JP2000304857A - Radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radar device capable of eliminating a necessity of a directional connection means branching a transmission signal to a mixing means and reducing the number of parts by reflecting a part of the transmission signal by an antenna and mixing the transmission signal for the reflection and a reflection signal from a target. SOLUTION: An oscillation means 1 oscillates and generates radio waves. A modulation means 2 modulates the radio waves by amplitude or frequency to generate a transmission signal. A circulator 3 shuts off the transmission signal for a mixing means 5, leads it to the direction of an antenna 4, and leads a reflection signal entering from the antenna 4 to the mixing means 5 on the contrary. The transmission signal and the reflection signal reflected in the antenna 4 pass the circulator 3 and are led to the mixing means 5 by passing through the same wave-guiding path. The mixing means 5 mixes the transmission signal and the reflection signal. A received signal processing means 6 detects a frequency of a beat signal changing by Doppler shift frequency by, for example, analyzing a signal for a fixed time by frequency and specifies the presence of a target based on its size on the contrary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used, for example, as a radar mounted on a vehicle or installed on a vehicle or on a road to detect a vehicle, a person, or an obstacle for the purpose of warning a danger or maintaining a distance between vehicles. The present invention relates to a radar device.

[0002]

2. Description of the Related Art As a conventional technique of this kind, for example, those disclosed in JP-A-7-302797 and JP-A-4-159949 are known. Hereinafter, an embodiment of a conventional radar device will be described with reference to the drawings.

FIG. 8 is a block diagram showing a configuration of a conventional radar device. In FIG. 8, the radar device includes an oscillation unit.
51, modulating means 52, circulator 53, antenna 54
, Mixing means 55, received signal processing means 56, and directional coupling means 57.

The oscillating means 51 oscillates and generates radio waves. For example, an in-vehicle millimeter-wave radar generates a 60 GHz or 76.5 GHz radio wave by oscillation using a dielectric oscillator or a Gunn diode.

[0005] The modulating means 52 generates a transmission signal by amplitude-modulating or frequency-modulating the radio wave. For example, several tens of ns
Perform amplitude modulation to generate ec pulses. The directional coupling means 57 transmits the modulated transmission signal to the circulator 53.
And the mixing means 55 in two directions. Circulator
Reference numeral 53 denotes an irreversible three-terminal element that blocks a transmission signal toward the mixing means and guides the signal toward the antenna, and conversely guides a reflected signal incident from the antenna to the mixing means 55.

The antenna 54 radiates a transmission signal of the transmission signal guided by the circulator 53 toward an external target (vehicle or the like), and the radiated transmission signal is reflected by a target such as a vehicle and returned. Receiving the reflected signal.

The mixing means 55 includes a reflection signal and a directional coupling means.
The transmission signal obtained by branching in step 57 is mixed. here,
When the target is moving, the output signal of the mixing means 55 has a beat that changes at the Doppler shift frequency because the frequency of the transmission signal is shifted from the frequency of the transmission signal by the Doppler frequency proportional to the relative speed with the radar device. Signal.

The received signal processing means 56 detects the frequency of the beat signal changing at the above-mentioned Doppler shift frequency, for example, by frequency-analyzing the signal for a certain period of time. Identify that. In the case of pulse modulation, the distance is obtained from the amount of delay time from the transmission pulse, and the relative speed is obtained from the Doppler shift frequency.

With the above configuration, the distance and the speed to the target can be obtained by transmitting the radio wave as a transmission signal to the outside and detecting the reflected signal from the target.

[0010]

However, in the conventional radar apparatus having the above-described structure, the directional coupling means is required so that the transmission signal can be used as an input to the mixing means. There is a problem that a member is required, miniaturization and cost reduction are hindered, and there is a problem that the output of the oscillating means must be increased by the power loss due to the insertion of the directional coupling means.

