JP2967870B2 - Radar equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a millimeter-wave band FM radar used for a warning device for preventing a rear-end collision of a vehicle.

[0002]

2. Description of the Related Art An on-vehicle radar device mounted on a vehicle such as a passenger car and used for an alarm device for rear-end collision or collision prevention is required to have a high detection range even at a close range of about several tens of centimeters. In terms of resolution, the form of the FM radar is more suitable than the form of the pulse radar. In addition, the distance measurement range to a target such as a preceding vehicle or an oncoming vehicle is several hundreds.
m is enough to prevent the radiated radio wave from propagating farther than necessary or interfering with existing microwave band communication equipment. Are suitable.

Japanese Patent Application No. 3-42979 entitled "FM Radar" previously filed by the present applicant discloses a millimeter-wave band FM radar apparatus having a configuration shown in the block diagram of FIG. A triangular wave is output from the sweep circuit 121 under the control of the timing control circuit 120, and a FM signal in the microwave band is output from the variable frequency oscillator 110 that receives the triangular wave. The FM signal in the microwave band is supplied to the power divider 1
The signal is divided into two by 11 and is converted into an FM signal in the microwave band of about 20 GHz by the up-converters 112 and 113, and is arranged at the subsequent stage through the switches 122 and 123 which are switched under the control of the timing control circuit 120. The signal is supplied to one of the three frequency multipliers 114a to 114d and one of the three frequency multipliers 115a to 115d in a time division manner.

The FM signals in the millimeter wave band of about 60 GHz output from the frequency multipliers 114a to 114d pass through circulators 116a to 116d and antennas 118a to 118d.
Millimeter-wave FM signals radiated from 8d and output from the triplers 115a to 115d are mixed with the mixers 117a to 117.
d is supplied to one input terminal. The millimeter-wave band FM signal reflected by the target and received by the antennas 118a to 118d passes through the circulators 116a to 116d, and
It is supplied to the other input terminals of 17a to 117d. The beat signals in the microwave band output from the mixers 117a to 117d are supplied to the detection circuit 119 via the switch 24. In order to shift the frequency of the beat signal output from the mixers 117a to 117d to a high frequency range not disturbed by 1 / f noise, the local oscillation frequencies of the upconverters 112 and 113 are set to different values.

[0005]

In the conventional millimeter-wave band FM radar apparatus shown in FIG.
Since a waveguide type 16 is used, there is a problem that the entire circuit becomes large and expensive. If this waveguide type circulator is changed to a microstrip line type circulator, the circuit size can be reduced. However, since the microstrip line type circulator is expensive, there is a problem that the cost cannot be reduced. In addition, this microstrip line type circulator has insufficient isolation and large wraparound of the transmission / reception system,
There is also a problem in characteristics that insertion loss is large.

[0006]

According to the present invention, there is provided a millimeter wave band FM radar apparatus comprising: means for generating an FM signal whose frequency increases and decreases with time; a plurality of transmitting antennas; and the FM signal transmitted to the plurality of transmitting antennas. Means for distributing and supplying power in a time-division manner, and a plurality of reception units arranged at different positions from the plurality of transmission antennas and receiving reflected signals radiated from the plurality of transmission antennas and reflected by an object. An antenna, a plurality of mixers arranged corresponding to the plurality of transmitting antennas, and a plurality of mixers for generating a beat signal by mixing a part of the FM signal generated by the FM signal generating means and a received signal; A detection circuit for detecting the position of the object from a plurality of beat signals output from the mixer.

That is, in the millimeter wave band FM radar apparatus of the present invention, by separately installing a transmission-only antenna and a reception-only antenna, a circulator required when the antenna is used for both transmission and reception is eliminated. I have. Hereinafter, the operation of the present invention will be described in detail with the following examples.

[0008]

1 and 2 are a plan view and a perspective view, respectively, showing a configuration of a transmitting / receiving section of a millimeter wave band FM radar apparatus according to an embodiment of the present invention. The transmission / reception unit of this embodiment includes a common dielectric substrate 1
It comprises a transmission system 10 and a reception system 20 formed in the form of a microstrip line above. The common dielectric substrate 1 is made of a suitable polymer material having a low relative dielectric constant of about 2 in consideration of easiness of radio wave emission from the planar antenna array for transmission, and is held in a metal housing 2. Is done. Transmission system 10 formed on common dielectric substrate 1
The reception system 20 is separated by the metal partition plate 3 to prevent electromagnetic interference from the transmission system to the reception system.

