JP5409323B2 - Dielectric resonator and high frequency filter using the same - Google Patents

Description

  The present invention relates to an image-type dielectric resonator used in a microwave band or a millimeter wave band, and a high-frequency filter configured using the dielectric resonator.

Conventionally, a dielectric resonator that resonates in a resonance mode called “TE01δ mode” has been widely used as a small, low-loss resonator used in a microwave band or a millimeter wave band.
The TE01δ mode dielectric resonator has a basic configuration in which a cylindrical dielectric is placed on a slightly smaller support (support dielectric) and fixed in a cavity shielded by a good conductor.

Conventionally, an image-type dielectric resonator is known as a resonator that further downsizes the above-described dielectric resonator.
The image-type dielectric resonator utilizes the fact that the TE01δ mode electric field exists only in the circumferential direction component of the cylindrical dielectric, and an arbitrary surface including the cylinder axis serves as an electric wall. For example, it can be realized by dividing the cylindrical dielectric by a plane including the axis of the cylinder and fixing the half plane to the inner wall surface of the shielding cavity.

In this case, since all surfaces including the axis of the cylinder are electric walls, the shape of the dielectric can be divided into ¼, ８, etc. An image-type dielectric resonator can be realized if both surfaces are closely fixed to the inner wall surface of the shielding cavity.
The image-type dielectric resonator has slightly lower electrical performance than a normal non-image-type dielectric resonator due to loss on the mounting surface to the shielding cavity, but the volume of the resonator is less than half. Therefore, there is a feature that the size is greatly reduced.

  In addition, since the image-type dielectric resonator does not require a support base, the cost can be reduced and assembly can be facilitated. The resonant dielectric is directly connected to the shielding cavity. Therefore, the thermal resistance from the dielectric material serving as the heat source to the shielding cavity is reduced, which is advantageous in terms of heat dissipation and is excellent in terms of power resistance.

  Conventional image-type dielectric resonators that use two adjusting screws whose projection amounts change in the axial direction of the cylinder in order to widen the tuning range of the resonance frequency (for example, see Patent Document 1), There has been proposed a filter (for example, see Patent Document 2) using a dielectric resonator including a dielectric obtained by dividing a cylinder into quarters and an adjusting screw whose projection amount changes in the radial direction of the cylinder.

  By the way, the resonance frequency of the image-type dielectric resonator is adjusted by a metal adjusting screw attached to the shielding cavity, as described in Patent Documents 1 and 2, and the TE01δ mode in the shielding cavity is adjusted. The size of the electromagnetic field distribution region is changed according to the amount of protrusion of the adjusting screw into the shielding cavity (the length of the protruding portion).

  In other words, if the protruding amount of the adjusting screw is increased to limit the region in which the electromagnetic field can be distributed, the resonance frequency increases. Therefore, if an adjusting screw having a large diameter is used, the adjustment range (tuning range) of the resonance frequency is increased. Can be set large.

  However, the image-type dielectric resonator uses an electrical wall to reduce the size of the entire resonator, making it difficult to use an adjustment screw with a large diameter compared to a normal non-image-type dielectric resonator. Therefore, the protruding amount of the adjusting screw tends to be large.

  In addition, since the periphery of the tip of the protruding portion of the adjusting screw has the effect of concentrating the electric field with the inner wall surface of the surrounding shielding cavity, if the protruding amount of the adjusting screw is large, the effective electrical dimension of the shielding cavity is reduced. The resonance frequency of the unnecessary resonance mode existing in the vicinity of the TE01δ mode is greatly changed.

Therefore, for example, when a band-pass filter is configured using an image-type dielectric resonator, the resonance frequency of the unnecessary resonance mode changes according to the adjustment of the resonance frequency of the TE01δ mode. The characteristics also change greatly, and there is a problem that it is difficult to stably obtain a high attenuation.
This problem is a phenomenon related to the sum of the protruding amount of the adjusting screw, even when the number of adjusting screws is increased as described in Patent Document 1, and thus is not likely to be fundamentally solved.

