JP3995929B2 - Waveguide plate and high frequency device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a single or multiple waveguide connection structure for transmitting high-frequency signals such as UHF, VHF band, microwave band, and millimeter wave band.
[0002]
[Prior art]
FIG. 3 is a top view showing an example of a conventional waveguide plate. FIG. 4 is a detailed view of part A in FIG. In the figure, reference numerals 1a and 1b denote opposing waveguide plates, 2 denotes a contact surface of two waveguide plates, 3 denotes a choke structure formed by digging in the contact surface, and 4 denotes two waveguide plates The gaps 10a to 12a and 10b indicate a plurality of waveguides.
[0003]
Next, the operation will be described. The waveguide plates 1a and 1b are opposed to the waveguides 10a and 10b that transmit high-frequency signals in each frequency band such as UHF, VHF band, microwave band, and millimeter wave band in a waveguide mode in the plate thickness direction. For example, a high-frequency band module and an antenna (not shown), high-frequency modules, or a part of a high-frequency module and a waveguide jig are used as a waveguide connection structure. A high frequency signal is transmitted from 10a to 10b. At this time, when the gap 4 between the two waveguide plates is generated, the transmission characteristic of the high-frequency signal from the waveguides 10a to 10b deteriorates. In order to improve the adhesiveness of the waveguide plate, for example, a contact surface 2 and a choke structure 3 (hereinafter referred to as a choke structure) formed with a digging in the contact surface are provided.
[0004]
In order to improve the adhesion between the single or plural waveguides provided on the two waveguide plates and to obtain good transmission / reflection characteristics of the high-frequency signal transmitted through the waveguide, For example, it is formed by highly accurate machining. However, in order to obtain sufficient electrical characteristics, there are strict requirements for surface roughness and flatness of the contact surface, which requires highly accurate machining, and there is a problem that expensive processing costs are required. In general, the illustrated choke structure is used to improve the adhesion of the contact surface around the waveguide. However, the outer peripheral dimensions of the contact surface around the waveguide (the contact surface as viewed from the top surface of FIG. 3). The resonance occurs at a specific frequency determined by the length of the boundary between the choke and the choke), and the high frequency signal transmitted through the waveguide between the two waveguide plates cannot be obtained at the frequency. There's a problem. Further, when a plurality of waveguide connection structures are provided in the same plane as shown in FIG. 3, for example, coupling between two waveguides 10 b and 11 b occurs due to the resonance, and adjacent waveguides are connected to each other. There also arises a problem that isolation characteristics cannot be obtained. In particular, a waveguide is used in the millimeter wave band (30 GHz to 300 GHz) in order to reduce the transmission loss of the transmission line. However, in order to reduce the size of the circuit, the choke structure is a number that is a limit value for machining. In many cases, a dimension of about mm is selected, and the dimension of several millimeters is close to the dimension of the free space propagation wavelength at the signal frequency in the millimeter wave band, so that resonance is likely to occur due to the choke structure.
FIG. 5 is a diagram showing the transmission and reflection characteristics of the transmission line when the signal frequency f ₀ transmitted through the waveguide is a resonance frequency generated by the choke structure, S11 is a reflection loss, S21 is a transmission loss, S41 indicates isolation. In the figure, it can be seen that the pass, reflection, and isolation characteristics deteriorate sharply before and after the signal frequency f ₀ becomes the resonance frequency generated by the choke structure.
[0005]
[Problems to be solved by the invention]
Conventional waveguide plates are configured as described above, and in order to obtain the required electrical characteristics, extremely high machining accuracy and flatness are required for the contact surface of each waveguide plate. Therefore, there is a problem that the processing cost is very expensive. Further, when a plurality of waveguides are connected in the same plane, there is a problem that isolation characteristics cannot be obtained in adjacent waveguides due to coupling or resonance.
[0006]
The present invention has been made to solve the above-described problems, can avoid resonance in the signal band generated by the structure, can suppress the coupling of waveguides between adjacent ones, and An object of the present invention is to obtain a waveguide connection structure that can greatly reduce the machining accuracy required for securing electrical characteristics.
[0008]
[Means for Solving the Problems]
To achieve the above object, waveguide plates of the present invention, have a plurality of waveguides formed in order to transmit a high-frequency signal of a millimeter wave band in the thickness direction, of the waveguide In a waveguide plate comprising first and second plates interconnected with a gap at the connecting end face ,
The first plate is approximately 1/4 of the free space propagation wavelength at the signal frequency at a position shifted from the waveguide end of the long side of each of the waveguides by approximately 1/4 of the free space propagation wavelength at the signal frequency. A rectangular parallelepiped-shaped choke that has a width and depth and at least a length longer than the long side of the waveguide, and is dug so that the ends protrude from the waveguide ends on both short sides of each waveguide. It has a structure.
