JP2003273605A - Waveguide type filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive, miniaturized and lightweight waveguide type filter in which a configuration or a form is not complicated, packaging into a signal processing circuit on a substrate is facilitated and an insertion loss is reduced. <P>SOLUTION: The waveguide type filter has a structure where a plurality of waveguide type resonators are connected, each resonator has a coupling part for electromagnetically coupling the resonators, a resonator for inputting or outputting a signal has an input/output electrode constitutive portion over a bottom face and one lateral side linked to the bottom face, the input/output electrode constitutive portion is composed of an input/output electrode and an insulation part, and almost all the surface of the resonator except the coupling part and the input/output electrode constitutive portion is covered with a ground electrode. In such a waveguide type filter, a shield part having a conductor part for covering the input/output electrode constitutive portion is formed on the one lateral side of the resonator having said input/output electrode constitutive portion. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide type filter, and more particularly to a waveguide type filter used in communication devices in the quasi-millimeter wave band or millimeter wave band.

[0002]

2. Description of the Related Art With the spread of mobile communication devices, the frequency band used has become higher, and filters in the quasi-millimeter wave band and the millimeter wave band are required. Conventional dielectric 1 /
In a four-wavelength coaxial resonator, the axial length dimension is too small, and it is difficult to construct a filter, and the loss is large, which is not practical.

Therefore, a waveguide type dielectric filter using dielectric ceramics for the waveguide type resonator has been proposed. The waveguide type dielectric filter has an advantage that it can be miniaturized to a shape that can be mounted on a circuit board by using a dielectric having an appropriate permittivity for a target signal frequency in a resonator.
For example, as disclosed in Japanese Unexamined Patent Publication No. 10-290104, a waveguide type filter has a plurality of rectangular parallelepiped resonators connected to each other, and the resonators are electromagnetically coupled to each other through a coupling portion. An outer conductor is formed on the. Input / output electrodes are formed on the resonators at both ends of the filter, and various methods have been devised for forming the input / output electrodes.

On the other hand, a filter using a cavity inside a metal housing as a cut-off waveguide has been conventionally proposed.
FIG. 10 is an example of a waveguide filter having a structure in which a plurality of disk-shaped dielectric resonant elements are arranged in a cavity inside a conventional metal housing, and FIG. 10A is a cross-sectional view seen from the top. , Figure 1
0 (b) is a sectional view seen from the side. The filter using the conventional waveguide type cavity resonator is mainly used in the millimeter wave region where the wavelength is on the order of millimeters, and the cavity portion 1 is internally provided.
It is formed of a metal casing 108 having a dielectric resonance element 105 mounted on a support 106 inside the metal casing 108. The structure is such that the adjusting screw 107 is attached. Furthermore, at both ends of the metal casing 108,
A mode converter 101 including a connector 103 for connecting to a signal transmission line and a coupling terminal (excitation line) 102 is attached. The mode converter 101 serves to convert the electromagnetic field mode of the signal from the transmission mode outside the filter to the resonance mode inside the metal housing. Coupling terminal 102
Has a special shape for electromagnetic field coupling with the resonance mode, and the connector 103 is adapted to be connected to a cable line used for a transmission line.

In general, signal radio waves propagating in space are extremely weak, and unnecessary signal radio waves also exist in adjacent frequencies. Therefore, in order to efficiently extract only necessary signals from signals received by an antenna. Requires low insertion loss and high attenuation filter performance. Generally, the waveguide type filter has a high Q value of the resonator, can realize a filter with low insertion loss and high attenuation characteristics, and is suitable for receiving a weak signal. For example, as shown in FIG. 11, a waveguide type filter 110 using a cavity resonator is connected to an antenna (not shown), and a shield that houses a signal processing circuit in which a high-frequency circuit component is mounted in the subsequent stage. The box 111 is arranged.

[0006]

However, the conventional quasi-millimeter wave band and millimeter wave band filters as described above have the following problems. For example, when a conventional waveguide type dielectric filter using dielectric ceramics is inserted into a signal processing circuit whose transmission line is a strip line, the signal is transmitted from the transmission mode until it reaches the input / output electrodes of the filter. The radiation loss that occurs when the waveguide type resonator inside the filter is converted into the resonance mode cannot be ignored, and the insertion loss increases. In particular, radiation of an electromagnetic field is likely to occur in the millimeter wave region where the wavelength is extremely short, and it is difficult to suppress the radiation loss as compared with the microwave region.
The radiation loss generated in the input / output electrode section causes an increase in insertion loss, and there is also a problem that the attenuation characteristic outside the pass band is deteriorated and the radiated electromagnetic field affects the peripheral circuits.