The present invention is directed to a direction in which a part of a transmission signal is reflected by an antenna, and the transmission signal corresponding to the reflection is mixed with a reflection signal from a target so that the transmission signal is branched to a mixing means. An object of the present invention is to provide a radar apparatus in which the number of parts is reduced by eliminating the need for a sexual coupling unit.

[0012]

According to the present invention, there is provided a radar apparatus which oscillates and generates a radio wave, and modulates or modulates the radio wave to generate a transmission signal. And a circulator, which is a non-reciprocal three-terminal element that blocks the transmission signal toward the mixing means and guides the signal toward the antenna, and conversely guides the reflected signal incident from the antenna to the mixing means, and a part of the transmission signal. An antenna that radiates most while reflecting light, and receives a reflected signal that is returned by reflecting the radiated transmission signal at the target, a part of the transmission signal reflected by the antenna, and incident from the antenna A mixing means for mixing the reflected signals, and a reception signal for detecting the presence or absence of a target and estimating a distance and a speed to the target by analyzing a reception signal output from the mixing means in time or frequency. Composed of the processing means.

By adopting such a configuration, conventionally,
It is possible to provide a radar apparatus which does not require the directional coupling means for branching the transmission signal to the mixing means, reduces the number of parts, and reduces the cost.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A radar device according to a first aspect of the present invention comprises: an oscillating means for oscillating and generating a radio wave; a modulating means for amplitude-modulating or frequency-modulating the radio wave to generate a transmission signal; And a circulator, which is an irreversible three-terminal element that guides the reflected signal incident from the antenna to the mixing means while blocking the transmission signal toward the mixing means, and reflects a part of the transmission signal. An antenna that radiates most, and receives a reflected signal that is returned by reflecting a radiated transmission signal on a target, a part of the transmission signal reflected by the antenna, and a reflection signal incident from the antenna Mixing means for mixing the signals, and reception signal processing means for detecting the presence or absence of a target by analyzing a received signal output from the mixing means in time or frequency, and estimating the distance and speed to the target. A transmission device and a reception signal can be mixed without using a directional coupling unit, so that miniaturization and cost reduction can be achieved. This has the effect that power loss does not have to be expected.

Further, the radar device according to the second aspect of the present invention includes an oscillating means for oscillating and generating a radio wave, an FM frequency modulating means for linearly frequency-modulating the radio wave to generate a transmission signal,
A circulator, which is an irreversible three-terminal element that blocks the transmission signal toward the mixing means and guides the signal toward the antenna, and conversely guides the reflected signal incident from the antenna to the mixing means, and reflects a part of the transmission signal And an antenna that receives the reflected signal returned by reflecting the transmitted signal reflected by the target object, a part of the transmitted signal reflected by the antenna, and incident from the antenna A mixing unit that mixes the reflected signals, and a reception signal processing unit that detects the presence or absence of a target by analyzing the reception signal output from the mixing unit in terms of frequency, and estimates the distance to the target and the speed. What is claimed is: 1. A radar apparatus for detecting a target by using an FMCW method, comprising: mixing a transmission signal and a reception signal without using directional coupling means, and changing a frequency of the beat signal depending on a distance and a relative speed. Not only it is obtained, downsizing and cost reduction, also has the effect that it is not necessary expected also power loss due to put directional coupling means.

According to a third aspect of the present invention, there is provided a radar apparatus according to the first aspect, wherein a non-radiative dielectric line (NRD) is used for a transmission path of each means. This has the effect that the structure of the radar device can be easily processed and mass-produced.

According to a fourth aspect of the present invention, there is provided an antenna for use in the radar apparatus according to the first aspect.
The antenna comprises a primary radiator having a wide directivity and a secondary radiator for enhancing the directivity, wherein the secondary radiator comprises:
A radar device characterized in that a part of the transmission wave is reflected without transmitting, and the amount of the transmission wave is adjusted while realizing the reflection of the transmission wave by devising its configuration in an antenna unit. Has the effect of being easy to do.

