JP2012177665A - Radar device, and radio wave transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a propagation loss due to displacement between a wave guide and a substrate.SOLUTION: A radar device includes: a planar antenna; a circuit board loaded with a radio wave transmission/reception part which transmits and receives radio waves to/from the planar antenna; a radio wave transmission device which connects the planar antenna with the circuit board; and a case which stores the planar antenna, the circuit board, the radio wave transmission device. The radio wave transmission device has: a waveguide in which the radio waves flow; and a taper part provided on the side of the circuit board of the waveguide and of which the opening on the side of the circuit board is formed larger than an opening on the side of the planar antenna.

Description

  The present invention relates to a technology of a radar device and a radio wave transmission device.

  One of the transmission lines is a waveguide. For example, Patent Document 1 discloses a waveguide having a tapered structure as a waveguide used for a conversion adapter.

JP 2005-175612 A JP-A-8-271768

  One of the transmission lines is a waveguide. The waveguide is also used to connect a high-frequency module and an antenna in, for example, a millimeter wave radar. Here, FIG. 1 shows an example of the structure of a conventional millimeter wave radar. The millimeter wave radar shown in FIG. 1 has an antenna 2x and an RF substrate 5x as a high-frequency module. The antenna 2x and the RF substrate 5x are through holes formed in a metal chassis constituted by the RF chassis 4x and the antenna chassis 3x. Are connected by a waveguide 10x. A baseband board 6x on which a millimeter wave radar microcomputer or the like is mounted is connected to the RF board 5x, and the antenna chassis 3x, the waveguide 10x, the RF board 5x, and the baseband board 6x are covered with a radome 1x and a case 7x. Yes. The radome 1x and the case 7x are connected via an O-ring 15x to ensure the waterproof property of the millimeter wave radar. In addition, the case 7x is provided with a breathing portion 8x, and the air pressure in the millimeter wave radar can be adjusted. Further, the case 7x is connected to an external connector 9x for connection to, for example, an ECU (Electronic Control Unit) of the vehicle.

  FIG. 2 is a cross-sectional view of a conventional waveguide, and FIG. 3 is an image diagram representing the positional relationship of connection between the conventional waveguide and the RF substrate in a plan view. As shown in FIG. 2, conventionally, the waveguide 10x and the RF substrate 5x are obtained by superimposing an opening 10x2 on the RF substrate side and an antenna conversion unit 50x made of a conductor pattern formed on the RF substrate 5x. And were connected by screws S. Then, as shown in FIG. 3, the waveguide 10x is connected to the RF substrate 5x so that the antenna conversion part 50x of the RF substrate is accommodated in the opening 10x2 on the RF substrate side.

  As described above, the millimeter wave radar is configured by stacking a plurality of members. However, if the members are not connected at an accurate position, the function of the millimeter wave radar may be deteriorated. In particular, in the connection between the waveguide 10x and the RF substrate 5x, if a positional shift occurs between the RF substrate 5x and the antenna conversion unit 50x, the antenna conversion unit 50x is moved to the waveguide wall, and the waveguide There is a concern that the reflection of radio waves passing through 10x becomes large and propagation loss increases.

  An object of the present invention is to provide a technique for reducing a propagation loss due to a positional deviation between a waveguide and a substrate.

  In the present invention, in order to solve the above-described problems, the waveguide is provided with a tapered portion, and the circuit board of the radar device and the antenna are connected.

  More specifically, the present invention relates to a planar antenna, a circuit board on which a radio wave transmission / reception unit that transmits / receives radio waves to / from the planar antenna, a radio wave transmission device that connects the planar antenna and the circuit board, and the planar antenna. A radar device comprising: a circuit board; and a case for accommodating the radio wave transmission device, wherein the radio wave transmission device is provided on the circuit board side of the waveguide and the waveguide through which the radio wave flows. And a tapered portion in which the opening on the circuit board side is formed larger than the opening on the planar antenna side.

