WO2020111397A1

WO2020111397A1 - Ceramic waveguide filter and method for manufacturing same

Info

Publication number: WO2020111397A1
Application number: PCT/KR2019/002984
Authority: WO
Inventors: 천동완
Original assignee: 주식회사 에이스테크놀로지
Priority date: 2018-11-26
Filing date: 2019-03-14
Publication date: 2020-06-04

Abstract

The present invention provides a ceramic waveguide filter and a method for manufacturing same, the ceramic waveguide filter comprising: multiple resonant cavities defined by multiple through-partition walls in a single ceramic block, the through-partition walls being formed to divide the ceramic block into sections according to a predetermined pattern; multiple resonant grooves formed in the sections of the multiple resonant cavities, divided by the through-partition walls; a metal layer formed on the inner surface of each of the multiple through-partition walls; and input/output interfaces formed in two resonant cavities for input and output of signals among the multiple resonant cavities. By forming the resonant grooves in the sections of the resonant cavities, a small-sized ceramic waveguide filter with improved spurious characteristics can be manufactured.

Description

Ceramic waveguide filter and manufacturing method thereof

The present invention relates to a ceramic waveguide filter, and more particularly, to a ceramic waveguide filter used in a mobile communication system.

As the communication service evolves, the data transmission rate increases, and for this, the system bandwidth must also increase, and it is necessary to improve reception sensitivity and minimize interference caused by carriers of other communication systems.

To this end, demands for low insertion loss, high rejection, and filters are increasing day by day. Coaxial resonant cavities manufactured using metal materials have advantages in terms of loss, size, and cost compared to other resonant cavities such as dielectric resonant cavities, and are mainly used to implement filters in mobile communication systems.

However, due to the low power and miniaturization of a base station system such as a massive MIMO antenna, there is a limitation in terms of size even when using an existing coaxial resonant cavity, and there is a need for implementation of an ultra-small filter.

As a filter to replace a filter using a conventional coaxial resonant cavity, research on ceramic waveguide filters has been actively conducted. The ceramic waveguide filter is a filter that fills a cavity with a ceramic material having low loss and high dielectric constant, which can significantly reduce the size compared to a conventional coaxial resonant cavity filter and also provide excellent loss characteristics.

1 is a view showing the structure of a conventional ceramic waveguide filter.

Referring to Figure 1, the existing ceramic waveguide filter is a plurality of ceramic cavities (111, 112, 113, 114), a plurality of partition walls (121, 122, 123) located between each cavity, the input interface port 140 And an output interface port 150.

In the conventional ceramic waveguide filter as shown in FIG. 1, each

cavity

111, 112, 113, and 114 is independently made of individual ceramic blocks, and

partition walls

121, 122, and 123 are formed on one surface of each cavity. The

partition walls

121, 122, and 123 may be formed through metallization of one surface of the cavity.

Slots

131, 132, and 133 are formed in each partition for inter-cavity coupling. The signal of the first cavity 111 can be coupled to the second cavity 112 through the first slot 131 formed in the first partition 121.

Such a conventional ceramic waveguide filter requires a process of manufacturing each ceramic cavity (111, 112, 113, 114) independently, forming a partition wall, and then combining each cavity. Here, the cavities are generally joined through soldering or the like.

The conventional ceramic waveguide filter shown in FIG. 1 is compact and exhibits excellent performance with low loss, but uses a square wave guide cavity resonant mode, so a higher order spurious mode is applied to the passband of the filter. Exist in close proximity. In addition, in order to suppress the high-order spurious mode, a low-pass filter must be additionally applied, and there is a problem in that loss is increased.

The present invention proposes a small size ceramic waveguide filter.

In addition, the present invention proposes a ceramic waveguide filter capable of improving spurious characteristics.

In addition, the present invention proposes a ceramic waveguide filter that is less affected by mechanical tolerances during manufacturing.

In order to achieve the above object, the ceramic waveguide filter according to an embodiment of the present invention is defined by a plurality of through partition walls formed to separate the sections of the ceramic block according to a predetermined pattern in a single ceramic block Resonant cavity; A plurality of resonant grooves formed in the partitions of the plurality of resonant cavities divided by the through partition walls; A metal layer formed on an inner surface of each of the plurality of through partition walls; And an input/output interface formed on two resonant cavities for inputting and outputting signals among the plurality of resonant cavities. It includes.

The plurality of resonant grooves may be formed at each center of a corresponding resonant cavity region among the plurality of resonant cavities on one surface or the other surface of the ceramic block.

The input/output interface may be formed in the form of a through hole penetrating the ceramic block.

The plurality of through partition walls penetrates the ceramic block so as to define the plurality of resonant cavities corresponding to the resonant groove and a predetermined frequency band, and divides the section of the ceramic block, and the plurality of resonant cavities connect the input/output interface. In response to a signal inputted through the coupling window between the plurality of through barrier ribs are sequentially coupled with adjacent resonance cavities while being spaced apart from each other to filter the frequency band, and at least one of the plurality of resonance cavities A plurality of resonant cavities may be disposed adjacent to each other to form a pattern to cause cross coupling.

The ceramic waveguide filter includes a coupling groove spaced from a through partition wall on one surface of the ceramic block between resonant cavities where the cross coupling is generated on one surface of the ceramic block; This is further formed, the metal layer may be further formed on the inner surface of the coupling groove.

The ceramic waveguide filter may include a coupling hole spaced apart from a through partition wall between the resonant cavities where the cross coupling occurs, and penetrates the ceramic block; This is further formed, the metal layer may be further formed on the inner surface of the coupling hole.