In addition, there is a close relationship between the performance of the dielectric resonator and the frequency characteristics formed using the dielectric resonator. For example, in the case of a band-pass filter, depending on the performance of the dielectric resonator. Therefore, an appropriate pass bandwidth is almost determined.
Basically, the higher the performance of the dielectric resonator, the narrower the passband width can be realized, and the resonance frequency tuning range of each resonator of the filter configured using a plurality of dielectric resonators. Considering the convenience of the adjustment, it is desirable that about several times the pass bandwidth can be secured.

  On the other hand, as described above, the performance of an image-type dielectric resonator does not exceed that of a normal non-image-type dielectric resonator. The bandwidth often becomes wider than a normal dielectric resonator that is not an image. Therefore, it is desired that the tuning range of the resonance frequency of the image-type dielectric resonator is larger than that of a normal dielectric resonator that is not an image-type.

JP-A-2-137502 Japanese Unexamined Patent Publication No. 63-280503

  The conventional image-type dielectric resonator has a narrow tuning range of the resonance frequency by the adjusting screw, and in order to increase the tuning range, an adjusting screw having a large diameter or a plurality of adjusting screws are used. Therefore, there has been a problem that the outer shape of the dielectric resonator becomes large and is not practical.

  In addition, since the resonance frequency of the unnecessary resonance mode located in the vicinity of the desired resonance mode varies greatly according to the protrusion amount of the adjusting screw, it is impossible to obtain a filter that can stably provide good attenuation characteristics. There was a problem.

  In addition, if the adjustment screw can be largely changed, the adjustment screw will inevitably remain outside the shielding cavity when the adjustment screw has a small protrusion into the shielding cavity after adjusting the resonance frequency. As the amount increases, the external shape of the resonator increases, and when a large number of adjusting screws are used, there is a problem that the size is further increased.

The present invention has been made to solve the above-described problems. In the image-type dielectric resonator, the resonance frequency tuning range by the adjusting screw is set large, and the TE01δ mode is present in the vicinity. It is an object of the present invention to obtain a dielectric resonator having a smaller outer shape, in which the resonance frequency of the unnecessary resonance mode is not greatly changed by the protruding amount of the adjusting screw.
It is another object of the present invention to provide a high frequency filter that can stably obtain good frequency characteristics regardless of resonance frequency adjustment when a high frequency filter is configured using the dielectric resonator according to the present invention.

The dielectric resonator according to the present invention has an input / output coupling means for an external circuit, a housing having a shielding cavity formed therein, a flat portion serving as a fixing surface, and a portion of the flat portion being dug. A dielectric body having a dielectric removal portion provided so as to be embedded, and the dielectric body is tightly fixed to the inner wall surface of the shielding cavity via a planar portion, so that the dielectric removal portion and the inner wall surface are A screw movable space formed therebetween, a resonance frequency adjusting screw inserted from the outside of the housing toward the screw moving space, and a fixing means for positioning and fixing the resonance frequency adjusting screw with respect to the housing. The resonance frequency adjusting screw is provided such that the tip portion protrudes into the screw movable space, the protrusion amount of the tip portion can be adjusted from the outside of the shielding cavity, and the resonance frequency is increased by increasing the protrusion amount of the tip portion. also raised It is.

According to the present invention, a dielectric having a three-dimensional shape having a planar portion serving as a fixing surface and having a dielectric removing portion provided so as to dig a portion of the planar portion is disposed on the inner wall surface of the shielding cavity. A resonance frequency adjusting screw with a tip protruding into the screw movable space formed between the dielectric removing portion and the inner wall surface is attached to the shielding cavity, and protruded into the screw movable space. By making the amount adjustable from the outside of the shielding cavity, it is possible to set a large tuning range of the resonance frequency by the adjusting screw, and the resonance frequency of the unnecessary resonance mode existing in the vicinity of the TE01δ mode is the protruding amount of the adjusting screw. Therefore, the outer shape can be further reduced.
In addition, by using the dielectric resonator according to the present invention, a high-frequency filter having good and stable frequency characteristics can be obtained regardless of the resonance frequency adjustment.