  In the radar apparatus of the present invention, the waveguide has a taper portion in which the opening on the circuit board side is formed larger than the opening on the planar antenna side, so that the positional deviation of the connection between the waveguide and the circuit board can be reduced. Can be tolerated. That is, even if a positional deviation occurs when the radar apparatus is assembled, the positional deviation can be further tolerated because the opening on the circuit board side is formed larger than the opening on the planar antenna side. As a result, reflection of radio waves flowing through the waveguide can be suppressed, and radio wave loss can be reduced.

  In the radar device of the present invention, the radio wave transmission device may have a flat chassis, and the waveguide and the tapered portion may be formed in the chassis. By using a flat chassis, the radar apparatus can be thinned.

  Further, in the radar device of the present invention, the size of the opening on the circuit board side of the waveguide is the size of the radio wave transmission / reception unit of the circuit board, the connection tolerance between the circuit board and the radio wave transmission device, It can be determined based on at least one of the frequency bands of the radio waves flowing through the waveguide. According to the present invention, it is possible to reduce radio wave loss by setting the opening on the circuit board side of the waveguide to an appropriate size. The size of the opening on the circuit board side can be expressed, for example, as a ratio to the size of the radio wave transmission / reception unit. The size is an area. Further, the connection tolerance includes not only tolerance at the time of connection but also due to variation in product dimensions.

  In the radar device of the present invention, the radio wave transmission device may further include a linear portion provided on the planar antenna side of the waveguide and having the same diameter as the opening on the planar antenna side. By providing the straight portion, reflection of radio waves flowing through the waveguide can be further suppressed. As a result, propagation loss is further reduced.

  In the radar apparatus of the present invention, the circuit board includes a plurality of the radio wave transmission / reception units, and the one plate-like chassis is provided with a plurality of waveguides corresponding to the radio wave transmission / reception units, Each waveguide may have a configuration in which the tapered portion is provided. By providing waveguides each having a tapered portion on one chassis, it is possible to reduce the number of components, suppress reflection of radio waves flowing through the waveguides, and reduce radio wave loss.

  Here, the present invention can also be specified as a radio wave transmission device in the radar device described above. That is, the present invention is a radio wave transmission device that connects a planar antenna of a radar device and a circuit board having a radio wave transmission / reception unit that transmits / receives radio waves to / from the planar antenna, the chassis and the radio wave formed in the chassis. A radio wave transmission device comprising: a waveguide through which the circuit board flows; and a tapered portion provided on the circuit board side of the waveguide and having a larger opening on the circuit board side than the opening on the planar antenna side. is there. According to the present invention, it is possible to tolerate more misalignment between the waveguide and the circuit board. As a result, reflection of radio waves flowing through the waveguide can be suppressed, and radio wave loss can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the technique which reduces the propagation loss by position shift with a waveguide and a board | substrate can be provided.

An example of the structure of a conventional millimeter wave radar is shown. A sectional view of a conventional waveguide is shown. The image figure showing the positional relationship of the connection of the conventional waveguide and RF board | substrate planarly is shown. 1 shows a structure of a millimeter wave radar according to an embodiment. The functional block diagram of the millimeter wave radar which concerns on embodiment is shown. A sectional view of a waveguide concerning an embodiment is shown. The image figure showing the positional relationship of the connection of a waveguide and RF board | substrate planarly is shown. A sectional view of a waveguide concerning a modification is shown.

  Next, an embodiment of a radar apparatus of the present invention will be described based on the drawings.

<Configuration>
FIG. 4 shows the structure of the millimeter wave radar according to the embodiment. FIG. 5 is a functional block diagram of the millimeter wave radar according to the embodiment. The millimeter wave radar 100 according to the embodiment has a square shape in front view (hereinafter, the radome side is a front surface) and has a box shape as a whole. The millimeter wave is generally a frequency band of 30 GHz to 300 GHz (wavelength 10 mm to 1 mm). The millimeter wave radar 100 of this embodiment employs a 76 GHz millimeter wave band. The modulation method is an FM-CW (Frequency-Modulated Continuous Waves) radar method. As shown in FIG. 4, the millimeter wave radar 100 according to the embodiment includes a radome 1, an O-ring 15, an antenna 2, an antenna chassis 3, an RF chassis 4, a waveguide 10, an RF substrate 5, and a baseband substrate 6. , A case 7, a breathing unit 8, and an external connector 9. The radar apparatus of the present invention is not limited to the millimeter wave radar described below.