The metal layer may be formed in an area other than the slot area defined on the inner surface of the coupling hole.

The coupling hole may be formed in a stepped structure on the inside, and the metal layer may be formed in an area of the stepped structure except for a predetermined slot area facing the one surface of the ceramic block.

The ceramic waveguide filter may include a conductive sticker attached to an area where the coupling hole is formed on one surface of the ceramic block; It may further include.

The thickness of the metal layer may be adjusted according to a predetermined frequency band.

In order to achieve the above object, a method of manufacturing a ceramic waveguide filter according to another embodiment of the present invention divides a section of the ceramic block according to a predetermined pattern in order to define a plurality of resonant cavities in a single ceramic block Forming a plurality of through partition walls; Forming a plurality of resonant grooves in a section of the plurality of resonant cavities divided by the through partition wall; Forming a metal layer on each inner surface of each of the plurality of through partition walls; And forming an input/output interface for inputting and outputting signals to two of the plurality of resonant cavities; It includes.

According to one embodiment of the present invention, it is possible to manufacture in a compact size by increasing the capacitance component of the resonance cavity. In addition, spurious characteristics can be improved, and stable characteristics can be exhibited even in mechanical tolerances during manufacturing.

1 is a view showing the structure of a conventional ceramic waveguide filter.

2 is a view showing the structure of a ceramic waveguide filter according to an embodiment of the present invention.

3 shows a result of simulating filter characteristics of the ceramic waveguide filter of FIG. 2.

4 and 5 respectively show a top view and a perspective projection view of a ceramic waveguide filter according to another embodiment of the present invention.

6 to 9 show various examples of the capacitive coupling structure.

10 shows a result of simulating filter characteristics of the ceramic waveguide filters of FIGS. 4 and 5.

11 shows a method of manufacturing a ceramic waveguide filter according to an embodiment of the present invention.

Hereinafter, the present invention will be described with reference to the accompanying drawings. However, the present invention may be implemented in various different forms, and thus is not limited to the embodiments described herein.

In addition, in order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and like reference numerals are assigned to similar parts throughout the specification.

Throughout the specification, when a part is "connected" to another part, this includes not only "directly connected" but also "indirectly connected" with another member in between. .

Also, when a part “includes” a certain component, this means that other components may be further provided, not excluding other components, unless otherwise specified.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a view showing the structure of a ceramic waveguide filter according to an embodiment of the present invention (a) is a top view, (b) is a perspective projection view.

Referring to FIG. 2, the ceramic waveguide filter according to the present embodiment includes a plurality of resonant cavities defined by a plurality of through

partition walls

221, 222, and 223 penetrating between one surface and the other surface of a single ceramic block 200 ( 211, 212, 213).

The plurality of through

partition walls

221, 222, and 223 are formed to penetrate the ceramic block 200 according to a predetermined pattern to define a plurality of

resonant cavities

211, 212, and 213 by dividing the sections of the ceramic block 200. do. In FIG. 2, as an example, a plurality of through

partition walls

221, 222, and 223 are illustrated as being formed in a pattern extending in a straight line in the lateral direction from the ceramic block 200, but this embodiment is not limited thereto. In this embodiment, the plurality of through

partition walls

221, 222, and 223 may be formed in various forms capable of easily distinguishing the sections of the ceramic block 200, and in some cases, such as T-shape or Y-shape. It may also be formed in the form of a branch pattern.

However, in this embodiment, the plurality of through

partition walls

221, 222, and 223 are formed spaced apart from each other. At this time, at least one of the plurality of through

partition walls

221, 222, and 223 may be formed up to the side boundary of the ceramic block 200. Since a plurality of through

partition walls

221, 222, and 223 are formed to be spaced apart from each other, even if all through

partition walls

221, 222, and 223 are formed to extend to a side boundary of the ceramic block 200, the ceramic block 200 is It can maintain the shape of a single structure without being cut.

In addition, the inner surfaces of the plurality of through

partition walls

221, 222, and 223 are formed with

metal layers

231, 232, and 233. The

metal layers

231, 232, and 233 may be formed by applying a metallization process such as plating, vapor deposition, and sputtering. Typically, in RF equipment such as filters and waveguides, silver (Ag) having excellent electrical conductivity is used among conductive materials to minimize loss, but conductive materials other than silver may be used to improve properties such as corrosion resistance.

In this embodiment, the plurality of

resonant cavities

211, 212, and 213 divided by the plurality of through

partition walls

221, 222, and 223 may include a plurality of ceramic cavities 111, in the conventional ceramic wave guide filter shown in FIG. 112, 113, 114).

Since the plurality of

resonant cavities

211, 212, and 213 are defined separately by the plurality of through

partition walls

221, 222, and 223, the plurality of through

partition walls

221, 222, and 223 function as a cavity wall In addition, the space between the plurality of through

partition walls

221, 222, and 223 may be viewed as a coupling window forming a coupling surface between the plurality of

resonant cavities

211, 212, and 213.

As the plurality of through

partition walls

221, 222, and 223 are formed to be spaced apart from each other, the resonant cavities adjacent to each other among the plurality of

resonant cavities

211, 212, and 213 are formed in the ceramic block 200 through the through

partition walls

221, 222, 223 ) May be coupled through an unformed region.

On the other hand, the ceramic wave guide filter according to the present embodiment, as shown in FIG. 2, a region divided by a plurality of through

partition walls

221, 222, 223 on one surface or the other surface of the ceramic block 200, that is, multiple

Resonant grooves

241, 242, and 243 are formed in respective regions of the

resonant cavities

211, 212, and 213. Here, the shape of the

resonant grooves

241, 242, and 243 is not limited. And, although not shown, a metal layer is formed on the inner surface of each of the plurality of

resonant grooves

241, 242, and 243, similarly to the plurality of through

partitions

221, 222, and 223.