1 is an exploded perspective view showing a dielectric resonator according to a first embodiment of the present invention. It is sectional drawing by the A-A 'line in FIG. It is explanatory drawing which shows the electric field distribution of TE01 (delta) mode in FIG. It is explanatory drawing which shows the relationship between the protrusion amount in the cavity of the adjustment screw in Embodiment 1 of this invention, the resonant frequency change rate of a TE01 (delta) mode, and a spurious detuning rate compared with the conventional characteristic. It is a disassembled perspective view which shows the dielectric resonator which concerns on Embodiment 2 of this invention. FIG. 6 is a cross-sectional view taken along line B-B ′ in FIG. 5. It is a disassembled perspective view which shows the dielectric resonator which concerns on Embodiment 3 of this invention. FIG. 8 is a cross-sectional view taken along line C-C ′ in FIG. 7. It is a disassembled perspective view of the high frequency filter which concerns on Embodiment 4 of this invention. FIG. 10 is a cross-sectional view taken along line D-D ′ in FIG. 9.

Embodiment 1 FIG.
1 is an exploded perspective view showing a dielectric resonator according to Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional view taken along line AA ′ in FIG.
1 and 2, the dielectric resonator is a dielectric 1, a box-shaped housing 2 that houses the dielectric 1, a lid 3 that covers the open end of the housing 2, and a support plate for the dielectric 1. A shield cavity (hereinafter simply referred to as “cavity”) 5 formed by the carrier 4, the housing 2 and the lid 3, an input / output terminal (input / output coupling means) 6 made of a conductor in the coaxial line, and an input / output terminal 6 A dielectric 8 that supports the outer periphery, a resonance frequency adjusting screw 10 that is inserted into the housing 2 via a nut (fixing means) 12, a screw 13 that fixes the carrier 4 to the inner wall of the housing 2, and a lid 3 And a screw 14 fixed to the open end of the housing 2.

The input / output terminal 6 is supported on one end portion of the housing 2 via the dielectric 8.
The half-divided cylindrical dielectric 1 is partially removed in the vicinity of the axis, and a semicircular dielectric removal portion 16 is formed in the vicinity of the axial position, and has a substantially C-shape. In addition, planar portions serving as fixing surfaces 9 for the carrier 4 are formed at both ends of the dielectric 1.

A screw hole 11 through which the resonance frequency adjusting screw 10 passes is formed at the center position of the carrier 4, and both upper surfaces of the screw hole 11 serve as the fixing positions 15 of the dielectric 1.
The fixing surface 15 of the dielectric 1 is bonded to the fixed position 15 of the carrier 4, and a screw movable space 17 is formed in a portion surrounded by the dielectric removing portion 16 and the carrier 4.

As shown in FIGS. 1 and 2, the half-columnar dielectric body 1 joins the fixing surface 9 of the dielectric body 1 (a planar portion formed by the end of the half-surface) and the fixing position 15 of the carrier 4. By doing so, it is fixed on the carrier 4.
Further, the carrier 4 is fixed to the bottom surface of the box-shaped casing 2 by screws 13, and the lid 3 is fixed to the top surface of the casing 2 by screws 14.

On one side of the housing 2, a coaxial line-like input / output terminal 6 (input / output coupling means including a conductor in the coaxial line) connected to an external circuit (not shown) is provided.
The resonance frequency adjusting screw 10 passes through the screw hole 11 provided in the carrier 4 from the bottom surface side of the housing 2 and is fixed to a desired position outside the housing 2 using a nut 12. The

That is, the tip of the resonance frequency adjusting screw 10 protrudes into a tunnel-like screw movable space 17 constituted by the dielectric removing portion 16 near the axis of the dielectric 1 and the carrier 4, and this protruding amount is outside the housing 2. Can be adjusted.
The box-shaped housing 2, the lid 3, the carrier 4, and the resonance frequency adjusting screw 10 are all made of a good conductor, or those having a good conductor plated on the surface of an arbitrary member.

