JPH056922B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a multi-stage dielectric filter with an integral structure used in high frequency bands such as microwave bands, and more specifically, to A wall was formed, input/output pin terminals were planted on the edge of the open surface, and the protruding wall was used to cover the open surface with a metal plate, eliminating the need for a metal base or metal case for installation. This invention relates to dielectric filters.

[Conventional technology]

Multi-stage resonant filters using dielectric ceramics such as barium titanate have the characteristics of low loss, high Q, and high dielectric constant, allowing for miniaturization, and are suitable for use in microwave bands such as car phones and satellite communications. It is widely used for.

As a prior art related to dielectric filters, for example, as shown in FIG. 6, resonator holes 12 and coupler holes 14 are alternately provided at predetermined intervals in the longitudinal direction of a rectangular parallelepiped dielectric block 10. By forming a conductive layer 16 by metallizing the outer surface of the resonator hole 12 and the inner surface of the resonator hole 12 except for one of the open surfaces (the open surface), the resonator hole 12 and the coupler hole 14 are formed. An integrated structure in which a large number of resonant elements having a resonant wavelength four times the length of 12 are formed is known.

In such a filter, each resonator hole 12 corresponds to an individual resonant element. For connection with an external circuit, for example, a coupling capacitor 1 is connected to the open end of a resonator hole formed at both ends of the dielectric block 10.
This is done by attaching 8.

In the case of a filter with pin terminals, a metal base 20 is used for fixing the input/output terminals and for arc conduction.
is used. The input/output pin terminals 22 are inserted and fixed into the metal base 20, the dielectric filter body is placed horizontally, the conductor layer on the side is fixed to the base 20, and the coupling capacitor 18 and the pin terminals 22 are connected with the lead wires 24. After connection, a structure is adopted in which the base 20 is covered with a lid 26 made of a metal plate.

Here, as the pin terminal 22, a glass terminal or a terminal made of special synthetic resin (polytetrafluoroethylene, etc.) is used so as not to impair high frequency characteristics. Further, the dielectric filter main body and the base 20 are fixed by adhesion using a conductive adhesive, soldering, or pressure bonding using a spring.

[Problems to be Solved by the Invention] In the above-mentioned conventional technology, it is necessary to completely surround the dielectric filter body with a metal base and cover, which results in a complicated and expensive structure and an increase in size. There were drawbacks such as: Further, the electrical connection between the conductor layer 16 formed on the side surface of the dielectric filter body and the metal base 20 tends to be unstable, which causes problems such as deterioration of filter characteristics.

The purpose of the present invention is to solve the above-mentioned drawbacks of the prior art, have a simple structure, be easy to manufacture, and be inexpensive.
Another object of the present invention is to provide a dielectric filter with an improved structure that can improve filter characteristics.

[Means for Solving the Problems] The present invention, which can achieve the above objects, includes a plurality of resonator holes arranged in the longitudinal direction of a dielectric block having a substantially rectangular parallelepiped shape. In a dielectric filter having an integral structure in which one of the surfaces in which the hole is open is an open surface and a conductor layer is formed on the other outer surface and the inner surface of the resonator hole, the dielectric block covers at least one of the edges of the open surface. It has a structure with a protruding wall in part, and input/output pin terminals are implanted on the edge of the open surface and connected to the input/output coupling part using a conductor, and the protruding wall is used to cover the open surface with metal. It is constructed to be covered with a board.

Here, the protruding walls formed on the open surface of the dielectric block are formed on all four edges so as to surround the open surface, and a conductor layer is formed by metallization up to the upper surface. Further, a recessed stepped portion without metallization is formed on the protruding wall on or near the short side, and an input/output pin terminal is implanted therein. Preferably, this input/output pin terminal is connected to, for example, a coupling capacitor via a lead plate or a lead wire. In this way, when covering with a metal plate, there will be a "relief" so that the stepped part does not come into contact with the connecting part between the input/output pin terminal and the lead plate, etc. The input/output pin terminals are drawn out through the metal plate in an insulated state (in a non-contact state or with an insulating material interposed) relative to the metal plate.

It is also effective to install a ground terminal close to the input/output pin terminal.

[Operation] Connection with an external circuit can be realized by inserting and soldering the input/output pin terminals implanted and fixed to the edges of the open surface of the dielectric block into holes in the printed circuit board, etc. In the present invention, the dielectric block itself holds the pin terminal, and the dielectric block itself functions as a case. Furthermore, in the present invention, it is sufficient to cover only the open surface portion with a simple metal plate.
Metal cases, bases, etc. are not required.

[Example] FIG. 1 is a perspective view showing an example of a dielectric filter according to the present invention, FIG. 2 is an enlarged view of the main part thereof, and FIG. 3 is a longitudinal sectional view. This embodiment is a four-stage integrated filter.

The dielectric filter main body 30 includes a substantially upright dielectric block 32 made of a sintered body of a high-permittivity ceramic material such as barium titanate.
Four resonator holes 34 are formed at intervals, and three connector holes 3 are formed between these resonator holes 34.
6 is provided, and a conductor layer 38 is further formed by metallization on all sides and bottom of the dielectric block 32 and on the inner surface of the resonator hole 34. Therefore, in this case, the upper surface of the dielectric block 32 becomes an open surface.

In order to make the drawings easier to understand, minute dots are added to portions where the dielectric base is exposed as it is without metallization.
Although the conductor layer 38 is depicted as having a considerable thickness (particularly in FIGS. 2 and 3), it is actually extremely thin, formed by baking silver paste or the like.

