JP2003188617A - Dielectric resonator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric filter of smaller size and lower cost, with good out-of-band characteristics, by reducing the number of dielectric resonators. <P>SOLUTION: One edge of a dielectric block 1 of near rectangular solid is cut to form a surface 2a, while another edge which is not parallel to the edge is cut to form a surface 2b. Thus, a triple-mode dielectric resonator in which three resonance modes of the dielectric block 1 are combined is disposed in a shield waveguide 3, and rod antennas 8 and 8 of which tips are opened with input/output terminals 9 and 9 are provided as an exciting means, to constitute a dielectric filter. Since the characteristics corresponding to those of a 3-stage filter are obtained by a single dielectric block, the size and cost are reduced. <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 dielectric filter used in radio communication in a high frequency band such as a microwave band and a quasi-microwave band, and a dielectric resonator used for such a dielectric filter, and more particularly, The present invention relates to a triple mode dielectric resonator that can use three resonance modes in one dielectric block, and a dielectric filter using such a dielectric resonator.

[0002]

2. Description of the Related Art A dielectric filter in which cylindrical or rectangular parallelepiped dielectrics are continuously arranged in a cutoff waveguide and resonance of a cylindrical TE ₀₁ mode or a rectangular TE ₁₁ mode of the dielectric is used is an unloaded type. Since it has a high Q and can be downsized as compared with a waveguide type filter, it is widely used for a filter that requires low loss and downsizing. Resonance of this mode is caused by repeated reflection of the electric field at the interface between the dielectric and air. The resonance frequency depends on the dielectric constant and size of the dielectric. The larger the dielectric constant, the smaller the resonator can be made. Further, the magnetic field generated by this resonance excites the resonator in the next stage, which corresponds to the coupling between the stages of the dielectric filter. The size of the coupling is mainly determined by the distance between the resonators, and the larger the distance, the smaller the coupling amount. As the adjusting means of such a dielectric filter, a screw is inserted in a direction perpendicular to the reflection surface of the electric field to increase the resonance frequency, a screw is inserted between the resonators to strengthen the coupling,
And so on.

On the other hand, there is also a dielectric filter which utilizes a dual mode dielectric resonator in order to reduce the size. This is, for example, in a cylindrical waveguide, a cylindrical dielectric resonator is arranged in the center of the waveguide with the axes of the cylinder aligned, and two resonances (HE ₁₁ mode) that occur in two directions orthogonal to this cylindrical axis.
Is disturbed and coupled from the waveguide side by means of a screw or the like by means of a screw or the like to obtain two resonances with one resonator.

[0004]

As described above, the resonance frequency of the resonator in the dielectric TE ₀₁ and rectangular TE ₁₁ modes depends on the dielectric constant and the size of the dielectric. Since the resonator can be downsized, the simplest method is to increase the dielectric constant of the dielectric in order to downsize the filter using the dielectric resonator.

However, in general, a low-loss dielectric material used in a dielectric filter has a characteristic that the larger the dielectric constant, the larger the dielectric loss. Therefore, there is a limit to miniaturization while keeping the insertion loss small. is there. Further, such a low-loss dielectric is expensive, and as the number of stages increases, the number of dielectrics used naturally increases, resulting in an expensive filter.

[0006] Also, in the filter using dual mode dielectric resonator of the HE ₁₁ for compactness, because HE ₁₁ is not a lowest-order mode, unnecessary modes much excited near band used Therefore, there is a problem that the characteristics outside the band often deteriorate.

The object of the present invention is to take advantage of the high unloaded Q of the conventional dielectric filter by the cylindrical TE ₀₁ and rectangular TE ₁₁ modes, while taking in the mode which has been unnecessary until now into the band. By acting as a part of resonance required for characteristics, it is possible to greatly reduce the number of dielectric resonators, reduce size and cost, and realize a dielectric filter with good out-of-band characteristics. Especially.