As a countermeasure against this, Japanese Patent Laid-Open No. 11-19590
A structure in which an input / output electrode is provided in an island shape on the bottom surface as described in Japanese Patent No. 4 is also proposed, but in this case, since the signal line connected to the input / output electrode is drawn out from the inside of the substrate, an expensive multilayer substrate And it was necessary to process through holes. Also, the input / output electrodes are connected by a conductor such as solder, but since they are in direct contact with the board, it is not possible to visually check the connection state, and fine adjustment of the electrical characteristic deviation after mounting due to the positional deviation during mounting, etc. There is a problem that you cannot do it.

Also, in the conventional waveguide type filter using air as the dielectric, the mode conversion for converting the electromagnetic field of the signal from the transmission mode to the resonance mode of the waveguide type resonator at both ends of the filter portion. 10 is used, the structure is complicated and the shape is large as shown in FIG. 10. Therefore, as shown in FIG. 11, the filter 110 has to be arranged separately from the signal processing circuit. It must be big and heavy. Therefore, it cannot be mounted on a substrate on which a signal processing circuit is formed. Regarding electrical characteristics, since a mode converter is inserted, there is a problem that transmission loss increases. Furthermore, the number of parts is large and a mode converter is required, which is very expensive.

The present invention has been made in view of the above points, and an object thereof is that the configuration and the shape are not complicated, the signal processing circuit on the board can be easily mounted, and the insertion loss can be improved. It is an object of the present invention to provide a low-cost, small-sized, lightweight waveguide filter.

[0010]

The present invention has a structure in which a plurality of waveguide type resonators are connected, and the resonator has a coupling portion for electromagnetically coupling the resonators. However, the resonator for inputting or outputting a signal has a bottom surface and an input / output electrode constituent portion over one side surface connected to the bottom surface, and the input / output electrode constituent portion is composed of an input / output electrode and an insulating portion,
In a waveguide filter in which substantially the entire surface of the resonator other than the coupling portion and the input / output electrode constituent portion is covered with a ground electrode, further, on the one side surface of the resonator having the input / output electrode constituent portion. The present invention relates to a waveguide filter, wherein a shield part having a conductor part covering the input / output electrode forming part is formed.

An aspect of the waveguide filter of the present invention is characterized in that the resonator and the shield portion are formed of a dielectric ceramic block.

As another aspect of the waveguide filter of the present invention, the conductor part of the shield part is formed of a case having conductivity, and the material inside the shield part is air. It is characterized by

Further, according to an aspect of the waveguide filter of the present invention, at least a part of a ground electrode of the resonator is formed of a conductive case, and a material inside the resonator is air. Is characterized by.

According to another aspect of the waveguide filter of the present invention, at least a part of the ground electrode of the resonator and at least a part of a conductor part of the shield part are formed of a conductive case. The material inside the resonator and inside the shield part is air.

According to another aspect of the waveguide filter of the present invention, the ground electrode of the resonator, the input / output electrode, and the conductor portion of the shield portion are formed of a conductive casing. The material inside the resonator and the inside of the shield part is air.

Further, according to an aspect of the waveguide filter of the present invention, a casing in which a portion of the resonator other than a bottom surface of the ground electrode and a portion of the shield portion other than a bottom surface of the conductor portion are conductive. The resonator is formed of a body, and the bottom surface portion of the ground electrode of the resonator and the bottom surface portion of the conductor portion of the input / output electrode forming portion and the shield portion are formed on the mounting substrate.

According to another aspect of the waveguide filter of the present invention, the input / output electrode extends in a band shape from an input / output point of an external signal, and the other end of the input / output electrode is formed on the outer surface of the resonator. It is characterized by having a structure in which the electrodes are short-circuited.

The waveguide type filter of the present invention has a structure in which a shield portion made of a conductor is formed so as to cover the input / output electrodes, so that transmission of an electromagnetic field of a signal until the signal reaches the filter. The mode can be converted into a resonance mode inside the waveguide with a small loss, the mounting on the substrate is easy, and the radiation loss and insertion in the input electrode can be reduced.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1A is a perspective view of an embodiment of a waveguide type filter in which a shield portion having a conductor covering the input / output electrode forming portion is formed on a side surface of a resonator according to the present invention,
FIG. 1B is an exploded perspective view thereof.