The transmission system 10 includes a planar array type transmission antenna 11, a tripler 12, a microwave band FM signal input terminal 12 and a bias input terminal 14 by a coaxial connector, and a transmission line connecting these elements. It is composed of The tripler 12 includes a tripler 12α, a low-pass filter 12β for blocking signals in the millimeter wave band,
It is composed of a band-pass filter 12γ for blocking harmonic signals in the millimeter-wave band and a signal in the microwave band, a high-frequency blocking filter 12δ for bias, and a matching pattern for impedance matching.

The receiving system 20 includes a planar array type receiving antenna 21, a tripler 22, a single balanced type mixer 23, a low noise amplifier 24 for beat signals, a high band rejection filter 25 for bias, and a coaxial connector. , An input terminal 27 for an FM signal in the microwave band, bias input terminals 28 and 29, and a transmission line connecting these elements. The tripler 22 includes a tripler element 22α, a low-pass filter 22β for blocking millimeter wave band signals, a band pass filter 22γ for blocking millimeter wave band harmonic signals and microwave band signals, and a bias. High-frequency rejection filter 22δ for
And a matching pattern for impedance matching.

In the transmission system 10, a 20 GHz microwave band F supplied to an input terminal 16 from a coaxial cable is provided.
The M signal is converted to a 60 GHz millimeter-wave band FM signal by the tripler 12.
It is converted into a signal and radiated from the planar array antenna 11. An appropriate matching pattern for impedance matching is formed before and after the tripler 12α, and a bias voltage is supplied to the triplerer 12α from the bias input terminal 14 via the high-pass filter 12δ. .

In the receiving system 20, a millimeter wave signal received by the receiving flat array antenna 21 is supplied to one input terminal of a mixer 23 of a single balanced type. At the other input terminal of the mixer 23, the FM signal in the microwave band of 19.5 GHz supplied from the coaxial line to the input terminal 27 is multiplied by 3 by the tripler 22, and 58.5.
It is supplied as a GHz millimeter-wave band FM signal. The 1.5 GHz beat signal output from the mixer 23 is amplified by the low noise amplifier 24, and the beat signal output terminal 26
And output to a coaxial cable. The bias voltage supplied to the bias input terminals 28 and 29 is applied to the tripler 2 via the high-frequency blocking filters 22δ and 25, respectively.
2 and the low noise amplifier 24.

FIG. 3 is a block diagram showing the overall configuration of a vehicle-mounted millimeter-wave band FM radar apparatus having four transmission / reception units configured as shown in FIGS. 1 and 2. In order to facilitate comparison with the prior art radar apparatus shown in FIG. 4, the same components as those in FIG. 4 are denoted by the same reference numerals as those in FIG. 4, and these common components are duplicated. Description is omitted.

In FIG. 3, a pair of transmitting and receiving antennas,
The combination of a tripler pair, a mixer and a low noise amplifier (T
a, Ra, 114a, 115a, 117a, APM
a), (Tb, Rb, 114b, 115b, 117b,
APMb), (Tc, Rc, 114c, 115c, 11
7c, APMc), (Td, Rd, 114d, 115
d, 117d, and APMd) correspond to the microstrip line type transmitter / receiver formed on the common dielectric substrate shown in FIG.
1. However, the triplers 114 and 115 in FIG. 3 correspond to the triplers 12 and 22 shown in FIG. 1, respectively, and the mixers 117a to 117d correspond to the mixer 23 in FIG.

The four transmission / reception units shown in FIG. 3 are discretely installed, for example, at four locations on the front, rear, left, and right sides of the vehicle. On the other hand, a common part arranged before the switches 22 and 23 and after the switch 24 is attached to one of the four transmission / reception units TRa to TRd, or is installed at another place apart from any of them. Is done. As is clear from comparison with FIG.
In the transmission / reception unit of FIG. 1, a circulator which is problematic in terms of circuit size and manufacturing cost is eliminated by separately installing a transmitting antenna and a receiving antenna.

In the prior art radar apparatus shown in FIG. 4, a low-noise amplifier for a beat signal is incorporated in a detection circuit 119 after the switch 124. In this embodiment, this low-noise amplifier is used for a receiving system. Component 24 (AMPa-A
MPd) are individually provided on the common dielectric substrate 1. As a result, as many low-noise amplifiers as the number of transmission / reception units are required. However, such low-noise amplifiers in the low frequency band are small and inexpensive, and thus are not so problematic. Rather,
By arranging the low-noise amplifier in front of the switch 124, it is possible to avoid deterioration of the SN caused by passage loss in the switch 124, thermal noise, switching noise, etc., and the detection unit 119
There is a greater advantage that the detection accuracy can be improved.

