JP2019029898A - Bandpass filter and multistep bandpass filter - Google Patents

Abstract

To provide a bandpass filter in which fine-tuning of resonance frequency is possible after manufacture by using an SIW.SOLUTION: A bandpass filter includes a substrate, a first conductor layer, a second conductor layer, and a post wall. The substrate has a first surface and a second surface facing the first surface, and is formed of a dielectric material. The first conductor layer covers the first surface, and is formed to have an opening. The second conductor layer covers the second surface. The post wall penetrates the substrate from the first surface toward the second surface, and is formed of multiple conductor posts electrically connected with the first and second conductor layers. The post wall is arranged to surround the opening in the plan view. The first conductor layer has a primary part surrounding the opening, an inner conductor part formed in the opening while spaced apart from the primary part, and a connection part for electrically connecting the primary part and the inner conductor part. The first conductor layer has a slot sectioned by the primary part, the inner conductor part and the connection part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a bandpass filter and a multistage bandpass filter.

With the expansion of communication capacity, the millimeter wave band, which can be broadened and densified, is attracting attention. Accordingly, a millimeter-wave bandpass filter is required.
As the bandpass filter, a structure in which a resonator is formed by a hollow waveguide and each resonator is electromagnetically coupled is used (see, for example, Patent Document 1). There is also a resonator using a dielectric waveguide (SIW) in which a conductor layer is formed on each of an upper surface and a lower surface of a dielectric substrate and the upper and lower surfaces are electrically connected through a through hole to form a waveguide. It has been attracting attention as a bandpass filter (see, for example, Patent Document 2 and Non-Patent Document 1).

JP-A-5-259719 JP 2003-229703 A

Fermin Mira, Jordi Mateu, Senior Member, et al, “Mechanical Tuning of Substrate Integrated Waveguide Resonators”, IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS, VOL. 22, NO. 9, SEPTEMBER 2012

Patent Document 1 discloses a resonator in which an adjustment screw is inserted into a hollow waveguide. Patent Document 1 discloses that the resonance frequency can be adjusted by changing the insertion depth of the adjusting screw into the hollow waveguide, and the manufacturing variation can be corrected.
However, when a hollow waveguide as disclosed in Patent Document 1 is used, it may be difficult to handle because the resonator is large and heavy.

As disclosed in Patent Document 2 and Non-Patent Document 1, if SIW is used, a resonator that is smaller and lighter than a hollow waveguide can be realized.
In Patent Document 2, it is disclosed that a pad electrically isolated from a conductor layer on one surface of a dielectric substrate is formed by forming a slot around a via hole forming a resonator. And it is disclosed that the filter characteristic is adjusted by connecting the pad and the conductor layer with a bonding wire or the like.
However, the technique described in Patent Document 2 does not disclose how the resonance frequency can be changed specifically, and may not be able to cope with a case where high adjustment accuracy is required.

In addition, Non-Patent Document 1 discloses a configuration in which a through hole filled with a conductor is provided in a waveguide in addition to a through hole forming a waveguide. In this technique, the conductor layer is removed so as to surround the opening of the through hole on the upper surface of the dielectric substrate, and the conductor layer and the conductor in the through hole on the upper surface have a predetermined direction with respect to the propagation direction of the electromagnetic wave. Electrically connected at an angle. Non-Patent Document 1 discloses that the resonance frequency is adjusted by adjusting the connection angle between the conductor layer and the conductor in the through hole.
However, in the technique described in Non-Patent Document 1, since the change in the resonance frequency is large with respect to the change in the connection angle, the resonance frequency may not be finely adjusted.

  In addition, when SIW as disclosed in Patent Document 2 and Non-Patent Document 1 is used, since the waveguide is made of a dielectric, for example, as in Patent Document 1, a metal rod is attached to the resonator after manufacturing the resonator. It is difficult to insert or adjust the depth.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a band-pass filter that can finely adjust a resonance frequency after manufacturing using SIW.

