JP2009010844A - Waveguide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waveguide which has a corner portion that is superior in the reflection properties of electromagnetic waves and in electric-power resistance properties and besides can readily be made compact and manufactured. <P>SOLUTION: The waveguide 100 is equipped with a pair of extending portions 10A, 10B extending in directions of tube axes 11A, 11B, a corner portion 12, which couples the extending portions to each other so that an angle made between one tube axis 11A and the other tube axis 11B in the pair of the extending portions become a desired angle, and one or more metallic bars 20 provided in the corner portion 12. The corner portion 12 has a hollow region 16 partitioned by a metallic surface 15, while the metallic bar 20 extends so as to penetrate the hollow region 16. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a waveguide, and more particularly to a technique for improving the reflection loss of an electromagnetic wave propagating through a corner portion of a waveguide.

  When constructing a rectangular waveguide circuit system, it is necessary to bend the rigid waveguide in view of the waveguide layout. When the waveguide is bent at a desired angle, this becomes a discontinuous portion, and a large reflected wave is generated in the discontinuous portion. In other words, a portion of such a waveguide bending structure (hereinafter referred to as “corner portion”) is a circuit having a characteristic impedance different from that of a linearly extending portion (hereinafter referred to as “extended portion”) of the same cross section. Become. For this reason, various bending waveguides have been proposed in the past so as to appropriately suppress the reflection loss of the electromagnetic wave propagating through the transmission path of the corner portion (for example, see Non-Patent Document 1), and already provided as a commercial product. Has been.

  For example, a conventional product (hereinafter referred to as “circular bend”) in which a rectangular waveguide is bent at 90 ° with a certain radius of curvature so that the direction of electromagnetic waves propagating in the rectangular waveguide can be smoothly changed along the bending direction. ) Thereby, the above-mentioned discontinuous portion is eliminated, and reflection loss of electromagnetic waves propagating through the waveguide can be appropriately suppressed.

Also, the rectangular waveguide is bent at a substantially right angle, and the outer corners are cut off in a taper direction in a direction of 45 ° with respect to the direction of the tube axis. There is also a conventional product called miter structure. In this case, it is said that the reflection loss can be reduced by inserting a capacitive conductor screw into a tube corresponding to the corner portion of the miter structure waveguide (hereinafter referred to as such). A miter waveguide with a conductor screw is called a “tuned miter bend”.
Bunichi Oguchi, “Microwave and Millimeter-wave Circuit” (Maruzen, 1964, 314-315)

However, in the above-mentioned circular bend, from the viewpoint of appropriately suppressing the reflection loss of electromagnetic waves, the radius of curvature of the corner portion of the rectangular waveguide cannot be sufficiently reduced, and the corner portion of the waveguide is increased in size. There's a problem. Further, the performance of the waveguide may be deteriorated due to distortion during drawing and bending of the waveguide. The reflection loss | S ₁₁ | (dB) at the S parameter at the corner of the waveguide is generally considered to be preferably −40 dB or less. However, in this circular bend, the reflection loss | S ₁₁ | not necessarily the be appropriate and sufficiently low. The measurement result of the reflection loss of the circular bend will be described later.

On the other hand, in the above-described tuned miter bend, electric field concentration due to electromagnetic waves is generated at the tip of the conductor screw, so that there is a difficulty in the power durability characteristics of the waveguide. In addition, it is considered that the reflection loss | S ₁₁ | (dB) at the S parameter of the waveguide corner is usually preferably “−40 dB” or less. However, in this tuned miter bend, this condition is satisfied. In some cases, the specific bandwidth that satisfies the above requirement is not necessarily sufficiently wide. The measurement result of the reflection loss of the tuned miter bend will be described later.

  Furthermore, it would be beneficial if the reflection characteristics of the corners could be adapted to various uses of the waveguide by simple design changes of the waveguide, but the conventional products described above (circular bend and tuned miter bend) are It is hard to say that it has excellent adaptability.

  As mentioned above, conventional products such as circular bends and tuned miter bends are still improving both in terms of performance such as electromagnetic wave reflection characteristics and power handling characteristics, and structural aspects such as compactness and ease of manufacture. There is a lot of room for it.

  The present invention has been made in view of such circumstances, and has a corner portion excellent in electromagnetic wave reflection characteristics and power durability characteristics, and can be made compact and easy to manufacture. The purpose is to provide.