According to a fifth aspect of the present invention, there is provided a radar apparatus which oscillates and generates a radio wave which is a transmission signal, and intercepts the transmission signal toward the mixing means and guides the transmission signal toward the antenna. A circulator, which is an irreversible three-terminal element that guides the incident reflected signal to the mixing means, and radiates most while reflecting a part of the transmission signal, and the radiated transmission signal reflects off the target. An antenna for receiving the returned reflected signal, a mixing unit for mixing a part of the transmission signal reflected by the antenna, and a reflected signal incident from the antenna, and a reception signal output from the mixing unit in frequency. A radar apparatus comprising: a reception signal processing means for detecting the presence or absence of a target by analyzing and estimating a speed to the target; and an excellent relative speed detection sensor capable of achieving miniaturization and cost reduction. An effect that can be obtained.

According to a sixth aspect of the present invention, there is provided a radar device according to the first aspect, wherein the antenna is a dielectric lens antenna, and another member having a different dielectric constant is separately bonded to the lens. Alternatively, the radar device is characterized in that a part of the transmission wave is stably reflected by coating, and has an effect that a part of the transmission wave can be stably reflected in the antenna unit.

According to a seventh aspect of the present invention, there is provided a radar apparatus according to the first aspect, wherein the antenna is a dielectric lens antenna, and a non-reflection coating is applied to a side where a reflected wave is incident. In this radar apparatus, a reflected wave from a target is received without being reflected by an antenna, and it is possible to prevent a multiple reflection in which a reflected signal is reflected again in the direction of the target by the antenna in the antenna unit. Has an action.

According to another aspect of the radar apparatus, the oscillating means for oscillating and generating a radio wave, the modulation means for amplitude-modulating or frequency-modulating the radio wave to generate a transmission signal, and the mixing means for mixing the transmission signal And a circulator, an irreversible three-terminal element that guides the reflected signal incident from the antenna to the mixing means, and radiates most while reflecting part of the transmission signal. And an antenna for receiving a reflected signal returned by reflecting a radiated transmission signal on a target, and a mixing unit for mixing a part of the transmission signal reflected by the antenna and a reflection signal incident from the antenna Receiving signal processing means for detecting the presence or absence of a target by estimating the reception signal output from the mixing means in time or frequency, and estimating the distance and speed to the target; Antenna reflection control means for controlling the amount of transmission signal reflection at the antenna from the output obtained by the signal processing means. , So that a good reception state can be maintained.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

(First Embodiment) FIG. 1 is a block diagram showing a configuration of a radar apparatus according to a first embodiment of the present invention. In FIG. 1, the radar device according to the first embodiment includes an oscillating unit 1, a modulating unit 2, a circulator 3, an antenna 4, a mixing unit 5, and a received signal processing unit 6.

The oscillating means 1 oscillates and generates radio waves. For example, an in-vehicle millimeter-wave radar generates a 60 GHz or 76.5 GHz radio wave by oscillation using a dielectric oscillator or a Gunn diode.

The modulating means 2 generates a transmission signal by amplitude-modulating or frequency-modulating the radio wave. For example, several tens of ns
Perform amplitude modulation to generate ec pulses.

The circulator 3 is a non-reciprocal three-terminal element that cuts off the transmission signal toward the mixing means 5 and guides the signal toward the antenna 4, and conversely guides the reflected signal incident from the antenna 4 to the mixing means 5. It is composed of

The antenna 4 reflects a part of the transmission signal of the transmission signal guided from the circulator 3 and radiates most of the transmission signal to the outside (target), and the radiated transmission signal is transmitted to a target such as a vehicle. Receives the reflected signal reflected by the object.

Here, to reflect a part of the transmission signal means that the VSWR (voltage standing wave ratio) of the antenna 4 is 1 or more, and the reflection is reduced by a certain amount of stable reflection (VSWR). By making the characteristic constant and good, it is intended to positively utilize the reflection which is normally set to 0 to make it worse.