The waveguide type filter 1 of FIG. 1 which is an embodiment of the present invention has a structure in which a plurality of waveguide type resonators 2 are connected, and the resonators 2 connect the resonators to each other. The resonator having a coupling portion 7 for electromagnetically coupling and inputting or outputting a signal has an input / output electrode configuration portion extending from a bottom surface 21 to one side surface 22 connected to the bottom surface 21. The portion 4 is composed of an input / output electrode 5 and an insulating portion 6,
A waveguide type filter in which substantially the entire surface of the resonator other than the coupling section 7 and the input / output electrode forming section 4 is covered with a ground electrode 8, further comprising: The shield portion 3 having a conductor portion that covers the input / output electrode constituent portion 4 is formed on the one side surface 22.

The bottom surface 21 of the resonator 2 is the lower surface of FIG. 1 and is the surface to be mounted on the substrate. Similarly, the bottom surface of the shield portion 3 is also the lower surface of FIG. 1 and is the surface in contact with the substrate.

In the embodiment shown in FIG. 1, the resonator has a form in which a dielectric ceramic block is coated with a conductive film, and the shield part is formed of, for example, a metal casing. That is, an example of a waveguide filter in which dielectric ceramics is used as the material inside the resonator, the material inside the shield part 3 is air, and the conductor part is formed of a conductive case (metal case). Is shown. In this case, the metal plate of the metal case covers the input / output electrode forming section as a conductor section. As the case having conductivity, a material having conductivity such as metal may be used as a material of the case, or the case itself may be made of a material having no conductivity such as plastic or ceramic. Alternatively, a conductive film may be formed on the surface (particularly the inner surface of the housing) by plating or coating.

Further, the adjacent resonators 2 of the waveguide type filter are formed with a coupling portion 7 which is not covered with a conductor as a window for electromagnetic field coupling on the surfaces contacting each other. Except for the coupling portion 7 and the input / output electrode forming portion 4, each resonator has a front surface covered with a conductor serving as a ground electrode.

The input / output electrode structure 4 comprises an input / output electrode 5 and an insulating portion 6 in contact therewith, and is formed from the bottom surface 21 of the resonator 2 at both ends and one side surface 22 connected to the bottom surface 21. The input / output electrode 5 does not have to be formed up to the one side surface 22 and may be formed only on the bottom surface 21. In that case, only the insulating portion 6 is formed as the input / output electrode forming portion 4 on the one side surface 22. However, in the case where the shield part 3 is to be retrofitted separately, if the shield part 3 is formed by partially extending the side face 22, it is possible to confirm the spread of solder or the like during mounting,
It is preferable because the input / output coupling can be adjusted by partially cutting the input / output electrodes.

In the embodiment shown in FIG. 1, the input / output electrode 5 formed on the bottom surface of the resonator has an input / output point 51 for an external signal.
That is, the input / output electrode 5 extends in a band shape from (that is, a portion where the transmission path of the external signal first contacts the resonator, is on a line intersecting two surfaces where the input / output electrode constituent portion is formed, and is not limited to a point). The other end is short-circuited to the ground electrode 8 formed outside the resonator at a short-circuit point 52 (the short-circuit point between the input / output electrode 5 and the ground electrode 8 is not limited to the point). , Does not necessarily have to have the short-circuit point 52,
An island-shaped electrode in which the input / output electrode 5 is insulated from the ground electrode may be used. With the electrode structure in which the input / output electrodes are short-circuited with the ground electrode on the bottom surface of the resonator as described above, mounting is easy and an external signal can be efficiently transmitted to the inside of the resonator 2. Further, with this electrode structure, it is possible to excite two or more resonance modes at the same time with one input / output electrode to form a filter having a plurality of pass bands.

The shield portion 3 has a structure in which a conductor portion connected to the ground electrode is provided on almost the entire outer surface of the substantially rectangular parallelepiped shape, but the transmission path from the outside to the input / output electrode is the substrate or the shield portion 3. Since it is formed on the bottom surface (downward in the figure), an insulating portion 31 is partially formed on the lower portion of the shield portion 3 so as to maintain insulation between the conductor (ground electrode 8) and the transmission line. Has been done. When the shield part 3 is a metal case, the insulating part 31 may have a shape in which a part of the metal case is cut off. When the shield part 3 is made of dielectric ceramics, it corresponds to the transmission path of the substrate. A transmission line may be printed at the position of the shield portion 3 to be protected, and an insulating portion 31 for maintaining insulation with a conductor may be formed around the transmission path.

