JP4105011B2 - Waveguide type dielectric filter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a waveguide type dielectric filter used in a high frequency region such as the GHz band, and relates to a waveguide type dielectric filter capable of obtaining a desired attenuation pole.
[0002]
[Prior art]
[Patent Document 1]
US Patent No. 5926079 [Patent Document 2]
Japanese Patent Laid-Open No. 6-177607
By coupling a plurality of dielectric waveguide resonators, various types of waveguide dielectric filters can be realized. FIG. 8 shows such a waveguide-type dielectric filter. The resonator block 81 includes three resonators 82A, 82B, and 82C, and an iris is formed between the resonators to adjust the coupling. is doing. Conductor strips extending from the bottom surfaces of the resonators 82A and 82C at the input / output ends to the end surfaces are used as the input electrode 85 and the output electrode 86, respectively. The dielectric is exposed only on both sides of the input / output electrodes and a part of the end face in contact with them, and the other entire surface is covered with a conductor film. In this example, a short dielectric portion having input / output electrodes formed on the bottom surface is formed outside the resonators at both ends.
[0004]
The above dielectric can be mounted on a planar circuit such as a printed circuit board. The inventors have proposed this mounting structure in Japanese Patent Application No. 2001-216919. However, conventional waveguide dielectric filter structures have been unable to generate an attenuation pole required as a filter in an arbitrary band. In order to improve the selection characteristics as a filter, it is necessary to obtain attenuation poles on the high band side or low band side or both of the pass band.
[0005]
[Problems to be solved by the invention]
The present invention provides a structure for obtaining an arbitrary attenuation pole in a monolithic waveguide type dielectric filter, and realizes a polarized type waveguide dielectric filter with a simple and highly productive structure. Is. In addition, when the wave tube type dielectric filter is mounted on a planar circuit formed on a printed circuit board or other wiring board, the discontinuity between the input / output terminals of the filter and the signal lines of the board is reduced as much as possible. The loss caused by the reflection and radiation of the electromagnetic field is reduced.
[0006]
[Means for Solving the Problems]
The present invention solves the above problems by adding a resonator. That is, in a waveguide type dielectric filter in which a plurality of dielectric waveguides are integrally formed in a dielectric block, a plurality of dielectric waveguides constituting the filter are formed in the dielectric block. The dielectric waveguide for forming the attenuation pole is disposed on at least one side thereof, and at least one of the dielectric waveguides forms the attenuation pole from the bottom surface of the dielectric waveguide constituting the filter. It is characterized in that an input / output electrode led out to the end face of the dielectric is provided via the bottom surface of the dielectric.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The basic components of the waveguide dielectric filter according to the present invention are as follows.
(1) A dielectric block in which a dielectric constituting a plurality of resonators constituting a filter unit and a polarized input / output structure (resonator) disposed at least on one end side are integrally formed. The coupling is adjusted with iris etc.
(2) Input / output electrodes with conductor strips extending from the bottom surface of the resonator at the input / output end to the end surface of the dielectric block, at least one of which crosses the bottom surface of the polarized input / output structure (resonator).
(3) A conductor film that covers the surface of the dielectric block except for both sides of the input / output electrode and the portion of the end face that contacts the input / output electrode, and is connected to the ground potential.
[0008]
Resonance modes and waveguides of a waveguide resonator constituting a polarized input / output structure in which input / output electrodes are connected to signal lines of a wiring board such as a printed circuit board and a signal from the wiring board generates an attenuation pole Coupled to the resonant mode inside the filter. Between the waveguide resonator that constitutes the polarized input / output structure that generates the attenuation pole and the resonator that constitutes the filter, the filter and the resonator that generates the pole are reduced by reducing the width of the dielectric. Adjust the bond between. Furthermore, at the end portion, which is the portion connecting the waveguide resonator that generates the attenuation pole and the input / output terminal, the end portion itself or the connection portion between the end surface and the filter (between the filter portion and the polarized input / output structure). Narrow the width in the part between the part where the width is narrow.
[0009]
【Example】
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a waveguide type dielectric filter according to the present invention having a three-element polarized input / output structure. Resonators 12A, 12B, and 12C constituting a three-element filter are disposed in a substantially rectangular parallelepiped dielectric block 11, and the coupling is adjusted by an iris formed by forming a groove from the side. In this example, a resonator 13 constituting a polarized input / output structure is arranged on the input side. On the bottom surface of the filter, the input electrode 15 is extended from the end face on the input side to the filter section through the resonator 13 constituting the polarized input / output structure and terminated, and on the opposite end face on the opposite side of the filter. An extending output electrode 16 is formed.
[0010]
In order to adjust the coupling between the filter portion and the polarized input / output structure, a groove is formed from the side surface in order to narrow the width of the connecting portion between the filter portion and the polarized input / output structure. In order to prevent loss due to radiation from the polarized input / output structure to the input side, the width of the end of the polarized input / output structure is also narrowed. The end of this polarized input / output structure narrows the width of the end face itself, or between the end face and the coupling part (the part where the width of the filter part and the polarized input / output structure is narrow). What is necessary is just to narrow the width in part.
[0011]