[0008]

In order to achieve the above object of the present invention, in the present invention, one dielectric block uses three resonance modes to miniaturize the dielectric filter.
That is, in a substantially rectangular parallelepiped block made of a dielectric material, one ridge portion of this dielectric block and another ridge portion which is not parallel to this ridge portion are omitted, so that the three Two resonance modes can be combined.

That is, by removing one ridge of a substantially rectangular parallelepiped dielectric block and omitting another ridge that is not parallel to the one ridge, the three ridges of the dielectric block are removed. It is characterized in that the resonance modes are coupled.

In a substantially rectangular parallelepiped dielectric block, it is clear from the physical symmetry that rectangular TE ₁₁ modes can exist in the directions of three axes orthogonal to each other. Conventional TE
_In the dielectric filter using the _11- mode or HE _11- mode, only one or two of the resonances in the three axial directions are used to construct the filter, and the remaining two or one resonance is rather It had an adverse effect as unnecessary resonance. In the present invention, the remaining resonance is positively utilized so that one resonator can serve the role of three resonators.

At least one cutoff waveguide is arranged.

The above dielectric resonator is incorporated in a cutoff waveguide.
This is because by arranging one or a plurality of filters to form a filter, a small-sized and low-loss dielectric filter can be manufactured.

Further, two or more of the dielectric resonators are arranged in the cutoff waveguide, and partition means made of a conductive material is provided between the dielectric resonators.

This is because, when a plurality of resonators are used, by providing a conductive partition between the resonators, the coupling amount of each mode between the resonators can be appropriately adjusted. This is because it becomes possible to obtain the amount of coupling required for the characteristics within the band and to create the attenuation pole outside the band.

Further, a metal rod whose one end is in contact with the cut-off waveguide is arranged in parallel with the side face at a position separated from the side face of the dielectric resonator by a predetermined distance. The resonance frequency of each resonance and the amount of coupling between the resonances are adjustable.

This is because the filter using the triple mode dielectric resonator according to the present invention has a cutoff waveguide parallel to the side surface of the dielectric resonator at a position separated from the side surface of the dielectric resonator by a certain distance. This is because by inserting a metal rod such as a screw, the resonance frequency and the coupling amount can be adjusted, and the adjustment range of the filter can be widened by combining this with the adjustment means of the conventional method.

A resonator other than the dielectric resonator is further mounted in the cutoff waveguide.

A triple mode dielectric resonator according to the invention;
This is because a compact filter having an arbitrary number of stages can be configured by combining resonators such as a dielectric TE ₀₁ mode and a TEM mode using a metal conductor. As the resonator to be combined, if the resonator having a small unnecessary resonance or a resonator far from the band where the unnecessary resonance is used is used, it is possible to improve the out-of-band characteristics of the entire filter.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a transparent perspective view showing a triple mode dielectric resonator according to an embodiment of the present invention. The triple mode dielectric resonator of this embodiment has a surface 2 in which one ridge portion of a substantially rectangular parallelepiped dielectric block 1 is omitted.
The three resonance modes of the dielectric block 1 are coupled by having the surface 2b which has a and which has another ridge not parallel to the one ridge. Although the xyz axes are shown separately from the dielectric block 1 in FIG. 1, these x, y, and z axes are respectively two planes of the original substantially rectangular parallelepiped dielectric block 1. Is orthogonal to. The same applies to the following figures.