Although the embodiment of FIG. 1 shows an example in which a metal case formed of a metal plate and having a hollow interior is used as the shield part 3 having a conductor part covering the input / output electrode constituent part, As shown in FIG. 2, an outer surface of a substantially rectangular parallelepiped dielectric ceramic block may be coated with a conductor such as Ag. FIG. 2A shows a waveguide in which both the resonator 2 and the shield portion 3 are formed of a dielectric ceramic block, and a ground electrode, an input / output electrode, and a conductor portion of the shield portion 3 are formed on the surface by a conductor. FIG. 2 is a perspective view showing an embodiment of a tubular dielectric filter, and FIG. 2B is an exploded perspective view thereof. When the dielectric ceramic block is used for the resonator and the shield part, it is possible to obtain a waveguide filter having various characteristics and sizes by selecting and combining the dielectric constants of the dielectric materials.

The shape of the shield portion 3 is not particularly limited, but it is preferably a substantially rectangular parallelepiped shape in terms of manufacturing, and the length (that is, thickness) of the shield portion 3 in the signal traveling direction is
1 of the longest side length of the resonator in which the input / output electrode 5 is arranged
It is preferably / 4 or less. The longest side of the resonator refers to the longest side of the length, width and height of the resonator in the signal traveling direction. If the thickness of the shield part 3 is larger than about 1/4 of the longest side of the resonator in which the input / output electrodes 5 are arranged, the improvement effect will be saturated, so that it is not appropriate when considering miniaturization. However, the thickness of the shield part 3 referred to here is the case where the shield part is made of the same dielectric material as the resonator, and when the shield part is made of a different dielectric material such as a dielectric constant, the optimized thickness is different. come.

In the embodiment of FIG. 2, the waveguide type filter 1 is used.
Is composed of a resonator 2 formed of a plurality of dielectric ceramic blocks and a conductor, and a shield portion 3 also formed of a dielectric ceramic block and a conductor, the shield portion 3 and a plurality of resonances. The waveguide type filter including the resonator 2 does not necessarily have to be formed of a plurality of dielectric blocks, and at least a part of the ground electrode of the resonator 2 is formed of an electrically conductive casing. The waveguide filter may be configured such that the material inside the vessel is air.

Further, by changing the thickness of the shield part (length in the signal traveling direction), an attenuation pole can be generated in a desired frequency band in an arbitrary frequency band near the pass band, and the attenuation characteristic is improved. can do. For example, if the thickness of the shield part is shortened, the attenuation pole can be formed on the high frequency side of the pass band, and if the thickness of the shield part is lengthened, the attenuation pole can be formed on the low frequency side of the pass band. You can Furthermore, it is possible to balance the attenuations on both sides of the pass band by setting the appropriate thickness of the shield part. At that time, the loss of the pass band is not sacrificed.

Similarly, the shield part 3 is also formed of a conductive case, and at least part of the ground electrode of the resonator and at least part of the conductor part of the shield part are conductive. The waveguide filter may be formed of a body, and the material inside the resonator and the inside of the shield part may be air. As a result, the waveguide filter can be formed with one housing, and the mounting on the substrate is easy with low loss.

FIG. 3A shows an external perspective view of the waveguide type filter 1 having a housing structure, and FIG. 3B shows an exploded perspective view thereof. In one embodiment of the present invention shown in FIG. 3 (b), three resonators 2 are formed by a housing 20, and they are separated by a partition 23.
Electromagnetic fields are coupled by the coupling portion 7 formed by the gap. Further, the input / output electrode constituent portion 4 is formed so as to extend from the bottom plate 25 to the end faces 22 of the resonators at both ends, and the shield portion 3 is integrally formed by the casing 20 on the outer side thereof. The shape and positional relationship between the bottom plate 25 and the housing 20 may be a structure in which the housing 20 is placed on the bottom plate 25, or the housing may be such that the bottom surface of the bottom plate 25 and the bottom surface of the housing 20 are flush with each other. The length of the internal partition plate 23 and the like may be adjusted so that the bottom plate 25 fits inside the housing 20, and there is no particular limitation.
The bottom plate 25 and the housing 20 may be connected only by fitting,
You may use solder or the like.