  A band-pass filter according to one embodiment of the present invention has a first surface and a second surface opposite to the first surface, covers a substrate formed of a dielectric material, covers the first surface, and has an opening. A first conductor layer formed as described above, a second conductor layer covering the second surface, and penetrating the substrate from the first surface toward the second surface, and the first conductor layer and the second conductor layer. A post wall formed of a plurality of conductive pillars electrically connected to the conductor layer and arranged to surround the opening in plan view, the first conductor layer including a main portion surrounding the opening; An inner conductor portion formed in the opening and separated from the main portion; and a connecting portion for electrically connecting the main portion and the inner conductor portion, the main portion and the inner conductor portion. And a slot defined by the connecting portion.

  In the band pass filter, it is preferable that the opening has a circular shape, the inner conductor portion has a circular shape, and the slot has a C shape.

  The distance from the base end to the tip end of the inner conductor portion is in the range of 2% to 100% with respect to the distance between the center of the post wall in plan view and the center of the conductor pillar closest to the center. Is preferred.

  The minimum width of the slot is preferably 10 μm to 200 μm.

  In the bandpass filter, it is preferable that the slot is not disposed in a central portion of a space surrounded by the post wall in a plan view.

  In the band-pass filter, it is preferable that the slot is disposed at a center portion in a propagation direction of the high-frequency signal in a space surrounded by the post wall in a plan view.

  The band pass filter may further include a dielectric layer covering the first conductor layer and the slot.

  A multi-stage bandpass filter according to another aspect of the present invention includes a plurality of the bandpass filters arranged in parallel.

  According to the above aspect of the present invention, it is possible to provide a band-pass filter that can finely adjust the resonance frequency after manufacturing using SIW.

1 is a perspective view of a bandpass filter 1 according to a first embodiment of the present invention. (A) is the top view which showed the structure of the band pass filter 1 typically, (b) is sectional drawing which follows the AA line of (a). 3 is a top view of a slot 6 of the bandpass filter 1. FIG. 6 is a top view of a slot 6A of a first modification of the bandpass filter 1. FIG. 6 is a top view of a slot 6B of a second modification of the bandpass filter 1. FIG. 12 is a top view of a slot 6C of a third modification of the bandpass filter 1. FIG. It is a top view of slot 6D of the 4th modification of band pass filter 1. FIG. 10 is a cross-sectional view of a bandpass filter 101 that is a fifth modification of the bandpass filter 1. It is a perspective view of the multistage band pass filter 201 concerning a 2nd embodiment of the present invention.

  Hereinafter, based on a preferred embodiment, the present invention will be described with reference to the drawings. The following embodiments are described by way of example in order to better understand the gist of the invention, and the present invention is not limited unless otherwise specified. In addition, in the drawings used in the following description, in order to make the features of the present invention easier to understand, the main part may be enlarged for convenience, and the dimensional ratios of the respective components are the same as the actual ones. Not necessarily. In addition, in order to make the features of the present invention easier to understand, some parts are omitted for convenience.

[First Embodiment]
The configuration of the bandpass filter 1 according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view schematically showing the configuration of a bandpass filter 1 according to the first embodiment of the present invention. 2A is a top view schematically showing the configuration of the bandpass filter 1, and FIG. 2B is a cross-sectional view taken along the line AA in FIG. 2A. FIG. 3 is a top view of the slot 6 of the bandpass filter 1. In FIG. 2, the configuration of the post wall is shown more simply than in FIG.

  In the following description, as shown in FIG. 1, the X direction is the length direction of the substrate 2 that is rectangular (for example, rectangular) in plan view. The Y direction is a direction orthogonal to the X direction within the plane along the substrate 2, and is the width direction of the substrate 2. The Z direction is a direction orthogonal to the X direction and the Y direction, and is the thickness direction of the substrate 2. The Z direction is the vertical direction. Plan view means viewing from the Z direction. A plane formed by the X direction and the Y direction is referred to as an XY plane.

  As shown in FIGS. 1 and 2, the bandpass filter 1 includes a substrate 2, conductor layers 3 and 4, and a post wall 5.

