JP3737034B2 - Coupling window and waveguide impedance matcher using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention includes a waveguide-type impedance matching device, for binding window used therefor.
[0002]
[Prior art]
The waveguide type bandpass filter and the waveguide type impedance matching device include a hollow case made of a metal material and a coupling window assembled to the case. An opening for transmitting microwaves is formed in the coupling window. This opening is formed with high accuracy according to the required characteristics. The coupling window is fixed to the case by fastening parts such as screws.
[0003]
Conventionally, in some cases, the case is made of a material having a low coefficient of thermal expansion (low thermal expansion material) such as Invar alloy in order to improve temperature characteristics. However, since the low thermal expansion material has low conductivity, a material having high conductivity, such as copper (Cu), has been used as a material for the coupling window in order to reduce transmission loss. However, copper has a large coefficient of thermal expansion, and there is a problem that the change of characteristics is large, for example, the opening contracts in response to a temperature change, which causes a mismatch with the incident microwave.
[0004]
In order to improve the temperature characteristics of the coupling window, it is proposed to reduce the transmission loss by forming the coupling window with a low thermal expansion material and plating the opening of the coupling window with Cu or Ag having a high conductivity. ing. For the same purpose, for example, as disclosed in Japanese Patent Laid-Open No. 7-170116, it is also proposed to increase the conductivity and reduce the transmission loss by baking Ag paste or Cu paste in the opening. ing.
[0005]
[Problems to be solved by the invention]
In the coupling window, the matching with the incident microwave may be shifted due to the limit on the processing accuracy of the opening, and the characteristics may be deteriorated. In addition, when Cu or Ag is plated on the opening as described above, the accuracy of the opening may deteriorate, for example, the plating layer at the end or corner of the opening tends to be locally thick. Similarly, when the paste of Cu or Ag is fired, the accuracy of the opening may be deteriorated. These also cause a decrease in microwave transmission characteristics.
[0006]
For this reason, to complete the product, measure the characteristics of the coupling window in the process of completion, make fine adjustments such as cutting the opening and adjusting the shape based on the measurement results, and then measure the characteristics again. By repeating the process of performing the process several times, a finished product that finally satisfies the required characteristics has been obtained.
[0007]
However, repeating the process for characteristic measurement and fine adjustment as described above requires a great amount of work and time until the product is completed, which increases the manufacturing cost. Moreover, since the plating layer is as thin as about 5 μm to 15 μm, if the opening is cut to some extent for fine adjustment of the characteristics, a part of the plating layer is removed.
[0008]
Therefore, when cutting the opening, it is necessary to remove the coupling window from the case and perform the plating operation again on the opening. In that case, it is necessary to detachably attach the coupling window to the case with screws or the like, which not only increases the number of parts but also eliminates the effort required for detachment. These are factors that require a great deal of work and time to complete the product.
[0009]
Accordingly, an object of the present invention is to provide a coupling window having excellent temperature characteristics, low transmission loss, and easy fine adjustment of the opening, and a waveguide type impedance matching device using the coupling window.
[0010]
[Means for Solving the Problems]
The coupling window of the present invention for achieving the above object is a coupling window having an opening through which microwaves are transmitted, a coupling window body made of a low thermal expansion material, and a conductive material having a higher conductivity than the coupling window body. An opening component member configured separately from the coupling window body, wherein the outer circumferential surface of the opening component member is diffusion bonded or brazed to the inner circumferential surface of the hole formed in the coupling window body And an opening component member having the opening portion fixed by an adhesive or an adhesive. In the present invention, it is preferable that a processing margin that allows fine adjustment processing of the opening dimension is sufficiently secured around the opening of the opening component member.
[0011]
In order to achieve the above object, a waveguide type impedance matching device of the present invention has a case and the coupling window incorporated in the case. In the present invention, it is preferable that a margin for fine adjustment of the opening dimension is secured around the opening of the opening component member.
[0012]
The present invention can be applied to a waveguide-type impedance matching device, which is an example of a waveguide-type microwave transmission body, or a waveguide-type bandpass filter, and has excellent temperature characteristics and low transmission loss. It is possible to provide a waveguide type impedance matching device, a waveguide type bandpass filter, and the like having a coupling window in which an opening can be finely adjusted in order to obtain desired characteristics.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a waveguide type impedance matching device 10 as an example of a waveguide type microwave transmission body. The waveguide type impedance matching unit 10 includes, for example, a cylindrical hollow metal case 11 and a disk-shaped coupling window 12 attached to the case 11. The coupling window 12 is fixed to a flange portion 13 formed at the end portion of the case 11 by a fastening component 14 such as a screw.
