阅读说明：本技术 滤波器 (Filter with a filter element having a plurality of filter elements ) 是由 木寺信隆 于 2019-01-08 设计创作，主要内容包括：本发明的滤波器具备导波路,该导波路形成于被导体壁包围的电介质,所述导体壁具有向所述导波路的内侧突出的至少一个控制壁,所述控制壁具有在所述控制壁的突出方向上的末端部和在所述突出方向上的中心部,所述末端部具有壁厚与所述中心部不同的壁部。(The filter of the present invention includes a waveguide formed in a dielectric body surrounded by a conductor wall, the conductor wall having at least one control wall protruding inward of the waveguide, the control wall having a terminal portion in a protruding direction of the control wall and a central portion in the protruding direction, the terminal portion having a wall portion different in wall thickness from the central portion.)

1. A filter, wherein,

the filter includes a waveguide formed in a dielectric surrounded by a conductor wall,

the conductor wall has at least one control wall protruding toward the inside of the waveguide,

the control wall has a distal end portion in a projecting direction of the control wall and a central portion in the projecting direction,

the distal end portion has a wall portion having a different wall thickness from the central portion.

2. The filter of claim 1, wherein,

the end portion has a wall portion thinner in wall thickness than the central portion.

3. The filter of claim 1, wherein,

the end portion has a wall portion having a greater wall thickness than the central portion.

4. The filter according to any one of claims 1 to 3,

the tip portion has: a first wall portion including a protruding end in the protruding direction; and a second wall portion located between the first wall portion and the center portion and having a different wall thickness from the first wall portion.

5. The filter of claim 4, wherein,

the length of the first wall portion in the protruding direction is shorter than the length of the second wall portion in the protruding direction.

6. The filter of claim 5, wherein,

when the length of the first wall portion in the protruding direction is set to L3 and the length of the second wall portion in the protruding direction is set to L2,

L3/(L2+ L3) is less than 0.2.

7. The filter of any one of claims 1-6,

the control wall is a combination of a plurality of conductor columns arranged in a fence shape,

the thickness of at least one of the plurality of conductive posts disposed at a position farthest from the root portion of the control wall in the projecting direction is different from the thickness of at least one of the plurality of conductive posts disposed at a position closest to the root portion.

8. The filter according to any one of claims 1 to 7,

the control wall is a combination of a plurality of conductor columns arranged in a fence shape,

the thickness of at least one of the plurality of conductive posts disposed at a position second distant from the root portion of the control wall in the projecting direction is different from the thickness of at least one of the plurality of conductive posts disposed at a position closest to the root portion.

9. The filter according to any one of claims 1 to 8,

the control wall is a combination of a plurality of conductor columns arranged in a fence shape,

the number of the conductive posts arranged at a position farthest from the root portion of the control wall in the projecting direction is different from the number of the conductive posts arranged at a position closest to the root portion.

10. The filter according to any one of claims 1 to 9,

the control wall is a combination of a plurality of conductor columns arranged in a fence shape,

at least one of the plurality of conductive posts disposed at a position farthest from the root portion of the control wall in the projecting direction has a diameter different from a diameter of at least one of the plurality of conductive posts disposed at a position closest to the root portion.

11. The filter according to any one of claims 1 to 10,

the conductor wall has a pair of side walls opposed to each other,

the control walls protrude from the pair of side walls, respectively.

12. The filter according to any one of claims 1 to 11,

the control walls are arranged at intervals in a prescribed direction,

the lengths of the control walls in the projecting direction increase or decrease in the order of arrangement thereof.

Technical Field

The present invention relates to filters.

Background

Conventionally, a filter of a SIW (Substrate Integrated Waveguide) structure in which a plurality of control walls are formed at predetermined intervals in a Waveguide formed in a dielectric layer sandwiched between a first conductor layer and a second conductor layer is known (for example, see patent document 1). There is also a filter in which a plurality of slits are formed at a predetermined interval on a pair of side surfaces of a dielectric waveguide line (see, for example, fig. 16 of patent document 2).

Patent document 1: japanese patent laid-open publication No. 2015-207969

Patent document 2: japanese patent laid-open No. 2005-020415

In the field of waveguide filters as described above, an efficient design method for realizing desired filter characteristics is not found, and it is difficult to adjust the filter characteristics to the desired filter characteristics. However, the present inventors have found that: by adjusting the wall thickness of the distal end portion of the control wall, it is possible to easily adjust the desired filter characteristics, as compared with the case of adjusting the wall thickness of the root portion of the control wall.

Disclosure of Invention

Accordingly, the present disclosure provides a filter that is easily adjusted to a desired filter characteristic.

The present disclosure provides a filter, wherein,

the filter includes a waveguide formed in a dielectric surrounded by a conductor wall,

the conductor wall has at least one control wall protruding toward the inside of the waveguide,

the control wall has a distal end portion in a protruding direction of the control wall and a central portion in the protruding direction,

the distal end portion has a wall portion having a different wall thickness from the central portion.

