JP2004172688A - Waveguide bend, waveguide plate, and high frequency apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waveguide bend capable of remarkably reducing machining precision being a requirement to ensure required electric characteristics such as a low loss over a broadband frequency range and an excellent pass characteristic causing less phase change and decreasing the manufacturing cost and having a structure of eliminating the restriction on the working caused by the structure. <P>SOLUTION: The waveguide bend has cavities directed outwardly from one corner or both corners of a waveguide whose guide axial direction is different at a waveguide corner part at which a propagation direction of electromagnetic waves in the waveguide are converted from a traveling direction into the different pipe axial direction. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a waveguide bend, and more particularly, to a waveguide circuit used for a waveguide feed circuit for a microwave band, a millimeter wave band, or the like, a high-frequency module for transmitting and receiving signals using a waveguide, and the like. .
[0002]
[Prior art]
Conventional waveguide bends are designed to bend the propagation direction of electromagnetic waves in the waveguide at the connection part of the waveguides whose pipe axis directions are different from each other, and to smoothly propagate the electromagnetic wave along the direction without causing unnecessary reflection. In addition, the waveguide is bent at a desired angle, and the inner surface outside the bent portion is formed as a stepped step surface (for example, see Patent Document 1).
[0003]
In addition, there is also one in which an outer inner surface of a bent portion is formed in a tapered shape so as to obtain the same effect as described above (for example, Non-Patent Document 1).
[0004]
However, the step surface of the waveguide bending portion as described above needs to cut a plurality of step surfaces in which planes parallel and perpendicular to the waveguide axis of the waveguide are alternately continued, and high processing is required. Precision is required. When the circuit as described above is manufactured in the microwave band or the millimeter wave band, the wavelength becomes smaller, and accordingly, the dimensions of the waveguide and the step surface also become smaller.
For example, the waveguide size in the W band (75 GHz to 110 GHz) is 2.54 mm × 1.27 mm (WR-10), and the waveguide step surface in this frequency band divides 1.27 mm into a plurality of stages. It is necessary to perform high-precision processing for cutting a small step surface (for example, 0.3 mm to 0.4 mm in the case of three steps).
[0005]
Also, by using two conductor plates, a single or a plurality of waveguide grooves for transmitting in the horizontal direction are formed in one of the conductor plates by cutting or the like, and a waveguide is formed in the conductor plate and the other conductor plate. A waveguide for transmitting a high-frequency signal from one waveguide to the other is formed by forming a waveguide for transmission in the vertical direction from both ends of the pipe groove and bonding these two conductor plates together. In the case where the waveguide bend is to be formed at a corner where the horizontal and vertical waveguides are orthogonal to each other, it is necessary to form the step surface on the conductor plate on which the waveguide groove is formed. There is.
In this case, it is possible to form the step surface on one corner, but on the corner having the waveguide in the vertical direction, the step surface is formed from the side where the waveguide groove is formed. Processing is impossible, and processing from the opposite side is performed by cutting through a waveguide formed in the upper and lower surfaces, so that extremely high precision is required and processing is difficult.
[0006]
Further, as a processing method for forming the plurality of waveguides at a lower cost as described above, injection molding or the like which has been conventionally used can be considered, but it is protruded from the inner wall of the waveguide as in the structure. Processing of the step surface cannot be performed by injection molding that can form only a punched structure.
[0007]
[Patent Document 1]
JP-A-9-246801 (pages 2-4, FIG. 1)
[Non-patent document 1]
GEORGE L. RAGAN, "MICROWAVE TRANSMISSION CIRCUITS",
1948 McGRAW-HILL, p203-207
[0008]
[Problems to be solved by the invention]
The conventional waveguide bend is configured as described above. In order to obtain the required electrical characteristics, the machining of the step surface of each waveguide bending portion is performed with extremely high processing accuracy and surface. Since precision was required, there was a problem that processing cost was very expensive. In addition, since the waveguide bend has a configuration in which the inner wall of the waveguide is projected, there are many processing restrictions that a processing method such as injection molding that can be expected to reduce costs cannot be adopted.
