JPH04103201A - Dielectric band stop filter - Google Patents

Abstract

PURPOSE:To realize a stable electric mechanical characteristic by connecting a chip capacitor to a slit of a groove in a way of cross-link and mounting other lumped constant such as an air-core coil to a plate. CONSTITUTION:Since the conductor film of a groove is cut and separated by a coupling block hole 38, a metallic connection piece 44 cross-links a slit 42. In this case, the entire inner face of the coupling block hole 38 placed in the middle of both resonator holes 36 is covered by a conductor film, and both the opening of a short-circuit face side and a groove end face at an opposite side are in continuity with an outer face conductor of a dielectric body, then the hole 38 shield the propagation of an electromagnetic wave between the resonators. Although the dielectric resonator 30 are of an integrated structure, the resonators acts as if they were independent of each other in terms of an electromagnetic wave. Thus, the stable band block filter is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dielectric filter mainly used in the microwave band. More specifically, the dielectric block has an end-faced shape and has coupling blocking holes between the resonator holes.
This invention relates to a dielectric band-stop filter that uses a four-resonance type integrated coaxial resonator and has a structure in which the resonators are coupled by a lumped constant element mounted on a plate-shaped protruding portion of the integrated coaxial resonator.

``Prior Art'' As a filter using a high dielectric constant ceramic material, there is a band rejection filter in which a plurality of dielectric prismatic resonators are coupled by a suitable lumped constant element.B in FIG. 9 is one example. 2 using two prismatic dielectric resonators 10
This is an example of a stage configuration.

The dielectric resonance aJO has a resonator hole 14 penetrating through the center of a prism 12 made of a high dielectric constant material for microwaves, and the outer surface except for the open surface (the top surface in the figure A, the right end surface in the figure B) A conductive film is attached to the inner surface of the hole to serve as an outer conductor and an inner conductor, respectively. While arranging the dielectric resonators 10 in parallel,
A coupling circuit board 18 is provided, and a capacitor 20 and a coil 22 are mounted thereon. The inner conductor of each dielectric resonator and the capacitor 20 are connected by a metal terminal 24, and input/output leads 26 are connected to both ends of the coil 22.

As shown in FIG. A, each resonator 10 has a capacitor 20.
(capacitance C1 C2), connect the input/output lead 26 and the other electrode of the capacitor 20, and further connect the other electrode of the capacitor 20 with a coil 22 (inductance). do. Each VQ body valve resonator 10 has a resonant frequency determined by its prism height, dielectric constant, etc., and the above configuration provides a /4 wavelength coaxial resonant band rejection filter.

[Problems to be solved by the invention] In the conventional technology, the number of parts increases because a plurality of single resonators are arranged, the number of assembly steps increases, and the positioning between the resonators and the accuracy of the outer conductor surface are also required. Become. Furthermore, there are also problems in terms of deterioration of mechanical strength and environmental reliability due to the need to bond the resonators together.

In addition, in order to add lumped constant elements, alumina, forsterite, etc., or εr-
More than 30 dielectric substrates must be prepared separately, and coils and capacitors must be mounted on them. However, in both cases, the coupling circuit board is mounted on a metal plate (housing) together with each dielectric resonator.
It has to be attached on top, which increases the volume of the divination, increases manufacturing costs, and causes problems with variations.

SUMMARY OF THE INVENTION An object of the present invention is to provide a dielectric band-stop filter that solves these problems in the prior art, has good manufacturability and design, and provides stable electrical and mechanical characteristics.

[Means for Solving the Problems] The dielectric resonator used in the dielectric band-stop filter according to the present invention has a rectangular parallelepiped portion and a plate portion that are generally L-shaped as a whole when viewed from the end face direction. A dielectric block with a stepped structure that is continuously integrated is used. Then, a plurality of resonator holes and coupling prevention holes are alternately arranged in parallel so that a groove is formed in the plate-like part that penetrates the rectangular parallelepiped part and continues therewith, and these holes are opened in the rectangular parallelepiped part. A conductive film is formed on the inner surface of each hole and the outer surface of the dielectric block, using the surface as a short-circuit surface. The conductor film in the resonator hole is connected to the dielectric block outer conductor film only on the short-circuit surface side, and the conductor film in the coupling blocking hole is connected to the dielectric block outer conductor film on the short-circuit surface and groove end sides. Furthermore, a slit deeper than the groove formed by the resonator hole is formed in the longitudinal direction of the base of the plate-shaped portion.