In order to solve the above problems, the present invention includes a pair of extending portions extending in the direction of the tube axis,
The pair of extension portions are mutually connected so that an angle formed between one tube axis of the pair of extension portions and the other tube axis of the pair of extension portions becomes a desired angle. A corner section to be connected;
One or more metal rods provided in the corner portion,
The corner portion has a hollow region defined by a metal surface, and the metal rod provides a waveguide extending through the hollow region.

  As described below, such a waveguide has a corner portion excellent in electromagnetic wave reflection characteristics and power durability characteristics, and is a tube member that can be expected to be compact and easy to manufacture.

  First, in the waveguide, the metal surface may be composed of a pair of opposed wide surfaces and a pair of opposed narrow surfaces, and the metal rod intersects an H plane parallel to the wide surface. You may extend in the direction.

  In such a waveguide, there are no conductive protrusions in the hollow region in the direction of the electric field of the electromagnetic wave, which improves the power handling characteristics of the waveguide, and Facilitates the application of tubes to high power circuit systems.

  In the waveguide, the angle formed may be set to a substantially right angle.

  Such a waveguide is considered to be more compact and easier to manufacture than circular bends and tuned miter bends.

  Specifically, this waveguide does not need to bend the H surface with a large radius of curvature unlike the circular bend described above, and has a wide-angle (H surface) right-angle corner structure. For this reason, by adopting the right-angled corner structure, the problem of increasing the size of the bent structure portion is solved, and as a result, the space for arranging the waveguide in the waveguide circuit system can be reduced.

  Further, in the manufacture of such a waveguide, as in the conventional tuned miter bend, the tube is cut into a taper shape in a direction of 45 ° with respect to the tube axis direction, and another tube is formed at the cut-off portion. A complicated process of disposing a wall is not required. For example, if a metal base is prepared and a groove is cut into an L shape on the surface, the waveguide can be easily manufactured.

  In the waveguide, the number of the metal rods may be three.

In this waveguide, due to the optimum design of the dimensions and mounting positions of the metal rods, | S ₁₁ | = −30 dB to −55 dB as electromagnetic wave reflection loss over almost the entire propagation frequency band of the single mode (fundamental mode). The low reflection characteristic is obtained. Therefore, it is possible to cover with a single corner portion so as to keep an appropriate and sufficiently low reflection loss over almost the entire frequency range (for example, 8.4 GHz to 12.4 GHz) of a standard waveguide.

  In the waveguide, the number of the metal rods may be two.

In this waveguide, the reflection loss of electromagnetic waves in a specific frequency band (for example, around 9.6 GHz) is extremely low reflection of | 50 dB as | S ₁₁ | Loss is obtained. Therefore, it is useful to incorporate this waveguide into a product that utilizes a specific frequency band (for example, a high-frequency heating device).

  Further, as described above, the above waveguide is very useful because the corner portion reflection characteristics can be adapted to various uses of the waveguide by simple design change of the metal rod.

  According to the present invention, it is possible to obtain a waveguide that has a corner portion excellent in electromagnetic wave reflection characteristics and power durability characteristics, and that can be made compact and easy to manufacture.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view showing an example of a configuration around a corner portion of a rectangular waveguide according to an embodiment of the present invention. FIG. 3 is a perspective view showing another configuration example around the corner portion of the rectangular waveguide according to the embodiment of the present invention. FIG. 1 shows an example in which three metal rods 20 are arranged, and FIG. 3 shows an example in which two metal rods 21 are arranged.

  FIG. 2 is a schematic view of the periphery of the corner portion of the rectangular waveguide shown in FIG. FIG. 4 is a schematic view of the periphery of a corner portion of the rectangular waveguide shown in FIG.

  First, the configuration of the rectangular waveguide 100 of the present embodiment will be described with reference to FIGS. 1 and 2. The configuration of the rectangular waveguide 110 shown in FIGS. 3 and 4 can be easily understood with reference to the following description and drawings. Here, the detailed configuration of the rectangular waveguide 110 will be described. Is omitted. In addition, the various dimensions “W”, “d”, “c”, “x”, “y”, “R”, “Rc” shown in FIG. 1, FIG. 2, FIG. 3 and FIG. It will be described later.

  As shown in FIGS. 1 and 2, the rectangular waveguide 100 of the present embodiment includes a pair of extending portions 10A and 10B extending in the direction of the tube axes 11A and 11B, and the tube axis of the extending portion 10A. The extending portions 10A and 10B are connected to each other so that an angle (crossing angle) θ formed between 11A and the tube axis 11B of the extending portion 10B is a desired angle (here, θ = 90 °). A corner portion 12 and three columnar metal bars 20 provided on the corner portion 12 are provided.

