WO2010107215A2

WO2010107215A2 - Bandstop filter

Info

Publication number: WO2010107215A2
Application number: PCT/KR2010/001602
Authority: WO
Inventors: 박남신; 이돈용; 김재홍
Original assignee: 주식회사 케이엠더블유
Priority date: 2009-03-16
Filing date: 2010-03-15
Publication date: 2010-09-23
Also published as: WO2010107215A3

Abstract

The present invention relates to a bandstop filter comprising: a resonating bar; a housing on the inside of which is formed a receiving space where the resonating bar is positioned, and which is made in a stepped form such that at least one part of an upper-end part is narrower than a lower-end part in terms of the internal width of the receiving space during the formation of the receiving space; a lower cover which has the resonating bar fitted thereto, is joined to the lower part of the housing and, when so joined, is assembled such that the resonating bar is inserted into the receiving space, and which forms the floor surface of the receiving space; and a hermetic-sealing cover which is provided within a recess pre-made in the housing in such a way as to couple with a resonator formed by the receiving space and the resonating bar on the inside of the receiving space, and is designed to hermetically seal the recess in the housing where a transmission line has been provided.

Description

Band stop filter

The present invention relates to a radio frequency (RF) filter using a resonator, and more particularly, to a band stop filter in a high frequency filter.

A high frequency filter (DR filter, cavity filter, wave guide filter, etc.) using a resonator usually has a structure of a kind of circuit for resonating high frequency, especially ultra high frequency. Resonant circuits by common coils and capacitors are not suitable for forming very high frequencies due to their large radiation losses. In this case, the RF filter is composed of a plurality of resonators, each resonator forms a cavity such as a metallic cylinder or a cuboid surrounded by a conductor, and a resonance composed of a dielectric resonance element (DR) or a metal resonant rod therein. By providing an element and having only an electromagnetic field of a natural frequency, it has a structure which enables resonance of a very high frequency.

As described above, the high frequency filter using the resonator can be largely classified into a band pass filter (BPF) pass and a band stop filter according to the filtering characteristics of the frequency band. At this time, the band stop filter is also called a band cut filter or a band stop tilter.

Such band-stop filters are constantly researched and developed to improve the filtering characteristics (as well as the band-pass filters) and to make easy adjustments. In particular, active researches are being conducted to suppress noise generated by various parasitic resonance modes. have.

Accordingly, an object of the present invention is to provide a band stop filter for effectively suppressing the generation of various parasitic resonance modes.

Another object of the present invention is to provide a band reject filter that can be implemented in a smaller size.

It is another object of the present invention to provide a band reject filter that can easily tune the filtering characteristics.

In order to achieve the above object, the present invention provides a band reject filter, comprising: a resonance rod; A housing configured to form an accommodation space in which the resonance rod is positioned, and wherein at least a portion of the upper end is narrower than the lower end in the inner width of the accommodation space when the accommodation space is formed; A lower cover which mounts the resonator rod and engages with a lower portion of the housing, and is assembled into a shape in which the resonator rod is inserted into the accommodation space when the resonator rod is coupled to the housing and forms a bottom surface of the accommodation space; A transmission line installed in a groove predetermined in the housing so as to be coupled to a resonator formed by the accommodation space and the resonance rod in the accommodation space, and connected between a signal input terminal and an output terminal of the band reject filter; And a sealing cover for sealing a groove of the housing in which the transmission line is installed.

The band reject filter according to the present invention as described above can effectively suppress the generation of various parasitic resonance modes, has a wide pass band, can be implemented in a smaller size, and can easily tune the filtering characteristics. .

1 is a partially exploded perspective view of a band reject filter in accordance with an embodiment of the present invention;

2 is a partial cutaway view of the plane and side of FIG.

3 is a partial cutaway view of the planar, bottom and side surfaces of the housing of FIG.

4 is a plan view and a side view of the signal transmission line of FIG.

5 is a partially exploded perspective view of a band reject filter according to another embodiment of the present invention;

6 is a partially exploded perspective view of a band reject filter in accordance with another embodiment of the present invention;

7 is a partial cutaway view of the side of FIG.

8 and 9 are graphs showing band rejection characteristics of a band reject filter according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, specific details such as specific components are shown, which are provided to help a more general understanding of the present invention, and it is understood that these specific details may be changed or changed within the scope of the present invention. It is self-evident to those of ordinary knowledge in Esau.