Further, as the constituent material of the carrier 4, it is desirable to employ a material having a linear expansion coefficient substantially equal to that of the dielectric 1.
Furthermore, the method for fixing the dielectric 1 to the carrier 4 may be any method found in the prior art, and need not be a specific fixing method.

FIG. 3 is an explanatory diagram showing the electric field distribution in the dielectric 1 with broken-line arrows, and shows the electric field distribution in TE01δ mode.
In FIG. 3, the thin dashed arrow indicates a small amplitude electric field component, and the thick dashed arrow indicates a large amplitude electric field component.
Each electric field component having a small amplitude and a large amplitude (see thin broken line arrows and thick broken line arrows) is only the circumferential component of the cylindrical dielectric 1, and the amplitude is uniform in the circumferential direction of the column.

In addition, as shown in the figure, there is an amplitude distribution of the electric field in the circumferential direction with respect to the radial direction of the cylinder, the amplitude is 0 near the axis of the cylinder, and the diameter coordinate is maximum at about half the cylinder radius. It has a distribution in which the amplitude approaches zero when the coordinates exceed the cylinder radius.
Furthermore, each electric field direction is perpendicular to the upper surface of the carrier 4 to which the dielectric 1 is fixed, and it goes without saying that the upper surface of the carrier 4 is equivalent to an electric wall.

The tip of the resonance frequency adjusting screw 10 protrudes into the screw movable space 17, that is, the central portion (electromagnetic field concentration portion) of the electric field distribution (broken arrow) in the TE01δ mode.
Therefore, since the conductor is arranged at the concentrated portion of the electromagnetic field, the amount of change in the resonance frequency with respect to the protruding amount of the resonance frequency adjusting screw 10 becomes large, and even if the resonance frequency adjusting screw 10 having a relatively small diameter is used. A large amount of change in resonance frequency can be obtained with a small amount of protrusion.

  As described above, the electric field amplitude of the TE01δ mode is 0 near the axis of the cylinder, and the axis of the cylinder can be regarded as a “cylindrical electric wall” having an infinitely small diameter. The protrusion of the resonance frequency adjusting screw 10 (conductor) in the vicinity of the axis does not hinder the resonance mode excitation itself.

  An increase in the protruding amount of the resonance frequency adjusting screw 10 into the screw movable space 17 (cavity) is equivalent to an increase in the diameter of the cylindrical micro electric wall, which is equivalent to the TE01δ mode electromagnetic field. Since this corresponds to narrowing the distribution region of the dielectric 1 in the radial direction, an action equivalent to reducing the cylindrical diameter of the dielectric 1 can be expected.

Since the change in the cylindrical diameter of the dielectric 1 acts to increase the resonance frequency for all the resonance modes, according to the first embodiment of the present invention, the resonance frequency interval between the TE01δ mode and the unnecessary resonance mode is increased. It will be easy to keep.
However, although the diameter of the screw movable space 17 is small and the protruding amount of the resonance frequency adjusting screw 10 is small, the presence of the conductor protruding into the cavity is equivalent to the electrical dimension of the cavity as described above. Strictly speaking, whether or not the resonance frequency interval can actually be maintained depends strictly on the electromagnetic field distribution for each unnecessary resonance mode.

  FIG. 4 is an explanatory diagram showing the effectiveness of the dielectric resonator according to the first embodiment of the present invention. The protrusion amount [mm] of the resonance frequency adjusting screw 10 into the cavity and the change rate of the resonance frequency of the TE01δ mode are shown. The relationship between [%] and the spurious detuning rate (the detuning rate of the latest high-frequency side unnecessary mode resonance) [%] is shown as one calculation result.

  In FIG. 4, the characteristic curve according to the first embodiment of the present invention (when using a φ4 mm screw) is indicated by a solid line (calculated value of a triangular point), and a conventional image-type dielectric resonator (when using a φ8 mm screw). ) Clarifies its usefulness when compared with characteristic curves (calculated values of dotted lines and square points).