Both the transmission signal and the reflected signal reflected by the antenna 4 pass through the circulator 3 again, and are guided to the mixing means 5 while passing through the same waveguide. The mixing means 5 mixes the transmission signal and the reflected signal. Here, when the target is moving, the output signal of the mixing means 5 is shifted by the Doppler shift frequency by the Doppler frequency, which is proportional to the relative speed with respect to the radar device, since the frequency is shifted from the frequency of the transmission signal. This is a changing beat signal.

The received signal processing means 6 detects the frequency of the beat signal changing at the Doppler shift frequency, for example, by frequency-analyzing the signal for a certain period of time. Identify that.

In the above description, the case of amplitude modulation has been described. In the case of pulse modulation, the distance is obtained from the delay time with respect to the transmission pulse, and the relative speed is obtained from the Doppler shift frequency.

With the above arrangement, the transmission signal and the reception signal can be mixed without using the directional coupling means,
It is possible to obtain an excellent radar device having an effect that the size and the cost can be reduced, and the power loss due to the insertion of the directional coupling means does not need to be expected.

(Second Embodiment) FIG. 2 is a block diagram showing a configuration of a radar apparatus according to a second embodiment of the present invention. In FIG. 2, the radar apparatus according to the second embodiment is substantially the same as the above-described first embodiment except that the modulation unit is specified as the FM modulation unit 7.

That is, the oscillating means 1, the circulator 3,
The operations of the antenna 4 and the mixing means 5 are the same as those in the first embodiment, but the FM modulation means 7 linearly frequency-modulates the radio wave obtained from the oscillation means 1 to generate a transmission signal. . Therefore, the frequency fb of the beat signal obtained by the mixing means 5 is expressed as fb = (2R / C) × (ΔF / ΔT) ± V / C × fc (1) with respect to the distance R and the relative speed V. Become. However, in the above equation (1), C: speed of light, f
c: carrier frequency, ΔF / ΔT: slope of linear frequency modulation, and the sign of ± indicates how ΔF / ΔT changes depending on whether it is positive or negative, that is, whether it is an up slope or a down slope. I have.

That is, it is possible to obtain information on the distance and the relative speed only by analyzing the frequency of the beat signal which is an output obtained by mixing the transmission signal reflected by the antenna 4 and the reflection signal reflected by the target by the mixing means 5. it can.

With the above arrangement, the size and cost can be reduced without using the directional coupling means, and the distance and relative speed can be obtained simply by analyzing the frequency of the output after mixing the transmission signal and the reception signal. An excellent radar device that can easily obtain the above information can be obtained.

(Third Embodiment) FIG. 3 is a block diagram showing a configuration of a radar apparatus according to a third embodiment of the present invention. In FIG. 3, the radar device according to the third embodiment includes an oscillating means 1, a modulating means 2, a circulator 3, a mixing means (mixer) 5, a dielectric line (NRD) 8, a primary radiation means 9, And secondary radiation means 10.

The primary radiating means 9 and the secondary radiating means 10 have the same function as the antenna 4 of the first embodiment, and the operation of each of the other elements is the same as that of the first embodiment. The description is omitted because it is the same.

In the radar apparatus according to the third embodiment of the present invention, the transmission paths of each means, for example, between the modulating means 2 and the circulator 3, between the circulator 3 and the primary radiating means 9, between the circulator 3 and the mixing means 5, a non-radiative dielectric line (NRD) is used.

As for the non-radiative dielectric line (NRD), for example, see “Transactions of the Institute of Electronics, Information and Communication Engineers C-1”, Vol.
73-C-1, No.3, pp.87-94, March 1990, etc., so detailed explanations are omitted here, but Teflon or ceramic dielectric is sandwiched between conductive plates, This is a waveguide that can realize a line with a small loss by restricting propagation of light to almost a dielectric guide.