1 is a partially exploded perspective view of a bandstop filter according to an exemplary embodiment of the present invention, and illustrates a state in which the lower cover 20 is disassembled from the housing 10 in a state viewed from below for convenience. FIG. 2 is a partial cutaway view of the plane and side of FIG. 1, and FIG. 2 (a) illustrates a plane before the sealing cover 60 is coupled in FIG. 1 for convenience, and FIG. 2 (b) is a view of FIG. 2. The side of the state which cut | disconnected AA 'part in (a) is shown. 3 is a partial cutaway view of the planar, lower, and side surfaces of the housing 10 of FIG. 1, wherein FIG. 3A illustrates a plan view, and FIG. 3B illustrates an AA ′ portion of FIG. 2A. The side surface of the housing | casing 10 of the state cut | disconnected is shown, and FIG.3 (b) shows a lower surface. 4 is a plan view and a side view of the signal transmission line 10 of FIG. 1, FIG. 4A is a plan view, and FIG. 4B is a side view.

1 to 4, the band reject filter according to an exemplary embodiment of the present invention includes a plurality of accommodation spaces 14 each having a resonance rod 30 formed of a metal such as brass or iron. And a plurality of receiving spaces 14 are separated from each other by a diaphragm. Each accommodation space 14 may be formed by a cutting process in the housing 10 made of a material such as aluminum alloy, the resonance is installed in each accommodation space 14 and the corresponding accommodation space 14 The rod 30 forms one resonator.

At this time, each resonator rod 30 is mounted to the lower cover 20 in accordance with the characteristics of the present invention, each receiving space in a batch when the lower cover 30 is coupled to the housing 10 through a screw coupling, etc. (14) can be assembled into a shape that is inserted into the interior. Therefore, each inner bottom surface of the accommodation space 14 is formed by the lower cover 20. As shown more clearly in FIG. 1, the lower cover 20 and the housing 10 of the corresponding portion are provided with a plurality of screw holes 22 and screw grooves 12 in place, and the screw holes 22. And a lower cover 20 may be coupled to the housing 10 by screws 24 fastened to the screw grooves 12.

In addition, a transmission line 50 for coupling with each resonator formed by each accommodating space 14 and a resonator rod 30 in the accommodating space 14 is provided above each resonator structure. The transmission line 50 is formed in a line, for example, in a straight line, zigzag form, or circular form, so as to connect between the signal input end 42 and the output end 44 of the band suppression filter. The signal is inputted from and transmitted to the output terminal 44. At this time, the corresponding frequency band is coupled and removed by a resonator located below while the corresponding signal passes through the transmission line 50, so that the filter has a band blocking characteristic. As shown in FIG. 4, the transmission line 50 may have a band shape. In addition, the transmission line 50 may have a shape such as a 50Ω cable and a square bar.

The transmission line 50 may be installed in a groove that is appropriately formed at the upper portion of the resonator position, for example, in the housing 10, and again the upper portion of the housing 10 at the upper portion of the transmission line 50 installed as described above. That is, the sealing cover 60 for sealing the groove in which the transmission line 50 is installed is coupled by screwing, etc., thereby forming a bandstop filter.

In the band stop filter configured as described above, according to the characteristics of the present invention, the inner width of the accommodation space 14 and the width of at least a portion of the upper end portion 142 are designed in multiple stages in a narrower shape than the lower end portion as a whole. As clearly shown in FIGS. 2 and 3, the upper end 142 of the accommodation space 14 has a narrow width so as to be quite close to the side of the upper end of the resonator rod 30. In the example of FIGS. 1 to 4, the planar shape of the lower end of the accommodation space 14 is approximately square, and the planar shape of the upper end is formed to be circular. Of course, such a planar shape of the receiving space can be varied in addition to the lower portion can also be formed in a circular shape. As such, setting the upper end 142 of the accommodation space 14 to a narrow width so as to be close to the upper side of the resonance rod 30 may include the upper end 142 of the accommodation space 14 and the upper side of the resonance rod 30. This is to increase the capacitance generated between and).

In general, the band stop filter designs a cutoff frequency by LC resonance, and the length of the resonance rod 30 mainly affects the inductance L, and is formed between the resonance rod 30 and the accommodation space 14. Has a close effect on capacitance (C). In the present invention, in order to suppress the occurrence of parasitic resonance modes (e.g. TE mode TM mode, etc.) other than the main resonance mode (e.g. TEM mode) required by the resonator, the design of the resonator corresponding to the desired cutoff frequency It is designed to increase capacitance (C) and reduce inductance (L). In addition, in order to suppress the parasitic resonance mode occurring in the accommodation space itself, the size of the accommodation space should be as small as possible.

As described above, in the present invention, by setting the upper end portion 142 of the receiving space 14 to a narrow width, it is possible to increase the capacitance generated between the resonator rod 30 by a considerable amount, thus increasing the capacitance in the resonator. In addition, it is possible to reduce the inductance accordingly, thereby reducing the length of the resonator rod 30, it can be designed to generate the secondary tertiary parasitic mode of the resonator rod 30 outside the pass band. In addition, the size (that is, the height) of the entire receiving space can be reduced, thereby reducing the size of the receiving space, thereby allowing the filter to be designed with a smaller size.