Then, a chip capacitor is connected to the slit part of the groove formed by the resonator hole in the plate-shaped part of the dielectric resonator in a bridging manner, and another lumped constant element, such as an air-core coil, is mounted on the plate-shaped part and between the resonators. A dielectric band-stop filter is constructed by combining the two.

[Function] Each resonator hole basically constitutes a quarter-wavelength coaxial resonator. The coupling blocking hole provided between the resonator holes has a conductive film formed on its inner surface, and the inner conductive film is connected to the outer surface conductor of the dielectric block at both open ends, so that electromagnetic waves between the resonators are prevented. Shields the propagation and prevents af7fi approximately 7fi. Therefore, since it is an integrated structure, magnetically it becomes almost equivalent to an array of single resonators.

Therefore, by additionally connecting a suitable lumped constant element to this dielectric resonator, it becomes possible to operate as a band i$ blocking filter.

The stepped portion of the dielectric block, that is, the plate-like portion protruding from the rectangular parallelepiped portion functions as a mounting board for the lumped constant element. Since the slit separates the conductor film in the groove formed by the resonator hole, the mounting is completed by mounting the chip capacitor on the slit so as to bridge it. Since the lumped constant element fits within the stepped portion, the overall size is reduced.

Embodiment FIG. 1 is a perspective view showing an embodiment of a dielectric band-stop filter according to the present invention, and is a two-stage filter in which two resonator holes are formed.

First, the dielectric resonator will be explained. This dielectric unit 30 has a stepped structure in which a rectangular parallelepiped portion 32 and a plate portion 34 are continuously integrated so as to form a substantially L-shape as a whole when viewed from the end face direction (the direction indicated by the white arrow). Using dielectric blocks of structure. Then, two resonator holes 36 and one coupling prevention hole 38 are alternately arranged in parallel so that a groove is formed in the plate-like portion 34 passing through the rectangular parallelepiped portion 32 and continuing thereto. The surface where these holes open in the rectangular parallelepiped part (
A conductor 11140 is formed on the inner surface of each hole and the outer surface of the dielectric block, with the right-hand odor surface in FIG.
The conductor film is connected to the outer conductor film of the dielectric block on both the short-circuit surface side and the groove end side.

In this embodiment, the step is formed at exactly half the position of each person, and the outer surface of the dielectric block includes the step surface excluding the groove and the open surface of the resonator hole (the surface opposite to the short-circuit surface). The dimensions of the 0th stage part, which has a conductive film attached to all areas other than the periphery of the block, are such that it can accommodate the lumped constant element to be used as described later, and the coupling prevention holes 38 are connected to the outer conductive film of the dielectric block at both ends. Select an appropriate value within the range that allows connection.

In the present invention, a slit 42 is further formed in the longitudinal direction of the base of the plate-like portion 34, which is deeper than the groove formed by the resonator hole 36. In other words, the conductor film in the groove formed by the resonator hole 36 is cut and separated by the slit 42 . In this embodiment, since the conductive film in the groove formed by the coupling prevention hole 38 is also cut and separated, the metal connecting piece 44 is connected to bridge the slit 42 (see Fig. 2). In Fig. 1, the shaded surface is the part where the conductive film is formed, and the dotted surface is the part where the conductive film is formed. It shows the part where there is no conductor film and the dielectric base is exposed. Here, the conductor film is a very thin layer of conductive material, such as baked-on silver paste.

The coupling prevention hole 38 located between the two resonator holes 36 has its entire inner surface covered with a conductive film and is electrically connected to the dielectric block outer surface conductor at both the open end on the short-circuit surface side and the groove end surface on the opposite side. This shields electromagnetic wave propagation between resonators. Although this dielectric resonator 30 has an integral structure, T
In terms of t and ili, the state is equivalent to that of each resonator being independent.

