JP5696499B2 - Waveguide connection structure - Google Patents

Description

  The present invention relates to a waveguide connection structure.

  Conventionally, for example, a choke groove having a predetermined depth (= λ / 4) by a signal propagation wavelength λ in free space is provided in a flange-like connection portion of a waveguide connected to a resin substrate, and the resin substrate and the waveguide are A high-frequency module that suppresses leakage of a high-frequency signal having a predetermined frequency at a connection boundary is known. (For example, refer to Patent Document 1).

International Publication No. 2007/091470

By the way, according to the high-frequency module according to the above-described prior art, leakage of a high-frequency signal having a predetermined frequency is suppressed by the choke groove having a predetermined depth (= λ / 4). Due to the formation of the resonator having the connection boundary and the choke groove as a path, resonance may occur at a resonance frequency in a frequency band other than the predetermined frequency.
For this reason, it is difficult to suppress leakage of high-frequency signals when the desired frequency band matches the frequency band including the resonance frequency in a setting using another frequency band as the desired frequency band in addition to the predetermined frequency. The problem that there is.

  The present invention has been made in view of the above circumstances, and provides a waveguide connection structure capable of suppressing leakage of a high-frequency signal in a desired frequency band at a connection boundary between a resin substrate and a waveguide. It is aimed.

In order to solve the above-described problems and achieve the object, a waveguide connection structure according to the present invention is a waveguide connecting a waveguide and a dielectric substrate formed by laminating a dielectric layer and a metal layer. In the connection structure, the dielectric substrate includes a metal layer through hole provided on a connection surface of the metal layer connected to the waveguide, a via provided in the dielectric substrate, and the metal layer. And a cavity communicating with the metal layer through-hole, and the cavity is formed by laminating a plurality of dielectrics having different dielectric constants .

According to the waveguide connection structure of the present invention, the dielectric substrate to which the waveguide is connected is provided with a cavity formed so as to be surrounded by the via and the metal layer. The high-frequency signal leaking to the connection boundary resonates along the connection boundary and the cavity. Thereby, compared with the case where the cavity is not provided, the resonant frequency can be lowered.
In addition, the resonance frequency can be controlled according to the size of the cavity, and the leakage of high frequency signals in the desired frequency band is suppressed by controlling the desired frequency band so as not to coincide with the frequency band including the resonance frequency. be able to.

It is a block diagram of the waveguide connection structure which concerns on embodiment of this invention. It is an example of the figure which looked at the waveguide of the waveguide connection structure concerning embodiment of this invention, and the cavity of a dielectric substrate from the axial direction. It is a block diagram of the waveguide connection structure which concerns on the 1st modification of embodiment of this invention. It is a block diagram of the waveguide connection structure which concerns on the 2nd modification of embodiment of this invention. It is a block diagram of the waveguide connection structure which concerns on the 3rd modification of embodiment of this invention. It is a block diagram of the waveguide connection structure which concerns on the 4th modification of embodiment of this invention. It is a block diagram of the waveguide connection structure which concerns on the 5th modification of embodiment of this invention. It is a block diagram of the waveguide connection structure which concerns on the 6th modification of embodiment of this invention. Compared to the waveguide connection structure according to the fifth modification of the embodiment of the present invention and the waveguide connection structure of the comparative example, the high-frequency signal input from the waveguide to the hollow portion of the dielectric substrate It is a figure which shows the result of the simulation of the change of the passage loss according to a frequency. In the waveguide connection structure according to the fifth modification of the embodiment of the present invention, the interval d between the vias forming both ends of the cavity is changed to three different intervals do, 1.4 do, and 1.8 do. It is a figure which shows the result of the simulation of the change of the passage loss according to the frequency of the high frequency signal input into the hollow part of a dielectric substrate from a waveguide with respect to the case.

Hereinafter, a waveguide connection structure according to an embodiment of the present invention will be described with reference to the accompanying drawings.
A waveguide connection structure 10 according to the present embodiment includes a waveguide 11 and a dielectric substrate 12 to which the waveguide 11 is connected, for example, as shown in FIG.