According to the filter of the present disclosure, adjustment to a desired filter characteristic is easy.

Drawings

Fig. 1 is a perspective view showing an example of the structure of a filter according to the present disclosure.

Fig. 2 is a plan view showing a filter according to a first embodiment of the present disclosure.

Fig. 3 is a plan view showing an example of the shape of a control wall formed by slits (comparative example).

Fig. 4 is a plan view showing an example of the shape of the control wall formed by the slit.

Fig. 5 is a plan view showing an example of the shape of the control wall formed by the slit.

Fig. 6 is a plan view showing an example of the shape of the control wall formed by the slit.

Fig. 7 is a plan view showing an example of the shape of the control wall formed by the slit.

Fig. 8 is a plan view showing a filter according to a second embodiment of the present disclosure.

Fig. 9 is a plan view showing an example of the shape of a control wall formed of a plurality of conductor posts (comparative example).

Fig. 10 is a plan view showing an example of the shape of a control wall formed of a plurality of conductor pillars.

Fig. 11 is a plan view showing an example of the shape of a control wall formed of a plurality of conductor pillars.

Fig. 12 is a plan view showing an example of the shape of a control wall formed of a plurality of conductor posts.

Fig. 13 is a plan view showing an example of the shape of a control wall formed of a plurality of conductor pillars.

Fig. 14 is a plan view showing an example of the shape of a control wall formed of a plurality of conductor pillars.

Fig. 15 is a plan view showing an example of the shape of a control wall formed of a plurality of conductor pillars.

Fig. 16 is a plan view showing an example of the shape of a control wall formed of a plurality of conductor posts.

Fig. 17 is a plan view showing an example of the shape of the control wall formed by the slit and the conductor post.

Fig. 18 is a diagram showing an example of a change in filter characteristics when the shape of the end of the slit forming the control wall is changed in the filter according to the first embodiment.

Fig. 19 is a diagram showing an example of a change in filter characteristics when the shape of the first conductor post from the end of the control wall is changed in the filter according to the second embodiment.

Fig. 20 is a diagram showing an example of a change in filter characteristics when the shape of the second conductor post from the end of the control wall is changed in the filter according to the second embodiment.

Fig. 21 is a diagram showing an example of a change in filter characteristics when the shape of the third conductor post from the end of the control wall is changed in the filter according to the second embodiment.

Fig. 22 is a diagram showing an example of a change in filter characteristics when the shape of the fourth conductor post from the end of the control wall is changed in the filter according to the second embodiment.

Detailed Description

Hereinafter, embodiments for carrying out the present invention will be described. In the following description, the X-axis direction, the Y-axis direction, and the Z-axis direction respectively indicate a direction parallel to the X-axis, a direction parallel to the Y-axis, and a direction parallel to the Z-axis. The X-axis direction, the Y-axis direction and the Z-axis direction are orthogonal to each other. The XY plane, the YZ plane, and the ZX plane respectively represent an imaginary plane parallel to the X-axis direction and the Y-axis direction, an imaginary plane parallel to the Y-axis direction and the Z-axis direction, and an imaginary plane parallel to the Z-axis direction and the X-axis direction.

The filter according to the present disclosure is a waveguide filter including a waveguide formed in a dielectric body surrounded by a conductor wall, and filters high-frequency signals of high-frequency bands (for example, 0.3GHz to 300GHz) such as microwaves and millimeter waves. The filter according to the present disclosure is suitable for filtering a high-frequency signal corresponding to a radio wave transmitted or received by an antenna in, for example, a fifth generation mobile communication system (so-called 5G) and a vehicle-mounted radar system.

Fig. 1 is a perspective view showing an example of the structure of a filter according to the present disclosure. The filter 10 according to the present disclosure shown in fig. 1 is a bandpass filter having a SIW structure formed of a first conductor layer 21, a second conductor layer 22, and a dielectric 23 interposed between the first conductor layer 21 and the second conductor layer 22. The filter 10 passes a high-frequency signal of a predetermined frequency band passing in the Y-axis direction, and cuts a high-frequency signal of a frequency band other than the frequency band.

The first conductor layer 21 and the second conductor layer 22 are planar conductors arranged parallel to the XY plane, and face each other in the Z-axis direction. The first conductor layer 21 and the second conductor layer 22 are formed in a rectangular shape with the Y-axis direction as the long side direction. Examples of the material of the first conductor layer 21 and the second conductor layer 22 include silver and copper.

The dielectric 23 is formed in a rectangular parallelepiped shape with the Y-axis direction as the longitudinal direction. Although not explicitly shown in fig. 1, in order to form the waveguide in the dielectric 23, a conductor wall is formed on a pair of side surfaces of the dielectric 23 facing in the X-axis direction or on a pair of boundary surfaces located inside the dielectric 23 and facing in the X-axis direction. Examples of the material of the dielectric 23 include glass such as quartz glass, ceramics, fluorine-based resins such as polytetrafluoroethylene, liquid crystal polymers, and cycloolefin polymers. The dielectric 23 is not limited to a solid, and may be a gas such as air.