As is clear from these figures, the present invention is significantly different from the prior art in that the dielectric block 32
has a structure in which a protruding wall 40 is formed on at least a part of the edge of the open surface, and an input/output pin terminal 42 is implanted in the edge of the open surface, and the protruding wall 40 is used to cover the open surface with metal. This is because it is configured to be covered with a plate 44. Such a dielectric block 32 can be easily manufactured by powder molding and sintering using a mold suitable for its shape.

In this embodiment, the protruding wall 40 is provided in a frame shape to surround the open surface, and the protruding wall 40
A conductor layer 38 is formed by metallization up to the upper surface of the conductor layer 38 . The input/output coupling section is a dielectric block 3.
A coupling capacitor 46 is mounted and fixed on the open ends of the resonator holes located at both ends of the resonator hole 2, and the coupling capacitor 46 is connected to the input/output pin terminal 42 by a conductor.

In this embodiment, as shown in detail in FIG. 2, of the frame-shaped projecting wall 40 formed on the dielectric block 32, a stepped portion 50 recessed inside the center of the projecting wall on both short sides is formed. establish. The stepped portion 50 has approximately the same height as the coupling capacitor 46 and is not metallized. Then, an input/output pin terminal 42 is implanted in the stepped portion 50, and ground terminals 52 are implanted on both sides thereof. and coupling capacitor 46
A lead plate 54 is disposed between the input/output pin terminal 42 and the input/output pin terminal 42 exactly along the surface of the stepped portion, and electrically connected by soldering or dielectric adhesive.

After adjusting the resonance frequency of each resonator hole 34, a metal plate 44 is placed and fixed so as to cover the open surface. This fixing may be done by soldering or conductive adhesive. The holes 56 formed in the center of both ends of the metal plate 44 are made much larger than the input/output pin terminals 42, and an insulating material is interposed between them to insulate them. The holes 58 through which the ground terminals 52 on both sides are inserted may be dimensioned to just fit therein. The dielectric filter thus assembled is connected by inserting the input/output pin terminals 42 and the ground terminal 52 into land holes of the conductor pattern formed on the printed circuit board and soldering them. Earth terminal 52
are arranged on both sides of the input/output pin terminal 42 because
This is to ensure grounding and to increase mechanical strength during installation.

The input/output pin terminal 42 may be installed at any position. For example, as shown in FIGS. 4 and 5, it may be provided on one long side of the frame-shaped projecting wall 40, or it may be provided on both long sides. Since FIGS. 4 and 5 are basically the same as FIGS. 2 and 3, corresponding parts are denoted by the same reference numerals and explanations thereof will be omitted.

In order to ensure ground continuity and improve filter characteristics, it is desirable to install the ground terminal close to the input/output pin, but in some cases, the input/output pin terminal may be L-shaped and formed on the dielectric block 32. The conductor layer 38 may be used to make surface contact with the printed circuit board as it is.

Mechanical coupling between the dielectric filter and the printed circuit board or the like can also be achieved using a strip-shaped fitting or the like. Alternatively, a mounting hole may be provided and a screw may be inserted and fixed.

The structure of the input/output coupling section is also arbitrary. In each of the above embodiments, a coupling capacitor is placed on the open end of the resonator hole located on both sides, and the coupling capacitor is connected to an external circuit using a lead plate. It's okay. Alternatively, a hole for input/output coupling may be formed at the end of the dielectric block, and a metal rod may be inserted into the hole for connection with an input/output pin terminal. Furthermore, the number of resonator holes formed in the dielectric filter is also arbitrary.

[Effects of the Invention] As described above, the present invention provides a dielectric block with a structure in which the edge of the open surface protrudes, and implants input/output pin terminals in the edge of the open surface, and utilizes the protruding wall. Since the open surface is covered with a metal plate, the input/output pin terminals are attached to the dielectric block itself and it also serves as a case, eliminating the need for a metal base or case, simplifying the structure, making it less expensive and more compact. It has the effect of making it more effective.

Furthermore, with the present invention, it is possible to securely connect the ground at the shortest distance, improving the attenuation characteristics, and also making it possible to easily and securely attach the metal plate to the dielectric block, thereby preventing leakage of radio waves and suppressing the generation of spurious signals. It has excellent effects such as:

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of a dielectric filter according to the present invention, FIG. 2 is a perspective view of the main parts thereof,
FIG. 3 is a longitudinal sectional view thereof, FIG. 4 is a perspective view of main parts showing another embodiment of the present invention, and FIG. 5 is a plan view thereof.
FIG. 6 is a perspective view showing an example of the prior art. 30...Dielectric filter body, 32...Dielectric block, 34...Resonator hole, 36...Coupler hole, 38...Conductor layer, 40...Protruding wall, 42...
Input/output pin terminal, 44... Metal plate, 46... Coupling capacitor, 50... Recessed step, 52...
Earth terminal.

Claims (1)

[Claims] 1 A plurality of resonator holes are arranged in the longitudinal direction of a dielectric block having a substantially rectangular parallelepiped shape, and one of the surfaces of the dielectric block where the resonator holes are open is an open surface, and the other outer surface and the above-mentioned In an integrated dielectric filter in which a conductor layer is formed on the inner surface of a resonator hole, the dielectric block has a protruding wall along all four sides of the open surface, and the conductor layer is also provided on the upper surface of the protruding wall. The protruding wall has a structure in which it is electrically connected to the conductor layer on the side surface, and an input/output pin terminal is implanted in a recessed step without metallization on the inside of the protruding wall. A dielectric filter characterized in that the open surface is covered with a metal plate using the projecting wall, and the input/output pin terminal is drawn out so as to penetrate the metal plate in an insulated state.