[0009]
The high frequency device according to this invention, equipped with the waveguide plate, those having a means for transmitting or receiving input or output by the millimeter wave between the waveguide plates.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
1 is a top view of a waveguide plate showing Embodiment 1 of the present invention. In the figure, 1a and 1b are opposing waveguide plates, 2 is a contact surface of two waveguide plates, 4 is a gap between the two waveguide plates, and 10a and 10b are plate thicknesses of the respective waveguide plates. Waveguide 100 formed in the direction, 100 indicates a choke.
[0011]
Next, the operation will be described. In FIG. 1, waveguide plates 1a and 1b are waveguides 10a and 10b that transmit high-frequency signals in respective frequency bands such as UHF, VHF band, microwave band, and millimeter wave band in the plate thickness direction in a waveguide mode. Are used as a connection structure of housing tubes having different waveguides, and transmit high-frequency signals from the waveguides 10a to 10b. At this time, when the gap 4 between the two waveguide plates is generated, the transmission characteristic of the high-frequency signal from the waveguides 10a to 10b deteriorates. In order to electrically short-circuit the connection end faces of the waveguides 10a and 10b, a choke 100 is provided in the long side direction of the waveguide 10b.
[0012]
The choke has a width and depth of at least about 1/4 of the free space propagation wavelength at the signal frequency at a position offset from the waveguide end of the long side of the waveguide by about 1/4 of the free space propagation wavelength at the signal frequency. The structure is provided with a digging having a length equal to or longer than the long side. With this structure, the waveguide end of the long side of the waveguide is equivalently electrically short-circuited at the connection end surface of the two waveguides 10a and 10b. The dimensions are dots. With this structure, it is possible to avoid resonance that occurs at the connection surface between the two waveguides and to obtain good transmission / reflection characteristics. In FIG. 1, the offset length D from the long side of the waveguide is approximately 1/4 of the propagation wavelength λ, the digging width W and the depth H are approximately 1/4 of the propagation wavelength λ, and the length L is the waveguide length. Set to be longer than the side (for example, when the signal frequency is 76.5 GHz and the propagation wavelength λ is 3.9 mm, the lengths of D, W, and H are 1 mm and L is 3 mm, respectively), and the choke Due to the structure, the waveguide end of the long side of the waveguide is equivalently electrically short-circuited at the signal frequency at the connection end face of the two waveguides 10a and 10b, and good transmission / reflection characteristics near the signal frequency are obtained. I am trying to do it.
[0013]
Embodiment 2. FIG.
FIG. 2 is a top view of a waveguide plate showing Embodiment 2 of the present invention. In the figure, reference numerals 10a to 12a and 10b denote a plurality of waveguides formed in the thickness direction of the respective waveguide plates. The same parts as those in the example shown in FIG.
[0014]
Next, the operation will be described. In FIG. 2, waveguide plates 1a and 1b are waveguides 10a to 12a that transmit high-frequency signals in respective frequency bands such as UHF, VHF band, microwave band, and millimeter wave band in the plate thickness direction in a waveguide mode. And 10b to 12b are provided to face each other. For example, a high-frequency module and an antenna having a plurality of waveguides in the same plane (not shown), high-frequency modules, or a high-frequency module and a waveguide jig A high-frequency signal is transmitted between a plurality of opposing waveguides provided on each plate. At this time, when the gap 4 between the two waveguide plates is generated, the transmission characteristics are deteriorated due to resonance at a specific frequency, and the isolation characteristics between adjacent waveguides are deteriorated due to the coupling of the waveguides 10b and 11b. Therefore, on the contact surface side of the waveguide plate 1a, choking is performed in the long side direction of the waveguides 10a to 12a in order to electrically short-circuit the connection end surfaces of the two opposing waveguides. 100 is provided.
[0015]
The choke has a width and depth of at least about 1/4 of the free space propagation wavelength at the signal frequency at a position offset from the waveguide end of the long side of the waveguide by about 1/4 of the free space propagation wavelength at the signal frequency. It has a structure with a digging with a length longer than the long side, and the waveguide end of the long side of the waveguide is equivalently electrically short-circuited at the connecting end surface of the multiple waveguides facing each other by the structure. The dimensions are dots. With this structure, it is possible to avoid resonance at a signal frequency, suppress coupling between a plurality of opposing waveguides, and obtain good pass / reflection and isolation characteristics.
