2). 42(-1,-2)...Dielectric plate, 23(-1~-□
), 33 (-1 to -4), 43 (-1 to -5)...resonant element, 24 (-1, -2), 34 (-1°-2), 4
4(-1,-2)...Exciter, 25(-1°-2),
35(-1,-'2')...Connector, 27(-1,
-2), 37 (-1 to -4). 47(-1 to -4)...Joining window, 28.38(-1
, -2), 48 (-1, -2)... Opening of support plate. Patent Applicant Fujitsu Limited Patent Application Agent Patent Attorney Akira Aomizu Patent Attorney Kazuyuki Nishidate Patent Attorney 1) Yukio Patent Attorney Akira Yamaguchi Figure 1 Figure 2 Figure 3 Figure 4 Country 5, 7vA B Figure 8 1A tl-1 Figure 12

Claims (1)

[Claims] 1 In #1, a plurality of conductors J[ were formed at required intervals on the surface of the body plate to constitute a resonant element, and a region that would become a resonator coupling window was removed on the 1 side of the order sieve body plate. A microstrip in which a conductor film is formed over almost the entire surface to form an outer conductor of 1 m, and two dielectric plates are closely fixed to each other on their back surfaces so that the windows for coupling the resonant element overlap. Line type dielectric filter.