JPH06174824A - Radar module - Google Patents

Abstract

PURPOSE:To provide a radar module wherein the number of part items is decreased, dimensions are reduced and resultant cost reduction is devised. CONSTITUTION:A single diode mixer 16 is connected to a high frequency signal generator such as an FM signal generator 11 via a non-radioactive dielectric line 22 and the like. A directional coupler 13 is formed of the non-radioactive dielectric line 22 and the like and a curved shape non-radioactive dielectric line 23 and the like arranged in the vicinity thereof. A transmission antenna 14 and a receiving antenna 15 of a non-radioactive dielectric line are connected respectively to both ends of the curved shape non-radioactive dielectric line 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar module used in a millimeter wave band radar device for vehicles.

[0002]

2. Description of the Related Art A vehicle-mounted radar device mounted on a vehicle such as a passenger car and used as a warning device for collision prevention or collision prevention,
High resolution is required because the detection range is set to a close range of several tens of centimeters. In terms of this high resolution, the form of the FM radar is more suitable than the form of the pulse radar. In addition, since the farthest distance measurement range to the target such as a preceding vehicle or an oncoming vehicle is a comparatively short distance of about several hundred meters, radiated radio waves can propagate more than necessary and communication in existing microwave bands can be performed. 60Ghz to avoid interference with equipment
A millimeter wave band radio wave with a large propagation attenuation is suitable. This millimeter wave band is used for the antenna and the F before and after the antenna.
It is also suitable for downsizing the radar module including the M signal generator and the mixer.

Conventionally, the millimeter-wave band radar module is constructed in the form of a microstrip line.
For this reason, there is a problem that the radiation power from the line increases and the loss increases, and interference easily occurs between the radar modules of a plurality of systems, and the measurement accuracy decreases. Further, further downsizing of the radar module, reduction of the number of parts, and cost reduction due to this are also required.

As a new line format for solving the above problems, the Institute of Electronics, Information and Communication Engineers, Journal Vol. J 73 C-1 No.
3 pp.87-94 (March 1990), "Non-radiative Dielectric Line (Non-Radio Dielectric Line)" as disclosed in Yoneyama et al. Radiat
ive Dielectric waveguide (NRD) is suitable. In this non-radiative dielectric waveguide, a rod-shaped dielectric is inserted between two conductor plates facing each other with a gap slightly smaller than a half wavelength, so that only the propagation along the rod is possible. In this non-radiative dielectric line, the top and bottom of the line are completely shielded by the conductor plates, and the propagation of radio waves that leak to the side of the line is completely blocked because the conductor spacing is less than half a wavelength. . Therefore, the power radiation from the line is extremely small, and radiation loss inside the module and mutual interference between the modules are effectively avoided.

Further, in the non-radiative dielectric line, various parts such as a directional coupler and an isolator can be easily prepared by bringing the lines close to each other or adding ferrite or the like. Therefore, after preparing each part separately, The miniaturization of the entire module can be realized as compared with the conventional microstrip type in which lines are connected to each other.

The above-mentioned paper by Yoneyama et al. Discloses a millimeter-wave band transmitter and receiver using a non-radiative dielectric line. The inventor of the present invention takes into consideration that the conventional FM radar module using the microstrip line is generally a method in which the FM signal generator on the transmitting side and the local oscillator on the receiving side are commonly used. A millimeter wave band FM radar module using a non-radiative dielectric waveguide having the structure shown was manufactured as a prototype. This radar module is based on a non-radiative dielectric waveguide composed of a linear or curved rod-shaped dielectric inserted between an upper conductor plate 30 and a lower conductor plate having the same shape as the Gunn diode. And FM signal generator 31, isolator 32, directional couplers 33 and 36, and transmission antenna 3 using varactor diodes
4, a receiving antenna 35 and a balanced mixer 37.

The millimeter-wave band FM signal generated by the FM signal generator 31 passes through the isolator 32, half of the power is supplied to the transmitting antenna 34 through the directional coupler 33, and the remaining half of the power is supplied. It is supplied to the balanced mixer 37 as a local signal. The FM signal supplied to the transmitting antenna 34 is radiated to the outside from its tip. The reflected wave from the object is received by the receiving antenna 35, the power of half of which is directly supplied to one mixer diode of the balanced type, and the other half is supplied to the other mixer diode through the directional coupler 36. . Further, half of the local signals supplied to the balanced mixer 37 are directly supplied to the other mixer diode, and the remaining half of the power is supplied to the one mixer diode.

[0008]

According to the FM radar module using the non-radiative dielectric waveguide shown in FIG.
Since the radiated power from the line is extremely small, it was confirmed that the line loss is small and mutual interference between modules is effectively avoided. However, the module of FIG. 6 is still insufficient in terms of downsizing and reduction of the number of parts.