The size of the dielectric filter decreases in inverse proportion to the square root of the dielectric constant of the dielectric material used for the resonator, but the shape of the dielectric filter becomes too small in the high-frequency millimeter wave band region. However, the processing accuracy becomes difficult when the filter is manufactured, and it becomes difficult to control the required electrical characteristics. However, the metal housing using air having the smallest permittivity as the dielectric material inside the resonator of this embodiment. Such a problem can be solved by the waveguide type filter made of.

It is also possible to form the portion corresponding to the bottom plate 25 of the waveguide filter 1 having the housing structure of the embodiment shown in FIG. 3 by directly printing electrodes on the substrate 9. In FIG. 4, a portion of the resonator other than the bottom surface of the ground electrode and a portion of the shield portion other than the bottom surface of the conductor portion are formed by a conductive case, and the ground electrode of the resonator is An embodiment is shown in which the bottom surface portion and the input / output electrode forming portion and the bottom surface portion of the conductor portion of the shield portion are formed on the substrate. In FIG. 4, the bottom plate 25 of the waveguide filter 1 having the housing structure shown in FIG. 3 is formed on the substrate 9. Here, the board 9 may be a board on which the housing is simply placed, or a mounting board on which other electronic components and circuits are formed. The structure of the housing 20 in FIG. 4 is the same as that of the housing 20 in FIG. In this way, by printing the ground electrode directly on the mounting substrate 9, the bottom plate 25 is unnecessary, and the number of components of the waveguide filter can be reduced. Mounting on the housing 20 and the board 9
It can be done with solder or the like.

3 and 4, the case 20 is placed on the bottom plate 25 or the board 9, but a recess is formed in a chassis made of aluminum or the like for accommodating another printed board or the like. The structure shown in the housing 20 as shown in FIG. 3 or FIG.
Alternatively, the bottom plate 25 or the substrate 9 as shown in FIG. 4 may be covered.

Incidentally, considering the temperature dependence of the electrical characteristics of the filter, it is desirable that the material of the housing has a low coefficient of thermal expansion, but it may be determined in consideration of the matching with the coefficient of thermal expansion of the substrate material. . The reason for choosing a material with a low coefficient of thermal expansion is that the resonant frequency of the cavity resonator depends on the dimensional change of the housing. As a preferable case material, a lead frame material such as a Ni-based alloy such as Kovar or a Cu-based alloy having a thermal expansion coefficient close to that of a general glass-epoxy-based laminated substrate can be mentioned.

[0038]

Embodiments of the present invention will now be described in more detail with reference to the drawings.

Example 1 A waveguide type filter having a cavity resonator 2 having a housing structure and a shield portion 3 as shown in FIG. 5 was produced as follows.

The housing 20 of the filter composed of the shield part 3 and the cavity resonator 2 is made of a Ni-based alloy having a low coefficient of thermal expansion, and is machined from a metal block by an NC processing machine to machine the cavity and then the housing. The inner wall was polished and an Ag film having good electric conductivity was plated. The thickness of the housing 20 is 0.5 mm, the upper housing 20 and the lower mounting board are separately manufactured, and after Ag plating, the inside of the housing is ground to adjust the resonator frequency. Then, it was prepared by bonding with a conductive adhesive. The cavity resonator 2 is 6
mm width × 6 mm depth, height 3 mm, the thickness of shield part 3 (hereinafter referred to as the inner size) is 0.75 mm, and the shape of the bottom surface of shield part 3 is the same as cavity 2 with the width of cavity 2 for ease of fabrication. A total of 6 mm width × 3 mm thickness was obtained. In order to provide an appropriate inter-stage coupling in the partition between the resonators, a notch is formed in a shape that is easy to process and a coupling 7 is formed. The input / output electrode 5 and the signal transmission path 60 are formed by providing two insulating portions on the bottom surface of the resonator 2 from the end surface of the shield portion 3 of the lower mounting substrate. The pattern of the resonator input / output electrodes formed on the mounting substrate has a width of 1.2 mm × 2.8 mm, and an insulating portion having a width of 0.8 mm is formed on both sides of the pattern. Further, in order to maintain insulation between the signal transmission line 60 and the input / output electrode 5, the wall on the boundary between the resonator 2 and the shield part 3 and the lower part of the shield part 3 have a width of 2.8 mm × 0.5.
A notch with a height of mm was formed.