Fig. 2 is a plan view showing a filter according to a first embodiment of the present disclosure. A filter 10A shown in fig. 2 is an example of the filter 10 shown in fig. 1, and includes a waveguide formed in a dielectric 23 surrounded by a conductor wall. The conductor wall surrounding the dielectric 23 has: an upper conductor wall corresponding to the first conductor layer 21; a lower conductor wall corresponding to the second conductor layer 22; and a pair of side conductor walls 41 and 42 formed on a pair of side surfaces of the dielectric 23 facing each other in the X-axis direction.

The dielectric portion surrounded by the pair of side conductor walls 41 and 42, the upper conductor wall, and the lower conductor wall functions as a waveguide extending in the Y-axis direction to guide electromagnetic waves in the Y-axis direction.

Each of the pair of side conductor walls 41 and 42 has a plurality of control walls protruding in the X-axis direction inside the waveguide. The filter 10A according to the first embodiment includes: control walls 43a to 47a protruding from the first side surface conductor wall 41 toward the second side surface conductor wall 42; and control walls 43b to 47b that protrude from the second side conductor wall 42 toward the first side conductor wall 41. The control walls are each formed by a conductor slit whose surface is covered with a conductor. Each conductor slit has an upper end connected to the upper conductor wall and a lower end connected to the lower conductor wall, and corresponds to a portion of the dielectric 23 where the surface of the slit is covered with a conductor by cutting or the like, for example.

The control wall is formed, for example, so as to be orthogonal to the upper and lower conductive walls parallel to the XY plane and to be orthogonal to the pair of side conductive walls 41 and 42 parallel to the YZ plane (that is, so as to be parallel to the ZX plane). The control walls 43a to 47a are formed at equal intervals in the Y-axis direction between adjacent control walls, for example, and are formed so as to protrude from the first side surface conductor wall 41 toward the second side surface conductor wall 42. Similarly, the control walls 43b to 47b are formed at equal intervals in the Y-axis direction between adjacent control walls, for example, and are formed so as to protrude from the second side surface conductive wall 42 toward the first side surface conductive wall 41. That is, the X-axis direction shown in fig. 2 indicates the projecting direction of each of the control walls 43a to 47a, 43b to 47b.

For example, the pair of control walls 43a, 43b, the pair of control walls 44a, 44b, the pair of control walls 45a, 45b, the pair of control walls 46a, 46b, and the pair of control walls 47a, 47b are formed in the same ZX plane, respectively. Further, the positions of each of the pair of control walls may be shifted from each other in the Y-axis direction.

L43 to L47 respectively indicate the lengths of the control walls 43a to 47a in the X axis direction. The control walls 43a to 47a are set to have a wall length when viewed from the electromagnetic wave propagating through the waveguide, and function as column walls that reflect the electromagnetic wave propagating through the waveguide. The control walls 43b to 47b may be set to the same length.

The interval L41 between the pair of side conductor walls 41 and 42 is preferably about the same as λ g/2 when the wavelength of the electromagnetic wave propagating through the waveguide (in-tube wavelength) is λ g. In addition, the distance between the control walls adjacent in the Y-axis direction is preferably about the same as λ g/2 when the wavelength of the electromagnetic wave propagating through the waveguide (in-tube wavelength) is λ g.

The control walls 43a to 47a are arranged at intervals in the Y axis direction, and the lengths of the control walls 43a to 47a in the X axis direction may be increased or decreased in the order of arrangement of the control walls 43a to 47a in the Y axis direction. This makes it possible to adjust the degree of suppressing the reflection loss of the electromagnetic wave propagating through the waveguide with high accuracy. For example, L47, L46, L45 increase in this order, and L44, L43 decrease in this order. Similarly, the lengths of the control walls 43b to 47b arranged at intervals in the Y-axis direction in the X-axis direction are also sequentially increased or decreased in accordance with the arrangement of the control walls 43b to 47b in the Y-axis direction, whereby the degree of suppressing the reflection loss of the electromagnetic wave propagating through the waveguide can be adjusted with high accuracy. Further, the lengths of the control walls in the X-axis direction may be set to be the same size.

The control walls 43a to 47a and 43b to 47b are formed of a pair of control walls facing each other in the X-axis direction and a pair of control walls adjacent to each other in the Y-axis direction, and form a plurality of resonators having a length of about λ g/2 (λ g is a wavelength of an electromagnetic wave (in-tube wavelength) propagating through the waveguide) arranged in the Y-axis direction. The coupling between the resonators is adjusted by the length of each control wall in the X-axis direction and the width (thickness) of each control wall in the Y-axis direction, and influences the reflection characteristics and frequency characteristics of the filter. As described above, the filter 10A is a bandpass filter having resonators of a plurality of stages (4 stages in the case of fig. 2) formed between the control walls adjacent in the Y-axis direction.