The resonance frequency change rate (black triangle point, left scale) in FIG. 4 is obtained on the basis of the resonance frequency when the protruding amount of the resonance frequency adjusting screw 10 is 0 mm.
On the other hand, the spurious detuning rate (white triangle point, right scale) is obtained for each protrusion amount of the resonance frequency adjusting screw 10, and the difference between the resonance frequency ft of the TE01δ mode and the resonance frequency fn of the unnecessary resonance mode is calculated. The value (ft−fn / ft) divided by the former ft is displayed in%.

The conventional image-type dielectric resonator shown in FIG. 4 differs from the dielectric resonator according to the first embodiment of the present invention in the attachment position of the resonance frequency adjusting screw 10 and the diameter φ. The shape of 1 and the cavity are the same.
The resonance frequency adjusting screw in the conventional image-type dielectric resonator can be attached to the box-shaped housing 2 in FIG. 1 at the tip position of the dotted arrow X, and the protrusion amount can be adjusted in the direction of the dotted arrow X, for example. It has become.

The diameter φ of the resonance frequency adjusting screw 10 is twice as large (φ8 mm) as the diameter (φ4 mm) of the resonance frequency adjusting screw in the first embodiment of the present invention in the conventional dielectric resonator.
The calculated values in FIG. 4 are derived in the L band (about 1 GHz), and the relative dielectric constant of the dielectric 1 is about 50.

  As is apparent from FIG. 4, according to the characteristic curve (dotted line, black square point) of the conventional dielectric resonator, the diameter of the resonance frequency adjusting screw is large in order to change the resonance frequency of the TE01δ mode by 2% ( In spite of (φ8 mm), a protrusion amount in the cavity of 9 mm or more (see broken line) is required.

  On the other hand, according to the dielectric resonator (solid line, black triangle point) according to the first embodiment of the present invention, in order to change the resonance frequency of the TE01δ mode by 2% (about 3 mm (conventional dielectric resonance) It can be seen that a protrusion amount (about one-third as compared to the vessel) is sufficient (see the dashed line).

On the other hand, with respect to the spurious detuning rate, in the conventional dielectric resonator (dotted line, white square point), a decrease of 10% or more is seen at the protrusion amount of 9 mm, whereas the dielectric according to the first embodiment of the present invention. It can be seen that there is no significant change in the body resonator (solid line, white triangle point).
In the first embodiment of the present invention, the spurious detuning rate slightly decreases as the protruding amount of the resonance frequency adjusting screw 10 increases. This is because the resonance frequency of the TE01δ mode increases. This is because the resonance frequency of the unnecessary resonance mode hardly changes.

  As described above, the dielectric resonator according to the first embodiment (FIGS. 1 to 4) of the present invention has the input / output terminal (input / output coupling means) 6 for the external circuit, and the cavity 5 is formed inside. A dielectric body 1 having a three-dimensional shape, having a planar portion to be the fixed surface 9 and having a dielectric removal portion 16 provided so as to dig a part of the planar portion; The dielectric 1 is tightly fixed to the inner wall surface of the cavity 5 through the screw movable space 17 formed between the dielectric removing portion 16 and the inner wall surface, and the screw movable space 17 from the outside of the housing 2. And a nut (fixing means) 12 for positioning and fixing the resonant frequency adjusting screw 10 with respect to the housing 2.

The resonance frequency adjusting screw 10 is provided such that the tip portion protrudes into the screw movable space 17 and the amount of protrusion of the tip portion can be adjusted from the outside of the cavity 5.
Further, by providing a flat carrier 4 having a linear expansion coefficient substantially coincident with that of the dielectric 1, and interposing the carrier 4 between the dielectric 1 and the inner wall surface, the dielectric removing portion 16 and the carrier 4 are provided. A screw movable space 17 is formed between the two.

The housing 2 is constituted by a box-shaped housing having an opening, and includes a flat lid 3 having a linear expansion coefficient substantially coincident with the dielectric 1, and the cavity 5 has a box-shaped housing. It is formed by covering the opening of the body 2 with the lid 3.
At least one input / output terminal 6 is provided on the lid 3 or the box-shaped housing 2.
The dielectric 1 is tightly fixed to one surface of the lid 3 on the side of the cavity 5 via a plane portion, and the screw movable space 17 is formed between the lid 3 and the dielectric removing portion 16.
The resonance frequency adjusting screw 10 is attached to the lid 3 using a nut 12.