In this case, as the width of the upper end portion 142 of the receiving space 14 is further narrowed or the width of the upper portion 142 is increased, the capacitance can be further increased. In this case, the coupling between the transmission lines 50 in the corresponding resonator The overall characteristics may deteriorate, such as weakening. Accordingly, in the present invention, the width and the ratio of the upper end 142 and the lower end of the upper end 142 of the accommodation space 14 are appropriately designed in consideration of the above points.

In addition, the coupling adjusting groove 146 is formed at the end of the upper end 142 of the accommodation space 14 to adjust the coupling between the resonator and the transmission line 50, as illustrated in FIGS. 2 and 3. It is possible to vary the size of the coupling adjustment groove 146 to adjust the band stop coupling amount.

On the other hand, the resonator rod 30 is typically installed in the form of being fixed to the bottom surface inside the receiving space 14, as shown in Figures 1 and 2 more clearly in accordance with the features of the present invention, the resonator rod 30 The lower end of the) may have a screw structure 32, such a screw structure 32 is configured to have a length of some more protruding out of the lower cover 30 through a screw hole formed in place of the lower cover 34 Can be. In addition, the nut 34 is coupled to the screw structure 32 of the resonance rod 30 to fix the resonance rod 30 outside the lower cover 30.

The screw structure 32 is formed in the resonator rod 30 as described above in order to enable frequency tuning in each resonator without providing a tuning screw for frequency tuning and the like. By appropriately adjusting the position of the resonator rod 30 through the withdrawal or withdrawal of the screw structure 32 of 30, it is possible to perform frequency tuning.

Meanwhile, in the example of FIG. 2, it is shown that the upper end and the lower end of the resonator rod 30 have different widths. That is, the lower end of the resonator rod 30 may be formed to have a narrower width than the upper end, which is to lower the cutoff frequency, and in this case, when the width of the lower end is too narrow, it may adversely affect the Q (Quality factor) characteristic. Given.

FIG. 5 is a partial cutaway view of the planar and side surfaces of the band reject filter according to another exemplary embodiment of the present invention, and FIG. 5A illustrates a plan view of the upper cover 60 'coupled thereto, and FIG. ) Shows a plane in a state before the upper cover 60 'is coupled for convenience, and FIG. 5C shows a side of the AA' portion cut away in FIG. Referring to FIG. 5, a band reject filter according to another exemplary embodiment of the present invention has a plurality of accommodation spaces each including resonant rods 30 ′ similarly to the configuration of the exemplary embodiment as illustrated in FIGS. 1 to 4. A resonator is formed through 14, and each accommodation space 14 is designed in multiple stages in such a manner that the width of the upper end portion 142 is narrower.

By the way, in the structure of another embodiment of the present invention, the lower end of the resonator rod 30 'is fixed to the lower cover 20' without having a screw structure. In addition, the transmission line 50 'is installed (with a band shape up) at a position deviating to one side from the central axis of the resonator according to another embodiment of the present invention, so that the input end 42' and the output end ( 44 '). In addition, the upper cover 60 'for sealing the upper portion of the housing 10' again may be coupled to the upper portion of the transmission line 50 installed as described above by screwing, respectively, to the upper cover 60 '. A screw hole is formed at a position corresponding to the resonator rod 30 'of the upper cover, and each screw hole has a tuning screw 72 capable of adjusting coupling with a corresponding resonance rod 30' at the corresponding position. It is provided to be able to pull in or take out with the length which protrudes inward and outward of 60 ', respectively. In addition, a nut 74 coupled to the tuning screw 72 to fix the tuning screw 72 is provided outside the upper cover 60 ′.

A feature of the band reject filter according to another embodiment of the present invention having such a configuration is that the resonator rod 30 'is fixed to a separate tuning screw 72 while fixing the resonator rod 30' in comparison with the embodiment shown in FIGS. The frequency tuning in each resonator can be performed by using this method.

FIG. 6 is a partially exploded perspective view of a band reject filter according to another exemplary embodiment of the present invention, and FIG. 7 is a partial cross-sectional view of the side of FIG. 6, and FIG. 6 and 7, the band reject filter according to another exemplary embodiment of the present invention may include a resonant rod 30 ′ similarly to the configuration of the exemplary embodiment as illustrated in FIGS. 1 to 4. The resonator is formed through a plurality of accommodation spaces 14 ', and each accommodation space 14' is designed in multiple stages in such a manner that the width of the upper end portion 142 'becomes narrower.