Fig. 3 is a plan view showing the shape of a control wall 48A as a comparative example of the control wall in the first embodiment. The control wall 48A has a rectangular slit shape. Therefore, the wall thickness W1 at the distal end portion of the control wall 48A is the same as the wall thickness W3 at the central portion of the control wall 48A.

In contrast, the end portions of the control walls 48B to 48E shown in fig. 4 to 7 each have a wall portion having a different thickness from the central portion of each control wall. The control walls 48B to 48E are examples of the control walls 43a to 47a and 43B to 47B in the first embodiment.

The control wall 48B has a tip end portion in which a protruding end protruding in the X-axis direction is rounded, and the tip end portion has a wall portion of a wall thickness W1 that is thinner than a wall thickness W3 of a central portion of the control wall 48B. Specifically, the distal end portion of the control wall 48B has a first wall portion and a second wall portion that are different in wall thickness from each other. The first wall portion is a semicircular portion including an arc-shaped protruding end and has a wall thickness W1. The second wall portion is a straight portion located between the first wall portion and the central portion of the control wall 48B, and has a wall thickness W3 that is thicker than the wall thickness W1.

The control wall 48C has a tapered distal end portion having a wall portion with a wall thickness W1 that is thinner than the wall thickness W3 at the central portion of the control wall 48C. Specifically, the distal end portion of the control wall 48C has a first wall portion and a second wall portion that are different in wall thickness from each other. The first wall portion is a triangular portion including a protruding end of an acute angle, and has a portion of a wall thickness W1. The second wall portion is a straight portion located between the first wall portion and the central portion of the control wall 48C, and has a wall thickness W3 that is thicker than the wall thickness W1.

The control wall 48D has a distal end portion in which a protruding end protruding in the X-axis direction is reduced to a rectangle, and the distal end portion has a wall portion with a wall thickness W1 that is thinner than the wall thickness W3 of the central portion of the control wall 48D. Specifically, the distal end portion of the control wall 48D has a first wall portion and a second wall portion that are different in wall thickness from each other. The first wall portion is a portion including a straight line portion of a rectangular projecting end and having a wall thickness W1. The second wall portion is a straight portion located between the first wall portion and the central portion of the control wall 48D, and has a wall thickness W3 that is thicker than the wall thickness W1.

The control wall 48E has a distal end portion in which a protruding end protruding in the X-axis direction is expanded into a rectangular shape, and the distal end portion has a wall portion with a wall thickness W1 that is thicker than the wall thickness W3 at the center portion of the control wall 48E. Specifically, the distal end portion of the control wall 48E has a first wall portion and a second wall portion that are different in wall thickness from each other. The first wall portion is a portion including a straight line portion of a rectangular projecting end and having a wall thickness W1. The second wall portion is a straight portion located between the first wall portion and the central portion of the control wall 48E, and has a portion of a wall thickness W3 that is thinner than the wall thickness W1.

In this way, the distal end portions of the control walls 48B to 48E in fig. 4 to 7 have wall portions having a different thickness from the central portions of the respective control walls. When the control wall 48A of fig. 3 having the same wall thickness at the end portion, the center portion, and the root portion is used as a reference, the filter characteristics can be easily adjusted to be desired when the wall thickness is different at the end portion and the center portion as compared with when the wall thickness is different at the root portion and the center portion as shown in fig. 4 to 7. This is because the electric field is most concentrated in the central portion of the waveguide, and therefore it is conceivable that the electric field distribution is easily changed by changing the thickness of the tip portion located in the vicinity of the central portion. That is, when the thickness of the distal end portion of the control wall is adjusted, the electric field distribution is likely to change significantly, and the desired filter characteristics can be easily adjusted, as compared with the case where the thickness of the root portion of the control wall, which is relatively distant from the central portion of the waveguide, is adjusted. As a result, the degree of freedom in designing the filter characteristics of the filter 10A is improved as compared with the case where the thickness of the root portion of the control wall is adjusted.

For example, when the thickness of the end portion is smaller than that of the central portion as shown in fig. 4 to 6, the bandwidth of the transmission characteristic of the filter 10A (the frequency band in which high-frequency signals can pass through the filter 10A) can be increased as compared with the case where the thickness of the end portion is the same as that of the central portion as shown in fig. 3. On the contrary, when the thickness of the end portion is larger than that of the central portion as shown in fig. 7, the bandwidth of the transmission characteristic of the filter 10A (the frequency band in which the high-frequency signal can pass through the filter 10A) can be reduced as compared with the case where the thickness of the end portion is the same as that of the central portion as shown in fig. 3.

Further, the inventors found that even if the length L3 of the first wall portion in the X-axis direction is shorter than the length L2 of the second wall portion in the X-axis direction, the desired filter characteristics can be easily adjusted. In addition, the present inventors found that even if L3/(L2+ L3) is less than 0.2, it can be easily adjusted to a desired filter characteristic.