As described above, the waveguide type filter including the plurality of resonators 2 and the shield portion 3 can be easily formed, and the resonance frequency can be finely adjusted before mounting. The adjustment screw used for adjustment is no longer required. Therefore, it is not necessary to cut the thread for fixing the mode converter connector and for the frequency adjusting screw, and thus the thickness of the housing can be reduced. Moreover, an expensive mode converter is not required. As a result, the size and weight can be reduced, and the number of processing steps, that is, the cost can be reduced.

As described above, the waveguide type filter of the present invention can be directly mounted on the strip line of the substrate with a simple electrode structure without using the mode converter used in the conventional filter. It can be housed in a shield box containing a signal processing circuit as shown in, and the device itself can be made smaller, lighter and lower in cost. Also, by shielding the high frequency circuit part at once, the mechanical
Improvement of electrical reliability can be expected.

The frequency characteristics of the waveguide type filter using the cavity type resonator having the casing structure having the shield portion 3 were measured. The frequency characteristic is shown in FIG. Further, various measured values are shown in Table 1. In the table, a is the length (thickness) of the shield portion in the signal traveling direction, b is the length of the longest side of the three sides of the resonator forming the filter, and a / b are those. Is the ratio of

[0044]

[Table 1]

Embodiments 2 to 5 A waveguide type filter having the same structure as that of the first embodiment except that the length of the signal traveling method of the shield portion of the first embodiment is changed to the length shown in Table 1. It was prepared and various characteristics were measured. The results are shown in Table 1. The length a of the shield part is 0.4 mm.
7 and 8 show frequency characteristics in the case of and 1.5 mm, respectively.

Comparative Example 1 A waveguide type filter using a cavity resonator having a casing structure having a structure excluding the shield part of the waveguide type filter of Example 1 was manufactured as follows. The manufacturing method, and the shape and size are the same as those in the first embodiment except that there is no shield part.

The frequency characteristic of this waveguide type filter was measured. The frequency characteristic is shown in FIG. Further, various measured values are shown in Table 1.

From the comparison between Example 1 and Comparative Example 1 which is a conventional example, it is found that the insertion loss of the signal in the input / output electrode forming section is remarkably reduced by forming the shield section in the waveguide filter. I understand. Further, by changing the thickness of the shield part, an attenuation pole can be generated in a desired frequency band in an arbitrary frequency band near the pass band, and the attenuation characteristic can be improved.

Example 6 A waveguide filter having a dielectric resonator and a shield portion as shown in FIG. 1 and having two dielectric resonators was produced. As a dielectric material for the resonator and the shield part, a cordierite composition-based dielectric ceramic having a dielectric constant ε of 5.4 was used. Each dielectric resonator was formed by baking an input / output electrode and a ground electrode of a predetermined pattern with Ag paste on the surface of a dielectric block having a width of 4 mm × 6 mm and a height of 3 mm. The pattern of the input / output electrodes formed on the resonator is 1.2 on the bottom.
mm width x 2.8 mm depth, width 0.8 mm on both sides
The insulating part (dielectric exposed part) was formed. In addition, a conductor pattern having a width of 2.0 mm and a height of 0.5 mm is provided on a side surface connected to the bottom surface, and 0.5 is provided on both sides and an upper portion of the conductor.
An insulating portion (dielectric exposed portion) having a width of mm was formed. In addition, the surface where the dielectric resonators are joined together has a width of 2.4 mm × 1.
A dielectric exposed portion having a height of 2 mm was formed as a joint portion.

In addition, the shield part has a metal casing in which a side surface connected to the bottom surface of the resonator is covered with an input / output electrode forming part so that a space of 4 mm width × 3 mm height × 0.75 mm thickness is formed. It is configured by joining. The two shield parts 3 and the two dielectric resonators 2 produced in this way were adhered with a conductor film to form a filter. The insertion loss of the waveguide type filter using the produced dielectric resonator was measured and found to be 1.5 dB.

Comparative Example 2 A waveguide type filter having a structure in which two shield portions were removed from the waveguide type filter of Example 6 consisting of two dielectric resonators and two shield portions was similarly prepared. Input / output electrodes,
The patterns of the ground electrode, the coupling portion, etc. are the same as in Example 6. The insertion loss of this waveguide filter was measured and found to be 1.8 dB.