The waveguide 11 is, for example, a cylindrical hollow waveguide that transmits microwaves, and is a rectangular waveguide whose cross-sectional shape orthogonal to the axial direction A is formed in a rectangular shape.
The waveguide 11 includes, at one end in the axial direction A, an incident / exit portion 11a through which microwaves enter or exit at one end in the axial direction A, and at the other end in the axial direction A, a dielectric substrate. 12 is provided with a flange-like connecting portion 21 having an open end 11 b connected to the head 12.

The dielectric substrate 12 is configured by alternately laminating dielectric layers 31 and metal layers 32, and faces the vias 33 electrically connected to the plurality of metal layers 32 and the open end 11 b of the waveguide 11. A hollow portion 34 communicating with the dielectric substrate 12 in the thickness direction is provided.
An appropriate dielectric may be disposed in the hollow portion 34.

  Then, at one end in the thickness direction of the dielectric substrate 12 (that is, the direction parallel to the axial direction A), the connection surface 32A of the metal layer 32 that faces the facing surface 21A of the connection portion 21 of the waveguide 11 is used. On the top, a metal layer through-hole 32a that penetrates the metal layer 32 in the thickness direction is provided.

  The dielectric substrate 12 is formed so as to be surrounded by the plurality of metal layers 32 including the metal layer 32 provided with the metal layer through-holes 32a and the plurality of vias 33, and faces the metal layer through-holes 32a. And a cavity 35 communicating with each other.

  The cavity 35 may be formed in parallel to the longitudinal direction L of the waveguide 11 having a rectangular cross section with respect to the axial direction A as shown in FIG. 2A, for example, as shown in FIG. As shown, the waveguide 11 having a rectangular cross section with respect to the axial direction A may be formed in parallel with the short direction S of the waveguide 11. For example, as shown in FIG. It may be formed so as to surround the periphery of the shaped waveguide 11.

  The waveguide connection structure 10 according to the present embodiment has the above-described configuration. Next, the waveguide connection structure 10 and microwave passage loss will be described.

  In this waveguide connection structure 10, the distance d between the vias 33, 33 forming both ends of the cavity 35 is set within the free space of the microwave input from the waveguide 11 to the hollow portion 34 of the dielectric substrate 12. By setting the quarter wavelength (= λ / 4) of the signal propagation wavelength λ, for example, a choke groove having a predetermined depth (= λ / 4) is formed on the facing surface 21A of the connection portion 21 of the waveguide 11. Without the necessity, the leakage of the microwave at the connection boundary between the dielectric substrate 12 and the waveguide 11 is suppressed.

  Furthermore, in this waveguide connection structure 10, a part of the microwave input from the waveguide 11 to the hollow portion 34 of the dielectric substrate 12 leaks to the connection boundary between the dielectric substrate 12 and the waveguide 11. Then, since the wave is guided through the connection boundary and the cavity 35 and resonates through the connection boundary and the cavity 35 as a path, for example, the resonance frequency is lowered compared with the case where the cavity 35 is not provided, and the leakage of the microwave is reduced. It is suppressed.

  Further, in this waveguide connection structure 10, the distance d between the vias 33, 33 forming both ends of the cavity 35 is changed to increase (that is, the length of the cavity 35 in the direction orthogonal to the axial direction A). Therefore, the resonance frequency of the resonance through the connection boundary and the cavity 35 changes in a decreasing tendency. Therefore, the resonance frequency is controlled according to the distance d between the vias 33 and 33, Microwave leakage is suppressed.

  As described above, according to the waveguide connection structure 10 according to the present embodiment, the cavity 35 formed so as to be surrounded by the via 33 and the metal layer 32 in the dielectric substrate 12 to which the waveguide 11 is connected. For example, even if the choke groove is not provided on the facing surface 21A of the connection portion 21 of the waveguide 11, the microwave leaks to the connection boundary between the dielectric substrate 12 and the waveguide 11. Can be suppressed.