The dielectric 1 has a three-dimensional shape in which a portion where the vicinity of the half-cylindrical axis is removed is a dielectric removal portion 16 and the half-face is a fixing surface 9.
The dielectric resonator according to the first embodiment of the present invention resonates in a resonance mode having a uniform electric field in the circumferential direction of the cylindrical shape of the dielectric 1.

  As a result, according to the first embodiment of the present invention, a tuning range of the TE01δ mode equal to or higher than the conventional one can be obtained by using the resonance frequency adjusting screw 10 smaller than the conventional one, and is unnecessary compared to the conventional one. The detuning rate of the resonance mode can be increased.

Further, as a result of applying the small resonance frequency adjusting screw 10, an image-type dielectric resonator having a small outer shape can be realized.
Furthermore, since the tuning range of the TE01δ mode is wide, the problem of not resonating at the required frequency due to the external dimension error of the dielectric 1 and variations in relative permittivity is suppressed, and the yield is improved.

1 and 2, the shape of the dielectric 1 has been described as a half cylinder, but the shape of the dielectric 1 is not limited to this, and may be a half of a polygonal column.
That is, the dielectric 1 only needs to have a shape that can resonate with an electromagnetic field distribution similar to the TE01δ mode, and the dielectric at the center of the electric field (see the broken line arrow in FIG. 3) is removed to remove the dielectric. The resonance frequency adjusting screw 10 is formed so that the tip portion protrudes from a tunnel-like portion (screw movable space 17) formed of the dielectric removing portion 16 and the hollow inner wall surface serving as an image surface. If installed, the same effect as described above can be expected.

Moreover, although the cavity which consists of the housing 2 and the lid 3 was made into the rectangular parallelepiped shape, it cannot be overemphasized that it is not this limitation.
Further, the input / output terminal 6 is not limited to the coaxial line, but may be a waveguide, and even if other transmission line forms are adopted, there is no difference in basic effects.

Embodiment 2. FIG.
In the first embodiment (FIGS. 1 and 2), the carrier 4 is provided with the opening of the box-shaped housing 2 facing upward, and the fixing surface 9 of the derivative 1 is placed on the fixing position 15 of the carrier 4. As shown in FIGS. 5 and 6, the opening of the box-shaped housing 2 is arranged downward to make the carrier 4 unnecessary, and the fixing surface 9 of the derivative 1 is fixed on the fixing position 15 of the lid 3. May be tightly fixed.

5 is an exploded perspective view showing an image-type dielectric resonator according to Embodiment 2 of the present invention, and FIG. 6 is a cross-sectional view taken along line BB ′ in FIG.
5 and 6, the same components as those described above (see FIGS. 1 and 2) are denoted by the same reference numerals as those described above and will not be described in detail.

In this case, only the point that the dielectric 1 is attached to the lid 3 and the resonance frequency adjusting screw 10 is screwed into the lid 3 is different from the first embodiment, and the schematic structure is the same as that described above.
The lid 3 is made of a member having a value similar to that of the dielectric 1 and a linear expansion coefficient.

  By applying the structure in which the dielectric 1 is fixed to the lid 3 as shown in FIGS. 5 and 6, the same effect as described above can be obtained and the carrier 4 is not necessary, so that the number of constituent members is reduced. In addition, the cost can be expected and the outer shape is further reduced.

Embodiment 3 FIG.
Although not particularly mentioned in the first and second embodiments (FIGS. 1 to 6), as shown in FIGS. 7 and 8, the surface is located around the tip of the resonance frequency adjusting screw 10. The groove 18 may be provided.

7 is an exploded perspective view showing an image-type dielectric resonator according to Embodiment 3 of the present invention, and FIG. 8 is a cross-sectional view taken along the line CC ′ in FIG.
7 and 6, the same components as those described above (see FIGS. 5 and 6) are denoted by the same reference numerals as those described above and will not be described in detail.