The

resonant grooves

241, 242, and 243 are formed in the center where the electric field (E-field) is concentrated in each region of the plurality of

resonant cavities

211, 212, 213, and the plurality of

resonant cavities

211, 212, 213 Each capacitive component is increased. Increasing the capacitive component causes an effect of lowering the resonant frequencies of the plurality of

resonant cavities

211, 212, and 213.

And if the size of the plurality of

resonant cavities

211, 212, 213 is reduced, the plurality of

resonant cavities

211, 212, 213 can maintain the same resonant frequency as before the

resonant grooves

241, 242, 243 are formed. . That is, when the resonant frequency is previously specified and the

resonant grooves

241, 242, and 243 are formed in the plurality of

resonant cavities

211, 212, and 213, the size of the plurality of

resonant cavities

211, 212, and 213 must be reduced. . Therefore, the size of the ceramic wave guide filter can be reduced compared to the case where the

resonance grooves

241, 242, and 243 are not formed.

Accordingly, the pattern of the plurality of through

partition walls

221, 222, and 223 is easily coupled between the plurality of

resonant cavities

211, 212, and 213, and a plurality of resonances in which

resonant grooves

241, 242, and 243 are formed The pattern may be adjusted such that the size of the resonant cavity in which the

cavities

211, 212, and 213 are resonated in a designated frequency band is determined. In FIG. 2, for example, the pattern of the plurality of through

partition walls

221, 222, and 223 is formed when the plurality of

resonant cavities

211, 212, and 213 are resonated in the TE101 mode.

Meanwhile, the high-order spurious mode is generated in the TE201 mode, the TE301 mode, and the electric field in the TE201 mode, for example, when the resonance cavity is divided into four equal parts in the first direction (for example, the y direction), the position of 1/4 and 1/3 It is most strongly distributed in location. Therefore, even if the

resonant grooves

241, 242, and 243 are formed in the center of a plurality of

resonant cavities

211, 212, and 213, the resonant frequency of the TE201 mode hardly changes.

However, when the size of the

resonance cavities

211, 212, and 213 is reduced, the resonance frequency of the TE201 mode is increased. That is, while the resonant frequencies of the plurality of

resonant cavities

211, 212, and 213 maintain a predetermined resonant frequency, the frequency of the higher-order spurious mode is increased so that the resonant frequencies of the

resonant cavities

211, 212, and 213 are separated from each other. do.

The frequency difference between the resonant frequency and the frequency of the higher-order spurious mode is used as a measure for determining the spurious characteristics of the filter, and is called a spurious free window. In addition, as the size of the spurious free window increases, spurious characteristics improve.

As described above, the ceramic waveguide filter additionally applies a low pass filter to suppress the higher order spurious mode, thereby increasing loss. The passband loss of the low pass filter depends on the cut-off frequency representing the stopband, and as the cut-off frequency moves away from the passband of the ceramic waveguide filter, that is, the resonance frequency band, the loss It has a decreasing characteristic.

Accordingly, as shown in FIG. 2, in the ceramic waveguide filter including a plurality of

resonant cavities

211, 212, and 213 in which the

resonant grooves

241, 242, and 243 are miniaturized, the

resonant grooves

241, 242, and 243 ), the higher order spurious mode frequency can be spaced farther away from the pass band, and thus, even if a low pass filter is additionally applied, losses generated can be minimized. That is, spurious characteristics are improved.

In the present exemplary embodiment, input/

output interfaces

251 and 252 are provided to the two

resonant cavities

211 and 213 of the initial stage and the last stage according to a designated coupling order among the plurality of

resonant cavities

211, 212, and 213 of the ceramic waveguide filter. Is formed. In addition, input/output interface ports for inputting and outputting signals through a ceramic waveguide filter may be inserted into the formed input/

output interfaces

251 and 252.

If the input/

output interfaces

251 and 252 are like the ceramic waveguide filter illustrated in FIG. 1, the input/output interface ports of the probe type do not penetrate the

resonance cavities

211 and 213, and the ceramic block 200 When the input/

output interfaces

251 and 252 are implemented to be inserted from one surface or the other surface to a predetermined predetermined depth, a capacitive coupling in which electric fields dominate between the input/output interface ports and the

resonant cavities

211 and 213 is performed to input and output signals.

At this time, when the

resonant grooves

241, 242, and 243 are formed in the plurality of

resonant cavities

211, 212, and 213, the

resonant grooves

211, 242, and 243 are formed in the

resonant cavities

211, 212, and 213 The electric field is concentrated in the corresponding area. Accordingly, when the

resonant grooves

241, 242, and 243 are formed in the

resonant cavities

211, 212, and 213, the ceramic waveguide filter is weak because the strength of the electric field coupled between the input/output interface port and the

resonant cavities

211, 213 is weak. Is unable to exhibit broadband characteristics.

On the other hand, when the input/

output interfaces

251 and 252 are formed as through holes penetrating between one surface and the other surface of the ceramic block 200, coupling of the magnetic field (H-field) is made stronger than that of the electric field. Since the signal is input and output, the ceramic waveguide filter can exhibit broadband characteristics.

In addition, when the input/

output interfaces

251 and 252 are formed as through holes, the input/output interface ports are insensitive to mechanical tolerances compared to the conventional ceramic waveguide filter, which must be inserted only to a predetermined depth from one surface or the other surface of the ceramic block 200. It has the advantage of being.