  Furthermore, the microwave leaked to the connection boundary between the dielectric substrate 12 and the waveguide 11 is guided through the connection boundary and the cavity 35 and resonates using the connection boundary and the cavity 35 as a path. The resonance frequency can be lowered compared with the case where no is provided, and microwave leakage can be suppressed.

  In addition, the distance d between the vias 33 and 33 forming both ends of the cavity 35 is changed to increase (that is, the length of the cavity 35 in the direction orthogonal to the axial direction A is changed to increase). Along with this, the resonance frequency of resonance through the connection boundary and the cavity 35 changes in a decreasing tendency, so that the resonance frequency can be controlled according to the distance d between the vias 33 and 33, and microwave leakage is easy. Can be suppressed.

  In the above-described embodiment, for example, as shown in FIGS. 3 and 4, a plurality of cavities 35,..., 35 having different configurations are formed so as to be axially asymmetric with respect to the waveguide 11. Also good.

  For example, in the waveguide connection structure 10 according to the first modification of the above-described embodiment shown in FIG. 3, two cavities arranged so as to sandwich the waveguide 11 from both sides in the direction orthogonal to the axial direction A. One of the cavities 35 (35 </ b> A) is formed by stacking a plurality of, for example, two cavity regions 41 and 42 in the thickness direction of the dielectric substrate 12.

The cavity regions 41 and 42 are formed so as to be surrounded by the metal layer 32 and the via 33 for each of the cavity regions 41 and 42, and the adjacent cavity regions 41 and 42 in the stacking direction are the cavity regions 41. , 42 are communicated by a metal layer through hole 32a provided in the metal layer 32.
Further, the cavity regions 41 and 42 are formed with the same distance d between the vias 33 and 33 forming both ends of the cavity regions 41 and 42.

  The other cavity 35 (35B) is configured by a single cavity region 43 formed so as to be surrounded by the metal layer 32 and the via 33.

  According to the first modification, leakage of microwaves can be suppressed in a plurality of desired frequency bands by the plurality of cavities 35,.

  Further, for example, in the waveguide connection structure 10 according to the second modification example of the above-described embodiment shown in FIG. 4, two waveguides 11 are arranged so as to sandwich the waveguide 11 from both sides in a direction orthogonal to the axial direction A. Of the cavities 35, 35, one cavity 35 (35 </ b> C) is formed by laminating a plurality of, for example, two cavity regions 44, 45 in the thickness direction of the dielectric substrate 12.

The cavity regions 44 and 45 are formed so as to be surrounded by the metal layer 32 and the vias 33 for each of the cavity regions 44 and 45, and the adjacent cavity regions 44 and 45 in the stacking direction are the cavity regions 44. , 45 are communicated by a metal layer through hole 32a provided in the metal layer 32.
Further, the cavity regions 44 and 45 are formed so that the distances d1 and d2 between the vias 33 and 33 forming both ends of the cavity regions 44 and 45 are different from each other.

  The other cavity 35 (35D) is formed by laminating a plurality of, for example, two cavity regions 46 and 47 in the thickness direction of the dielectric substrate 12.

The cavity regions 46 and 47 are formed so as to be surrounded by the metal layer 32 and the vias 33 for each cavity region 46 and 47, and the adjacent cavity regions 46 and 47 in the stacking direction are the cavity regions 46. , 47 are communicated by a metal layer through hole 32a provided in the metal layer 32.
The metal layer through hole 32a provided in the metal layer 32 between the cavity regions 46 and 47 and the metal layer through hole 32a provided in the metal layer 32 facing the connection portion 21 of the waveguide 11 are axial It is provided at a position shifted in a direction orthogonal to the axial direction A so as not to face each other in a direction parallel to the direction A.

According to the second modification, leakage of microwaves in a plurality of desired frequency bands can be suppressed by the plurality of cavities 35,.
Further, the metal layer through hole 32 a provided in the metal layer 32 between the cavity regions 46 and 47 laminated in the thickness direction of the dielectric substrate 12 and the metal layer 32 facing the connection portion 21 of the waveguide 11 are provided. It is not necessary to face the provided metal layer through-hole 32a in a direction parallel to the axial direction A, and the design freedom of the dielectric substrate 12 can be improved.