The center portion of the control wall indicates a portion through which the center line 30 that bisects the length L1 of the control wall in the projecting direction passes, the tip portion of the control wall indicates a portion between the projecting end of the control wall in the projecting direction and the center portion of the control wall, and the root portion of the control wall indicates a portion through which the control wall projects from the conductor wall. L1, L2, and L3 respectively denote the length of the control wall in the X-axis direction, the length of the second wall portion in the X-axis direction, and the length of the first wall portion in the X-axis direction. The boundary between the first wall portion and the second wall portion corresponds to a portion where the thickness changes.

Fig. 8 is a plan view showing a filter according to a second embodiment of the present disclosure. A filter 10B shown in fig. 8 is an example of the filter 10 shown in fig. 1, and includes a waveguide formed in a dielectric 23 surrounded by a conductor wall. Note that, in the second embodiment, the description of the same configuration and effects as those of the first embodiment is omitted by referring to the above description.

In the second embodiment, the conductor wall surrounding the dielectric 23 includes: an upper conductor wall corresponding to the first conductor layer 21; a lower conductor wall corresponding to the second conductor layer 22; and a pair of column walls 11 and 12 formed on a pair of boundary surfaces of the dielectric 23 facing each other in the X-axis direction.

The dielectric portion surrounded by the pair of pillar walls 11 and 12, the upper conductor wall, and the lower conductor wall functions as a waveguide extending in the Y-axis direction to guide electromagnetic waves in the Y-axis direction.

Each of the pair of column walls 11 and 12 is a combination of a plurality of conductor columns arranged in a fence shape. Each conductor pillar is a columnar conductor having an upper end connected to the upper conductor wall and a lower end connected to the lower conductor wall, and is, for example, a conductor plating layer formed on a wall surface of a through hole penetrating the dielectric 23 in the Z-axis direction.

The pair of column walls 11 and 12 each have a plurality of control walls protruding in the X-axis direction inside the waveguide. The filter 10B in the second embodiment includes: control walls 13a to 17a protruding from the first column wall 11 toward the second column wall 12; and control walls 13b to 17b that protrude from the second column wall 12 toward the first column wall 11. The control walls are each a combination of a plurality of conductor columns arranged in a fence-like manner. Each conductor pillar is a columnar conductor having an upper end connected to the upper conductor wall and a lower end connected to the lower conductor wall, and is, for example, a conductor plating layer formed on a wall surface of a through hole penetrating the dielectric 23 in the Z-axis direction. Each control wall may be formed of a plurality of conductive columns arranged in a plurality of rows (two rows in the case of fig. 8), or may be formed of a plurality of conductive columns arranged in a row.

L13 to L17 respectively indicate the lengths of the control walls 13a to 17a in the X axis direction. The conductor columns in the control walls 13a to 17a are arranged at intervals sufficiently shorter than the wavelength of the electromagnetic wave propagating through the waveguide. The distance between the conductor posts in the control walls 13a to 17a and the conductor posts in the first post wall 11 is also set sufficiently shorter than the wavelength of the electromagnetic wave propagating through the waveguide. The control walls 13a to 17a are set to have a wall length when viewed from the electromagnetic wave propagating through the waveguide, and function as column walls that reflect the electromagnetic wave propagating through the waveguide. The control walls 13b to 17b may be set to have the same length.

The interval L24 between the pair of column walls 11 and 12 is preferably about the same as λ g/2 when λ g is the wavelength of the electromagnetic wave propagating through the waveguide (in-tube wavelength). In addition, the distance between the control walls adjacent in the Y-axis direction is preferably about the same as λ g/2 when the wavelength of the electromagnetic wave propagating through the waveguide (in-tube wavelength) is λ g.

Thus, the filter 10B is a bandpass filter having resonators of plural stages (4 stages in the case of fig. 2) formed between the control walls adjacent in the Y-axis direction.

Fig. 9 is a plan view showing the shape of a control wall 18A as a comparative example of the control wall in the second embodiment. The control wall 18A has a rectangular columnar shape. Therefore, the wall thickness W1 at the distal end portion of the control wall 18A is the same as the wall thickness W3 at the central portion of the control wall 18A.

In contrast, the end portions of the control walls 18B to 18H shown in fig. 10 to 16 have wall portions having a different thickness from the central portions of the respective control walls. The control walls 18B to 18H are examples of the control walls 13a to 17a and 13B to 17B in the second embodiment.