By additionally connecting an appropriate lumped constant element to the plate-shaped portion 34 of this resonator 30, a band rejection filter is constructed.

In other words, the plate-shaped portion 34 functions as a circuit board.
In FIG. 1, a chip capacitor 46 having a pole 1 at each end is soldered to bridge the slit portion of the groove formed by the resonator hole 32, and is curved to the conductor film on the open end side of both grooves. An input/output terminal 48 having a connecting portion is soldered (see FIG. 3), and a coil 49 is connected between the curved connecting portions of both output terminals 48.

This results in an equivalent circuit substantially similar to that shown in FIG. 9A. That is, a coil is connected between the input and output terminals, and a chip capacitor is connected between the input and output terminals and the resonator. Each resonator has a resonant frequency determined by the dimensions of its hole or groove, the dielectric constant of the dielectric, etc., and the above configuration provides a quarter-wavelength coaxial resonant band rejection filter characteristic.

Next, a simple method for manufacturing such a dielectric resonator will be described. FIGS. 4A, B, and C are examples. First, as shown in FIG. A, two resonator holes 52 and one coupling blocking hole 54 are arranged alternately in parallel in a dielectric block 5o that has a rectangular parallelepiped shape as a whole, and these holes are open. A conductive film is formed on the inner surface of each hole and the outer surface of the dielectric block, with one surface (the front left surface in the drawing) being an open surface and the other surface being a short-circuit surface. This conductor film is attached so that the conductor film of the resonator hole 52 is attached only on the short-circuit surface side, and the conductor film of the coupling prevention hole 54 is attached so that it is connected to the outer conductor film of the dielectric block at both open ends. Therefore, here, masking is applied so that the dielectric base is exposed in a ring shape only around the open end of the resonator hole 52, and the conductor film is attached. Of course, a method may also be used in which a conductive film is attached to the entire surface of the dielectric block and then peeled off only around the open end of the resonator hole. After that, the dielectric block is shaped into an approximately L shape when viewed from the end surface direction by, for example, surface grinding.
Scrape off the area surrounded by six sides (the shaded area in A in the same figure). The shaved state is shown in Figure B, and as shown in Figure C, the groove formed by the resonator hole 52 is cut using a slicer or the like in the longitudinal direction of the base of the plate-shaped portion thus formed. A clean slit 56 is also formed. In this manner, by cutting out approximately half of the open surface side of the dielectric block and performing slit processing, a dielectric resonator having a stepped integral structure can be easily manufactured.

FIGS. 5A and 5B show other examples of dielectric resonators. The basic idea is the same as in the above case. In the embodiment described above, the conductor film in the groove formed by the coupling prevention hole is also separated by the slit, so it is necessary to separately solder the metal connection piece. This was devised to eliminate that process. In both cases, the groove formed by the coupling prevention hole in the plate-like portion is deeper than the slit. In Figure A, the cross-sectional shape of the coupling prevention hole 38 is elongated.

In FIG. B, the coupling prevention holes 38 are arranged in a staggered manner with respect to the resonator holes 36. Note that the symbol d represents the slit depth.

6 to 8 show structural examples of input/output terminals. FIG. 6 shows an example of a metal terminal. It is a press-molded product having a curved portion 60 having the same curvature as the groove formed by the resonator hole 36 and a bent lead portion 62 continuous thereto. The curved portion 60 is fitted into the groove and soldered. The example shown in FIG. 7 is an input/output terminal using the wall surface of a dielectric block. In the figure A, an input/output cover turn 64 is formed on the open surface so as to extend from the groove formed by the resonator hole 36. In Figure B, an entry/exit cover turn 66 is formed on the end face. In either case, the input/output cover turns 64, 66 are separated so as not to be electrically connected to the conductor film on the outer surface of the dielectric block.