  The radome 1 protects the antenna 2. The radome 1 according to the embodiment is made of resin and has a quadrangular shape. Screw holes 11 are provided at the four corners of the radome 1 to be used when connecting to the case 7.

  The O-ring 15 is a sealing member and is provided between the radome 1 and the case 7 and prevents water from entering from the connecting portion between the radome 1 and the case 7.

  The antenna 2 transmits a transmission wave in the millimeter wave band, and receives a reception wave including a reflected wave obtained by reflecting the transmission wave on the target. The antenna 2 according to the embodiment is configured by a planar antenna made of a printed board having a microstrip line. The antenna 2 only needs to have at least one transmission port and at least one reception port, and the number of ports is not particularly limited. The transmission port and the reception port may be a switchable shared port.

  The antenna chassis 3 is plane-connected to the antenna 2 and supports the antenna 2. The RF chassis 4 is surface-connected to the RF substrate 5 and supports the RF substrate 5. The antenna chassis 3 and the RF chassis 4 also have a function of blocking noise propagation between the RF substrate 5 and the antenna 2. In the present embodiment, both the antenna chassis 3 and the RF chassis 4 are made of a metal chassis. The antenna chassis 3 and the RF chassis 4 are approximately quadrangular and are provided with protrusions on both sides. In addition, a screw hole 31 used when connecting to the RF substrate 5 is formed in the protrusion. The antenna chassis 3 and the RF chassis 4 correspond to the chassis of the present invention.

The waveguide 10 allows a radio wave (76 GHz in this embodiment) transmitted from the patch 50 of the antenna conversion unit of the RF substrate 5 to flow. The waveguide 10 is formed by through holes formed in the antenna chassis 3 and the RF chassis 4. In the present embodiment, six waveguides 10 are formed in the lateral direction of the antenna chassis 3 and the RF chassis 4. Further, the waveguide 10 of the present embodiment is provided with a tapered portion 10c in which the opening 10b on the RF substrate side is formed larger than the opening 10a on the antenna side. The details of the waveguide 10 including the tapered portion 10c will be described later including the connection mode between the waveguide 10 and the RF substrate 5.

  The RF substrate 5 is provided with an analog circuit unit 502 including a millimeter wave transmission / reception unit 501, a transmission control circuit 504, and a reception circuit 503. The millimeter wave transmission / reception unit 501 transmits and receives millimeter wave transmission waves and reception waves with the antenna 2. Specifically, transmission / reception waves are transmitted and received by the patch 50 of the antenna conversion unit. The transmission control circuit 504 performs frequency modulation and generates a transmission wave under the control of a digital signal processor (DSP) 505. The reception circuit 503 detects a beat signal from the reception wave received by the millimeter wave transmission / reception unit 501. The RF substrate 5 according to the embodiment is configured by a printed board. RF board screw holes 51 are formed on both sides of the RF board 5 at positions corresponding to the antenna chassis screw holes 31 and the RF chassis screw holes 41. The RF substrate 5 has an inner layer (not shown) that shields noise from the RF substrate 5.

  The baseband substrate 6 is provided with a digital signal processing unit 505, a microcomputer 506, and the like. The digital signal processing unit 505 generates a transmission wave by controlling the frequency modulation by the transmission control circuit 504. The digital signal processing unit 505 performs FFT frequency analysis of the beat signal received from the receiving circuit 503. The microcomputer 506 controls the entire millimeter wave radar based on a command given via the external connector 9. Further, the baseband substrate 6 is further provided with a connector 61 for connection with the RF substrate and a connector 62 for connection with the outside.

  Case 7 accommodates antenna 2, antenna chassis 3, RF chassis 4, RF substrate 5, and baseband substrate 6. The case 7 has a box shape with a square front surface opened, and screw holes 71 corresponding to the screw holes 11 of the radome are formed at the four corners. The case 7 and the radome 1 are connected by screws via the O-ring 15, so that the airtightness in the case 7 is ensured. A breathing section 8 is provided on the back surface of the case 7 so that air can be taken in and out. Thereby, the radome 1 can be prevented from being damaged due to the contraction / expansion of the air in the case 7 accompanying the temperature change.