  As shown in FIG. 1, the extension portions 10 </ b> A and 10 </ b> B and the corner portion 12 described above have an inner wall surface 15 (metal surface) including a pair of opposed wide surfaces 13 and a pair of opposed narrow surfaces 14. Have. The inner wall surface 15 is made of a metal such as aluminum or copper, and a hollow area 16 having a rectangular cross section defined by the inner wall surface 15 is used as a transmission path for microwaves and millimeter waves.

The cross-sectional shape of the hollow region 16 is normally set to a predetermined size in consideration of the cutoff frequency of electromagnetic waves transmitted through the hollow region 16 and selection of an electromagnetic wave mode. Since the method of setting the dimension of the hollow region 16 is well known in the rectangular waveguide, detailed description thereof is omitted here. However, in the rectangular waveguide 100 of the present embodiment, TE ₁₀ (basic in a predetermined propagation frequency band) (Mode) electromagnetic waves can be propagated.

  In the present embodiment, the surface parallel to the wide surface 13 corresponds to the H surface parallel to the magnetic field direction of the electromagnetic wave, and the surface parallel to the narrow surface 14 corresponds to the electric field direction of the electromagnetic wave. Corresponds to a parallel E plane. Then, in the corner portion 12 of the rectangular waveguide 100, as shown in FIG. 2, both sides of the wide surface 13 (H surface) (in other words, the upper sides of the pair of narrow surfaces 14) are the outer corner portion 13A and the inner side. The corner portion 13B has an H-plane right-angle corner structure that is bent at a right angle. Thus, since the wide surface 13 (H surface) is bent in a plane at a right angle, a wide propagation frequency band can be obtained.

  Further, as shown in FIG. 1, the three cylindrical metal rods 20 are arranged between a pair of wide surfaces 13 in a direction intersecting (here, orthogonal) with an H surface parallel to these wide surfaces 13. , Extending through the hollow region 16 of the corner portion 12.

  Thereby, all the conductors existing in the hollow region 16 except for the wide surface 13 of the inner wall surface 15 including the metal rod 20 (details will be described later) are parallel to the electric field of the electromagnetic wave, and induce dielectric breakdown. It is a structure that does not easily cause electric field concentration. Thus, there is no conductive protrusion in the hollow region 16 with respect to the direction of the electric field of the electromagnetic wave, which improves the power durability characteristics of the rectangular waveguide 100 and the rectangular waveguide. The application of the tube 100 to a high power circuit system is facilitated.

  Then, as described below, by optimally designing the dimensions and mounting positions according to the number of metal bars 20, the interference effect of electromagnetic waves (incident waves and reflected waves) transmitted through the corner portion 12 is determined. The reflection loss can be appropriately suppressed.

  Next, a design example of the metal bars 20 and 21 in the corner portion 12 of the rectangular waveguides 100 and 110 will be described.

  Here, for each of the two columnar metal bars 21 and the three columnar metal bars 20, the optimum design of the mounting positions and dimensions of the metal bars 20, 21 from the viewpoint of reducing the reflection loss of electromagnetic waves. Although an example is described, the form of the metal rods 20 and 21 is not limited to this. For example, even if the shape of the metal rods 20 and 21 is a triangular prism or a quadrangular prism, an optimum design suitable for this can be performed, and even if the number of the metal rods 20 and 21 is four or more, it is suitable for this. Can be optimized.

  Table 1 below summarizes the results of the optimum design for the dimensions and mounting positions of the metal bars 20, 21.

まず、３本の金属棒２０の寸法および装着位置についての最適設計の結果を述べる。

First, the result of the optimum design for the dimensions and mounting positions of the three metal bars 20 will be described.

  As shown in Table 1 and FIG. 2, the optimum radius “Rc” of the central metal rod 20 arranged on the virtual straight line 101C (see the broken line in FIG. 2) passing through the inner corner portion 13B and the outer corner portion 13A is The metal rod 20 has a length “d” (corresponding to the width of the narrow surface 14) of 10.2 mm. In this case, the optimum mounting position of the metal rod 20 based on two virtual straight lines 101A and 101B (see the dotted lines in FIG. 2) drawn vertically from the inner corner portion 13B to the outer narrow surface 14 is used. The distance “c” from the virtual straight lines 101A and 101B to the center of the metal rod 20 is 14.99 mm. Here, the wider width “W” of the rectangular hollow region 16 (corresponding to the width of the wide surface 13) is set to 22.9 mm (hereinafter the same).