[0014]
The material of the case 11 is an invar alloy or a super invar alloy as an example of a low thermal expansion material, a low thermal expansion cast steel material (low carbon steel material or extremely low carbon steel material), and the like. The chemical composition (mol%) of the Invar alloy is Fe: 64.6% and Ni: 35.4%. The super invar alloy is Fe: 64.2%, Ni: 31.0%, Co: 4.8%. Other various invar alloys (for example, stainless invar, Fe—B, Cr—Fe—Mn, Mn—Ge, etc.) may be employed.
[0015]
As shown in FIG. 2, the coupling window 12 includes a coupling window main body 21 and an opening component member 22 provided at the center of the coupling window main body 21. An opening 23 having a shape that allows microwaves to pass therethrough (for example, a rectangle) is formed in the opening member 22.
[0016]
As shown in FIGS. 3A to 3D, the coupling window 12 includes a low thermal expansion material 21 a that is a material of the coupling window body 21 and a disk-shaped conductive material 22 a that is a material of the opening component member 22. That is, by using a metal having higher conductivity than the low thermal expansion material 21a (for example, Cu, Ag, or an alloy thereof), for example, by joining the low thermal expansion material 21a and the opening component member 22 by diffusion bonding described below. Produced.
[0017]
As shown to (A) in FIG. 3, the circular hole 30 is formed in the center part of the low thermal expansion material 21a. The inner peripheral surface 31 of the hole 30 is a tapered surface inclined at an angle θ1 over the entire periphery. The outer peripheral surface 32 of the conductive material 22a is a tapered surface having an angle θ2 corresponding to the angle θ1. The angles θ1 and θ2 are preferably in the range of 60 degrees to 80 degrees, for example. Desirably, the plate thickness T1 of the conductive material 22a is slightly larger than the plate thickness T2 of the low thermal expansion material 21a.
[0018]
For example, the conductive material 22a made of Cu, for example, is fitted into the hole 30 of the low thermal expansion material 21a made of Invar alloy, and the inner peripheral surface 31 and the outer peripheral surface 32 are aligned as shown in FIG. Then, the low thermal expansion material 21a and the conductive material 22a are pressurized in the thickness direction, and the conductive material 22a is plastically deformed to bring the inner peripheral surface 31 of the low thermal expansion material 21a and the outer peripheral surface 32 of the conductive material 22a into close contact with each other.
[0019]
In such a state where the low thermal expansion material 21a and the conductive material 22a are brought into close contact with each other, the region including the inner peripheral surface 31 and the outer peripheral surface 32 is heated to the diffusion temperature and held for a predetermined time, whereby the metal atoms of the conductive material 22a (For example, Cu) and metal atoms of the low thermal expansion material 21a are diffused mutually. By this diffusion, the low thermal expansion material 21a and the conductive material 22a can be joined extremely firmly metallicly. The heating temperature at that time is, for example, about 70% to 90% of the melting point of Cu (about 1084 ° C.).
[0020]
After cooling, the shape may be adjusted by machining or the like as shown in FIG. 3C, or the distortion is removed by applying heat treatment such as plastic working or annealing. After that, as shown in FIG. 3D, an opening 23 through which microwaves are transmitted is formed in the opening constituting member 22 by machining such as cutting.
[0021]
In the coupling window 12 formed in this manner, depending on the accuracy of the opening 23, the matching with the incident microwave may be shifted and the characteristics may be deteriorated. For this reason, the characteristics of the coupling window 12 are measured, and after performing fine adjustment processing such as finishing machining such as cutting the opening 23 based on the measurement result, the characteristics are measured again. The process may be repeated.
[0022]
Since the waveguide type impedance matching device 10 of this embodiment is obtained by joining a conductive material 22a such as Cu to the center portion of the low thermal expansion material 21a, a portion having a high conductivity such as Cu around the opening 23 is provided. The thickness can be 2 to 3 mm or more. That is, the machining margin M for fine adjustment of the characteristics can be secured in the opening 23 by 1 mm or more, which is much larger than the case of forming a Cu or Ag layer (5 μm to 15 μm) by plating. The machining margin M can be obtained.