[0009]
The present invention has been made to solve the above-described problems, and has a low loss over a wide frequency range, a good pass characteristic with a small phase change, and the like, to secure necessary electric characteristics. It is an object of the present invention to obtain a waveguide bend having a structure capable of greatly reducing the machining accuracy and manufacturing cost required for the structure and eliminating the processing restrictions imposed by the structure.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a waveguide bend according to the present invention has a different tube axis direction at a waveguide corner portion that converts the propagation direction of an electromagnetic wave in a waveguide from a traveling direction to a different tube axis direction. The waveguide has a cavity extending outward from one or both corners of the waveguide.
[0011]
Further, the waveguide plate according to the present invention has a single or a plurality of waveguides formed for transmitting a high-frequency signal in a horizontal direction from an upper and lower surface direction using two conductor plates. Has a cavity extending outward from one or both corners of the waveguide formed in the planar or horizontal direction at the waveguide corner.
[0012]
Further, the high-frequency device according to the present invention is provided with the above-mentioned waveguide plate mounted thereon, and means for transmitting or receiving a high-frequency signal such as a millimeter wave or a microwave input or output to or from the waveguide plate. Things.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a perspective view of a waveguide bend showing the first embodiment of the present invention. In the drawing, the waveguide axes of a waveguide 1 and a waveguide 2 are orthogonal to each other, and at one of two waveguide connecting portions, one or both corners of the waveguides are extended to extend the end surfaces of the outer conductor wall. Thus, the cavity 5 is formed. FIGS. 2A to 2D are cross-sectional views of various forms in which the waveguide and the waveguide bend formed in the two metal plates 4a and 4b are cut at the center of the H plane by cutting or the like. 3 (a) shows a detailed cross-sectional view of FIG. 2, in which the waveguides 1 and 2 are formed on metal plates 4a and 4b by cutting or the like, and any one of the waveguides is connected at the waveguide connection portion. The cavity 5 is formed by extending one or both corner outer conductor wall end surfaces 6. FIG. 3B shows the distribution of the electric field (standing wave) excited at the waveguide corner. The waveguides 1 and 2 in the drawing show an example in which a bend is formed at a right angle (so that the tube axes are orthogonal).
[0014]
Next, the operation will be described. Generally, in a bent waveguide connection portion, reflection occurs because a series inductance and a parallel capacitance that are mismatched with respect to the impedance of the transmission system are added. As shown in the section C-C of FIG. 3, the outer inner surface of the waveguide bending portion is formed with one or more step surfaces 3 having an appropriate dimension Lc with respect to the waveguide dimension. By changing the position of the wall surface (electrically short-circuited surface) and providing a series inductance and a parallel capacitance that do not cause reflection to the impedance of the transmission system, reflection occurs over a wide frequency range of transmission within the waveguide. , And a waveguide transmission system with low loss and little phase change can be formed.
[0015]
In FIGS. 1 and 2 (a) to 2 (d), a cavity formed by extending the end face 6 of the outer conductor wall at one or both corners of the waveguide at the connection between the waveguides 1 and 2. Although the cavities 5, 5a to 5d are provided, each of the cavities 5, 5a to 5d plays a role equivalent to the step surface.
That is, in FIG. 3B, since electromagnetic waves such as microwaves and millimeter waves show a constant distribution (standing wave distribution) in a transmission system with a period of の of the wavelength in the waveguide, the cavity 5 is formed by a conductor wall. The end face 6 is used as a short-circuit plane, and a virtual electric short-circuit plane is formed from this position every half of the guide wavelength in the cavity.
[0016]
The cavity dimension (distance L from the inner wall end face of the waveguide 1 to the cavity conductor end face 6) in FIG. 3A is determined by the short-circuit plane CC ( (A position protruding from the inner wall end surface of the waveguide 1 by a distance Lc), and is shorter than the length of a half of the guide wavelength in the cavity by Lc. For this reason, the cavity 5 provides a series inductance and a parallel capacitance equivalent to the step surface at the waveguide bending portion, and bends the direction of the electromagnetic wave propagating from the waveguide 1 to the waveguide 2 and is unnecessary within the desired signal band. Electromagnetic waves can be propagated smoothly without causing significant reflection.