  Further, the optimum radius “R” of the metal rod 20 arranged on the electromagnetic wave entrance side from the virtual straight line 101C is 1.0 mm, and the length “d” of the metal rod 20 (corresponding to the width of the narrow surface 14). Is 10.2 mm. In this case, the optimum mounting position of the metal rod 20 based on the two virtual straight lines 101A and 101B vertically drawn from the inner corner 13B to the outer narrow surface 14 is a metal from the virtual straight line 101B. The distance “x” to the center of the bar 20 is 20.29 mm, and the distance “y” from the virtual straight line 101A to the center of the metal bar 20 is 7.33 mm.

  Further, the optimum radius “R” of the metal rod 20 arranged on the electromagnetic wave exit side from the virtual straight line 101C is 1.0 mm, and the length “d” of the metal rod 20 (corresponding to the width of the narrow surface 14). Is 10.2 mm. In this case, the optimum mounting position of the metal rod 20 based on the two virtual straight lines 101A and 101B vertically drawn from the inner corner 13B to the outer narrow surface 14 is a metal from the virtual straight line 101A. The distance “x” to the center of the bar 20 is 20.29 mm, and the distance “y” from the virtual straight line 101B to the center of the metal bar 20 is 7.33 mm.

  Next, the result of the optimum design for the dimensions and mounting positions of the two metal bars 21 will be described.

  As shown in Table 1 and FIG. 4, the optimum radius “R” of the metal rod 21 arranged on the electromagnetic wave entrance side from the virtual straight line 101C (see the broken line in FIG. 4) passing through the inner corner portion 13B and the outer corner portion 13A. Is 0.7 mm, and the length “d” (corresponding to the width of the narrow surface 14) of the metal rod 21 is 10.2 mm. In this case, as an optimal mounting position of the metal rod 21 based on two virtual straight lines 101A and 101B (see dotted lines in FIG. 4) drawn vertically from the inner corner portion 13B to the outer narrow surface 14. The distance “x” from the virtual straight line 101B to the center of the metal bar 21 is 17.70 mm, and the distance “y” from the virtual straight line 101A to the center of the metal bar 21 is 8.89 mm.

  Further, the optimum radius “R” of the metal bar 21 arranged on the electromagnetic wave exit side from the virtual straight line 101C is 0.7 mm, and the length “d” of the metal bar 21 (corresponding to the width of the narrow surface 14). Is 10.2 mm. In this case, the optimum mounting position of the metal rod 21 based on the two virtual straight lines 101A and 101B vertically drawn from the inner corner portion 13B to the outer narrow surface 14 is a metal from the virtual straight line 101A. The distance “x” to the center of the bar 21 is 17.70 mm, and the distance “y” from the virtual straight line 101B to the center of the metal bar 21 is 8.89 mm.

  Next, the simulation result and the measurement result of the prototype for the frequency characteristics of the rectangular waveguide 100 (in the case of the three metal rods 20) will be described. In addition, a simulation result on the frequency characteristics of the rectangular waveguide 110 (in the case of the two metal rods 21) will be described.

  FIG. 5 is a diagram showing a simulation result of frequency characteristics of the rectangular waveguide according to the present embodiment.

The horizontal axis of FIG. 5 represents the frequency of the electromagnetic wave (Frequency [GHz]), and the vertical axis represents the calculated value of the reflection loss | S ₁₁ | (dB) with the S parameter. FIG. 5 shows a simulation result of the frequency characteristics of the rectangular waveguide 110 conforming to the above-described optimal design of the metal rod 21 (see the broken line in FIG. 5) and a rectangular waveguide conforming to the above-described optimal design of the metal rod 20. The simulation result of the frequency characteristic of the tube 100 (see the solid line in FIG. 5) is shown.

  In the process of arriving at the optimum design of the metal bars 20 and 21, as described above, there are a wide variety of design parameters related to the characteristics of the metal bars 20 and 21. The frequency characteristics of the rectangular waveguides 100 and 110 are efficiently and repeatedly calculated by design software that combines "" and an original analysis method. However, the design software itself is already known, and detailed description thereof is omitted here.

  FIG. 5 also shows the simulation results of the frequency characteristics of the rectangular waveguide 100 (only in the case of the metal rod 20) using a general-purpose high-frequency three-dimensional electromagnetic field analysis simulator (HFSS; trademark). (See round dot in FIG. 5).