That is, in the x-y-z orthogonal coordinate system shown in FIG. 1, the electromagnetic field is first excited so that the z direction is the TE wave propagation direction. Then, the electric field is reflected by 180 ° at the interface between the dielectric and air, and the reflection is repeated in the z direction, causing resonance in the rectangular TE ₁₁ mode shown in FIGS. 2A and 2B at a certain frequency. However, as shown in FIG. 1, if one edge portion parallel to the y-axis of this dielectric block 1 is missing and there is a surface 2a with the missing edge portion, the tangent line of the electric field on the surface 2a. Component (y component)
Reflects in the 90 ° direction and propagates in the x direction. That is, the y component of the propagation direction z is reflected on the surface 2a and propagates in the propagation direction x.
Y component of. The radio waves generated in the x direction are repeatedly reflected on the boundary surface as in the z direction, and resonance is excited. According to the same principle, when one ridge portion parallel to the z axis of the dielectric block 1 is missing and the surface 2b having the ridge portion is missing, resonance in the y direction is excited, and one resonator is used. The three resonances are excited one after the other. The above is the principle of coupling. The actual electromagnetic field in the resonator is degenerate because components in three directions are present at the same time. However, as shown in FIG. 3A, resonance in the z direction is caused by the first stage of the filter shown in FIG. ), X
It can be considered that the direction is the second step, and the y direction is the third step, as shown in FIG. Regarding the resonance frequency, when the dielectric block is a cube, the resonance frequency at the second stage becomes high. In order to match the three resonance frequencies, the dimension of the dielectric block 1 may be shortened in the second stage, that is, in the x direction of FIG. Regarding the connection, the surface 2a with the ridge missing
Can be considered to be the connection of the first step and the second step, and the surface 2b lacking the ridge can be considered to be the connection of the second step and the third step.

It is examined how the coupling changes when the above-mentioned dimension for cutting the ridge is changed, and the result is shown in FIG. 4 (a). Here, the dimension C of the portion where the ridge portion of the substantially cubic dielectric block 1 is missing and the dimension L of the entire surface including this missing portion are taken as shown in FIG. 4B, and C / L The change in the coupling coefficient was examined for four cases with different values. As shown in FIG. 4A, the coupling coefficient monotonically increases as the ratio of the dimension C of the portion where the ridge portion is omitted to the entire dimension L increases. Therefore, it was found that in the dielectric block 1, the larger the size of the portion where the ridge portion is omitted, the stronger the coupling.

(Embodiment 1) FIG. 5 is a transparent perspective view of a dielectric filter of embodiment 1 utilizing one of the above triple mode dielectric resonators. That is, as shown in FIG. 5, the dielectric filter of the present embodiment has a substantially rectangular parallelepiped dielectric block 1 in which one ridge portion is cut off to form a surface 2a, and the dielectric filter is parallel to the one ridge portion. One triple-mode dielectric resonator 50 in which the three resonance modes of the dielectric block 1 are coupled is formed in the cutoff waveguide 3 by forming another surface 2b by omitting another ridge that does not become A dielectric filter is provided by providing rod-shaped antennas 8 and 8 which are arranged and whose ends are opened by input / output terminals 9 and 9 as excitation means. In the dielectric filter of the first embodiment, the open-ended antennas 8 are used as the excitation means of the dielectric resonator 50. In practice, the dielectric resonator 50 is supported by a low dielectric constant dielectric or the like so as not to come into contact with the cutoff waveguide 3, but the low dielectric constant dielectric or the like is omitted in this figure. FIG. 6A shows an example of characteristics of the dielectric filter shown in FIG.
And (b). As shown in FIG. 6A, three poles of reflection loss appear, and it can be seen that the characteristics corresponding to the three-stage filter are obtained. Further, as shown in FIG. 6B, it was found that two attenuation poles 62 and 64 are generated on the side of the frequency higher than the center frequency.

(Comparative Example 1) FIG. 7 is a transparent perspective view showing Comparative Example 1 of a three-stage dielectric filter utilizing the conventional TE ₁₁ mode. That is, in the dielectric filter of Comparative Example 1, three dielectric blocks 1 are arranged at a predetermined distance from each other in the longitudinal cutoff waveguide 3, and the cutoff waveguide 3 is arranged in the longitudinal direction. At both ends, rod-shaped antennas 8 having open ends by input / output terminals 9 are provided as excitation means. Further, between the three dielectric blocks 1, screws 4 and 4 having one ends in contact with the blocking waveguide 3 are arranged to adjust the coupling between the dielectrics. In addition, 10 is a stand for supporting each resonator (dielectric block 1), and the resonance frequency of each resonator (dielectric block 1) is adjusted by each metal rod 12.