In FIG. 2, for example, the input/

output interfaces

251 and 252 are illustrated as being formed in the first resonant cavity 211 and the third resonant cavity 213. In addition, it is assumed here that the input interface port penetrates the input/output interface 251 formed in the first resonant cavity 211. In this case, the first resonant cavity 211 receives a signal from an input interface penetrating the input/output interface 251, and adjacent first resonant cavity 211 through a coupling window that is a space between the first through partition walls 221. ) And the second resonant cavity 212. In addition, coupling is made between the adjacent second resonant cavity 212 and the third resonant cavity 213 through a coupling window that is a space between the second through partition walls 222, and the third resonant cavity 213 is input/output. The signal is output to the output interface port passing through the interface 252.

In this case, each of the plurality of

resonant cavities

211, 212, and 213 may be resonated in a frequency band designated according to the size and shape and the

resonant grooves

241, 242, and 243 defined by the plurality of through

partition walls

221, 222, and 223. Can be. Therefore, in the ceramic waveguide filter according to the present embodiment, a plurality of

resonant cavities

211, 212, and 213 defined by a plurality of through

partition walls

221, 222, and 223 filter the signal transmitted through the input interface port in multiple stages. You can output through the output interface port. That is, in the ceramic waveguide filter according to the present embodiment, the first to third

resonant cavities

211, 212, and 213 sequentially filter signals input from the input interface, similar to the conventional ceramic waveguide filter of FIG. It can be output through the output interface.

On the other hand, when a plurality of

resonant cavities

211, 212, and 213 are sequentially coupled as in the ceramic waveguide filter of FIG. 1, the plurality of through

partitions

221, 222, and 223 are lateral to the ceramic block 200. It may be formed in a pattern extending parallel to each other. However, in this case, cross coupling between the plurality of

resonant cavities

211, 212, and 213 is difficult to implement.

On the other hand, in the ceramic waveguide filter according to the present embodiment shown in FIG. 2, the plurality of through partition walls 221 so that the first resonant cavity 211 is also adjacent to the second resonant cavity 212 and the third

resonant cavity

213, 222 and 223 are formed in a pattern extending in different directions from the center of the ceramic block 200 to the side. This is to facilitate cross-coupling in the ceramic waveguide filter according to this embodiment.

As described above, when the order of the first resonant cavity 211, the second resonant cavity 212, and the third resonant cavity 213 is a coupling path, the first resonant cavity 211 and the second resonant cavity 211 are arranged according to a specified order. A coupling is made between the two resonant cavities 212. In addition, cross coupling may be performed between the first resonant cavity 211 and the third resonant cavity 213. That is, as the plurality of through

partition walls

221, 222, and 223 are formed so that the first resonant cavity 211 is disposed adjacent to the third resonant cavity 213 as well as the second resonant cavity 212, the first resonant cavity is formed. Cross coupling between the 211 and the third resonant cavity 213 may be easily performed. At this time, an inductive cross coupling in which a magnetic field (H-field) predominates may be formed between the plurality of

resonant cavities

211, 212, and 213.

The cross-coupling between the first resonant cavity 211 and the third resonant cavity 213 generates a transmission-zero, thereby improving the attenuation characteristics of the ceramic waveguide filter. That is, the ceramic waveguide filter according to the present embodiment easily implements cross-coupling without additional work according to the formation pattern of the plurality of through

partition walls

221, 222, and 223, thereby easily generating transmission-zero. I can do it.

The inductive cross coupling between the first resonant cavity 211 and the third resonant cavity 213 may generate a transmission zero point at a frequency where the ceramic waveguide filter is higher than the passband.

In some cases, in order to suppress cross-coupling between the first resonant cavity 211 and the third resonant cavity 213, the third through partition wall 223 is formed to extend to the side surface of the ceramic block 200 You may.

Meanwhile, a ceramic waveguide filter made of a ceramic material is sensitive to mechanical tolerances. Therefore, tuning is essential to ensure that the ceramic waveguide filter performs accurate filtering.

The ceramic waveguide filter according to the present embodiment is provided with a metal layer formed on the inner surface of the plurality of through

partition walls

221, 222, and 223 and an inner surface of the plurality of

resonant grooves

241, 242, and 243 when tuning is required. Tuning may be performed by adjusting the thickness of at least one of the formed metal layers in a manner such as grinding. That is, the tuning operation for adjusting the characteristics of the ceramic waveguide filter can be easily performed.

In addition, although the ceramic block 200 is shown as an example of a rectangular parallelepiped in FIG. 2, it is not limited thereto and may be implemented in various forms to improve the performance of the ceramic waveguide filter. In addition, the size of the ceramic block 200 may also be variously changed according to the frequency band of the signal to be filtered.

In addition, although not shown, the ceramic waveguide filter according to the present exemplary embodiment is a resonance cavity (here, arranged differently from a specified order among a plurality of

resonance cavities

211, 212, 213) on one surface or the other surface of the ceramic block 200 For example, at least one coupling groove (not shown) may be further formed at a position corresponding to the through partition wall 223 between the first and third

resonant cavities

211 and 213.

If a coupling groove is formed in the cross coupling path between the first resonant cavity 211 and the third resonant cavity 213 that are different from the designated coupling order, the first resonant cavity 211 and the third resonant cavity 213 ), there is a capacitive cross coupling in which the electric field (E-field) predominates.

In contrast to inductive cross coupling, which generates a transmission zero at frequencies higher than the pass band, capacitive cross coupling can generate transmission zero at frequencies lower than the pass band.