  The external connector 9 is connected to an external connection connector 62 and electrically connects an external device (for example, a vehicle ECU) and the millimeter wave radar 100.

  The power source 508 supplies power used by each device in the millimeter wave radar 100.

<Details of waveguide>
Here, FIG. 6 shows a cross-sectional view of the waveguide according to the embodiment. FIG. 7 shows an image diagram representing the positional relationship of the connection between the waveguide and the RF substrate in a plan view. The waveguide 10 according to the embodiment is provided in the antenna chassis 3, is provided in the RF chassis 4 with a straight part 10 d having the same diameter as the opening 10 a on the antenna side, and the opening 10 b on the RF substrate 5 side is the antenna 10. And a tapered portion 10c formed larger than the opening 10a on the side. The antenna chassis 3 and the RF chassis 4 are surface-connected by inserting screws into the screw holes 31 of the antenna chassis, the screw holes 41 of the RF chassis, and the screw holes 51 of the RF board. When the taper portion 10c is not provided, the patch 50 of the antenna conversion portion fits in the opening portion 10b on the RF substrate side of the waveguide 10 due to variations in the dimensions of screws and screw holes and displacement at the time of connection. It is assumed that it will disappear. However, in the present embodiment, since the tapered portion 10c is provided, the patch 50 of the antenna conversion portion is guided even when there is a variation in the dimensions of the screws and screw holes or when a positional deviation occurs during connection. It fits in the opening 10b on the RF substrate side of the wave tube 10 (see FIG. 7). Reference symbol P in FIG. 7 indicates an imaginary line of the opening when the tapered portion is not provided. In the case where the taper portion is not provided, even when the patch 50 of the antenna conversion portion does not fit in the opening 10b on the RF substrate side of the waveguide 10, the taper 50c is provided to guide the patch 50 of the antenna conversion portion. The tube 10b can be accommodated in the opening 10b on the RF substrate side. The diameter of the opening 10 on the RF substrate side is at least one of the size of the patch 50 of the antenna conversion portion of the RF substrate 5 and the connection tolerance between the RF substrate 5, the antenna chassis 3, and the RF chassis 4. It can be determined based on one. Note that the patch 50 of the antenna changing portion is preferably located at the center of the opening 10b on the RF substrate side of the waveguide 10, but it is only necessary to be within the opening 10b.

<Design example of waveguide>
The diameter of the waveguide can be designed based on the standard of the waveguide. Since the millimeter wave radar according to the embodiment employs the 76 GHz millimeter wave band, the E-band band (60 to 90 GHz) and the V-band band (50 to 75 GHz) are compatible. In the E-band band (60 to 90 GHz), the size of the rectangular waveguide needs to be 1.55 mm × 3.1 mm or less. Further, in the V-band band (50 to 75 GHz), the size of the rectangular waveguide needs to be 1.88 mm × 3.76 mm or less. Therefore, in the present embodiment, the dimension of the opening 10a on the antenna side of the waveguide 10 is 1.55 mm × 3.1 mm, and the dimension of the opening 10b on the RF substrate side of the waveguide 10 is V-band band. Designed to be 1.84 mm x 3.49 mm, smaller than 1.88 mm x 3.76 mm. Thereby, the alignment between the waveguide 10 and the patch 50 of the antenna conversion unit can be relaxed to ± 0.2 mm.

<Operation>
The outline of the operation of the millimeter wave radar described above is as follows. The digital signal processing unit 505 controls the frequency modulation by the transmission control circuit 504 to generate a transmission wave. The generated transmission wave is transmitted to the millimeter wave transmission / reception unit 501, and a transmission wave in the millimeter wave band is transmitted from the patch 50 of the antenna conversion unit of the millimeter wave transmission / reception unit 501 to the antenna 2 through the waveguide 10. A millimeter wave band transmission wave is transmitted from the antenna 2, and a reception wave including a reflected wave reflected by the target is received by the antenna 2. The received wave is input to the receiving circuit 503 via the millimeter wave transmitting / receiving unit 501 and the waveguide 10, and the receiving circuit 503 detects a beat signal from the received received wave. The digital signal processing unit 505 detects the target position by performing FFT frequency analysis of the beat signal and calculating distance, relative speed, and angle information.