As can be seen from the comparison between Comparative Example 2 and Example 6, even in the waveguide type filter using the dielectric resonator made of dielectric ceramics, by providing the shield part of the present invention, It is possible to provide a waveguide type filter with low output loss.

[0053]

EFFECTS OF THE INVENTION The waveguide type filter having the shield portion on the end face of the resonator according to the present invention has a simple shape, is easy to mount on the substrate, and has a small input loss. A filter can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view (a) and an exploded perspective view (b) showing an embodiment of a waveguide type dielectric filter according to the present invention.

FIG. 2 is a perspective view (a) and an exploded perspective view (b) showing another embodiment of the waveguide type dielectric filter according to the present invention.

FIG. 3 is an exploded perspective view (a) and its explanatory view (b) showing an embodiment of a waveguide type dielectric filter having a housing structure according to the present invention.

FIG. 4 is an exploded perspective view showing another embodiment of a waveguide type dielectric filter having a housing structure according to the present invention.

FIG. 5 is a configuration diagram of a waveguide filter having a casing structure of the present invention including two resonators manufactured in Example 1.

6 is a frequency characteristic diagram of the waveguide filter manufactured in Example 1. FIG.

7 is a frequency characteristic diagram of the waveguide filter manufactured in Example 2. FIG.

FIG. 8 is a frequency characteristic diagram of the waveguide filter manufactured in Example 3;

9 is a frequency characteristic diagram of the waveguide filter manufactured in Comparative Example 1. FIG.

FIG. 10 shows a structure of a conventional waveguide type filter (a).
It is sectional drawing seen from the upper surface and sectional view seen from the (b) side surface.

FIG. 11 is an explanatory diagram showing an arrangement of a conventional antenna and a signal processing circuit of a waveguide filter using a cavity resonator.

[Explanation of symbols]

1 Waveguide filter 2 resonator 3 Shield part 4 Input / output electrode components 5 input / output electrodes 6 insulation 7 connection 8 ground electrodes 9 substrates 20 housing 21 Bottom 22 One side connected to the bottom 23 partitions 25 Bottom plate 31 Insulation part 51 I / O points 52 short-circuit point 60 signal transmission path 101 Mode converter 102 coupling terminal (excitation line) 103 connector 104 cavity 105 Dielectric resonator 106 support 107 Adjustment screw 108 metal housing 110 Waveguide type filter 111 Shield box containing signal processing circuit 112 coaxial line

Claims (7)

[Claims] 1. A structure in which a plurality of waveguide type resonators are connected to each other, wherein the resonator has a coupling portion for electromagnetically coupling the resonators to each other, and inputs or outputs a signal. The resonator to be performed has an input / output electrode constituent portion extending from a bottom surface to one side surface connected to the bottom surface, and the input / output electrode constituent portion is composed of an input / output electrode and an insulating portion. In a waveguide type filter in which substantially the entire surface of the resonator other than the constituent portion is covered with a ground electrode, the conductive material covering the input / output electrode constituent portion on the one side surface of the resonator having the input / output electrode constituent portion. A waveguide type filter having a shield part having a body part. 2. The waveguide type filter according to claim 1, wherein the resonator and the shield portion are formed of a dielectric ceramic block. 3. The waveguide filter according to claim 1, wherein the conductor part of the shield part is formed of a case having conductivity, and the material inside the shield part is air. 4. The waveguide type according to claim 1, wherein at least a part of a ground electrode of the resonator is formed of a conductive case, and a material inside the resonator is air. filter. 5. The resonator has at least a part of a ground electrode and at least a part of a conductor part of the shield part formed of a conductive case, and the inside of the resonator and the inside of the shield part. The waveguide type filter according to claim 1, wherein the material is air. 6. The ground electrode of the resonator, wherein a portion of the resonator other than the bottom surface of the ground electrode and a portion of the shield portion other than the bottom surface of the conductor portion are formed of a conductive casing. 2. The waveguide type filter according to claim 1, wherein a bottom surface portion of the substrate and a bottom surface portion of the conductor portion of the shield portion and the input / output electrode forming portion are formed on the substrate. 7. The input / output electrode has a structure in which it extends in a band shape from an input / output point of an external signal and the other end of the input / output electrode is short-circuited to a ground electrode formed on the outer surface of the resonator. Item 2. The waveguide filter according to item 1.