That is, the ceramic waveguide filter according to the present embodiment can adjust the frequency at which the transmission zero point occurs depending on whether a coupling groove is additionally formed between two resonant cavities in which cross coupling is performed.

In addition, the coupling groove cannot be formed by overlapping the through

partition walls

221, 222, and 223. Therefore, when the coupling groove is formed, the lengths of the through

partitions

221, 222, and 223 of the corresponding position may be adjusted so as not to overlap with the position of the coupling groove. In addition, when the coupling groove is formed, the inner surface of the coupling groove may also be formed with a metal layer as in the

resonance grooves

241, 242, and 243.

In some cases, the metal layer may be formed to cover the outer surface of the ceramic block 200.

FIG. 2 shows a ceramic waveguide filter having three

resonant cavities

211, 212, and 213 formed by three through

partition walls

221, 222, and 223 on a ceramic block 200 as a simple example for convenience of explanation. However, the present invention is not limited to this.

3 shows a result of simulating the loss characteristics of the ceramic waveguide filter of FIG. 2.

FIG. 3 shows a comparison result obtained by simulating loss characteristics of a ceramic waveguide filter having a center frequency of 3.6 GHz and a bandwidth of 100 MHz. In FIG. 3, a and b indicate return loss and insertion loss of the ceramic waveguide filter in which the resonant grooves 241 to 243 are formed according to the present embodiment, and c and d return reflection and insertion of the conventional ceramic waveguide filter. Indicates loss.

Referring to FIG. 3, the ceramic waveguide filter formed with the resonant grooves 241 to 243 according to the present exemplary embodiment can be confirmed that the spurious free window has been increased by 1.6 GHz or more compared to the conventional ceramic waveguide filter to improve the spurious characteristics. have.

In addition, although not shown, the ceramic waveguide filter according to the present embodiment in which the

resonant grooves

241, 242, and 243 are formed can be reduced in size by 26% or more compared to when the

resonant grooves

241, 242, and 243 are not formed. It was confirmed that it can.

In the ceramic waveguide filter according to the present invention, a plurality of resonant cavities may be defined by a plurality of through partition walls formed through the ceramic block 400 according to a predetermined pattern. Accordingly, in FIGS. 4 and 5, six through partition walls 421 to 426 penetrating between one surface and the other surface of the ceramic block 400 are formed according to a predetermined pattern to divide the ceramic block 400 into six sections, Six resonant cavities 411 to 416 are defined.

The six through partition walls 421 to 426 are formed in a pattern for dividing the ceramic block 400 into six sections, and the shapes of the six through partition walls 421 to 426 may be formed differently. Also, as shown in FIGS. 4 and 5, the six through partition walls 421 to 426 may be formed in different patterns from each other, and some may be formed in the form of branch patterns such as T-shape or Y-shape. have.

In addition, resonant grooves 441 to 446 are formed at a central position of each region of the plurality of resonant cavities 411 to 416 on one surface or the other surface of the ceramic block 400. As the resonant grooves 441 to 446 are formed in the plurality of resonant cavities 411 to 416, the ceramic waveguide filter can be more compact than when the resonant grooves 441 to 446 are not formed, and spurious characteristics are improved. Can be.

Meanwhile, metal layers 431 to 436 are formed on the inner surfaces of each of the six through partition walls 421 to 426, and metal layers (not shown) are also formed on the inner surfaces of the resonant grooves 441 to 446.

And among the six resonant cavities 411 to 416, input and

output interfaces

451 and 452 into which the input/output interface ports are inserted are formed in the first resonant cavity 411 and the sixth resonant cavity 416 located at both ends in the coupling sequence. do. The first resonant cavity 411 receives a signal from an input interface port inserted in the input/output interface 451, is sequentially coupled in the second to sixth resonant cavities 412 to 416, and the sixth resonant cavity 416 outputs a signal to the output interface port inserted in the input/output interface 452.

The first to sixth resonant cavities 411 to 416 may be sequentially coupled through a coupling window between six through partition walls 421 to 426 formed spaced apart. That is, coupling is made between the first resonant cavity 411 and the second resonant cavity 412 through a coupling window corresponding to the first and second through

partition walls

421 and 422, and the second and third through holes are formed. Coupling is performed between the second resonant cavity 412 and the third resonant cavity 413 through a coupling window corresponding to the

partition walls

422 and 423, and the third and fourth through

partition walls

423 and 424 Coupling may be performed between the third resonant cavity 413 and the fourth resonant cavity 414 through a corresponding coupling window. And coupling is made between the fourth resonant cavity 414 and the fifth resonant cavity 415 through a coupling window corresponding to the fourth and fifth through

partition walls

424, 425, and the fifth and sixth penetrations Coupling may be performed between the fifth resonant cavity 415 and the sixth resonant cavity 416 through a coupling window corresponding to the

partition walls

425 and 426.

At this time, the first to sixth resonant cavities 411 to 616 are resonated in the designated frequency band to filter signals in the designated frequency band. Therefore, the ceramic waveguide filter illustrated in FIGS. 4 and 5 functions as a multi-stage filter performing 6-stage filtering.

Meanwhile, in the ceramic waveguide filter illustrated in FIGS. 4 and 5, cross coupling between the first resonant cavity 411 and the third resonant cavity 413 through a coupling window corresponding to the second through partition wall 422. This can be easily done. In addition, cross-coupling may be performed between the second resonant cavity 412 and the fourth resonant cavity 414, and cross-coupling may also be performed between the third resonant cavity 413 and the fifth resonant cavity 415. In addition, cross coupling may be performed between the fourth resonant cavity 414 and the sixth resonant cavity 416. That is, in the ceramic waveguide filter illustrated in FIGS. 4 and 5, cross coupling may occur between a plurality of resonant cavities.