The volume of the dielectric block 1 is slightly larger in the dielectric filter according to Example 1 shown in FIG. 5 than in Comparative Example 1 shown in FIG. 7, but in Comparative Example 1 it is shown in FIG. As described above, a distance corresponding to the coupling amount is required between the dielectric blocks 1. In the dielectric filter according to the first embodiment shown in FIG. 5, since one dielectric block 1 can obtain the characteristics corresponding to the three-stage filter,
Since such a distance is unnecessary, the volume of the entire filter may be one third or less of that of Comparative Example 1. As described above, in the first embodiment, it is possible to realize a small dielectric filter by using the triple mode dielectric resonator.

(Comparative Example 2) FIG. 8 is a transparent perspective view showing Comparative Example 2 of a conventional dielectric filter utilizing the HE ₁₁ double mode. That is, the dielectric filter of Comparative Example 2 is a cylindrical cut-off waveguide 3 supported by a dielectric material (not shown) having a low dielectric constant so as not to come into contact with the cut-off waveguide 3. The dielectric block 1 is arranged, and rod-shaped antennas 8, 8 whose ends are opened by input / output terminals 9, 9 are provided at both ends of the cutoff waveguide 3 at different angles. The two resonances in the dual mode dielectric resonator have their coupling adjusted by the metal rod 13.

FIG. 9 shows the pass characteristics of the dielectric filter of Comparative Example 2 shown in FIG. Note that FIG. 9 shows exactly the same band as FIG.

In the dielectric filter of Comparative Example 2, unnecessary resonance is excited near the high frequency side of the pass band, as indicated by reference numeral 92 in FIG. On the other hand, in the dielectric filter according to the above-described first embodiment, as shown in FIG.
As shown in (b), steep attenuation poles 62 and 64 are formed on the high frequency side of the pass band, and it is clear that the filter has more excellent characteristics.

(Embodiment 2) FIG. 10 is a transparent perspective view of a dielectric filter of embodiment 2 utilizing two of the above triple mode dielectric resonators. That is, in the dielectric filter of the second embodiment, two triple mode dielectric resonators shown in FIG. 1 are arranged in the cutoff waveguide 3 with a predetermined distance from each other.
Bar-shaped antennas 8 and 8 opened from both end surfaces in the longitudinal direction of the cutoff waveguide 3 by input / output terminals 9 and 9 at the both end surfaces,
Each is provided in the x-axis direction. A screw 4 having one end in contact with the upper surface of the cutoff waveguide 3 is arranged between the two triple mode dielectric resonators to adjust the coupling between the dielectrics. Each resonator (dielectric block 1)
The table for supporting is also omitted in this figure.

Since the dielectric filter of the second embodiment has two triple mode dielectric resonators, it has a total of six stages. In FIG. 10, a metal rod (screw) 4 is inserted between the resonators in order to strongly couple the two dielectric resonators by resonance in the y direction.

(Embodiment 3) FIG. 11 shows a dielectric filter using two triple mode dielectric resonators as described above.
A metal partition 5 is provided between the two dielectric blocks 1.
FIG. 7 is a transparent perspective view of a dielectric filter according to a third embodiment. That is,
The dielectric filter according to the third embodiment has two triple mode dielectric resonators shown in FIG. 1 in the cutoff waveguide 3 at a predetermined distance from each other, as in the second embodiment. Bar-shaped antennas 8 and 8 are arranged in the x-axis direction from both end faces in the longitudinal direction of the cutoff waveguide 3 and opened by input / output terminals 9 and 9 at the both end faces. In this embodiment, two 3
A metal partition 5 is provided between the heavy mode dielectric resonators instead of the screw 4 of the second embodiment. Also, FIG.
As shown in FIG. 1, the surface 2b of the one dielectric block 1 in which the other one of the above-mentioned ridges is omitted is formed at a position different from that of the second embodiment shown in FIG. Incidentally, a base for supporting each resonator (dielectric block 1) is also omitted in this figure.