The control wall 18B has a distal end portion formed by two conductive posts 19a forming a protruding end protruding in the X-axis direction and having a smaller wall thickness than that formed by two conductive posts 19c forming a central portion. That is, the distal end portion thereof has a wall portion having a wall thickness W1 that is thinner than the wall thickness W3 of the central portion of the control wall 18B. Specifically, the distal end portion of the control wall 18B has a first wall portion and a second wall portion that are different in wall thickness from each other. The first wall portion is a portion formed of two conductor posts 19a disposed at the farthest positions from the root portion of the control wall 18B in the X-axis direction and two conductor posts 19B disposed at the second farthest positions from the root portion of the control wall 18B in the X-axis direction, and has a thickness W1. The second wall portion is a straight portion located between the first wall portion and the central portion of the control wall 18B, and has a wall thickness W3 that is thicker than the wall thickness W1. The thickness W1 formed by the two conductive posts 19a disposed at the positions farthest from the root is thinner than the thickness formed by the two conductive posts 19d disposed at the positions closest to the root.

The control wall 18C has a distal end portion formed by one conductor post 19a in an elongated hole shape forming a protruding end protruding in the X-axis direction and having a smaller thickness than the two conductor posts 19C forming the center portion. That is, the distal end portion has a wall portion having a thickness W1 that is thinner than the thickness W3 of the central portion of the control wall 18C. Specifically, the distal end portion of the control wall 18C has a first wall portion and a second wall portion that are different in wall thickness from each other. The first wall portion is a portion formed of one conductor post 19a disposed at a position farthest from the root portion of the control wall 18C in the X-axis direction and two conductor posts 19b disposed at positions second farthest from the root portion of the control wall 18C in the X-axis direction, and has a thickness W1. The second wall portion is a straight portion located between the first wall portion and the central portion of the control wall 18C, and has a wall thickness W3 that is thicker than the wall thickness W1. The thickness W1 formed by the one conductor post 19a located farthest from the root is thinner than the thickness formed by the two conductor posts 19d located closest to the root.

The control wall 18D has a tip portion formed by one conductor post 19a of a perfect circle shape forming a protruding end protruding in the X-axis direction and having a wall thickness narrower than that formed by two conductor posts 19c forming a central portion. That is, the distal end portion has a wall portion having a thickness W1 that is thinner than the thickness W3 of the central portion of the control wall 18D. Specifically, the distal end portion of the control wall 18D has a first wall portion and a second wall portion that are different in wall thickness from each other. The first wall portion is a portion formed of one conductor post 19a disposed at a position farthest from the root portion of the control wall 18D in the X-axis direction and two conductor posts 19b disposed at positions second farthest from the root portion of the control wall 18D in the X-axis direction, and has a thickness W1. The second wall portion is a straight line portion located between the first wall portion and the central portion of the control wall 18D, and has a wall thickness W3 that is thicker than the wall thickness W1. The thickness W1 formed by the one conductor post 19a disposed at the position farthest from the root is thinner than the thickness formed by the two conductor posts 19d disposed at the positions closest to the root.

The control wall 18E has a distal end portion formed by two conductive posts 19a forming a protruding end protruding in the X-axis direction and having a larger wall thickness than that formed by two conductive posts 19c forming a central portion. That is, the distal end portion has a wall portion having a thickness W1 that is thicker than the thickness W3 of the central portion of the control wall 18E. Specifically, the distal end portion of the control wall 18E has a first wall portion and a second wall portion that are different in wall thickness from each other. The first wall portion is a portion formed of two conductive posts 19a disposed at the farthest positions from the root portion of the control wall 18E in the X-axis direction and two conductive posts 19b disposed at the second farthest positions from the root portion of the control wall 18E in the X-axis direction, and has a thickness W1. The second wall portion is a straight portion located between the first wall portion and the central portion of the control wall 18E, and has a portion of a wall thickness W3 that is thinner than the wall thickness W1. The thickness W1 formed by the two conductive posts 19a disposed at the positions farthest from the root is thicker than the thickness formed by the two conductive posts 19d disposed at the positions closest to the root.

The control wall 18F is identical in structure to the control wall 18E except for the point where the wall thickness W1 of the first wall portion is thicker than in the case of the control wall 18E.

The control wall 18G has a distal end portion formed by one conductor post 19a forming a protruding end protruding in the X-axis direction and having a smaller wall thickness than that formed by one conductor post 19c forming a central portion. That is, the distal end portion has a wall portion having a thickness W1 that is thinner than the thickness W3 of the central portion of the control wall 18G. Specifically, the distal end portion of the control wall 18G has a first wall portion and a second wall portion that are different in wall thickness from each other. The first wall portion is a portion formed of one conductor post 19a disposed at a position farthest from the root portion of the control wall 18G in the X-axis direction and one conductor post 19b disposed at a position second farthest from the root portion of the control wall 18G in the X-axis direction. The first wall portion has a portion with a wall thickness W1 corresponding to the diameter of one conductor post 19 a. The second wall portion is a straight portion located between the first wall portion and the central portion of the control wall 18G, and has a wall thickness W3 that is thicker than the wall thickness W1. The second wall portion has, for example, a portion having a wall thickness W3 corresponding to the diameter of one conductor post 19 c. The diameter of one of the conductive posts 19a disposed at the position farthest from the root is smaller than the diameter of one of the conductive posts 19d disposed at the position closest to the root. Therefore, the wall thickness formed by one conductor post 19a is thinner than the wall thickness formed by one conductor post 19 d.