In the radar apparatus presented according to the present invention, since the directional coupler can be omitted, for example, the linear NR
It is possible to provide a simple configuration including a non-radiative dielectric line (NRD) in a very simple form of three D and a triangular NRD corresponding to the primary radiation means 9 and each means.

With the above configuration, it is possible to obtain a radar device having an excellent structure that can be easily processed and mass-produced.

(Fourth Embodiment) A radar apparatus according to a fourth embodiment of the present invention has the same appearance as the radar apparatus according to the third embodiment shown in FIG. A radar device according to a fourth embodiment will be described.

In the radar device according to the fourth embodiment of the present invention, the antenna comprises a primary radiator 9 having a wide directivity and a secondary radiator 10 for improving the directivity. In the secondary radiator 10, the electromagnetic wave once radiated from the primary radiator 9 can be controlled. For example, in the case of a planar antenna having a slit structure or a slot structure, by changing the shape and pitch of holes and grooves, it is possible to configure so that a part of the transmission wave is reflected without transmitting.

With the above configuration, it is possible to obtain an excellent radar device in which the amount of the transmitted wave can be easily adjusted while realizing the reflection of the transmitted wave by devising the configuration of the antenna unit in the radar device of the present invention.

(Fifth Embodiment) FIG. 4 is a block diagram showing a configuration of a radar apparatus according to a fifth embodiment of the present invention. As shown in FIG. 4, in the radar device according to the fifth embodiment of the present invention, the modulating means 2 is eliminated as compared with the radar device according to the first embodiment of the present invention.

If the radar device only needs to be able to detect the presence of a target and its relative speed (for example, as a speed radar, a speed sensor directed to the ground, a side sensor, etc.), A simple continuous wave without adding the modulating means 2 to the configuration
It is sufficient that the frequency of the beat signal and its amplitude can be known by mixing the reflected waves due to. Therefore, by omitting the modulating means 2, it is possible to provide a very simple configuration specialized for the relative speed detection sensor.

With the above configuration, it is possible to obtain an excellent relative speed detection sensor capable of reducing the number of components, reducing the size and cost, and providing an excellent radar device using the sensor.

(Sixth Embodiment) FIG. 5 is a block diagram showing a configuration of a radar apparatus according to a sixth embodiment of the present invention. In FIG. 5, components other than the primary radiator 9 and the lens antenna 11 of the radar device according to the sixth embodiment of the present invention are not shown, but include the components according to the above-described first embodiment. Since the operation is the same, the description is omitted here.

Here, the antenna configuration is composed of the primary radiating means 9 and the lens antenna 11. The lens antenna 11 is a dielectric lens antenna, and the ratio of reflection and transmission of radio waves can be changed by separately bonding or coating another member having a different dielectric constant to the lens.

Therefore, by performing the above-described contrivance on the lens antenna 11 in advance so that a sufficient transmission signal can be obtained on the mixing means 5 side, a part of the transmission wave can be reflected stably. As shown in FIG. 5, the lens antenna 11 may be an integrally formed antenna or a plywood type obtained by combining thin plates.

With the above configuration, it is possible to obtain an excellent radar device having an effect that a part of a transmission wave can be stably reflected relatively easily in the antenna section.

(Seventh Embodiment) FIG. 6 is a block diagram showing a configuration of a radar apparatus according to a seventh embodiment of the present invention. In FIG. 6, components other than the primary radiator 9 and the lens antenna 11 of the radar device according to the seventh embodiment of the present invention are not shown, but include the components according to the above-described first embodiment. Since the operation is the same, the description is omitted here.

The structure of the antenna is the primary radiation means 9
And a lens antenna 11. Lens antenna
Reference numeral 11 denotes a dielectric lens antenna. Therefore, the drawing is the same as the fifth embodiment described above, except that the lens antenna 11 is devised. In other words, if the reflected signal from the target object is re-reflected when it enters the lens antenna 11, the worst case is multiple reflections in which radio waves travel between the radar device and the target object many times. Detection becomes difficult.