  In the above-described embodiment, a plurality of, for example, two different dielectric constants are provided in the cavity 35 as in the waveguide connection structure 10 according to the third modification of the above-described embodiment shown in FIG. The dielectrics 51 and 52 may be stacked in the thickness direction of the dielectric substrate 12.

According to the third modification, the dielectrics 51 and 52 having different dielectric constants are stacked in the thickness direction of the dielectric substrate 12, thereby connecting the boundary between the dielectric substrate 12 and the waveguide 11. It is easy to guide the microwave leaked into the cavity 35, and the effectiveness of the microwave leakage suppression by the cavity 35 can be improved.
For example, a dielectric having a low dielectric constant is disposed at a position close to the connection portion 21 of the waveguide 11 in the thickness direction of the dielectric substrate 12, and a dielectric is disposed at a position away from the connection portion 21 of the waveguide 11. By disposing a high-permittivity dielectric, the difference in dielectric constant between the air layer at the connection boundary between the dielectric substrate 12 and the waveguide 11 and the inside of the cavity 35 can be reduced, and the micro leaked to the connection boundary. It becomes easy to guide the wave into the cavity 35.

  In the above-described embodiment, for example, an open end 34a on the waveguide 11 side of the hollow portion 34 as in the waveguide connection structure 10 according to the fourth modification of the above-described embodiment shown in FIG. May be blocked by the metal layer 32 facing the facing surface 21A of the connecting portion 21 of the waveguide 11.

According to the fourth modification, the microwave transmitted from the waveguide 11 toward the dielectric substrate 12 in the axial direction A passes through the open end 34 a on the waveguide 11 side of the hollow portion 34 of the dielectric substrate 12. The transmission direction is changed in a direction orthogonal to the axial direction A by the metal layer 32 to be closed.
That is, a so-called bend portion is formed by the metal layer 32, and leakage of microwaves in the bend portion can be suppressed by the cavity 35, and the resonance resonance frequency including the bend portion as a path is controlled. can do.

In the above-described embodiment, the waveguide 11 has a flange-like connection portion 21 like the waveguide connection structure 10 according to the fifth modification of the above-described embodiment shown in FIG. You may provide the groove part 61 provided on 21 A of opposing surfaces.
The groove portion 61 of the waveguide 11 is disposed so as to face and communicate with the metal layer through hole 32 a provided in the metal layer 32 facing the connection portion 21 of the waveguide 11.

  According to the fifth modification, the microwave leaked to the connection boundary between the dielectric substrate 12 and the waveguide 11 is guided through the connection boundary, the groove 61 and the cavity 35, and the connection boundary and the groove 61 and Since resonance is performed using the cavity 35 as a path, for example, the resonance frequency can be lowered compared to the case where the groove 61 and the cavity 35 are not provided, and microwave leakage can be suppressed.

Further, in the fifth modification, the distance d between the vias 33, 33 forming both ends of the cavity 35 is set to 1, the resonance path length other than the groove 61 is 1, and the signal propagation wavelength λ in the free space of the microwave Depending on the depth h of the groove 61, the effective electrical length may be set to satisfy d = (λ / 2) −h−1.
In this case, the resonance frequency can be controlled in accordance with the distance d between the vias 33 and 33, and microwave leakage can be easily suppressed.

  In the fifth modification, for example, in the waveguide connection structure 10 according to the sixth modification shown in FIG. The metal layer through-hole 32a provided in the opposing metal layer 32 may be provided at a position shifted in a direction orthogonal to the axial direction A so as not to oppose in a direction parallel to the axial direction A.

  According to the sixth modification, the groove portion 61 of the waveguide 11 and the metal layer through-hole 32a provided in the metal layer 32 facing the connection portion 21 of the waveguide 11 are parallel to the axial direction A. There is no need to face each other in the direction, and the design freedom of the dielectric substrate 12 can be improved.