In this case, on the side of the lid 3 on which the dielectric 1 is attached, only the point that the groove 18 that is locally recessed is provided by cutting around the portion to which the resonance frequency adjusting screw 10 is attached. Unlike 2, the schematic structure is the same as described above.
Here, the case where the present invention is applied to the configuration of FIG. 5 and FIG. 6 (Embodiment 2) is shown, but the present invention can also be applied to the configuration of Embodiment 1 (FIGS. 1 and 2) described above. Needless to say.

  In the dielectric resonator (FIGS. 7 and 8) according to the third embodiment of the present invention, the inner wall surface of the cavity 5 and the dielectric 1 of the lid 3 positioned around the tip of the resonance frequency adjusting screw 10 The groove 18 is provided on the mounting surface (fixed position 15) or the mounting surface of the carrier 4 with the dielectric 1 (fixed position 15). It is set lower than the upper surface position of the part to be closely fixed, and is recessed from the fixed position 15.

As described above, by providing the groove portion 18, the tuning range of the resonance frequency by the resonance frequency adjusting screw 10 can be made wider than that described above.
Further, by providing the groove portion 18, the tip end portion (metal conductor) of the resonance frequency adjusting screw 10 is substantially moved away from the dielectric 1 in the tunnel-like portion (screw movable space 17), and the resonance frequency adjusting screw 10. Contrary to the increase in the resonance frequency due to the protrusion, the decrease in the resonance frequency is expected, so that the total tuning range can be further increased.

Embodiment 4 FIG.
In the first to third embodiments (FIGS. 1 to 8), the dielectric resonator has been described. However, as shown in FIGS. 9 and 10, a high frequency filter is configured using the above-described dielectric resonator. Also good.

9 is an exploded perspective view showing a high-frequency filter using an image-type dielectric resonator according to Embodiment 4 of the present invention, and FIG. 10 is a cross-sectional view taken along the line DD 'in FIG.
9 and 10, the same parts as those described above (see FIGS. 7 and 8) are denoted by the same reference numerals as those described above, or by adding “a” and “b” after the reference numerals. Omitted.

In this case, the high frequency filter is configured by arranging two image-type dielectric resonators side by side.
Here, the case where the configurations of FIGS. 7 and 8 (Embodiment 3) are applied is shown, but the configurations of Embodiments 1 and 2 (FIGS. 1, 2, 5, and 6) described above are shown. Needless to say, it is applicable to the configuration.

9 and 10, two dielectrics 1 a and 1 b are mounted and fixed on fixing positions 15 a and 15 b of one lid 3 through fixing surfaces 9 a and 9 b, and are box-shaped together with the lid 3 by screws 14. It is fixed to the housing 2.
Two input / output terminals 6a and 6b are provided on the side surface of the housing 2 corresponding to the dielectrics 1a and 1b.

The resonance frequency of the two image-type dielectric resonators configured inside the housing 2 is adjusted to a desired frequency f0 by the resonance frequency adjusting screws 10a and 10b, respectively.
Further, electromagnetic coupling between the input / output terminal 6a and the dielectric 1a, between the dielectric 1a and the dielectric 1b, and between the dielectric 1b and the input / output terminal 6b with a predetermined strength, respectively. As shown, each spacing and structure is selected.

As a result, in the high frequency filters shown in FIGS. 9 and 10, the high frequency signal near the frequency f0 incident from the input / output terminal 6a is transmitted to the input / output terminal 6b with low loss.
On the other hand, since the dielectrics 1a and 1b do not resonate with high frequency signals other than the frequency f0 incident from the input / output terminal 6a, between the input / output terminals 6a and 6b and each resonator and between each resonator. In either case, no signal is transmitted and received, and the signal is completely reflected.
Thereby, the high frequency filter of FIG. 9, FIG. 10 operate | moves as a band pass filter.