In addition, a conductor pattern (exposed narrower than the waveguide resonator) is formed on the end face with a part of the dielectric exposed. The other surface is covered with a dielectric film (the end surface and the bottom surface with the input / output electrodes have exposed portions of the dielectric), and the adjacent conductive films are connected to each other. Yes. In this example, the output electrode 16 is formed without a polarized input / output structure. As shown in FIGS. 2 and 3, the input / output electrodes are mounted on the wiring boards 18 and 19 and connected to a signal line formed by a conductor strip formed on the surface thereof. Since the conductor strip and the input / output electrode form one continuous conductor strip, radiation due to mismatch of the input / output portions can be suppressed.
[0012]
Electricity of a conventional three-element waveguide dielectric filter described in Japanese Patent Application No. 2001-216919 of the prior application and a waveguide dielectric filter having a three-element polarized input / output structure according to the present invention. FIG. 4 shows a comparison of characteristics (transmission characteristics). In this example, the waveguide-type dielectric filter according to the present invention has an attenuation pole on the high side of the pass band, and the attenuation characteristics near the attenuation pole as compared with the conventional filter. It can be seen that is greatly improved.
[0013]
Another embodiment of the present invention will be described. FIG. 5 includes a polarized input / output structure on the output side, and is structurally the same as that shown in FIG. Further, FIG. 6 is arranged on both the input and output sides, so that attenuation poles can be multistaged. The frequency and the like of the attenuation pole can be adjusted by adjusting the shape and coupling state of the resonator serving as the polarized input / output structure. The coupling adjustment between the resonators constituting the filter can also be performed by a through hole or the like.
[0014]
A three-stage filter having the structure shown in FIG. 1 was prototyped as an actual sample. When the dielectric had a length of 46 mm, a width of 10.2 mm, and a thickness of 3.2 mm, a filter with an attenuation pole appearing on the high side of the passband with a central frequency of 3.45 GHz was obtained. The characteristics are shown in FIG. 7, and it was confirmed that the return loss characteristics in the passband are also good and can be sufficiently used as a filter.
[0015]
【The invention's effect】
The effects of the present invention are listed as follows.
1. Since the input / output conductor pattern is formed in a continuous form as if the signal line on the wiring board (printed circuit board) was extended, the waveguide resonance caused by the bottom conductor pattern connected to the signal line The electromagnetic field inside the filter is coupled with the fundamental resonance mode of the waveguide resonator that generates the attenuation pole and the waveguide resonator of the filter unit, and as a result, coupling with an external circuit occurs. It is possible to realize a polarized filter with
2. Since the input / output terminals of the filter are on the same plane as the signal lines of a planar circuit such as a printed circuit board, the continuity between the signal lines of the printed circuit board and the input / output terminals of the filter is well maintained, and high-frequency signals generated by discontinuities Therefore, it can be mounted on a wiring board such as a printed board, and a low-loss element can be obtained.
3. Since the end portion or a part of the end portion is narrower in the width direction than the waveguide resonator, it becomes a cutoff waveguide for the frequency of the fundamental resonance mode of the resonator. Low loss due to the fact that the field is not leaked to the outside and the width of the exposed part of the electrode pattern on the end face is narrower than that of the waveguide resonator. Can be realized.
4). By adopting a structure that has high continuity with the input / output signal lines and the signal lines are terminated at the bottom of the resonator, the pattern on the printed circuit board on which the filter is mounted does not change the electrical termination position of the conductor pattern on the bottom Any pattern is acceptable. For example, if the filter according to the present invention is mounted on a continuous strip line, it is not necessary to re-create the conductor pattern on the substrate even when the size of the filter is slightly changed, which is highly convenient.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of the present invention. FIG. 2 is a perspective view showing a mounting method on a substrate. FIG. 3 is a perspective view showing a mounting method on another substrate. FIG. 5 is a perspective view showing another embodiment of the present invention. FIG. 6 is a perspective view showing another embodiment of the present invention. FIG. 7 is a waveguide according to the present invention. FIG. 8 is a perspective view showing a conventional waveguide type dielectric filter.
11, 81: Dielectric block
12, 82: Resonator
13: Polarized input / output structure (resonator)
15, 85: Input electrode
16, 86: Output electrode
18, 19: Wiring board

Claims (2)

In a waveguide type dielectric filter in which a plurality of dielectric waveguides are integrally formed in a dielectric block,
The dielectric block is formed with a plurality of dielectric waveguide resonators formed by covering the surfaces of a plurality of dielectric bodies formed from the side surfaces constituting the filter with a conductor film, and an attenuation pole A dielectric waveguide resonator is formed at least on one end,
A waveguide characterized in that at least one of the input / output electrodes of the conductor strip drawn from the bottom surface of the resonator at the input / output end to both end surfaces of the dielectric passes through the bottom surface of the resonator for forming the attenuation pole. Type dielectric filter. In a waveguide type dielectric filter in which a plurality of dielectric waveguides are integrally formed in a dielectric block,
The dielectric block is formed with a plurality of dielectric waveguide resonators formed by covering the surfaces of a plurality of dielectric bodies formed from the side surfaces constituting the filter with a conductor film, and an attenuation pole A dielectric waveguide resonator is formed at least on one end,
It is characterized in that at least one of the input / output electrodes by the coplanar line of the conductor strip drawn from the bottom surface of the resonator at the input / output end to the both end surfaces of the dielectric passes through the bottom surface of the resonator for forming the attenuation pole. Waveguide type dielectric filter.

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