Therefore, the lens antenna 11 is provided with an anti-reflection coating on the side where the reflected signal from the target is incident, so that the reflected signal is reflected on the reflected signal incident side of the lens antenna 11 and again the target object. Radiation can be prevented.

According to the above configuration, it is possible to obtain an excellent radar apparatus having an effect that it is possible to prevent a multiple reflection in which a signal reflected from a target object is reflected again by the antenna toward the target object at the antenna unit.

(Eighth Embodiment) FIG. 7 is a block diagram showing a configuration of a radar apparatus according to an eighth embodiment of the present invention. 7, the operation of the radar apparatus according to the eighth embodiment of the present invention other than the antenna reflection control means 12 and the received signal processing means 6 is described in the first embodiment. Since the operation is the same as that of the first embodiment, the description is omitted here.

Now, in the case of the present invention, the transmission signal is guided to the receiving side (mixing means 5) using the reflection at the antenna 4, but the amount of reflection,
The impedance may change greatly. Then, the quality of the beat signal obtained when the target is present in the received signal processing means 6 changes greatly, and the worst-case detection may not be possible.

Therefore, when a target is detected, or the maximum radiation direction of the antenna is deliberately tilted toward the ground (automatically) to catch the reflection of the ground, and the signal analysis result from the target or the ground becomes the best. As described above, the antenna reflection control means 12 controls the reflection state of the antenna 4.

More specifically, for example, the reception signal processing means 6
The reflection state of the antenna is controlled so that the amplitude of the beat signal obtained as a result of the analysis becomes larger than a certain magnitude and the spectrum width is also minimized. If the reflection state is specifically controlled, for example, in the case of a lens antenna, a diaphragm is provided in the antenna, and the amount of reflection is adjusted by the diaphragm. Alternatively, when the antenna 4 is composed of primary radiating means and secondary radiating means, it can be adjusted by slightly changing the relative positional relationship between the two.

With the above configuration, an excellent radar device having an effect that even if the reflection characteristic of the antenna changes every moment, it can be controlled so as to have a constant reflection so that the reception state can be kept good. be able to.

[0062]

As described above, according to the radar apparatus of the present invention, a part of the transmission signal is reflected by the antenna instead of the directional coupling means provided in the conventional radar apparatus, and the reflected component is reflected. By reducing the number of components and reducing the cost by mixing the transmission signal and the reflection signal from the target object and eliminating the need for the directional coupling unit that splits the transmission signal to the mixing unit. There is an effect that a radar device can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a radar apparatus according to a first embodiment of the present invention;

FIG. 2 is a block diagram showing a configuration of a radar device according to a second embodiment of the present invention;

FIG. 3 is a block diagram showing a configuration of a radar device according to third and fourth embodiments of the present invention;

FIG. 4 is a block diagram showing a configuration of a radar device according to a fifth embodiment of the present invention;

FIG. 5 is a block diagram showing a configuration of a radar device according to a sixth embodiment of the present invention;

FIG. 6 is a block diagram showing a configuration of a radar apparatus according to a seventh embodiment of the present invention;

FIG. 7 is a block diagram showing a configuration of a radar apparatus according to an eighth embodiment of the present invention;

FIG. 8 is a block diagram illustrating a configuration of a conventional radar device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 51 Oscillation means 2, 52 Modulation means 3, 53 Circulator 4, 54 Antenna 5, 55 Mixing means 6, 56 Received signal processing means 7 FM modulation means 8 Dielectric line (NRD) 9 Primary radiation means 10 Secondary radiation Means 11 Lens antenna 12 Antenna reflection control means 57 Directional coupling means

Claims (8)