[0023]
In addition, the waveguide type impedance matching device 10 does not require re-plating after fine adjustment of the opening 23. Therefore, a time-consuming process such as removing the coupling window 12 from the case 11 or reassembling after re-plating. It is unnecessary.
[0024]
Since it is not necessary to remove the coupling window 12 from the case 11 as described above, the coupling window 12 is integrated with the inside of the case 11 as in the waveguide type impedance matching device 10 'of the second embodiment shown in FIG. It is also possible to provide them, and it is not necessary to use removable parts such as screws, so that the number of parts required can be greatly reduced, such as fewer parts.
[0025]
Further, since it is not necessary to perform plating of Cu or Ag on the opening 23 or to fire Cu or Ag paste, the end and corner of the opening 23 can be finished with high accuracy. For this reason, it is possible to reduce the characteristic measurement and the processing for fine adjustment of the opening 23 required until the product is completed.
[0026]
5A to 5D show an example in which the coupling window 12 is manufactured by brazing. As shown to (A) in FIG. 5, the low thermal expansion material (for example, Invar alloy) 21a which has the circular hole 30, the disk-shaped electrically-conductive material (for example, Cu) 22a, and the brazing material 40 are used. The inner peripheral surface 31 of the hole 30 and the outer peripheral surface 32 of the conductive material 22a may be tapered surfaces inclined at an angle of 60 to 80 degrees, as in the example of diffusion bonding shown in FIG. The brazing material 40 may be in the form of a foil or a rod, or may be in the form of powder or paste.
[0027]
The conductive material 22a is fitted into the hole 30 of the low thermal expansion material 21a, and the brazing material 40 is melted by heating and then cooled, as shown in FIG. 5B, the low thermal expansion material 21a. The inner peripheral surface 31 and the outer peripheral surface 32 of the conductive material 22 a are joined to each other by the brazing material 40.
[0028]
When brazing the conductive material 22a made of Cu and the low thermal expansion material 21a made of Invar alloy or Super Invar alloy, for example, Ag brazing, solder, Ni brazing, or the like can be used as the brazing material 40. The usable temperature of the bonding window 12 manufactured by Ag brazing is from room temperature to around 300 ° C. In the case of solder joint, the usable temperature of the joint window 12 is from room temperature to around 200 ° C. In the case of Ni brazing, the usable temperature is from room temperature to around 700 ° C. Thus, what is necessary is just to select the material of the brazing material 40 according to use temperature.
[0029]
After the brazing material 40 is cured, as shown in FIG. 5C, the shape is adjusted by machining or plastic working, and the strain is removed by heat treatment such as annealing as necessary. After that, as shown in FIG. 5D, an opening 23 through which microwaves are transmitted is formed by machining such as cutting.
[0030]
Instead of using the brazing material 40, the conductive material 22a and the low thermal expansion material 21a may be joined by an adhesive. Although illustration is omitted about the case where an adhesive is used, the low thermal expansion material 21a and the conductive material 22a similar to the example described in FIG. 5 are used, and the inner peripheral surface 31 of the low thermal expansion material 21a and the outer periphery of the conductive material 22a. An adhesive is supplied between the surface 32 instead of the brazing material 40 and dried to fix the low thermal expansion material 21a and the conductive material 22a to each other. After the adhesive is cured, the opening 23 is formed by machining or the like, similar to (D) in FIG. Examples of the adhesive used here include polyimide, phenolic, silicon, and epoxy resin adhesives.
[0031]
Further, as in the third embodiment shown in FIG. 6, the opening component member having the opening 23 by spraying a conductive material 51 such as Cu or Ag on the inner peripheral portion of the opening 50 of the coupling window main body 21. 22 may be formed. In this case, it is assumed that the conductive material 51 is sufficiently sprayed so that the opening component member 22 has a thickness that can secure the processing margin for adjusting the characteristics described above.
[0032]
Alternatively, as in the fourth embodiment shown in FIG. 7, the cylindrical first base material 60 made of a low thermal expansion material such as Invar alloy, which is the material of the coupling window main body 21, and the material of the opening component member 22. A rod-shaped intermediate product 62 is manufactured by bonding the rod-shaped second base material 61 made of a conductive material such as Cu with the aforementioned diffusion bonding or brazing, and bonding with an adhesive to form the opening 23. May be. In this case, by slicing the intermediate product 62 in the radial direction, a large number of coupling windows 12 having a predetermined thickness t can be efficiently manufactured.