The control wall 18H is the same as the control wall 18G in structure except that it has a terminal portion formed by one conductor post 19a forming a protruding end protruding in the X-axis direction and having a larger wall thickness than that formed by one conductor post 19c forming the center portion. The diameter of one of the conductive posts 19a disposed at the position farthest from the root is larger than the diameter of one of the conductive posts 19d disposed at the position closest to the root. Therefore, the wall thickness formed by one conductor post 19a is thicker than the wall thickness formed by one conductor post 19 d.

In this way, the end portions of the control walls 18B to 18H in fig. 10 to 16 have wall portions having a different thickness from the central portions of the respective control walls. When the control wall 18A of fig. 9 having the same wall thickness at the end portion, the center portion, and the root portion is used as a reference, the filter characteristics can be easily adjusted to be desired when the wall thickness is different at the end portion and the center portion as compared with when the wall thickness is different at the root portion and the center portion as shown in fig. 10 to 16. The reason is the same as that of the first embodiment. Therefore, the degree of freedom in designing the filter characteristics of the filter 10B is improved as compared with the case where the thickness of the root portion of the control wall is adjusted.

For example, when the thickness of the end portion is smaller than that of the central portion as shown in fig. 10 to 12 and 15, the bandwidth of the transmission characteristic of the filter 10B (the frequency band in which high-frequency signals can pass through the filter 10B) can be increased as compared with the case where the thickness of the end portion is the same as that of the central portion as shown in fig. 9. On the contrary, when the wall thickness of the end portion is larger than that of the central portion as shown in fig. 13, 14 and 16, the bandwidth of the transmission characteristic of the filter 10B (the frequency band in which the high-frequency signal can pass through the filter 10A) can be reduced as compared with the case where the wall thickness of the end portion is the same as that of the central portion as shown in fig. 9.

In the filter according to the present disclosure, each control wall may be formed of at least one conductor slit and at least one conductor post. For example, the control wall 49 shown in fig. 17 is formed of one conductor slit 49b having a wall thickness W3 and one conductor post 49a having a wall thickness W1 smaller than the wall thickness W1. In fig. 17, the thickness W1 may be larger than the thickness W3. Similarly to the above case, when the wall thickness is made different at the distal end portion and the central portion as shown in fig. 17, the desired filter characteristics can be easily adjusted as compared with the case where the wall thickness is made different at the root portion and the central portion.

The tangent line 31 is an imaginary straight line defining a boundary (a portion where the wall thickness changes) between the first wall portion and the second wall portion, and represents a tangent line between the first wall portion and the second wall portion.

Fig. 18 is a diagram showing an example of a change in filter characteristics when the shape of the end of the slit forming the control wall is changed in the filter according to the first embodiment. Fig. 18 shows filter characteristics (pass characteristics S21 as one of S parameters) when the control walls 48A to 48C of fig. 3 to 5 are applied to the control walls of the filter 10A of fig. 2, respectively. In the case of the control walls 48B and 48C having the thickness at the end portion thinner than that at the center portion, the bandwidth of the pass characteristic of the filter 10A (the frequency band in which high-frequency signals can pass through the filter 10A) can be expanded on the low-band side as compared with the case of the control wall 48A having the same thickness at the end portion as that at the center portion.

In the simulation of fig. 18, the dimensions of the portions of fig. 2 to 5 are set to mm per unit

L41：4.2

L42：17.75

L43：1.0

L44：1.3

L45：1.35

L46：1.3

L47：1.0

Distance in the X-axis direction between the left end of the filter 10A and the control wall 47a (47 b): 2.35

Distance in the X-axis direction between the control wall 47a (47b) and the control wall 46a (46 b): 2.8

Distance in the X-axis direction between the control wall 46a (46b) and the control wall 45a (45 b): 3.1

Distance in the X-axis direction between the control wall 45a (45b) and the control wall 44a (44 b): 3.1

Distance in the X-axis direction between the control wall 44a (44b) and the control wall 43a (43 b): 2.8

Distance in the X-axis direction between control wall 43a (43b) and the right end of filter 10A: 2.35

W3 (FIGS. 3-5): 0.25

L3 (fig. 4, 5): 0.125.

the dimensions of the portions of the pair of control walls opposed in the X-axis direction are the same as each other. In the simulation, quartz glass (having a relative dielectric constant r of 3.85 and a dielectric loss tangent tan of 0.0005) was assumed as a material of the dielectric 23 by using a Finite Element Method (FEM).