  The substrate 2 is made of, for example, a single dielectric material. The dielectric material is preferably a low dielectric constant, low dielectric loss tangent resin such as quartz glass or glass cloth that can propagate high-frequency signals with low loss, and low-temperature co-fired ceramics (LTCC). What is necessary is just to select the magnitude | size and thickness of the board | substrate 2 suitably according to the characteristic of the high frequency signal to propagate. When used for high frequency signals of E band (71 to 86 GHz), for example, a substrate having a thickness of 400 μm can be used.

As shown in FIG. 2, the substrate 2 has a rectangular shape (for example, a rectangular shape) in plan view. The substrate 2 has an upper surface (first surface) 2a and a lower surface (second surface) 2b. A plurality of through holes 51 are formed in the substrate 2 so as to penetrate the substrate 2 from the upper surface 2a to the lower surface 2b. The through hole 51 has, for example, a substantially circular cross section along the XY plane. In the through hole 51, a conductor column 52 constituting the post wall 5 is formed.
The through hole 51 can be formed by an etching method using a mask. As an opening diameter of the through-hole 51, 50-200 micrometers is mentioned from a viewpoint of easiness of preparation, for example.

The conductor layers 3 and 4 are formed of a thin film made of a metal such as copper, for example.
The conductor layer 3 (first conductor layer) is formed on the upper surface 2 a of the substrate 2 with an opening 10. The conductor layer 3 covers the entire upper surface 2a of the substrate 2 except for the slot 6 (described later).
The conductor layer 3 includes a main part 11, an inner conductor part 12, and a connection part 13.
The main portion 11 is a region formed surrounding the opening 10. The opening 10 is formed in a circular shape in plan view. The main portion 11 is a region outside the opening 10 and is a region extending from the inner peripheral edge of the opening 10 to the outer peripheral edge of the upper surface 2 a of the substrate 2.

As shown in FIG. 3, the inner conductor portion 12 is formed inside the opening 10 in plan view. The inner conductor portion 12 has a circular shape in plan view. The outer diameter of the inner conductor portion 12 is smaller than the inner diameter of the opening 10. Therefore, the inner conductor portion 12 is separated from the main portion 11 by the slot 6. The inner conductor portion 12 is preferably circular and concentric with the opening 10.
Reference numeral 12a denotes a base end (one end in the X direction) of the inner conductor portion 12. 12b is the front end of the inner conductor portion 12 (the other end in the X direction, that is, the end opposite to the base end 12a).

  A difference d (diameter difference d) between the inner diameter of the opening 10 and the outer diameter of the inner conductor portion 12 corresponds to the width of the slot 6. The diameter difference d is preferably 10 μm to 200 μm. When the diameter difference d is 10 μm or more, the slot 6 can be formed with high accuracy. When the diameter difference d is 200 μm or less, high-frequency signal radiation can be suppressed. The diameter difference d may be the minimum value of the difference between the inner diameter of the opening 10 and the outer diameter of the inner conductor portion 12. The diameter difference d may be a distance in the X direction between the front end 12b of the inner conductor portion 12 and the inner edge of the opening 10.

The connection part 13 electrically connects the main part 11 and the inner conductor part 12. The connecting portion 13 is formed along the X direction which is the radial direction of the main portion 11 and the inner conductor portion 12 at one place in the circumferential direction of the main portion 11 and the inner conductor portion 12. For example, the connecting portion 13 has a strip shape having a certain width (dimension in the Y direction). The end of the connecting portion 13 on the main portion 11 side is called a base end 13a. The connecting portion 13 extends from the base end 13 a toward the inner conductor portion 12 in the X direction and reaches the base end 12 a of the inner conductor portion 12.
The width of the connecting portion 13 may be, for example, about the diameter of the conductor column 52 (see FIG. 2A) or smaller.
The connecting portion 13 may be formed after the main portion 11 and the inner conductor portion 12 are formed and a necessary adjustment amount of the resonance frequency is estimated. The connection portion 13 may be formed simultaneously with the conductor layer 3.