[0033]
The present invention can also be applied to, for example, a dielectric filter 10A as in the fifth embodiment shown in FIG. Similar to the impedance matching device 10, the dielectric filter 10 </ b> A includes a case 11 and a coupling window 12. The coupling window 12 is more conductive than the coupling window body 21 made of a low thermal expansion material. And an opening component member 22 made of a highly conductive material. A dielectric 70 is accommodated in the case 11.
[0034]
The present invention can also be applied to, for example, a waveguide bandpass filter 10B as in the sixth embodiment shown in FIG. Similarly to the impedance matching device 10, the waveguide type bandpass filter 10 </ b> B includes a case 11 and a coupling window 12. The coupling window 12 includes a coupling window body 21 made of a low thermal expansion material, and the coupling window body 21. And an opening constituting member 22 made of a conductive material having a high conductivity.
[0035]
In carrying out the present invention, the present invention includes the specific shape of the case and the coupling window, the shape of the opening, the shape of the coupling window body, the shape of the opening component, the component of the low thermal expansion material or the conductive material, etc. It goes without saying that the above-described components can be appropriately modified and implemented without departing from the scope of the invention.
[0036]
【The invention's effect】
According to the first aspect of the present invention, it is possible to finely adjust the opening for obtaining desired characteristics, and since the thermal expansion is small, the temperature characteristic is excellent, and the opening has high conductivity, so that transmission loss is low. small coupling window is Ru obtained.
[0037]
According to the invention described in claim 2 , fine adjustment can be performed so that desired characteristics can be obtained by performing processing such as cutting the opening based on the actual measurement result of the characteristics. The possible range can be taken far wider than the plating layer.
[0039]
According to the third aspect of the present invention, the waveguide-type impedance is capable of fine adjustment of the opening, excellent in temperature characteristics because of small thermal expansion, and low in transmission loss because of high conductivity of the opening. Ru it is possible to provide a matching unit.
[Brief description of the drawings]
FIG. 1 is a side view of a waveguide type impedance matching device showing a first embodiment of the present invention.
FIG. 2 is a front view of a coupling window of the waveguide type impedance matching device shown in FIG.
3 is a cross-sectional view showing a low thermal expansion material, a conductive material, and the like in the order of steps when the bonding window shown in FIG. 2 is manufactured by diffusion bonding.
FIG. 4 is a side view of a waveguide type impedance matching device showing a second embodiment of the present invention.
FIG. 5 is a cross-sectional view showing a low thermal expansion material, a conductive material, and the like in the order of steps when the bonding window shown in FIG. 2 is manufactured by brazing.
FIG. 6 is a front view of a coupling window showing a third embodiment of the present invention.
FIG. 7 is a perspective view of a coupling window showing a fourth embodiment of the present invention and an intermediate product used for manufacturing the coupling window.
FIG. 8 is a side view of a dielectric filter showing a fifth embodiment of the present invention.
FIG. 9 is a side view of a waveguide type bandpass filter showing a sixth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10, 10 '... Waveguide type | mold impedance matching device 10A ... Dielectric filter 10B ... Waveguide-type end-pass filter 11 ... Case 12 ... Coupling window 21 ... Coupling window main body 21a ... Low thermal expansion material 22 ... Opening component 22a ... conductive material 23 ... opening M ... processing

Claims (3)

A coupling window having an opening through which microwaves pass,
A combined window body made of a low thermal expansion material;
An opening component member made of a conductive material having a higher conductivity than the coupling window main body and configured separately from the coupling window main body, and an outer peripheral surface of the opening component member is formed on the coupling window main body An opening component fixed to the inner peripheral surface of the hole formed by diffusion bonding, brazing, or adhesive, and having the opening;
A coupling window characterized by comprising:   The coupling window according to claim 1, wherein a machining margin that enables fine adjustment processing of an opening dimension is secured in the opening of the opening component member. A case and a coupling window incorporated in the case;
The waveguide type impedance matching device according to claim 1, wherein the coupling window is a coupling window according to claim 1.

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