  The simulation described above is made on the assumption that the structure is a perfect conductor (that is, an ideal conductor having an infinite conductivity). In the design of microwave circuits and electromagnetic field analysis, there is usually no significant error even if the structure is assumed to be a perfect conductor.

  Here, as shown in FIG. 5, the simulation result (solid line) by the above-mentioned design software and the simulation result by HFSS (round dot) almost coincide with each other, which supports the validity of the simulation result by this design software. ing.

According to FIG. 5, the rectangular waveguide 100 (three metal rods 20) of the present embodiment has | S ₁₁ | as an electromagnetic wave reflection loss over almost the entire propagation frequency band of the single mode (fundamental mode). It can be seen that it has a low reflection characteristic of −30 dB to −55 dB. Therefore, according to the rectangular waveguide 100 of the present embodiment, almost the entire use frequency band (for example, 8.4 GHz to 12.4 GHz) of the standard rectangular waveguide is kept appropriately and sufficiently low in reflection loss. Thus, it can cover using the single corner part 12. That is, as long as it is limited to the range of the used frequency band, the reflection loss of the electromagnetic wave by the corner portion 12 is “−40 dB or less”, the standing wave ratio VSWR is 1.02 or less, and the ratio bandwidth is 43%, which is preferable. .

Further, according to FIG. 5, the rectangular waveguide 110 (two metal rods 21) of the present embodiment has | S ₁₁ | as “−50 dB” as a reflection loss of electromagnetic waves in the frequency band near 9.6 GHz. It can be seen that the ultra-low reflection loss is as follows. Therefore, it is useful to incorporate the rectangular waveguide 110 into a product that utilizes a specific frequency band (for example, a high-frequency heating device). In this case, the frequency band that results in low reflection loss can be changed based on the size and mounting position of the metal rod 21.

  As described above, the rectangular waveguides 100 and 110 of the present embodiment are extremely useful because the reflection characteristics of the corner portion 12 can be adapted to various uses of the waveguide by simple design changes of the metal rods 20 and 21. .

  In the present embodiment, a prototype of the rectangular waveguide 100 conforming to the optimum design of the three metal rods 20 described above is manufactured (hereinafter, this prototype is referred to as “trial waveguide 120”). .

  Therefore, the measurement results of the frequency characteristics of the prototype waveguide 120 will be described below.

  As shown in FIG. 6, the prototype waveguide 120 includes a hard aluminum base 41 having an L-shaped groove 40 formed therein and a flat hard aluminum lid 42 using positioning pins 43. It is manufactured by overlapping. The wall surface of the concave groove 40 and the inner surface of the lid 42 correspond to the inner wall surface 15 shown in FIG. 1, and these are surface-finished. Further, three cylindrical posts 44 made of hard aluminum corresponding to the metal rod 20 shown in FIG. 1 are mounted at appropriate positions in the corner portion of the concave groove 40 based on the optimum design values described above.

  Such a prototype waveguide 120 is considered to be more compact and easier to manufacture than circular bends and tuned miter bends.

  Specifically, this prototype waveguide 120 does not need to bend the H surface with a large radius of curvature unlike a conventional circular bend, and has a right-angled corner structure with a wide surface 13 (H surface). For this reason, by adopting this right-angled corner structure, the problem of an increase in the size of the bent structure portion is solved, and as a result, the space for arranging the waveguide in the waveguide circuit system can be reduced.

  Further, in the manufacture of the prototype waveguide 120, as in a conventional tuned miter bend, the tube wall is cut into a taper shape in a direction of 45 ° with respect to the tube axis direction, and a tube wall of another member is formed at the cut-off portion. If the base 41 is prepared and the groove 40 is cut into an L shape on the surface as described above, the prototype waveguide 120 can be easily manufactured. .

  FIG. 7 is a diagram showing the measurement results of the frequency characteristics of the prototype waveguide. The frequency characteristics are measured using a network analyzer (HP8510B) manufactured by Hewlett-Packard (the same applies to FIGS. 8 and 10).

The horizontal axis of FIG. 7 represents the frequency of electromagnetic waves (Frequency [GHz]), and the vertical axis represents the measured value of the reflection loss | S ₁₁ | (dB) with the S parameter. For the purpose of comparison with the simulation result of the frequency characteristics by HFSS shown in FIG. 5, the data is also shown in FIG. 7 (see the round dot in FIG. 7).