For example, in FIG. 9, the waveguide 11 is hollow from the waveguide 11 to the waveguide connection structure 10 according to the fifth modification of the embodiment described above and the waveguide connection structure of the comparative example. The result of the simulation of the change of the passage loss according to the frequency of the high frequency signal input to the unit 34 is shown.
The waveguide connection structure of the comparative example corresponds to the waveguide connection structure 10 according to the fifth modification example of the above-described embodiment in which the cavity 35 is omitted.

In the comparative example, three resonances are generated in a frequency band near 1.5 fo and 1.1 fo with respect to the predetermined frequency fo (Hz), and the passage loss increases at the resonance frequency of these resonances. Yes.
On the other hand, in the fifth modification, the frequency band in which the resonance occurs is entirely lowered, and the number of resonances in this frequency band is reduced to two, 1.3fo and 1.05fo.
That is, it is recognized that the resonance frequency of the resonance including the connection boundary between the waveguide 11 and the dielectric substrate 12 as a path can be lowered in the fifth modified example having the cavity 35 as compared with the comparative example. .

  Further, for example, in FIG. 10, in the waveguide connection structure 10 according to the fifth modification example of the above-described embodiment, the distance d between the vias 33 that form both ends of the cavity 35 is represented by three different distances do. , 1.4 do, and 1.8 do, the simulation result of the change in the passage loss according to the frequency of the high frequency signal input from the waveguide 11 to the hollow portion 34 of the dielectric substrate 12 is shown. Indicated.

  Along with changing the distance d between the vias 33 forming both ends of the cavity 35 in an increasing tendency (that is, changing the length of the cavity 35 in the direction orthogonal to the axial direction A), It can be seen that the resonance frequency of the resonance including the connection boundary between the waveguide 11 and the dielectric substrate 12 as a path changes in a decreasing tendency.

DESCRIPTION OF SYMBOLS 10 Waveguide connection structure 11 Waveguide 12 Dielectric board | substrate 21 Connection part 31 Dielectric layer 32 Metal layer 33 Via 34 Hollow part 35 Cavity 61 Groove part

Claims (9)

A waveguide connection structure for connecting a dielectric substrate formed by laminating a dielectric layer and a metal layer and a waveguide,
The dielectric substrate is
A metal layer through-hole provided on a connection surface of the metal layer connected to the waveguide;
A via formed in the dielectric substrate and surrounded by the metal layer , and a cavity communicating with the metal layer through-hole ,
The waveguide connection structure , wherein the cavity is configured by laminating a plurality of dielectrics having different dielectric constants . The dielectric constant of the dielectric disposed at a position close to the waveguide is lower than the dielectric constant of the dielectric disposed at a position separated from the waveguide. The waveguide connection structure described. Each of the cavity regions is formed so as to be surrounded by the metal layer and the via,
The cavity regions adjacent in the stacking direction communicate with each other through a through hole provided in the metal layer between the cavity regions,
3. The waveguide connection structure according to claim 1, wherein an interval between the vias forming both ends of the cavity region is different for each of the plurality of cavity regions. The waveguide according to any one of claims 1 to 3, wherein the waveguide includes a groove portion provided on a connection surface of a connection portion connected to the dielectric substrate. Connection structure. The distance d between the vias forming both ends of the cavity is determined by the following equation: d = (λ //), where the resonance path length other than the groove is 1, and the signal propagation wavelength λ in free space and the depth h of the groove. 2) The waveguide connection structure according to claim 4, wherein the waveguide connection structure is set to satisfy -h-1. 5. The waveguide according to claim 1, wherein an interval between the vias forming both ends of the cavity is a quarter wavelength of a signal propagation wavelength in free space. Pipe connection structure. The waveguide connection structure according to any one of claims 1 to 6, wherein the cavity is formed in parallel with a longitudinal direction of the waveguide. The waveguide connection structure according to any one of claims 1 to 6, wherein the cavity is formed in parallel with a short direction of the waveguide. The waveguide connection structure according to any one of claims 1 to 6, wherein the cavity is formed so as to surround a periphery of the waveguide.

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