[0017]
Although the above-mentioned L is the minimum length of the cavity, a short-circuit surface is similarly formed when L is added to an integral multiple of 内 of the guide wavelength, so that substantially the same characteristics can be obtained. The cavity shape is shown in FIG. 3 as an example in which a rectangular parallelepiped cavity 5 is formed only on the metal plate 4a side. However, as shown in FIGS. 2 (a) to 2 (d), the cavity shape is Any shape may be used as long as the virtual electric short-circuit surface is selected so as to be equivalent to the C-C portion in the figure.
[0018]
Further, in the figure, the configuration using the waveguide bend on the E-plane is shown, but when the waveguide bend on the H-plane is also configured, a cavity having a dimension serving as a virtual electrical short-circuit surface is formed. It is feasible.
[0019]
By adopting the waveguide bend configuration as described above, it is possible to suppress reflection over a wide frequency range to be transmitted as a waveguide mode, and to realize a waveguide transmission system with low loss and small phase change. Can be formed.
[0020]
Further, since the waveguide bend does not have a minute and complicated structure unlike the step surface of a conventional waveguide bending portion, high-precision cutting is not required.
[0021]
Further, when a waveguide is formed by using two metal plates 4a and 4b, the waveguides formed on the respective metal plates are all punched out structures, so that it is possible to manufacture by press working or injection molding. A significant reduction in manufacturing costs can be expected.
[0022]
Embodiment 2 FIG.
FIG. 4 is a perspective view of a waveguide plate according to the second embodiment of the present invention. FIG. 5 is a cross-sectional view of the waveguide plate taken along the line DD in FIG. In the figure, waveguide plates 4a and 4b transmit high-frequency signals in each frequency band such as a microwave band and a millimeter wave band in the upper and lower plane directions in the waveguide mode and in the horizontal direction. A plurality of waveguides 2 are provided. For example, the waveguides 2 are used as interfaces for connecting the high-frequency device 10 having a plurality of waveguides in the same plane and the planar antenna 11 to each other, and provided on each plate. A high-frequency signal is transmitted between the plurality of opposed waveguides.
[0023]
Although FIG. 5 shows an example of connection between the high-frequency device and the planar antenna, the high-frequency module may also be used as a waveguide connection structure that is part of a high-frequency module and a waveguide jig. Is possible. At this time, the waveguides 1a and 2 and the waveguides 1b and 2 whose tube axis directions are different from each other are connected, and electromagnetic waves can be smoothly transmitted without causing unnecessary reflection within a desired signal band. For propagation, a tapered surface 7 and cavities 5a and 5b are provided on the inner surface outside the bent portion.
[0024]
The cavities 5a and 5b have a short-circuit surface at the cavity end, similarly to the waveguide bends of FIGS. 1 to 3 shown in the first embodiment. Form a short circuit surface.
The dimensions of the cavity are selected so that this virtual electrical short-circuit surface is equivalent to the step surface of the waveguide bend. The cavity has a series inductance and a parallel capacitance equivalent to the step surface at the waveguide bend. Is obtained, the direction of the electromagnetic wave propagating from the waveguide 1 to the waveguide 2 is bent, the reflection is suppressed over a wide frequency range transmitted as the waveguide mode, and the waveguide having low loss and little phase change is obtained. A tube transmission system can be formed.
[0025]
In addition, by configuring a plurality of waveguide transmission systems in the same plane, it is possible to collectively process and mold the transmission lines, thereby enabling a significant reduction in manufacturing cost.
[0026]
In addition, the waveguide bend configuration using the above cavity can greatly ease the requirement of machining accuracy, and a waveguide plate that can obtain good electrical characteristics by an inexpensive processing method such as die casting or pressing. It is also possible to manufacture.
[0027]
Embodiment 3 FIG.