According to FIG. 7, the prototype waveguide 120 has a low reflection characteristic of | S ₁₁ | = −30 dB to −55 dB as an electromagnetic wave reflection loss over almost the entire propagation frequency band of the single mode (fundamental mode). It can be seen that Further, according to the frequency characteristics of the prototype waveguide 120 in FIG. 7, the reflection loss of electromagnetic waves | S ₁₁ | can be a fractional bandwidth appropriately and sufficiently wide in the "-40dB" used frequency band of the rectangular waveguide It can be seen that almost the entire region (for example, 8.4 GHz to 12.4 GHz) can be covered.

  In addition, as shown in FIG. 7, since the simulation result (round dot) by HFSS and the measurement result by the prototype waveguide 120 substantially coincide, the validity of the simulation result by the above-described design software is experimentally verified. It is also supported from the side.

  FIG. 8 is a diagram showing a comparison result between the measurement result of the frequency characteristic of the prototype waveguide and the measurement result of the frequency characteristic of the first conventional product (commercially available product).

  As the first conventional product 130, a commercially available product having a propagation frequency band substantially equivalent to that of the prototype waveguide 120 is selected. Here, as shown in FIG. 9, a circular bend (THB-) manufactured by Tokyo Electric Seiki Co., Ltd. is used. 10) is used.

The horizontal axis of FIG. 8 represents the frequency of electromagnetic waves (Frequency [GHz]), and the vertical axis represents the measured value of the reflection loss | S ₁₁ | (dB) with the S parameter. FIG. 8 shows the measurement results of the frequency characteristics of the prototype waveguide 120 (see the thick solid line in FIG. 8) and the frequency characteristics of the first conventional product 130 (see the thin solid line in FIG. 8).

According to the frequency characteristics of the first conventional product 130 in FIG. 8, the electromagnetic wave reflection loss | S ₁₁ | can be appropriately and sufficiently reduced in the use frequency band of the rectangular waveguide (for example, 8.4 GHz to 12.4 GHz). Therefore, it can be seen that there is a difficulty in performance that low reflection characteristics cannot be obtained.

  FIG. 10 is a diagram showing a comparison result between the measurement result of the frequency characteristic of the prototype waveguide and the measurement result of the frequency characteristic of the second conventional product (commercially available product).

  As the second conventional product 140, a commercially available product having a propagation frequency band substantially equivalent to that of the prototype waveguide 120 is selected. Here, as shown in FIG. 11, a tuned miter bend (H Bend) is used.

The horizontal axis of FIG. 10 represents the frequency of the electromagnetic wave (Frequency [GHz]), and the vertical axis represents the measurement value of the reflection loss | S ₁₁ | (dB) with the S parameter. FIG. 10 shows the measurement results of the frequency characteristics of the prototype waveguide 120 (see the thick solid line in FIG. 10) and the frequency characteristics of the second conventional product 140 (see the thin solid line in FIG. 10).

  According to the frequency characteristics of the second conventional product 140 of FIG. 10, the specific bandwidth in the use frequency band (for example, 8.4 GHz to 12.4 GHz) of the rectangular waveguide cannot be increased, and the broadband characteristics cannot be obtained. It can be seen that there are difficulties in terms of performance.

  As described above, the rectangular waveguide 100 of the present embodiment includes the pair of extending portions 10A and 10B extending in the direction of the tube axes 11A and 11B, as shown in FIGS. A corner portion 12 for connecting the extending portions 10A and 10B to each other such that an angle θ formed between the tube shaft 11A of the existing portion 10A and the tube shaft 11B of the extending portion 10B is a right angle (90 °); And three cylindrical metal rods 20 mounted on the corner portion 12. The extending portions 10A and 10B and the corner portion 12 have a rectangular hollow region 16 partitioned into a pair of wide surfaces 13 and a pair of narrow surfaces 14 of the inner wall surface 15 (metal surface). The metal rod 20 extends through the hollow region 16 in a direction orthogonal to the wide surface 13.

  According to the configuration of such a rectangular waveguide 100 (particularly, the configuration of the corner portion 12 and the metal rod 20), performance such as electromagnetic wave reflection characteristics and power durability characteristics, and structures such as compactness and ease of manufacture are provided. The following effects can be obtained with respect to the surface.