However, at least one through partition wall of the six through partition walls 421 to 426 may be formed to extend to a side boundary of the ceramic block 400 so that cross coupling between the resonant cavities is suppressed. As an example, cross coupling between the second resonant cavity 412 and the fourth resonant cavity 414, the fourth resonant cavity 644 and the sixth resonant cavity 416 in the ceramic waveguide filters of FIGS. 4 and 5 To prevent this, each of the third through partition wall 423 and the fifth through partition wall 425 may be formed to extend to a side boundary of the ceramic block 400.

In FIGS. 4 and 5, the first and third resonant cavities are further formed by forming a capacitive coupling structure 460 together with the second through partitions 422 between the first and third

resonant cavities

411 and 413. A capacitive cross coupling can be made between (411, 413). At this time, the pattern of the second through partition wall 422 may be adjusted so as not to overlap with the region where the capacitive coupling structure 460 is formed. In addition, a metal layer may be formed on the inner surface of the capacitive coupling structure 460.

As a result, referring to FIGS. 4 and 5, the ceramic waveguide filter according to the present exemplary embodiment can easily implement a plurality of resonant cavities 411 to 416 by forming a plurality of through partitions 421 to 426 in a single ceramic block. In addition, by forming the resonant grooves 441 to 446 in each of the plurality of resonant cavities 411 to 416, the ceramic waveguide filter can be miniaturized and spurious characteristics can be improved.

In addition, the input/

output interfaces

451 and 452 are formed as through holes, so that the ceramic waveguide filter has broadband characteristics and can be robust against mechanical tolerances.

6 to 9 show various examples of the capacitive coupling structure.

In FIG. 6, as shown in FIGS. 4 and 5, one surface of the ceramic block 500 such that a capacitive cross coupling in which an electric field predominates between the plurality of

resonant cavities

411 and 413 in the ceramic waveguide filter is achieved. The case where the coupling groove 561 is formed as the capacitive coupling structure 560 in the direction from the other surface is illustrated.

The coupling groove 561 may be formed so as not to overlap the second through partition wall 422 between the first resonant cavity 411 and the third resonant cavity 413 on one surface of the ceramic block 500. In addition, a metal layer 562 is formed on the inner surface of the coupling groove 561 like the plurality of through partition walls 421 to 426.

Here, the depth of the coupling groove 561 may be adjusted according to the frequency at which the capacitive cross coupling is performed. Therefore, depending on the frequency at which the capacitive cross coupling should be performed, the depth of the coupling groove 561 may be deep, and the thickness of the ceramic block 500 may be very thin at the position where the coupling groove 561 is formed. In this case, damage may occur in a region where the coupling groove 561 is formed during manufacture and handling of the ceramic waveguide filter.

7 shows a case where the capacitive coupling structure 660 is implemented as a coupling hole 661 penetrating one surface and the other surface of the ceramic block 600. In addition, a metal layer 662 is formed on the inner surface of the coupling hole 661. In FIG. 7, as the capacitive coupling structure 660 is formed in a hole shape penetrating the ceramic block 600, damage caused by the capacitive coupling structure to the ceramic block 600 may be prevented. have.

Here, the metal layer 662 may be removed from a portion of the inner surface of the coupling hole 661 to further form a slot (not shown).

Meanwhile, in FIG. 8, the capacitive coupling structure 760 is implemented as a coupling hole 761 penetrating one surface and the other surface of the ceramic block 700 as in FIG. 7, but the coupling hole 761 is shown in FIG. 7. Unlike the coupling hole 661 of the, it is formed in a stepped structure. And the metal layer 762 is formed on the inner surface of the coupling hole 761. In this case, in FIG. 8, the metal layer 762 may be removed from a portion of the inner surface of the stepped structure coupling hole 761 to further form a slot 763. The slot 763 may be formed in a portion of a surface parallel to one surface of the ceramic block 700 on the inner surface of the coupling hole 761.

When the slot 763 is formed, the size of the slot 763 may be adjusted by a grinder or the like to perform tuning for a frequency at which the capacitive cross coupling is performed, so that the coupling groove 561 or the coupling hole ( The thickness of the metal layers 562 and 662 or slots (not shown) formed on the inner surface of 661 is adjusted by a method such as grinding so that tuning can be performed more easily.

In FIG. 9, the capacitive coupling structure 860 may have a stepped structure coupling hole 861, a metal layer 862, and a slot 863 similar to FIG. 8. In addition, in FIG. 9, a conductive sticker 865 for preventing signal leakage by the slot 863 is further attached to one surface of the ceramic block 800. The conductive sticker 865 may be attached to the entire surface of the ceramic block 800, but may be attached only to an area corresponding to the coupling hole 861.

In addition, a conductive sticker may be attached to regions corresponding to the coupling holes 661 and 761 of FIGS. 6 and 7.

The

capacitive coupling structures

660, 760, and 860 of FIGS. 7 to 9 prevent damage caused by the coupling groove 561 shown in FIG. 6 during manufacture and handling of the ceramic waveguide filter. It is a structure for.

In FIG. 10, capacitive coupling structures 460 are formed between the first and third

resonant cavities

411 and 413 in the ceramic waveguide filters of FIGS. 4 and 5, and the third and fifth through

partition walls

423 , 425 extends to the lateral boundary of the ceramic block 400 to cross couple between the second resonant cavity 412 and the fourth resonant cavity 414 and the fourth resonant cavity 414 and the sixth resonant cavity 416. It is assumed that the ring is suppressed.