[0016]
In addition, since a plurality of waveguides are configured in the same plane, a large area is required for the waveguide plate. Therefore, the conventional waveguide plate has good electrical characteristics in the connection between the waveguides. In order to ensure high accuracy flatness was required, but by adopting the above choke structure, the requirements of machining accuracy can be greatly relaxed, and inexpensive processing such as die casting and pressing It is also possible to produce waveguide plates that obtain good electrical properties by the method.
[0017]
Embodiment 3 FIG.
In the 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 to or output from the waveguide plate of the first or second embodiment will be described. As this high-frequency device, for example, a millimeter-wave radar that transmits an RF signal in the millimeter wave band and receives a reflected wave from the surroundings to measure the distance and direction to an object existing in the surroundings, or a microwave communication signal A microwave communication device equipped with a transmitter to transmit or a receiver to receive a microwave communication signal, or a video of an object existing in the surroundings by scanning a transmission beam in the millimeter wave band and generating an image from the received wave There are millimeter wave imaging devices that obtain images.
[0018]
In the waveguide plate shown in FIG. 1 or 2, input / output terminals 10 a to 12 a and 10 b to 12 b for inputting and outputting a high-frequency RF signal are connected to an antenna element or the like (not shown) or a high-frequency module. In particular, in the millimeter wave band (30 GHz to 300 GHz), a low-loss waveguide is used instead of a planar line having a large transmission loss such as a microstrip line. However, a waveguide having a plurality of waveguides as described above. By using the plate as an external interface for high-frequency devices such as millimeter-wave radar and millimeter-wave communication devices, it is possible to obtain good transmission / reflection characteristics at the waveguide connection and isolation characteristics between adjacent waveguides. This greatly contributes to the increase in the number of transmission / reception channels and the diversification of module structures. In addition, since the demand for machining accuracy is relaxed, it is possible to configure a low-cost device as a whole high-frequency device compared to conventional machined products.
[0020]
【The invention's effect】
According to the present invention, it has a plurality of waveguides formed in order to transmit a high-frequency signal of a millimeter wave band in the thickness direction, interconnected with a gap in the connection end face of the waveguide In the waveguide plate including the first and second plates, the first plate is shifted from the waveguide end of the long side of each waveguide by approximately ¼ of the free space propagation wavelength at the signal frequency . in position, with at least the waveguide long side length greater than the width and depth of approximately 1/4 of the free space propagation wavelength at the signal frequency from the waveguide end in the both short sides of the respective waveguide By having a rectangular parallelepiped-shaped choke structure dug so that the end protrudes to the outside , resonance at the signal frequency is avoided, and coupling between a plurality of opposing waveguides is suppressed, Good transmission / reflection, isolation It is possible to obtain a waveguide plate having sex, it is possible to manufacture the die-cast molding and press working inexpensive processing methods in waveguide plates to obtain good electrical characteristics such as.
[0021]
Furthermore, it is possible to obtain a high-frequency device that is more inexpensive and operates stably.
[Brief description of the drawings]
FIG. 1 is a top view of a waveguide plate showing Embodiment 1 of the present invention.
FIG. 2 is a top view of a waveguide plate showing a second embodiment of the present invention.
FIG. 3 is a top view showing an example of a conventional waveguide plate.
FIG. 4 is a detailed top view showing an example of a conventional waveguide plate.
FIG. 5 is an example of transmission, reflection, and isolation characteristics at a connection surface portion of a waveguide formed on a conventional waveguide plate.
[Explanation of symbols]
1a, 1b Waveguide plate, 2 Contact surface, 3 Conventional choke, 4 Gap between waveguide interface, 10a-12a, 10b-12b Waveguide, 100 choke

Claims (2)

Formed in order to transmit a high-frequency signal of a millimeter wave band in the thickness direction a plurality of waveguides to possess respectively, first interconnected with a gap in the connection end face of the waveguide, the second A waveguide plate comprising:
The first plate is approximately 1/4 of the free space propagation wavelength at the signal frequency at a position shifted from the waveguide end of the long side of each of the waveguides by approximately 1/4 of the free space propagation wavelength at the signal frequency. has a width and depth at least the waveguide length greater than the long side, the ends of the waveguide end of both short sides of the respective waveguide is engraved so as to protrude outward, a rectangular parallelepiped shape A waveguide plate characterized by having a choke structure. A high-frequency device equipped with the waveguide plate according to claim 1 and provided with means for transmitting or receiving a high-frequency signal such as a millimeter wave or a microwave input to or output from the waveguide plate.

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