  The distance r1 from the base end 12a of the inner conductor portion 12 to the tip end 12b of the inner conductor portion 12 is 1% to 50% with respect to the dimension L1 of the post wall 5 in plan view (see FIG. 2 (a), which will be described later). It is preferable to be in the range. When the distance r1 is 1% or more of the dimension L1 of the post wall 5, the resonance frequency can be adjusted effectively. When the distance r1 is 50% or less of the dimension L1 of the post wall 5, the fluctuation range of the resonance frequency is suppressed and fine adjustment is possible. The distance r1 is equal to the outer diameter of the inner conductor portion 12.

The object to be compared with the distance r1 may not be the dimension L1 of the post wall 5 but the dimension L2 shown in FIG. The dimension L2 is the distance between the center C1 of the post wall 5 and the center of the conductor column 52 closest to the center C1 in plan view. Therefore, the preferable range of the distance r1 described above “1% to 50% with respect to the dimension L1” can be rephrased as “2% to 100% with respect to the dimension L2.”
When the distance r1 is 2% or more of the dimension L2 of the post wall 5, the resonance frequency can be adjusted effectively. When the distance r1 is 100% or less of the dimension L2 of the post wall 5, the fluctuation range of the resonance frequency is suppressed and fine adjustment is possible.
The center C1 of the post wall 5 is, for example, the center of gravity of the post wall 5 in plan view (for example, the intersection of diagonal lines of the rectangular post wall 5).

  The slot 6 has a shape (C shape) in which a ring defined by the main portion 11 and the inner conductor portion 12 is divided by the connection portion 13. The slot 6 has a certain width in the circumferential direction of the main portion 11 and the inner conductor portion 12, for example. The width of the slot 6 is a diameter difference d between the opening 10 and the inner conductor portion 12. Therefore, the width of the slot 6 (for example, the minimum width) is preferably in the above-described range (10 μm to 200 μm).

  The connection part 13 partially connects the main part 11 and the inner conductor part 12 at a position at a predetermined angle θ with respect to a direction perpendicular to the propagation direction (X direction) of the high-frequency signal in plan view. The angle θ is a line extending from the center of the inner conductor portion 12 in a plan view to a direction opposite to the center of the substrate 2 in a direction perpendicular to the propagation direction (X direction) of the high-frequency signal. It is an angle with the line which goes to the center part of the end 13a.

In the band pass filter 1, the resonance frequency can be adjusted by changing the angle θ.
The change in the resonance frequency when the angle θ is changed is smaller than the variation in the resonance frequency when the via conductor is formed in the through hole of the substrate. Therefore, if the bandpass filter 1 is used, the resonance frequency can be finely adjusted by adjusting the position of the connecting portion 13 even after the dielectric waveguide (SIW) is manufactured. Therefore, it is possible to provide a bandpass filter that can cope with a case where target accuracy is high.

  In the band-pass filter, the size of the resonator and the coupling amount with the resonator are important. When the slot 6 is close to an opening 7 described later, the coupling amount changes. Therefore, the slot 6 is preferably located away from each opening 7 in order to reduce the influence. Therefore, it is preferable that the slot 6 is located in the center of the propagation direction (X direction) of the high-frequency signal in the region surrounded by the post wall 5 in plan view.

  In the direction perpendicular to the propagation direction (X direction) (Y direction), the electric field strength is strong in the vicinity of the center. Therefore, the slot 6 is preferably arranged at a position closer to the post wall 5 than the central portion. Thereby, the adverse effect of the electric field can be suppressed.

The conductor layer 4 (second conductor layer) covers the entire lower surface 2 b of the substrate 2. As long as it functions as a resonator, the conductor layer 3 and the conductor layer 4 may not cover the entire upper surface 2a and lower surface 2b, respectively.
When the conductor layers 3 and 4 are copper thin films, the thickness is preferably 1 μm to 40 μm. When the thickness of the conductor layers 3 and 4 is 1 μm or more, loss can be suppressed, and when the thickness is 40 μm or less, the conductor layers 3 and 4 can be easily formed. The conductor layers 3 and 4 can be formed by, for example, a copper plating method.