In a third embodiment of the present invention, a high-frequency device that transmits or receives high-frequency radio waves such as millimeter waves and microwaves that are input or output to and from the waveguide plate of the second embodiment will be described. As this high-frequency device, for example, a millimeter-wave radar that transmits a millimeter-wave band RF signal and measures a distance and a direction to an object existing in the surroundings by receiving a reflected wave from the surroundings, and a microwave communication signal. A microwave communication device equipped with a transmitter for transmitting or a receiver for receiving a microwave communication signal, or scanning a millimeter wave band transmission beam, generating an image from the received wave, and video of an object present in the surroundings There is a millimeter-wave imaging device for obtaining an image.
[0028]
In the waveguide plate shown in FIG. 5, input / output terminals 1a, 1b, and 2 for inputting and outputting a high-frequency RF signal are connected to the planar antenna 11, the high-frequency device 10, and the like. In particular, in a frequency band where transmission loss is a problem, such as a millimeter wave band (30 GHz to 300 GHz), a waveguide plate having a plurality of waveguides is converted from a small and integrated high-frequency package to a planar antenna as described above. By utilizing it as an external interface such as a microstrip line or a triplate line that is usually used as a transmission line in a high-frequency package, it is possible to significantly reduce the line loss, (Multiple transmission / reception channels) and diversification of module structure.
Further, since the requirement for machining accuracy is eased, it is possible to configure a low-cost device as a whole high-frequency device as compared with a conventional machined product.
[0029]
【The invention's effect】
According to the present invention, in a waveguide corner portion that changes the propagation direction of an electromagnetic wave in a waveguide from a traveling direction to a different tube axis direction, the waveguide axis direction differs from one or both corners of the different waveguides. Having a cavity toward the outside provides a waveguide bend that has low loss over a wide frequency range, has good transmission characteristics with little phase change, and can greatly reduce machining accuracy and manufacturing cost. be able to.
[Brief description of the drawings]
FIG. 1 is a perspective view of a waveguide bend showing Embodiment 1 of the present invention.
FIG. 2 is a sectional view of a waveguide bend showing the first embodiment of the present invention.
FIG. 3 is a detailed sectional view of a waveguide bend and an electric field (standing wave) distribution at a corner portion according to the first embodiment of the present invention.
FIG. 4 is a perspective view of a waveguide plate according to a second embodiment of the present invention.
FIG. 5 is a perspective view of a waveguide plate according to a second embodiment of the present invention.
[Explanation of symbols]
1, 1a, 1b waveguides traveling in the upper and lower direction,
2 waveguides whose waveguide axes are orthogonal to waveguides 1, 1a and 1b, 3 stepped step surfaces,
4a, 4b a metal plate for forming each waveguide;
5, 5a-5d cavity, 6 conductor wall end surface of cavity 5, 7 taper surface,
10 Microwave and millimeter wave band high frequency devices,
11 Microwave and millimeter wave band planar antenna.

Claims (6)

At the waveguide corner where the propagation direction of the electromagnetic wave in the waveguide is changed from the traveling direction to a different tube axis direction, the cavity is directed outward from one or both corners of the waveguide with different tube axis directions. A waveguide bend comprising: The waveguide bend according to claim 1, wherein the cavity has a shape formed by any one of a spherical shape, an elliptical shape, a cubic shape, a rectangular parallelepiped shape, or a combination thereof. 3. The waveguide bend according to claim 1, wherein the cavity has a dimension equal to or less than 1/2 of a guide wavelength in the cavity. Using two conductor plates, one or more waveguide grooves for transmitting in the horizontal direction are formed in one conductor plate, and the conductor plate and the other conductor plate are formed from both ends of the waveguide groove. A waveguide for transmitting in the upper and lower direction is formed, and the two conductor plates are bonded to each other, and have waveguide openings at different positions on upper and lower surfaces, and a waveguide for transmitting a high-frequency signal through the waveguide groove. In the tube plate,
A waveguide plate having a cavity extending outward from one or both corners of the waveguides in the horizontal direction and the upper and lower surface directions orthogonal to each other. The waveguide plate according to claim 4, wherein the waveguide plate is made by injection molding or press working. A means for mounting the waveguide plate according to claim 4 or 5 and transmitting or receiving a high-frequency signal such as a millimeter wave or a microwave input or output between the waveguide plate and the waveguide plate. Radio frequency device characterized by the above-mentioned.

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