Fig. 19 is a diagram showing an example of a change in filter characteristics when the shape of the first conductor post 19a from the end of the control wall is changed in the filter according to the second embodiment. Fig. 19 shows filter characteristics (passage characteristics S21) when the control walls 18A to 18F of fig. 9 to 14 are applied to the control walls of the filter 10B of fig. 8, respectively. In the case of the control walls 18B to 18D having the thickness of the end portion thinner than that of the central portion, the bandwidth of the transmission characteristic of the filter 10A (the frequency band in which high-frequency signals can pass through the filter 10A) can be expanded on the low-band side as compared with the case of the control wall 18A having the same thickness of the end portion and the central portion. In the case of the control walls 18E and 18F having the thickness of the end portion larger than that of the central portion, the low-band side of the bandwidth of the pass characteristic of the filter 10A (the frequency band in which high-frequency signals can pass through the filter 10A) can be made smaller than in the case of the control wall 18A having the same thickness of the end portion and the central portion.

Fig. 20 is a diagram showing an example of a change in filter characteristics (passing characteristics S21) in the case where the shape of the second conductor post 19b from the end of the control wall is changed in the filter according to the second embodiment. That is, 18Bb shows a control wall in which the conductor post 19a and the conductor post 19B are replaced with the control wall 18B in fig. 10. Reference numeral 18Cb denotes a control wall in which the conductor post 19a and the conductor post 19b are replaced with the control wall 18C in fig. 11. Fig. 18Db shows a control wall 18D of fig. 12, in which the conductor post 19a and the conductor post 19c are replaced. Fig. 18Eb shows a control wall 18E of fig. 13 in which the conductor post 19a and the conductor post 19c are replaced. Fig. 18Fb shows a control wall 18F of fig. 14, in which the conductor post 19a and the conductor post 19c are replaced.

Fig. 21 is a diagram showing an example of a change in filter characteristics (pass characteristic S21) when the shape of the third conductor post 19c from the end of the control wall is changed in the filter according to the second embodiment. Similarly to the above, 18Bc, 18Cc, 18Dc, 18Ec, and 18Fc represent control walls having a structure in which the conductor post 19a and the conductor post 19c are replaced in the control walls 18B to 18F of fig. 10 to 14, respectively.

Fig. 22 is a diagram showing an example of a change in filter characteristics (pass characteristic S21) in the case where the shape of the fourth conductor post 19d from the end of the control wall is changed in the filter according to the second embodiment. Similarly to the above, 18Bd, 18Cd, 18Dd, 18Ed, and 18Fd are control walls having the structure in which the conductor post 19a and the conductor post 19d are replaced in the control walls 18B to 18F shown in fig. 10 to 14, respectively.

As shown in fig. 19 to 22, the passing characteristic S21 hardly changes even if the wall thickness of the wall portion formed of the conductor pillar is changed as the distance from the root of the control wall increases. In this way, it is shown that the thickness can be easily adjusted to a desired filter characteristic when the thickness is different between the end portion and the central portion, as compared with when the thickness is different between the root portion and the central portion.

In the simulations of FIGS. 19 to 22, the dimensions of the portions of FIGS. 8 to 14 are expressed in units of mm

L13：0.9

L14：1.2

L15：1.25

L16：1.2

L17：0.9

L21: 4.8 (furthermore, the filter characteristics are determined by L24)

L22：17.75

L24：4.0

Distance in the X-axis direction between the left end of the filter 10B and the control wall 17a (17B): 2.35

Distance in the X-axis direction between the control wall 17a (17b) and the control wall 16a (16 b): 2.8

Distance in the X-axis direction between the control wall 16a (16b) and the control wall 15a (15 b): 3.1

Distance in the X-axis direction between the control wall 15a (15b) and the control wall 14a (14 b): 3.1

Distance in the X-axis direction between the control wall 14a (14b) and the control wall 13a (13 b): 2.8

Distance in the X-axis direction between the control wall 13a (13B) and the right end of the filter 10B: 2.35

W3 (FIGS. 9-14): 0.25

L3 (FIGS. 9-14): 0.3

W1 (fig. 10): 0.231

W1 (fig. 11): 0.175

W1 (fig. 12): 0.100

W1 (fig. 13): 0.412

W1 (fig. 14): 0.475.

the dimensions of the portions of the pair of control walls opposed in the X-axis direction are the same as each other. In the simulation, quartz glass (having a relative dielectric constant r of 3.85 and a dielectric loss tangent tan of 0.0005) was assumed as a material of the dielectric 23 by using a Finite Element Method (FEM).

Although the filter has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various modifications and improvements such as combination or replacement with part or all of the other embodiments can be made within the scope of the present invention.

For example, the number of control walls included in the conductor wall is not limited to a plurality of control walls, and may be one control wall.

The international application claims that the entire content of the japanese patent application No. 2018-.

Description of the reference numerals

10. A filter; 11. a column wall; 13 a-17 a, 13 b-17 b, 43 a-47 a, 43 b-47 b.. control walls; a first conductor layer; a second conductor layer; a dielectric; 41. a side conductor wall.