  As shown in FIG. 2A, the post wall 5 is composed of a plurality of conductor columns 52, and has a pair of first wall portions 5a and a pair of second wall portions 5b. The conductor column 52 is electrically connected to the conductor layers 3 and 4 at both ends thereof. In the first wall portion 5a, a plurality of conductor columns 52 are arranged in parallel to two opposite sides of the substrate 2 in plan view. The first wall portions 5a are respectively formed at positions close to the two opposite sides of the substrate 2. In the second wall portion 5b, the plurality of conductor columns 52 are arranged in parallel in a direction perpendicular to the direction in which the conductor columns 52 of the first wall portion 5a are arranged. In addition, the pair of second wall portions 5b are arranged at a predetermined interval from each other.

The plurality of conductor columns 52 are arranged in the first and second wall portions 5a and 5b at intervals that prevent high-frequency signals propagating through the dielectric waveguide (SIW) from leaking to the outside. However, the second wall 5 b is arranged so that an opening 7 through which a high-frequency signal with a predetermined wavelength can pass is formed at the center in the parallel direction of the conductor pillars 52. That is, in the bandpass filter 1, the direction in which the conductor columns 52 of the first wall 5a are arranged in parallel is the high-frequency signal propagation direction. This propagation direction coincides with the X direction.
The post wall 5 is formed surrounding the slot 6 in plan view.
Note that the opening 7 may not be formed in the central portion of the conductor columns 52 in the parallel direction, and may be formed at a position close to the first wall 5a.

  The conductor columns 52 constituting the post wall 5 can be formed by a copper plating method, and may be formed simultaneously with the conductor layers 3 and 4. Further, in the conductor column 52, the inside of the through hole 51 may not be completely filled as long as the conductor covers the entire inner surface of the through hole 51. The conductor may be completely filled in the through hole 51.

  The dimension L1 of the post wall 5 is, for example, a rectangular structure formed by the first wall 5a and the second wall 5b in plan view in the parallel direction (X direction) of the conductor columns 52 in the first wall 5a. It is either a dimension or a dimension in the parallel direction (Y direction) of the conductor columns 52 in the second wall portion 5b. Here, the dimension L1 is the dimension of the second wall 5b, which is the shorter of the first wall 5a and the second wall 5b in the rectangular structure. The dimension L1 is the distance between the centers of the two conductor columns 52 located at both ends in the parallel direction in plan view.

  In the band-pass filter 1, as described above, after the dielectric waveguide (SIW) is manufactured by changing the distance r1 between the connecting portion 13 and the inner conductor portion 12 and the angle θ of the connecting portion 13. Also, the resonance frequency can be finely adjusted.

(First modification)
FIG. 4 is a top view of a slot 6A of a bandpass filter 1A that is a first modification of the bandpass filter 1. FIG. In the following description, components that are the same as those already described are denoted by the same reference numerals and description thereof is omitted.
As shown in FIG. 4, in the band pass filter 1A, the inner conductor portion 12A has the same width (dimension in the Y direction) as the connecting portion 13, and extends in the X direction.

The distance r2 from the base end 13a of the connecting portion 13 to the tip of the inner conductor portion 12A is 1% to 50% with respect to the dimension L1 (see FIG. 2A) of the post wall 5 or 2 with respect to the dimension L2. % To 100% is preferable. When the distance r2 is 1% or more of the dimension L1 of the post wall 5 (or 2% or more of the dimension L2), the resonance frequency can be adjusted effectively. When the distance r2 is 50% or less of the dimension L1 of the post wall 5 (or 100% or less of the dimension L2), the fluctuation range of the resonance frequency is suppressed and fine adjustment is possible. The bandpass filter 1A may be the same as the bandpass filter 1 (see FIG. 3) except for the shape of the inner conductor portion 12A.
In the band-pass filter 1A, similarly to the band-pass filter 1 (see FIG. 3), the resonance frequency can be finely adjusted by changing the angle θ of the connecting portion 13.