The frequency characteristic of this dielectric filter is shown in FIG.
Shown in. In the dielectric filter of Example 3, the metal partition 5
Thereby, the coupling between the resonators due to the resonance in the x direction and the z direction can be weakened, and the coupling between the resonators can be obtained mainly by the resonance in the y direction. Further, by changing the position of the metal partition 5 and the direction of each dielectric block 1, it becomes possible to form an attenuation pole at an arbitrary position. When the resonator shape, the excitation means, and the metal partition 5 as in the third embodiment shown in FIG. 11 are used, attenuation poles are provided on both the low frequency side and the high frequency side of the pass band, as shown in FIG. 122, 124 can be made.

(Embodiment 4) FIG. 13 is a diagram showing a method of adjusting the dielectric filter with a metal rod. Actually, a screw is used as a metal rod, and the adjustment is performed by taking this screw in and out. This metal rod acts on the magnetic field leaking from the dielectric. The metal rod at the position 6a in FIG. 13 is linked to the magnetic flux of this resonance at the resonance in the x direction, so that the magnetic field is strengthened and the resonance frequency is lowered. This is equivalent to a larger equivalent inductance in the parallel resonant circuit. Similarly, 6b lowers the resonance frequency in the y direction. As in the prior art, since the metal rod at the position 6c raises the resonance frequency in the z direction, the frequency can be adjusted in a wide range by combining this adjustment in the three directions of x, y, and z. Regarding the coupling, 7a acts to weaken the coupling of resonances in the x and y directions, and 7b works to strengthen the coupling on the contrary, so that the adjustment range is wide. As described above, since the post-adjustment using the metal rod is possible, it is possible to relax the accuracy required for the dimensions and the dielectric constant of the dielectric block when manufacturing the resonator, thereby reducing the manufacturing cost. It can be kept low.

(Embodiment 5) FIG. 14 shows an eight-stage dielectric filter according to Embodiment 5, which is constituted by combining a triple mode dielectric resonator of the present invention and a TEM mode resonator made of metal. It is a transparent perspective view. That is, in the dielectric filter according to the fifth embodiment, two triple mode dielectric resonators shown in FIG. 1 are arranged in the cutoff waveguide 3 with a predetermined distance from each other, and both sides of the dielectric resonator are arranged. TE made of metal
The M-mode resonator 11 is arranged. The cutoff waveguide 3
Rod-shaped antennas 8 and 8 opened by input / output terminals 9 and 9 are provided at both ends in the y-axis direction, respectively. In this embodiment, two triple mode dielectric resonators are mutually connected, and each triple mode dielectric resonator and each TEM mode resonator 11 are arranged.
A total of three metal partitions 5 are provided between them. Note that the base that supports each resonator is also omitted in this figure. If the filter is made using only the triple mode dielectric resonator, the filter can be configured only by the number of stages of multiples of 3. However, in the triple mode dielectric resonator of the present invention, for example, from the conventional technology, By combining the single TE ₀₁ mode resonators of the dielectrics, etc., it becomes possible to construct a filter with an arbitrary number of stages. Also, as shown in FIG. 14, when the TEM mode resonator 11 is combined, unnecessary resonance other than an odd multiple of the resonance frequency can be suppressed.

[0034]

As described above, according to the present invention, 1
It is possible to realize a triple mode dielectric resonator that plays the role of three resonators with one dielectric block. Further, by using this triple mode dielectric resonator, the size of the dielectric filter can be reduced. As a result of downsizing, the weight can be reduced and the number of resonators used can be reduced, leading to cost reduction. Further, it is possible to obtain an effect that an attenuation pole is arbitrarily arranged and unnecessary resonance can be avoided.

[Brief description of drawings]

FIG. 1 is a transparent perspective view showing a triple mode dielectric resonator according to an embodiment of the present invention.

2A and 2B are diagrams for explaining resonance in a rectangular TE ₁₁ mode, in which FIG. 2A shows a direction in which an electric field acts, and FIG. 2B shows a direction in which a magnetic field acts.