As a first effect, in the rectangular waveguide 100, the reflection loss of electromagnetic waves | S over almost the entire propagation frequency band of the single mode (fundamental mode) by the optimum design of the size and mounting position of the metal rod 20 A low reflection characteristic of ₁₁ | = -30 dB to -55 dB is obtained. Therefore, a single corner portion 12 can be used to cover almost the entire frequency range (for example, 8.4 GHz to 12.4 GHz) of a standard rectangular waveguide with an appropriate and sufficiently low reflection loss. .

  As a second effect, in the rectangular waveguide 100, all the conductors existing in the hollow region 16 except for the wide surface 13 of the inner wall surface 15 are parallel to the electric field of the electromagnetic wave, including the metal rod 20. In this structure, electric field concentration that induces dielectric breakdown is unlikely to occur. Thus, there is no conductive protrusion in the hollow region 16 with respect to the direction of the electric field of the electromagnetic wave, which improves the power durability characteristics of the rectangular waveguide 100 and the rectangular waveguide. The application of the tube 100 to a high power circuit system is facilitated.

  As a third effect, it is considered that the rectangular waveguide 100 (for example, the above-described prototype waveguide 120) can be made more compact and easier to manufacture than a circular bend or a tuned miter bend.

  Specifically, the rectangular waveguide 100 does not need to bend the H surface with a large radius of curvature unlike a conventional circular bend, and has a right-angle corner structure with a wide surface 13 (H surface). For this reason, by adopting the right-angled corner structure, the problem of increasing the size of the bent structure portion is solved, and as a result, the space for arranging the waveguide in the waveguide circuit system can be reduced.

  Further, in the manufacture of such a rectangular waveguide 100, as in a conventional tuned miter bend, it is cut off in a taper shape in the direction of 45 ° with respect to the direction of the tube axis, and a separate member is formed on the cut-off portion. For example, if a metal base 41 is prepared and the groove 40 is cut into an L shape on the surface, the prototype waveguide 120 is formed. Easy to manufacture.

  On the other hand, as shown in FIGS. 3 and 4, the rectangular waveguide 110 of this embodiment includes a pair of extending portions 10A and 10B extending in the direction of the tube axes 11A and 11B, and a tube of the extending portion 10A. A corner portion 12 that connects the extending portions 10A and 10B to each other such that an angle θ formed between the shaft 11A and the tube shaft 11B of the extending portion 10B is a right angle (90 °), and the corner portion 12 And two columnar metal bars 21 attached to the. The extending portions 10A and 10B and the corner portion 12 have a rectangular hollow region 16 partitioned into a pair of wide surfaces 13 and a pair of narrow surfaces 14 of the inner wall surface 15 (metal surface). The metal rod 21 extends so as to penetrate the hollow region 16 in a direction orthogonal to the wide surface 13.

  According to such a configuration of the rectangular waveguide 110 (particularly, the configuration of the corner portion 12 and the metal rod 21), performance characteristics such as electromagnetic wave reflection characteristics and power resistance characteristics, and structures such as compactness and ease of manufacture are provided. The following effects can be obtained with respect to the surface.

In this rectangular waveguide 110, | S ₁₁ | is “−50 dB” as a reflection loss of electromagnetic waves in a specific frequency band (here, around 9.6 GHz) by optimal design of the size and mounting position of the metal rod 21. The ultra-low reflection loss is obtained. Therefore, it is useful to incorporate the rectangular waveguide 110 into a product that utilizes a specific frequency band (for example, a high-frequency heating device).

  The rectangular waveguide 110 also exhibits the same effects as the above-described second effect (power durability) and the above-described third effect (compact and easy manufacture). Description is omitted.

Furthermore, the rectangular waveguides 100 and 110 of the present embodiment also have an effect that the reflection characteristics of the corner portion can be adapted to various uses of the waveguide by simple design changes of the metal rods 20 and 21.
(First modification)
In the present embodiment, the three metal rods 20 to the two metal rods 21 are exemplified, but this is only an example until the tiredness. It is expected that the reflection loss in a specific frequency band can be reduced by mounting one metal bar at an appropriate position in the corner portion instead of these metal bars 20 and 21.

Therefore, according to the rectangular waveguide of this modification, the corner portion of the rectangular waveguide incorporated in a product that utilizes a specific frequency band (for example, a high-frequency heating device) can be easily configured and may be beneficial. . However, in this case, the specific frequency band with low reflection loss is considered to be narrower than that of the rectangular waveguide 110 (in the case of the two metal rods 21).
(Second modification)
In the present embodiment, the H-plane right-angle corner structure is exemplified as the configuration of the corner portion 12, but this is only an example until it gets tired. For example, even a waveguide having an acute angle (for example, 60 °) formed between one tube axis of the pair of extending portions and the other tube axis of the pair of extending portions. If the configuration of the metal rod in the waveguide is optimized, it is considered that the same effect as that described in the present embodiment can be obtained.