FIG. 8 is an example in which the input/output bin terminal 6B is used. A through hole is formed in the groove formed by the resonator hole 36, and the input/output pin terminal 68 is inserted into it and soldered to the conductor film part of the groove (
(See Figure A), and as shown in Figure B, a ring-shaped non-conductive film portion 70 is formed on the opposite surface to prevent electrical conduction with the conductive film on the outer surface of the dielectric block.

Although the above-mentioned embodiments are all examples of a two-stage configuration in which two resonator holes are provided in the dielectric block, it goes without saying that the present invention can also be applied to cases where there are three or more resonator holes.

C Effects of the invention] As described above, the present invention is basically an integrated type of dielectric block, and the mounting board part of the lumped constant element is also integrated, so it has good manufacturability and stable electrical and mechanical properties. Easy to get. In addition, the number of parts is small, and the lumped constant element can be housed in the stepped portion of the dielectric block, and the overall size can be reduced.

In the present invention, the capacitor connection portion is formed by dividing the groove formed by the resonator hole with a slit, so that chip capacitors can be easily mounted by connecting them in a bridging manner. Furthermore, the groove formed by the resonator hole can be used as a terminal, and mechanical strength can be improved by connecting input and output terminals to it.

Furthermore, the filter according to the present invention is easy to design because of the coupling using lumped constant elements, and frequency and coupling adjustment are also easy. As a result, cheaper band-elimination filters and band-pass filters can be realized.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one embodiment of a dielectric filter according to the present invention, FIG. 2 is a sectional view of the dielectric filter at the position of the coupling prevention hole, and FIG.
The figure is a cross-sectional view at the position of the resonator hole, Figures 4A, B, and C are explanatory diagrams showing an example of the manufacturing process of a dielectric resonator, and Figures 5A,
B is an explanatory diagram showing another example of a dielectric resonator. 6th is an explanatory diagram showing an example of an input/output terminal, FIGS. 7A and 7B are explanatory diagrams showing another example of an input/output terminal, and FIG. 8A is an explanatory diagram showing another example of an input/output terminal. B is an explanatory diagram showing still another example of input/output terminals. 9th
Figures A and B are explanatory diagrams showing an example of the conventional technology. 30... Dielectric resonator, 32... Rectangular parallelepiped part, 34
... Plate-shaped portion, 36... Resonator hole, 38... Coupling prevention hole, 40... Conductor film, 42... Slit, 44
...Metal connection piece, 46...Chip capacitor, 48
...Input/output terminal, 49...coil. Patent applicant: Fuji Electrochemical Co., Ltd. Agent: Joi Shigeru 41
! l Diagram

Claims (3)

[Claims] 1. A dielectric block with a stepped structure in which a rectangular parallelepiped part and a plate-like part are continuously integrated so that the whole is approximately L-shaped when viewed from the end face direction, and a plate is inserted through the rectangular parallelepiped part and continuous thereto. A plurality of resonator holes and coupling prevention holes are alternately arranged in parallel so that grooves are formed in the rectangular parallelepiped portion, and the opening surfaces of the holes in the rectangular parallelepiped portion are used as short-circuit surfaces to connect the inner surface of each hole and the dielectric material. A conductor film is formed on the outer surface of the block, and the conductor film of the resonator hole is connected to the outer conductor film of the dielectric block only on the short-circuit surface side, and the conductor film of the coupling prevention hole is connected to the outer surface of the dielectric block on the short-circuit surface side and the groove end side. A dielectric resonator is connected to a conductor film and has a slit deeper than the groove formed by the resonator hole in the plate-like part in the longitudinal direction of the base of the plate-like part. A dielectric band-stop filter in which a capacitor is connected in a bridging manner, and other lumped constant elements are mounted on a plate-like part to couple the resonators. 2. In order that the grooves formed by the coupling prevention holes in the plate-shaped part are deeper than the slits, the coupling prevention holes have an elongated cross section or are arranged in a staggered manner, so that the conductor film in the grooves formed by the coupling prevention holes is continuous. The filter according to claim 1. 3. 3. The filter according to claim 1, further comprising an input/output terminal provided in the plate-like portion.