The switches 122, 123, and 124 are synchronously switched based on the control of the timing control unit 120, so that the four transmission / reception units are activated in the arrangement order.
A scan of the target around the vehicle is performed. Since the antenna gain of this planar array antenna is lower than that of conventional three-dimensional antennas such as parabolic antennas and horn reflector antennas, the reach of radiated radio waves also becomes shorter, but it is necessary to detect relatively close targets such as when driving at low speed. It is particularly suitable for application to an alarm device for warning the danger of a collision or a rear-end collision.

The configuration using the tripler as the frequency multiplier has been described above, but the frequency multiplier may be a multiplier having an appropriate multiplication order, such as a doubler or a quadrupler.

Further, the configuration in which the low-noise amplifier is mounted on the dielectric substrate has been illustrated, but it may be configured to be installed outside the dielectric substrate.

[0020]

As described above in detail, in the millimeter wave band FM radar apparatus according to the present invention, since the antenna dedicated to transmission and the antenna dedicated to reception are separately provided, the antenna is shared for transmission and reception. The circulator required in the case can be eliminated. As a result, the peripheral circuit of the tripler can be formed by a microstrip line in place of the conventional waveguide, so that the size and the cost can be reduced, and the problem of wraparound of transmission / reception generated inside the circulator can be solved. Is improved.

Further, according to a preferred embodiment of the present invention, each of the transmitting and receiving antennas is formed by a microstrip line type planar array antenna, and these are also formed by a microstrip line type frequency multiplier, Since the structure is formed integrally on a common dielectric substrate together with the mixer and the like, further reduction in size and cost can be realized.

Further, according to the embodiment in which the low noise amplifier of the beat signal is installed on the common dielectric substrate, the degradation of SN caused by the coaxial transmission line and the switch between the low noise amplifier and the mixer is prevented. There is also an effect that the detection is avoided and the detection accuracy is improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of a transmitting / receiving section of a millimeter wave band FM radar device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of a transmission / reception unit of the millimeter wave band FM radar device according to the embodiment of the present invention.

FIG. 3 is a block diagram showing an overall configuration of a millimeter wave band FM radar apparatus according to one embodiment of the present invention.

FIG. 4 shows a prior art millimeter wave band F according to the prior application of the present applicant.
FIG. 3 is a block diagram illustrating a configuration of an M radar device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 common dielectric substrate 2 metal housing 3 metal partition plate 10 transmission system 11 transmission plane array antenna 12 tripler 14 FM signal input terminal in microwave band 20 reception system 21 reception plane array antenna 22 Multiplier 23 Mixer 24 Low noise amplifier for beat signal 26 Output terminal for beat signal 27 Input terminal for FM signal in microwave band

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01S 7/00-7/42 G01S 13/00-13/95

Claims (3)

(57) [Claims] 1. A means for generating an FM signal whose frequency increases and decreases with time; a plurality of transmitting antennas; a means for distributing the FM signal to the plurality of transmitting antennas in a time-division manner and supplying power; A plurality of receiving antennas, which are arranged at different positions from the transmitting antennas and receive reflected signals radiated from the plurality of transmitting antennas and reflected by an object, are arranged corresponding to the plurality of transmitting antennas, The FM
A plurality of mixers for generating a beat signal by mixing a part of the FM signal generated by the signal generating means and the received signal; and detecting the position of the object from the plurality of beat signals output from the plurality of mixers A radar device comprising: 2. The radar apparatus according to claim 1, further comprising a switch for selecting a beat signal output from the plurality of mixers and supplying the selected beat signal to a single detection circuit. Means 3. A frequency to generate an FM signal to increase or decrease over time, unlike the transmitting antenna emits a signal into the space, means for feeding said FM signal to said transmitting antenna, and the plurality of transmit antennas And a plurality of receiving antennas that receive reflected signals radiated from the plurality of transmitting antennas and reflected by an object, and are disposed corresponding to the plurality of transmitting antennas. , The FM
A plurality of mixers for generating a beat signal by mixing a part of the FM signal generated by the signal generation means and the received reflected signal; and the object based on the plurality of beat signals output from the plurality of mixers. And a detection circuit for detecting the position of the radar.