As the capacitive coupling structure 460 is formed between the first and third

resonant cavities

411 and 413, the capacitive cross coupling is formed between the first and third

resonant cavities

411 and 413. On the other hand, an inductive cross coupling is performed between the third resonant cavity 413 and the fifth resonant cavity 415.

As described above, inductive cross coupling generates a transmission zero at frequencies higher than the pass band, while capacitive cross coupling generates a transmission zero at frequencies lower than the pass band.

Accordingly, the ceramic waveguide filters of FIGS. 4 and 5 in which both inductive cross-coupling and capacitive cross-coupling are generated, as shown in FIG. 10, can be confirmed that transmission zeros are generated at both ends of the passband frequency. . And these results indicate that the ceramic waveguide filter according to this embodiment can function as a band pass filter with very good performance.

A method of manufacturing the ceramic waveguide filter of FIG. 11 will be described with reference to FIGS. 2 to 10.

Prior to manufacturing the ceramic waveguide filter, the frequency band and filtering characteristics that the ceramic waveguide filter should filter are predetermined. Then, a ceramic block is manufactured according to the determined frequency band (S10). Here, the ceramic block may be manufactured by determining the size and shape according to the determined frequency band.

Also, a plurality of through partitions penetrating one surface and the other surface of the ceramic block are formed in a predetermined pattern according to a frequency band to be filtered and whether a resonance groove is formed, thereby dividing the sections of the ceramic block into a plurality to realize a plurality of resonance cavities. (S20). Here, when forming a through partition wall, whether to form a resonance groove together is because when the resonance groove is formed, a plurality of through partition walls must be formed so that the size of the resonance cavity is smaller. And a plurality of through partition walls are formed spaced apart from each other. Since the plurality of through partition walls are formed spaced apart from each other, the plurality of resonant cavities can be coupled through a spaced apart coupling window between the plurality of through partition walls.

When a plurality of through partition walls are formed and a plurality of resonance cavities are implemented, a resonance groove is formed in each region of the plurality of resonance cavities (S30). Here, the resonant groove may be formed at a central position of each region of the plurality of resonant cavities. As described above, when resonant grooves are formed in a plurality of resonant cavities, the ceramic waveguide filter can be miniaturized and spurious characteristics can be improved.

When a plurality of resonant grooves are formed, if a capacitive cross coupling is required according to a predetermined filtering characteristic, that is, if a transmission zero point needs to be generated at a frequency lower than the pass band, a cap for generating a capacitive cross coupling The sieve coupling structure is further formed (S40). The capacitive coupling structure may be formed so as not to overlap with a through partition wall corresponding between two resonant cavities of the plurality of resonant cavities. In addition, the capacitive coupling structure may be formed in the form of coupling grooves 561 or

coupling holes

661, 761, and 861, as shown in FIGS. In addition, the coupling hole may be formed in a step shape.

Here, the step of forming the capacitive coupling structure may be omitted when capacitive cross coupling is not required.

On the other hand, a metal layer is formed by applying a metallization process such as plating, vapor deposition, sputtering, etc. to a conductive material such as silver on the inner surface of each of the plurality of through partition walls and the inner surface of the resonance groove (S50). At this time, the metal layer is formed not only on the inner surface of each of the plurality of through partition walls and the resonant grooves, but also on the inner surface of the capacitive coupling structure. And it can also be formed on the outer surface of the ceramic block. When the capacitive coupling structure is formed of stepped

coupling holes

761 and 861, a metal layer may not be formed to allow

slots

763 and 863 to be formed on a portion of the coupling hole. Alternatively, the metal layer is formed irrespective of the

slots

763 and 863, and may be adjusted in a tuning step (S70) described later with a metal layer formed on the inner surface of the through partition wall in a manner such as grinding.

In addition, an input/output interface is formed in two resonant cavities of the plurality of resonant cavities (S60). Here, the input/output interface is both ends in a sequence in which a plurality of resonant cavities of a ceramic waveguide filter are sequentially coupled to receive a signal from an input interface port and output a filtered signal to an output interface port. It can be formed in the resonance cavity. Here, the input/output interface may be formed in the form of a through hole penetrating one surface and the other surface of the ceramic block so that the ceramic waveguide filter has broadband characteristics and is insensitive to mechanical tolerances.

Then, by fine-tuning the coupling value between the plurality of resonant cavities by adjusting the thickness, such as grinding the metal layer formed on the inner surface of each of the plurality of through partitions and the inner surface of the resonant groove, tuning the properties of the ceramic waveguide filter (S70).

At this time, when the capacitive coupling structure is formed, the thickness of the inner surface of the capacitive coupling structure can be adjusted together. And the frequency formed by the capacitive cross coupling by grinding the metal layers formed on the inner surfaces of the coupling holes 761 and 861 to form the

slots

763 and 863 or by adjusting the size of the formed slots 763 and 863 I can tune it.

In the method of manufacturing the ceramic waveguide filter of FIG. 11, forming a resonant groove (S30) and forming a capacitive coupling structure (S40), forming a metal layer (S50), and forming an input/output interface ( S60) may be adjusted in order to improve process efficiency.

The present invention has been described with reference to the embodiments shown in the drawings, but these are merely exemplary, and those skilled in the art will understand that various modifications and other equivalent embodiments are possible therefrom.

Therefore, the true technical protection scope of the present invention should be defined by the technical spirit of the appended claims.