[Claims] An oscillation means for oscillating and generating a radio wave, a modulation means for amplitude-modulating or frequency-modulating the radio wave to generate a transmission signal, and a transmission signal cut off toward a mixing means and directed toward an antenna. A circulator, which is an irreversible three-terminal element that guides the reflected signal incident from the antenna to the mixing means, and radiates most while reflecting part of the transmission signal, and radiates the transmitted signal. An antenna for receiving the reflected signal reflected back from the target, a part of the transmitted signal reflected by the antenna, and a mixing unit for mixing the reflected signal incident from the antenna; and an output of the mixing unit. A radar apparatus comprising: reception signal processing means for detecting presence / absence of a target by analyzing a received signal in terms of time or frequency and estimating a distance and a speed to the target. 2. An oscillating means for oscillating and generating a radio wave, and an FM for linearly frequency-modulating the radio wave to generate a transmission signal.
A frequency modulating means, a circulator as an irreversible three-terminal element for blocking a transmission signal toward the mixing means and guiding the signal toward the antenna, and conversely guiding a reflected signal incident from the antenna to the mixing means; An antenna that radiates most while reflecting a part of the antenna, and receives a reflected signal that has been returned from the radiated transmission signal reflected by the target, and a part of the transmission signal reflected by the antenna, Mixing means for mixing the reflected signals incident from the antenna, and reception for detecting the presence or absence of the target and estimating the distance and speed to the target by analyzing the reception signal output from the mixing means in frequency. And a signal processing means for detecting a target by the FMCW method. 3. The radar apparatus according to claim 1, wherein a non-radiative dielectric line (NRD) is used in a transmission path of each means. 4. The antenna used in the radar device according to claim 1, wherein the antenna comprises a primary radiator having a wide directivity and a secondary radiator improving the directivity.
A radar device characterized in that a secondary radiator is configured so that a part of a transmission wave is reflected without transmitting. 5. An oscillating means for oscillating and generating a radio wave as a transmission signal, and intercepting the transmission signal toward the mixing means and guiding the signal toward the antenna, and conversely transmitting a reflected signal incident from the antenna to the mixing means. A circulator that is an irreversible three-terminal element that guides, and radiates most while reflecting part of the transmission signal,
And, an antenna that receives a reflected signal that is reflected by a radiated transmission signal reflected from a target, and a part of the transmission signal that is reflected by the antenna, and a mixing unit that mixes the reflection signal that is incident from the antenna. A reception signal processing means for detecting presence or absence of a target by analyzing a reception signal output from the mixing means in terms of frequency, and estimating a speed to the target. 6. An antenna used in the radar device according to claim 1, wherein the antenna is a dielectric lens antenna, and another member having a different dielectric constant is separately adhered or coated on the lens to reduce the transmission wave. A radar device characterized in that a part is stably reflected. 7. The antenna used in the radar device according to claim 1, wherein the antenna is a dielectric lens antenna, and the reflection wave is incident on the side on which the reflection wave is incident so that the reflection wave from the target is reflected. A radar device for receiving signals without being reflected by an antenna. 8. An oscillating means for oscillating and generating a radio wave, a modulating means for amplitude-modulating or frequency-modulating the radio wave to generate a transmission signal, and intercepting the transmission signal toward the mixing means and directing the transmission signal toward the antenna. A circulator, which is an irreversible three-terminal element that guides the reflected signal incident from the antenna to the mixing means, and radiates most while reflecting part of the transmission signal, and radiates the transmitted signal. An antenna for receiving the reflected signal reflected back from the target, a part of the transmitted signal reflected by the antenna, and a mixing unit for mixing the reflected signal incident from the antenna; and an output of the mixing unit. Received signal processing means for detecting the presence or absence of a target by analyzing the received signal in time or frequency, and estimating the distance to the target, speed, and the output obtained by the received signal processing means, A radar device comprising: antenna reflection control means for controlling a transmission signal reflection amount at an antenna.