(Second modification)
FIG. 5 is a top view of a slot 6B of a bandpass filter 1B which is a second modification of the bandpass filter 1. FIG.
As shown in FIG. 5, in the band pass filter 1B, the inner conductor portion 12B has a rectangular shape (for example, a rectangular shape) having a wider width (dimension in the Y direction) than the connecting portion 13. The inner conductor portion 12B is formed with the long side direction oriented in the X direction. The bandpass filter 1B may be the same as the bandpass filter 1 (see FIG. 3) except for the shape of the inner conductor portion 12B.
Even in the band-pass filter 1B, the resonance frequency can be finely adjusted by changing the distance r2 and the angle θ of the connecting portion 13.

(Third Modification)
FIG. 6 is a top view of a slot 6 </ b> C of a bandpass filter 1 </ b> C that is a third modification of the bandpass filter 1.
As shown in FIG. 6, in the bandpass filter 1C, the opening 10C has a rectangular shape (for example, a rectangular shape). The bandpass filter 1C may be the same as the bandpass filter 1A (see FIG. 4) except for the shape of the opening 10C.
Even in the band pass filter 1 </ b> C, the resonance frequency can be finely adjusted by changing the distance r <b> 2 and the angle θ of the connecting portion 13.

(Fourth modification)
FIG. 7 is a top view of a slot 6D of a bandpass filter 1D that is a fourth modification of the bandpass filter 1. FIG.
As shown in FIG. 7, in the band pass filter 1D, the connection portion 13D is formed by a metal wiring portion (wire). The connecting portion 13D is formed along the X direction in plan view. The base end 13Da of the connection portion 13D is connected to the main portion 11 and the tip end 13Db is connected to the inner conductor portion 12. The bandpass filter 1D may be the same as the bandpass filter 1 (see FIG. 3) except that the connection unit 13D is provided instead of the connection unit 13.
Even in the band-pass filter 1D, the resonance frequency can be finely adjusted by changing the distance r1 and the angle θ of the connecting portion 13.

(Fifth modification)
FIG. 8 is a cross-sectional view of a bandpass filter 101 which is a fifth modification of the bandpass filter 1.
As shown in FIG. 8, in the band pass filter 101, the slot 6 and the conductor layer 3 are covered with a dielectric layer 8. The dielectric layer 8 is covered with a conductor layer 9.
Examples of the material of the dielectric layer 8 include polyimide from the viewpoints of applicability, dielectric constant, and the like. The conductor layer 9 can be formed by a copper plating method. Other configurations may be the same as those of the bandpass filter 1 of the first embodiment.
Note that the band-pass filter may be configured without a conductor layer covering the dielectric layer.

[Second Embodiment]
The configuration of the multistage bandpass filter 201 according to the second embodiment of the present invention will be described with reference to FIG. In addition, about the structure which is common in 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

FIG. 9 is a perspective view of the bandpass filter 201.
As shown in FIG. 9, the multistage bandpass filter 201 includes three bandpass filters 1 according to the first embodiment arranged in parallel. In the multistage bandpass filter 201, the pair of first wall portions 5a of each bandpass filter 1 are provided in the same straight line. Moreover, the 2nd wall part 5b of the adjacent band pass filter 1 is shared.

  In the multistage bandpass filter 201, the filter characteristics can be improved by configuring a plurality of bandpass filters 1 in parallel as compared with a single-stage bandpass filter.

In FIG. 9, three band pass filters 1 are arranged in parallel, but the present invention is not limited to this. Two may be arranged in parallel, or four or more may be arranged in parallel. In FIG. 9, the bandpass filters 1 are arranged in one direction, but the invention is not limited. For example, an opening may be provided in the first wall 5a so that the bandpass filter 1 is arranged in two directions.
In FIG. 9, the width of the opening 7 of each bandpass filter 1 is constant, but is not limited to this. The width of the opening 7 may be different depending on the required resonance frequency. Further, in FIG. 9, the interval between the second wall portions 5b in the high-frequency signal propagation direction (X direction) is also constant, but is not limited thereto. The intervals between the second wall portions 5b may be different depending on the required resonance frequency.