Claims

A plurality of resonant cavities defined by a plurality of through partition walls formed to separate the sections of the ceramic block according to a predetermined pattern in a single ceramic block;

A plurality of resonant grooves formed in the partitions of the plurality of resonant cavities divided by the through partition walls;

A metal layer formed on an inner surface of each of the plurality of through partition walls; And

An input/output interface formed in two resonance cavities for inputting and outputting signals among the plurality of resonance cavities; Ceramic waveguide filter, characterized in that it comprises a.
The method of claim 1, wherein the plurality of resonant grooves

A ceramic waveguide filter formed at each of the centers of a corresponding resonance cavity region among the plurality of resonance cavities on one surface or the other surface of the ceramic block.
The method of claim 2, wherein the input and output interface

A ceramic waveguide filter formed in the form of a through hole penetrating the ceramic block.
The method of claim 1, wherein the plurality of through partition walls

The ceramic block is divided through the ceramic block so as to define the plurality of resonant cavities corresponding to the resonant groove and a predetermined frequency band.

The plurality of resonant cavities are spaced apart from each other to filter the frequency band while sequentially coupling with adjacent resonant cavities through a coupling window between the plurality of through partitions in response to a signal input through the input/output interface,

A ceramic waveguide filter formed in a pattern such that at least one resonant cavity among the plurality of resonant cavities is disposed adjacent to the plurality of resonant cavities to cause cross coupling.
The method of claim 4, wherein the ceramic waveguide filter

A coupling groove spaced from the through partition wall on one surface of the ceramic block between the resonance cavities where the cross coupling is generated on one surface of the ceramic block; Is formed more,

The metal layer

A ceramic waveguide filter further formed on the inner surface of the coupling groove.
The method of claim 4, wherein the ceramic waveguide filter

A coupling hole spaced apart from the through partition wall between the resonant cavities where the cross coupling occurs, and penetrates the ceramic block; Is formed more,

The metal layer

Ceramic waveguide filter is further formed on the inner surface of the coupling hole.
The method of claim 6, wherein the coupling hole

The inside is formed in a stepped structure,

The metal layer

A ceramic waveguide filter formed in an area except for a predetermined slot area facing the one surface of the ceramic block on the inner surface of the coupling hole having a stepped structure.
The method of claim 6, wherein the ceramic waveguide filter

A conductive sticker attached to an area where the coupling hole is formed on one surface of the ceramic block; Ceramic waveguide filter further comprising a.
The method of claim 1, wherein the metal layer

Ceramic waveguide filter whose thickness is adjusted according to a predetermined frequency band.
Forming a plurality of through partition walls separating the sections of the ceramic block according to a predetermined pattern to define a plurality of resonant cavities in a single ceramic block;

Forming a plurality of resonant grooves in a section of the plurality of resonant cavities divided by the through partition wall;

Forming a metal layer on each inner surface of each of the plurality of through partition walls; And

Forming an input/output interface for inputting and outputting signals to two of the plurality of resonant cavities; Method of manufacturing a ceramic waveguide filter comprising a.
11. The method of claim 10, The step of forming the plurality of resonant grooves

A method of manufacturing a ceramic waveguide filter in which the resonant grooves are formed in each of the centers of corresponding resonant cavity regions among the plurality of resonant cavities on one or the other surface of the ceramic block.
The method of claim 11, wherein the step of forming the input and output interface

A method of manufacturing a ceramic waveguide filter in which the input/output interface is formed in the form of a through hole penetrating the ceramic block.
11. The method of claim 10, The step of forming the plurality of through partition walls

The ceramic block is divided through the ceramic block so as to define the plurality of resonant cavities corresponding to the resonant groove and a predetermined frequency band.

The plurality of resonant cavities are spaced apart from each other to filter the frequency band while sequentially coupling with adjacent resonant cavities through a coupling window between the plurality of through partitions in response to a signal input through the input/output interface,

A method of manufacturing a ceramic waveguide filter in which the plurality of through partition walls are formed in a pattern such that at least one resonance cavity among the plurality of resonance cavities is disposed adjacent to the plurality of resonance cavities to generate cross coupling.
The method of claim 13, wherein the method of manufacturing the ceramic waveguide filter

Forming a coupling groove spaced from the through partition wall between the resonant cavities where the cross coupling occurs on one surface of the ceramic block; And

Forming the metal layer on an inner surface of the coupling groove; Method of manufacturing a ceramic waveguide filter further comprising.
The method of claim 13, wherein the method of manufacturing the ceramic waveguide filter

Forming a coupling hole spaced apart from the through partition wall between the resonant cavities where the cross coupling occurs, and penetrates the ceramic block; And

Forming the metal layer on the inner surface of the coupling hole; Method of manufacturing a ceramic waveguide filter further comprising.
The method of claim 15, wherein the step of forming the coupling hole

The inside of the coupling hole is formed in a stepped structure,

The step of forming on the inner surface of the coupling hole

A method of manufacturing a ceramic waveguide filter, wherein the metal layer is formed in an area except for a predetermined slot area facing the one surface of the ceramic block on the inner surface of the coupling hole having a stepped structure.
The method of claim 16, wherein the manufacturing method of the ceramic waveguide filter

Attaching a conductive sticker to an area where the coupling hole is formed on one surface of the ceramic block; Method of manufacturing a ceramic waveguide filter further comprising.
The method of claim 10, wherein the method of manufacturing the ceramic waveguide filter

Adjusting the thickness of the metal layer according to a predetermined frequency band; Method of manufacturing a ceramic waveguide filter further comprising.
The method of claim 6, wherein the ceramic waveguide filter

A conductive sticker attached to an area where the coupling hole is formed on one surface of the ceramic block; Ceramic waveguide filter further comprising a.