  As described above, the high frequency filter according to the fourth embodiment (FIGS. 9 and 10) of the present invention is configured using the image-type dielectric resonator according to the third embodiment (FIGS. 7 and 8). Therefore, as an image-type dielectric resonator, the resonance frequency tuning range is wide, the resonance frequency can be adjusted relatively easily, and the outer dimensions error of the dielectrics 1a and 1b and the variation in relative permittivity are caused. There is an effect that the yield reduction can be suppressed.

In addition, the resonance frequency of the adjacent unnecessary resonance mode does not change greatly depending on the protruding amount of the resonance frequency adjusting screws 10a and 10b, and a good attenuation characteristic can be stably obtained in the stop band.
Furthermore, the resonance frequency adjusting screws 10a and 10b are small, the outer shape is compact, the number of constituent members is small, the structure is simple, and a high-reliability high-frequency filter can be realized.

  Although an example of a two-stage filter using two dielectric resonators has been shown here, the same effect can be obtained with a three-stage or more filter, and in addition to a band-pass filter, a band-stop filter or the like can be used. Needless to say, the same effects can be obtained even in the case of the configuration.

  1, 1a, 1b Dielectric material, 2 housing, 3 lid, 4 carrier, 5 cavity (shielding cavity), 6, 6a, 6b input / output terminal (input / output coupling means), 9, 9a, 9b fixing surface (planar part) 10, 10a, 10b Resonance frequency adjusting screw, 12, 12a, 12b Nut (fixing means), 15, 15a, 15b Fixed position, 16, 16a, 16b Dielectric removal part, 17, 17a, 17b Screw movable space, 18 , 18a, 18b Grooves.

Claims (7)

A housing having input / output coupling means for an external circuit and having a shielding cavity formed therein,
A dielectric body having a three-dimensional shape having a planar portion to be a fixing surface and having a dielectric removing portion provided so as to dig a part of the planar portion;
A screw movable space formed between the dielectric removing portion and the inner wall surface by tightly fixing the dielectric to the inner wall surface of the shielding cavity via the planar portion;
A resonance frequency adjusting screw inserted from the outside of the housing toward the screw movable space;
A fixing means for positioning and fixing the resonance frequency adjusting screw with respect to the housing,
The resonance frequency adjusting screw has a tip projecting into the screw movable space, and a projecting amount of the tip can be adjusted from the outside of the shielding cavity, and the projecting amount of the tip is increased. A dielectric resonator characterized in that a resonance frequency is increased . A planar carrier having a linear expansion coefficient substantially coincident with the dielectric;
2. The dielectric according to claim 1, wherein the screw movable space is configured between the dielectric removing portion and the carrier by interposing the carrier between the dielectric and the inner wall surface. Body resonator. Comprising a flat lid having a linear expansion coefficient substantially coincident with the dielectric;
The casing is configured by a box-shaped casing having an opening,
The shielding cavity is formed by covering the opening of the box-shaped housing with the lid,
The input / output coupling means is provided in at least one of the lid or the box-shaped housing, and the dielectric is closely fixed to one surface of the lid on the shielding cavity side via the planar portion,
The screw movable space is formed between the lid and the dielectric removing portion,
The dielectric resonator according to claim 1, wherein the resonance frequency adjusting screw is attached to the lid using the fixing means. A groove is provided on the inner wall surface of the shielding cavity, the attachment surface of the lid with the dielectric, or the attachment surface of the carrier with the dielectric, which is located around the tip of the resonance frequency adjusting screw.
4. The dielectric according to claim 1, wherein an upper surface position of the groove portion is set lower than an upper surface position of a portion where the planar portion of the dielectric is closely fixed. 5. Body resonator.   5. The dielectric according to claim 1, wherein the dielectric has a three-dimensional shape in which a portion where the vicinity of the axis of the half-cylindrical cylinder is removed serves as the dielectric removal portion, and a half-side surface serves as the fixing surface. The dielectric resonator according to any one of the above.   6. The dielectric resonator according to claim 5, wherein the dielectric resonator resonates in a resonance mode having a uniform electric field in a circumferential direction of the cylindrical shape of the dielectric.   A high frequency filter comprising at least one dielectric resonator according to any one of claims 1 to 6.

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