[0009]

According to the radar module of the present invention, a single diode mixer is connected to a high frequency signal generator such as an FM signal generator via a non-radiative dielectric line, and the mixer and the high frequency signal are connected. A directional coupler is formed by the non-radiative dielectric line connecting the generator and the curved non-radiative dielectric line arranged close to the non-radiative dielectric line. The antenna of the non-radiative dielectric line is connected to each.

[0010]

In the radar module of the present invention, the single diode mixer is adopted in place of the conventional balanced mixer to reduce the number of parts and downsize. That is, as described above, the non-radiative dielectric line inherently has a high-frequency blocking filtering function that almost completely suppresses the propagation of high-frequency signals such as millimeter-wave band FM signals. It is possible to take out a beat signal containing no high frequency signal through the lead wire extending between the parallel conductor plates without depending on the suppression function of the high frequency signal by the adoption. Even if a balanced mixer is used, it is quite difficult to accurately divide the power by two mixer diodes and a directional coupler at high frequencies in the millimeter wave band. The components cannot be suppressed sufficiently.

A high frequency signal output from a high frequency signal generator such as an FM signal generator passes through a non-radiative dielectric line and is supplied as a local signal to a single diode mixer. On the other hand, a non-radiative dielectric line connecting between the high-frequency signal generator and the single diode mixer, and a curved non-radiative dielectric line arranged in the vicinity of the non-radiative dielectric line are used for both transmission and reception. And a transmitting / receiving antenna is connected to each of both ends of the curved non-radiative dielectric waveguide. Part of the high-frequency signal supplied from the high-frequency signal generator is radiated from the transmitting antenna through the directional coupler for both transmission and reception, and the reflected wave received by the receiving antenna is also single through the directional coupler for both transmission and reception. Supplied to the diode mixer,
A beat signal is generated by mixing with a local signal.

[0012]

1 is a plan view showing the structure of an FM radar module according to an embodiment of the present invention. 10 is an upper conductor plate, 11 is an FM signal generator, 12 is an isolator, 13
Is a directional coupler, 14 is a transmitting antenna, 15 is a receiving antenna, 16 is a single diode mixer, 21, 2
Reference numerals 2 and 23 are dielectric rods.

The structure of the peripheral portion of the FM signal generator 11 of FIG. 1 is shown by the perspective view of FIG. 2 with the upper conductor plate 10 and the lower conductor plate 10 'partially removed. A low-pass filter for bias is formed, and a dielectric substrate on which a Gundiode GD and a varactor diode VD for frequency modulation are mounted is fixed to a side surface of a metal holder that also functions as a heat sink. Between the Gunn diode GD and the dielectric rod 21 forming the non-radiative dielectric line, a metal strip MS also serving as a resonator for guiding the FM signal to the dielectric rod 21 is formed. Gunn diode GD
The bias voltage for and the modulation signal for the varactor diode are provided via leads L1, L2 and a low pass filter.

The upper conductor plate 10 and the lower conductor plate 10 'are
Since the Gunn diode GD is arranged in parallel with a spacing slightly smaller than the half wavelength of the FM signal in the millimeter wave band generated by the Gunn diode GD, this FM signal can propagate only along the high-dielectric-constant dielectric rod 21. Become. There are two main propagation modes, the LSM ₀₁ mode and the LSE ₀₁ mode, but of these, only the low loss LSM ₀₁ mode is used. In order to suppress the LSE ₀₁ mode that occurs at the location where the symmetry of the circuit structure is impaired, the mode suppressor M
S is embedded in the corresponding part of the dielectric rod.

The single diode mixer 16 of FIG.
3 is shown in a plan view of FIG. 3 with the upper conductor plate 10 removed. For impedance matching, a void GP is formed near the end of the dielectric rod 22, and a dielectric plate 23 having a high dielectric constant is arranged at the end, and a mixer is provided between the dielectric plate 23 and the holder 24. A dielectric plate 25 having a diode mounted thereon is held. As shown in FIG. 4, a low-pass filter is formed on the dielectric plate 25, and a mixer diode MD is mounted on the dielectric plate 25, and a bias voltage is supplied via a lead wire L3 drawn out to the outside through the upper and lower conductor plates. This lead wire L3
The beat signal is taken out through.

The structure of the peripheral portion of the isolator 12 of FIG. 1 is shown in the perspective view of FIG. 5 with the upper conductor plate 10 removed. Ferrite disk resonators 25 and 26 are arranged in close contact with the upper and lower conductor plates between three dielectric rods 21, 22 and 24 which are arranged at an angle of 120 ^{° to} each other, and are perpendicular to the conductor plates. A DC magnetic field is applied in the direction. The dielectric rod 24 is for constituting a non-reflective terminator,
Three pieces of the electromagnetic wave absorber AS are horizontally inserted in the upper and lower intermediate positions.