<Effect>
According to the millimeter wave radar 100 according to the embodiment described above, the waveguide 10 has the tapered portion 10c in which the opening 10b on the RF substrate side is formed larger than the opening 10a on the antenna side of the waveguide 10. A displacement of the connection between the tube 10 and the RF substrate 5 can be allowed. That is, even if a positional deviation occurs when the millimeter wave radar 100 is assembled, the RF board side opening 10b is formed to be larger than the antenna side opening 10, and thus a larger positional deviation is allowed. Can do. As a result, the distance between the antenna converter and the waveguide wall can be ensured even if a positional shift occurs, and as a result, reflection of millimeter waves flowing through the waveguide 10 can be suppressed, and radio wave loss can be reduced. can do. Further, by providing the straight portion 10d, it is possible to further suppress the reflection of millimeter waves flowing through the waveguide 10. As a result, propagation loss is further reduced.

The waveguide 10 can be manufactured by die casting, which is a casting method in which a molten metal is press-fitted into a mold to produce a casting. However, the provision of the tapered portion 10c improves the removal of the mold. As a result, work efficiency is improved. Conventionally, it has been necessary to inspect whether the patch 50 of the antenna conversion unit is accommodated in the opening of the waveguide 10. In the present embodiment, such inspection can be omitted or simplified.

<Modification>
In the embodiment described above, the cross-sectional shape of the waveguide 10 is a square, but the cross-sectional shape of the waveguide 10 may be a circle. Moreover, you may comprise the surface of the taper part 10c by a curved surface. The antenna 2 may be surface-connected to the RF chassis 4. Thereby, the number of parts can be reduced. In this case, the waveguide 10 can have a shape that does not have a straight portion (see FIG. 8).

  The preferred embodiments of the present invention have been described above, but the radar apparatus according to the present invention is not limited to these, and can include combinations thereof as much as possible.

DESCRIPTION OF SYMBOLS 1 ... Radome 2 ... Antenna 3 ... Antenna chassis 4 ... RF chassis 5 ... RF board 6 ... Baseband board 7 ... Case 8 ... Breathing part 9 ... External connector 10 ... waveguide 15 ... O-ring 10c ... tapered portion

Claims (6)

A planar antenna;
A circuit board on which a radio wave transmitting / receiving unit for transmitting and receiving radio waves to and from the planar antenna is mounted
A radio wave transmission device connecting the planar antenna and the circuit board;
A radar device comprising: the planar antenna; the circuit board; a case accommodating the radio wave transmission device;
The radio wave transmission device includes a waveguide through which the radio wave flows, and a taper provided on the circuit board side of the waveguide, wherein the opening on the circuit board side is formed larger than the opening on the planar antenna side. A radar apparatus having a unit.   The radar device according to claim 1, wherein the radio wave transmission device has a flat chassis, and the waveguide and the tapered portion are formed in the chassis.   The size of the opening on the circuit board side of the waveguide is the size of the radio wave transmission / reception unit of the circuit board, the connection tolerance between the circuit board and the radio wave transmission device, and the frequency band of the radio wave flowing through the waveguide The radar apparatus according to claim 1, wherein the radar apparatus is determined based on at least one of the two.   The radar according to any one of claims 1 to 3, wherein the radio wave transmission device further includes a linear portion that is provided on the planar antenna side of the waveguide and has the same diameter as an opening on the planar antenna side. apparatus.   The circuit board includes a plurality of the radio wave transmission / reception units, and a single plate-like chassis is provided with a plurality of waveguides corresponding to the radio wave transmission / reception units, and each waveguide has the taper. The radar apparatus according to claim 2, wherein a section is provided. A radio wave transmission apparatus for connecting a planar antenna of a radar apparatus and a circuit board on which a radio wave transmitting / receiving unit for transmitting and receiving radio waves is mounted to the planar antenna,
The chassis,
A waveguide through which the radio wave flows formed in the chassis;
A radio wave transmission apparatus comprising: a tapered portion provided on the circuit board side of the waveguide, wherein the opening on the circuit board side is formed larger than the opening on the planar antenna side.

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