Furthermore, by providing two corner portions of the H-plane right-angle corner structure, a U-shaped waveguide formed in a substantially U-shape, or a plurality of U-shaped waveguides are connected to make the transmission path zigzag. Even if the waveguides are lengthened, it is considered that the same effects as those described in the present embodiment can be obtained if the configuration of the metal rods in these waveguides is optimized.
(First application example)
As a first application example, an example in which the rectangular waveguides 100 and 110 of the present embodiment are incorporated in a circuit having an input / output unit that requires a structure that bends at right angles is assumed. For example, the H-plane right-angle corner structure of the rectangular waveguides 100 and 110 of this embodiment may be integrally formed at the input / output portion of the short slot hybrid circuit. Thereby, a small and high performance short slot hybrid circuit is obtained.
(Second application example)
As a second application example, an example in which the metal rods 20 and 21 of the rectangular waveguides 100 and 110 of the present embodiment are incorporated in a dielectric substrate waveguide is assumed.

  The dielectric substrate waveguide has a pair of conductor layers sandwiching the dielectric substrate, and a dielectric substrate is formed by two rows of through conductor rod groups formed by electrically connecting the pair of conductor layers. A transmission path of the waveguide is formed. Each bar of the through conductor bar group is located at the end of the transmission path and is arranged at a predetermined interval along the direction of the transmission path.

  When the transmission path of such a dielectric substrate waveguide is bent, the metal rod described in the present embodiment may be attached to the inner side of each row of the through-conductor rod groups constituting the transmission path. If it does so, it is thought that the reflection loss of the said bending part can be suppressed appropriately.

  The waveguide of the present invention is expected to have a corner portion excellent in electromagnetic wave reflection characteristics and power durability characteristics, and to be compact and easy to manufacture. Therefore, the waveguide of the present invention can be used for various waveguide circuits incorporating a waveguide, for example.

It is the perspective view which showed one structural example of the corner part periphery of the rectangular waveguide by embodiment of this invention. FIG. 2 is a schematic view in plan view of the periphery of a corner portion of the rectangular waveguide of FIG. 1. It is the perspective view which showed the other structural example periphery of the corner part of the rectangular waveguide by embodiment of this invention. It is the schematic diagram which planarly viewed the corner part periphery of the rectangular waveguide of FIG. It is the figure which showed the simulation result of the frequency characteristic of the rectangular waveguide by this embodiment. It is the figure which showed the external appearance and the inside of a trial manufacture waveguide. It is the figure which showed the measurement result of the frequency characteristic of a trial manufacture waveguide. It is the figure which showed the comparison result between the measurement result of the frequency characteristic of a trial manufacture waveguide, and the measurement result of the frequency characteristic of a 1st conventional product. It is the figure which showed the external appearance of the 1st conventional product. It is the figure which showed the comparison result between the measurement result of the frequency characteristic of a trial manufacture waveguide, and the measurement result of the frequency characteristic of a 2nd conventional product. It is the figure which showed the external appearance of the 2nd conventional product.

Explanation of symbols

10A, 10B Extension part 11A, 11B Pipe shaft 12 Corner part 13 Wide surface 13A Inner corner part 13B Outer corner part 14 Narrow surface 15 Inner wall surface (metal surface)
16 hollow region 20, 21 metal rod 40 concave groove 41 base 42 lid 43 positioning pin 44 cylindrical post 100, 110 rectangular waveguide 120 trial waveguide 130 first conventional product 140 second conventional product

Claims (4)

A pair of extending portions extending in the direction of the tube axis;
The pair of extension portions are mutually connected so that an angle formed between one tube axis of the pair of extension portions and the other tube axis of the pair of extension portions becomes a desired angle. A corner section to be connected;
One or more metal bars provided in the corner portion;
With
The corner portion has a hollow region defined by a metal surface,
The waveguide, wherein the metal rod extends through the hollow region. The metal surface comprises a pair of opposed wide surfaces and a pair of opposed narrow surfaces,
The waveguide according to claim 1, wherein the metal bar extends in a direction intersecting an H plane parallel to the wide surface.   The waveguide according to claim 2, wherein the angle formed is substantially a right angle.   The waveguide according to any one of claims 1 to 3, wherein the number of the metal bars is two or three.

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