Referring to FIG. 1, the millimeter-wave band FM signal generated by the FM signal generator 11 propagates along the dielectric rod 21 and is supplied to the input terminal of the isolator 12. Output from the output terminal to the linear dielectric rod 22. The directional coupler 13 is formed by the linear dielectric rod 13 and the semicircular dielectric rod 23 arranged close to the linear dielectric rod 13.
A part of the FM signal output from the isolator 12 moves to the dielectric rod 23, and is radiated to the outside from the transmitting antenna 14 formed at the tip of one of the dielectric rods 23. The remaining part of the FM output from the isolator 12 propagates along the linear dielectric rod 22 to its tip and is supplied as a local signal to the single diode mixer 16 formed therein.

Of the reflected waves from the object, the receiving antenna 15
Part of the received signal is transferred to the linear dielectric rod 22 through the directional coupler 23 and supplied to the single diode mixer 16, and the remaining part is re-radiated from the transmitting antenna 14. It The single diode mixer 16 receives a local signal supplied from the output terminal of the isolator 12 via the dielectric rod 22, and a reflected wave supplied from the receiving antenna 15 via the directional coupler 13, and outputs both signals. A beat signal is generated by mixing and is output to the lead wire L3 drawn through between the upper and lower conductor plates.

On the other hand, the reflected wave from the object is also received by the transmitting antenna 14, which propagates along the semicircular dielectric rod 23 to the receiving antenna 15 and is radiated again. Further, a part of the reflected wave received by the transmitting antenna 14 is supplied to the isolator 12 through the directional coupler 13 and the dielectric rod 22, and is absorbed by the non-reflection end 24 thereof. As described above, in the radar module of FIG. 1, since the transmitting / receiving antennas 14 and 15 share the directional coupler 13, re-radiation and re-radiation from each antenna occur, and the reflected wave received with this re-radiation occurs. Is a unnecessary wave that is re-input to the single diode mixer 13 later than the originally necessary reflected wave. However, since this unwanted wave is generated by the FM signal that reciprocates between the antenna and the reflecting object more than twice, it is sufficiently lower than the originally necessary reflected wave in consideration of the relatively low antenna gain of transmission and reception and large spatial propagation loss. It becomes a level and the influence on the radar function can be ignored.

The radar module of the present invention has been illustrated above by taking the case of the FM radar module as an example. However, it is obvious that the configuration of the present invention can be applied to the case where the Doppler radar is configured by using a fixed frequency high frequency signal generator instead of the FM signal generator.

[0021]

As described in detail above, the radar module of the present invention includes a non-radiative dielectric line connecting the single diode mixer and the high-frequency signal generator, and a curved non-radiating dielectric line arranged close to the non-radiative dielectric line. Since a directional coupler for both transmission and reception is formed by the radiative dielectric line and the transmitting antenna and the receiving antenna are connected to both ends of this curved non-radiative dielectric line, respectively, the conventional configuration shown in FIG. Compared with this, the number of parts of the mixer diode and the directional coupler is reduced by half, and a compact and inexpensive module is realized.

Further, an isolator is installed between the single diode mixer and the high frequency signal generator, and the non-radiative dielectric line connecting between the output terminal of this isolator and the single diode mixer is made linear and transmitted. By forming the non-radiative dielectric line connected to the receiving antenna in a semicircular shape, it is possible to reduce the generation of unnecessary modes and the manufacturing labor.

[Brief description of drawings]

FIG. 1 is a plan view showing the overall configuration of an FM radar module according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of an FM signal generator 11 in FIG.

FIG. 3 is a plan view showing a configuration of a single diode mixer 16 and its peripheral portion in FIG.

4 is a plan view showing a configuration of a single diode mixer 16 in FIG.

5 is a perspective view showing a configuration of an isolator 12 and its peripheral portion in FIG.

FIG. 6 is a plan view showing the overall configuration of an FM radar module configured by applying the prior art.

[Explanation of symbols]

 11 FM signal generator 12 Isolator 13 Directional coupler 14 Transmitting antenna 15 Receiving antenna 16 Single diode mixer 21-24 Dielectric rod

Claims (3)

[Claims] 1. A radar module in which a high-frequency signal generator, a transmitting / receiving antenna of a non-radiative dielectric line and a mixer are connected via a directional coupler of a non-radiative dielectric line, wherein the mixer is a single diode mixer. And a non-radiative dielectric line that is connected to the high-frequency signal generator via a non-radiative dielectric line and that connects the mixer and the high-frequency signal generator, and a curved shape that is arranged close to the non-radiative dielectric line. The non-radiative dielectric line and the directional coupler are formed, and the transmitting and receiving antennas of the non-radiative dielectric line are connected to both ends of the curved non-radiative dielectric line, respectively. Radar module. 2. The isolator according to claim 1, wherein an isolator is installed between the mixer and the high-frequency signal generator, and a linear non-radiative dielectric line is provided between the mixer and the output terminal of the isolator. Radar module characterized by being connected. 3. The radar module according to claim 2, wherein the curved non-radiative dielectric waveguide forming the directional coupler has a substantially semicircular shape.