3A and 3B are diagrams for explaining the principle that three resonances are excited one after another by one resonator. FIG. 3A is a first resonance of the filter in the z direction, and FIG. 3B is x. Direction is the second step,
(C) shows that the y direction is the third stage.

FIG. 4 is a diagram for explaining how the coupling changes when the dimension for removing the ridge is changed,
(A) shows the graph which shows the result, (b) shows the dimension C of the part which lacks a ridge part, and how to take the dimension L of the whole surface including this missing part, respectively.

FIG. 5 is a transparent perspective view of the dielectric filter according to the first embodiment, which uses one triple mode dielectric resonator.

6A and 6B are diagrams showing an example of characteristics of the dielectric filter shown in FIG. 5, in which FIG. 6A shows the relationship between the pass loss and the return loss and the frequency, and FIG. Show.

FIG. 7 is a transparent perspective view showing a comparative example 1 of a three-stage dielectric filter utilizing the conventional TE ₁₁ mode.

FIG. 8 is a transparent perspective view showing a second comparative example of a dielectric filter using a conventional HE ₁₁ double mode.

9 shows pass characteristics of the dielectric filter of Comparative Example 2 shown in FIG.

FIG. 10 is a transparent perspective view of a dielectric filter according to a second embodiment, which uses two triple mode dielectric resonators.

FIG. 11 is a transparent perspective view of a dielectric filter of Example 3 in which a metal partition is provided between two dielectric blocks in the dielectric filter that uses two triple mode dielectric resonators.

12 is a diagram showing frequency characteristics of the dielectric filter shown in FIG.

FIG. 13 is a diagram showing a method of adjusting a dielectric filter with a metal rod.

FIG. 14 is a transparent perspective view showing an eight-stage dielectric filter according to a fifth embodiment, which is configured by combining a triple mode dielectric resonator of the present invention and a TEM mode resonator made of metal.

[Description of Reference Signs] 1 dielectric block 2a, 2b surface where ridge of dielectric block is missing 3 cutoff waveguide 4 screw for adjusting coupling between dielectrics 5 metal partition 6a for adjusting coupling between dielectrics , 6b Position 6c of metal rod for adjusting resonance frequency of triple mode resonator 7c, 7b Position of metal rod for adjusting resonance frequency by conventional method 7a, 7b Position 8 of metal rod for adjusting coupling amount of triple mode resonator Antenna 9 Input / output terminal of filter 10 Base supporting resonator 11 TEM mode resonator 12 Metal rod 13 for adjusting resonance frequency by a conventional method 13 Metal rod for coupling two resonances with a dual mode dielectric resonator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yellow             6-7 Koriyama, Taichiro-ku, Sendai City Stock Association             In company Tokin (72) Inventor Akihiro Isomura             6-7 Koriyama, Taichiro-ku, Sendai City Stock Association             In company Tokin F term (reference) 5J006 HC03 HC12 HC14 JA01 JA11                       LA03 LA22 MA01 MB01 NA01                       ND05 NE01 NE11 PA01

Claims (4)

[Claims] 1. A triple mode dielectric resonator in which three resonance modes are coupled in a substantially rectangular parallelepiped dielectric block, wherein the dielectric resonator lacks one ridge portion of the dielectric block. A triple mode dielectric having a first surface formed by being formed and a second surface formed by omitting another ridge that is not parallel to the one ridge. Body resonator. 2. The triple mode dielectric resonator according to claim 1, wherein the coupling amount of the three resonance modes is changed by changing the dimensions of the first and second surfaces. 3. A triple mode dielectric resonator in which three resonance modes are coupled in a substantially rectangular parallelepiped dielectric block, wherein the dielectric resonator lacks one ridge portion of the dielectric block. And a second surface formed by omitting another ridge that is not parallel to and does not intersect with the one ridge.
Heavy mode dielectric resonator. 4. A triple mode dielectric resonator according to claim 3, wherein the coupling amount of the three resonance modes is changed by changing the dimensions of the first and second surfaces.