  In the first and second embodiments described above, only the elements constituting the bandpass filter are formed on the substrate 2, but the present invention is not limited to this. For example, a planar circuit and a conductor pin that can propagate a high-frequency signal to the band-pass filter may be formed on the same substrate 2.

  Hereinafter, the present invention will be specifically described with reference to examples. In addition, this invention is not limited only to this Example.

As the configuration of the bandpass filter of the embodiment, the configuration of the bandpass filter 1 shown in FIGS. 1 to 3 was used. A quartz glass substrate having a thickness of 400 μm was adopted as the substrate, and in each example, a simulation was performed with the exception of the angle θ and the distance r1 being constant, and changes in resonance frequency were compared.
The diameter difference d was 50 μm. The angle θ was set to four conditions of 0 °, 90 °, 180 °, and 270 °. The distance r1 was three conditions of 100 μm, 150 μm, and 200 μm. The results are shown in Table 1.

  From Table 1, it can be seen that the resonance frequency can be adjusted by setting the angle θ and the distance r1.

The band-pass filter and the multistage band-pass filter of the present invention have been described above. However, the present invention is not limited to the above examples, and can be appropriately changed without departing from the spirit of the invention.
The planar view shape of the opening of the conductor layer and the inner conductor portion is not limited to a circular shape or a rectangular shape. The planar view shape of the opening of the conductor layer and the inner conductor portion may be, for example, an elliptical shape, or may be a polygonal shape (triangular shape, pentagonal shape, hexagonal shape, etc.) other than a rectangular shape.
The shape of the post wall in plan view is not limited to a rectangular shape. The plan view shape of the post wall may be, for example, a polygonal shape other than a rectangular shape (triangular shape, pentagonal shape, hexagonal shape, etc.), circular shape, elliptical shape, or the like.
The connecting portion may be formed integrally with the main portion and the inner conductor portion, or may be separate from the main portion and the inner conductor portion.

DESCRIPTION OF SYMBOLS 1,101 ... Band pass filter, 2 ... Board | substrate, 2a ... Upper surface (1st surface), 2b ... Lower surface (2nd surface), 3 ... Conductor layer (1st conductor layer), 4 ... Conductor layer (2nd conductor layer) 5) Post wall, 6 ... Slot, 8 ... Dielectric layer, 201 ... Multi-stage bandpass filter, r1 ... Distance from the proximal end to the distal end of the inner conductor portion.

Claims (8)

A substrate having a first surface and a second surface facing the first surface, the substrate being formed of a dielectric material;
A first conductor layer covering the first surface and having an opening;
A second conductor layer covering the second surface;
The first surface is formed of a plurality of conductive pillars penetrating the substrate from the first surface toward the second surface and electrically connected to the first conductor layer and the second conductor layer, and the opening in the plan view. A post wall arranged to surround,
The first conductor layer electrically connects the main portion surrounding the opening, the inner conductor portion formed in the opening and separated from the main portion, and the main portion and the inner conductor portion. And
A slot defined by the main part, the inner conductor part and the connection part;
Bandpass filter. The opening is circular,
The inner conductor portion is circular,
The band-pass filter according to claim 1, wherein the slot has a C shape.   The distance from the proximal end to the distal end of the inner conductor portion is in the range of 2% to 100% with respect to the distance between the center of the post wall in plan view and the center of the conductor column closest to the center. The band-pass filter according to claim 1 or 2.   The bandpass filter according to any one of claims 1 to 3, wherein a minimum width of the slot is 10 m to 200 m.   The band pass filter according to any one of claims 1 to 4, wherein the slot is not disposed in a central portion of a space surrounded by the post wall in a plan view.   The band pass filter according to claim 5, wherein the slot is disposed at a central portion in a propagation direction of a high-frequency signal in a space surrounded by the post wall in a plan view.   The band pass filter according to claim 1, further comprising a dielectric layer covering the first conductor layer and the slot.   A multistage bandpass filter comprising a plurality of bandpass filters according to any one of claims 1 to 7 arranged in parallel.

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