However, in the structure of another embodiment of the present invention, the lower end of the resonator rod 30 'is fixedly mounted to the lower cover 20' without having a screw structure. In addition, the transmission line 50 'is installed in a groove (in the form of a band) standing properly formed at a position corresponding to the upper side of the resonator position in the housing 10' according to another embodiment of the present invention. In addition, it is connected to the input end 42 'and the output end 44' of the band stop filter installed at a corresponding position outside the housing 10 '. In addition, an airtight cover 60 'for sealing the groove in the housing 10' in which the transmission line 50 'is installed is coupled to the housing 10' from the side by screwing or the like.

In addition, a screw hole is formed at a position corresponding to each of the resonant rods 30 'on the upper plate of the housing 10', and each screw hole is coupled to a corresponding resonant rod 30 'at the corresponding position. A tuning screw 72 capable of ring adjustment is installed to be retractable or withdrawable, having a length projecting to the inside and the outside of the top plate of the housing 10 ', respectively. In addition, a nut 74 coupled to the tuning screw 72 to fix the tuning screw 72 is provided outside the upper plate of the housing 10 ′.

A feature of the band reject filter according to another embodiment of the present invention having such a configuration is that in contrast to the embodiment shown in FIGS. 1 to 4, the resonator rod 30 ′ is fixed while a separate tuning screw 72 is provided. The frequency tuning in each resonator is possible by using.

8 and 9 are graphs showing band rejection characteristics of a band reject filter according to an embodiment of the present invention. 8 and 9, the band reject filter according to the present invention has a center cutoff frequency of, for example, about 2.64 GHz, while substantially blocking the effects of other parasitic resonance modes up to about 14.7 GHz. It can be seen. That is, in the present invention, by designing a part (or all) of the upper end of the receiving space to a narrower width than the lower end to form a narrower gap with the resonant rod to increase the capacitance during LC resonance, the secondary tertiary parasitic of the resonant rod The frequency can be pushed up to 5th, 6th, or higher frequencies. In addition, it is possible to reduce the size of the receiving space, thereby pushing up a number of parasitic modes generated in the receiving space itself to a desired frequency (about 6 to 7 times the stopping frequency).

As described above, the band stop filter according to the embodiments of the present invention can be configured and operated. Meanwhile, the above-described description of the present invention has been described with reference to specific embodiments, but various modifications can be made without departing from the scope of the present invention. Can be. For example, in the above description, as in one embodiment of the present invention, the resonator rod itself draws in or out, so that frequency tuning is possible, and in another embodiment, a structure for enabling frequency tuning with a separate tuning screw is possible. However, in other embodiments of the present invention by combining the structures, it is also possible to adopt a structure having both the inlet and out of the separate tuning screw and the resonator rod itself. As such, there may be various modifications or changes of the present invention, and therefore, the scope of the present invention should be determined by the claims and the equivalents of the claims.

Claims

In the band reject filter,

Resonant rod,

A housing configured to form an accommodation space in which the resonance rod is positioned, and at least a portion of the upper end of the housing space having a narrower shape than the lower end in the inner width of the accommodation space;

A lower cover which mounts the resonator rod and engages with the lower portion of the housing, and is assembled into a shape in which the resonator rod is inserted into the accommodation space when combined with the housing, and forms a bottom surface of the accommodation space;

A transmission line installed in a groove predetermined in the housing to be coupled to a resonator formed by the accommodation space and the resonance rod in the accommodation space, and connected between a signal input terminal and an output terminal of the band reject filter;

And a sealing cover for sealing a groove of the housing in which the transmission line is installed.
The lower end of the resonance rod has a screw structure,

The screw structure has a length projecting out of the lower cover through a screw hole formed at a position corresponding to the installation position of the resonator rod of the lower cover,

Outside of the lower cover is coupled to the screw structure of the resonator rod, the band blocking filter, characterized in that provided with a nut for fixing the resonator rod.
According to claim 1, The upper plate of the housing is formed with a screw hole in a position corresponding to the resonance rod,

The screw hole is installed so that the tuning screw capable of adjusting the coupling with the corresponding resonator rod at the corresponding position has a length projecting to the inside and the outside of the housing upper plate, respectively, can be pulled in or out,

Outside of the upper plate of the housing band stop filter, characterized in that coupled with the tuning screw, a nut for fixing the tuning screw is provided.
According to claim 2, The upper plate of the housing is formed with a screw hole in a position corresponding to the resonance rod,

The screw hole is installed so that the tuning screw capable of adjusting the coupling with the corresponding resonator rod at the corresponding position has a length projecting to the inside and the outside of the housing upper plate, respectively, can be pulled in or out,

Outside of the upper plate of the housing band stop filter, characterized in that coupled with the tuning screw, a nut for fixing the tuning screw is provided.
The band reject filter according to any one of claims 1 to 4, wherein the lower end of the resonance rod is formed to have a narrower width than the upper end of the resonance rod.
The band reject filter according to any one of claims 1 to 4, wherein a coupling adjustment groove for adjusting coupling is formed at an end of the upper end of the accommodation space.