JPH0777576A - Millimetric wave transmitter/receiver, millimetric wave receiver and millimetric wave transmitting/receiving antenna - Google Patents

Abstract

PURPOSE:To realize a millimetric wave transmitter/receiver having a simple circuitry. CONSTITUTION:A Gunn diode and a metal strip resonator generate an oscillation frequency in the range of 50-70GHz. Output from an oscillator is modulated and radiated as a radio wave from an antenna 7 and a signal identical to that radiated from the antenna 7 is also fed to a frequency mixer 9. The radio wave is reflected on an obstacle, if any, and returned back to the antenna 7 then fed to the frequency mixer 9. A signal previously inputted to the frequency mixer 9 is affected by the signal thus returned. Consequently, the position and relative speed of an obstacle present in the radiating direction of radio wave can be detected by observing the deformation of output signal from the mixer 9. This transmitter/receiver can be applied to the front end of a 60GHz mobile radar.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is used as a transmission / reception device in the millimeter wave region. The present invention was developed for use in a proximity warning device, a collision prevention device, and other radar devices that use electromagnetic waves, which are installed in automobiles, but can also be used in other devices. The present invention is a non-radiative dielectric line (NRD guide, Non Radiative Dielectric Guide).
The present invention relates to a high frequency circuit using.

[0002]

2. Description of the Related Art It has been attempted to equip a vehicle with a proximity warning device for a preceding vehicle, a collision prevention device for warning an approaching object, and the like by a radar device utilizing an electromagnetic wave having an extremely high frequency. In recent years, it has been planned to allocate radio waves in the 60 GHz band to radar devices for automobiles.

A technique for an oscillator or an integrated circuit in this frequency band is disclosed in, for example, "Yoneyama: Non-radiative Dielectric Line (N
Millimeter-wave integrated circuit using RD guide, IEICE Transactions CI, Vol J73-CI No3 pp87-94 1990 3
There is disclosure in "Month". This document describes an oscillator, a guide, a power distributor, an antenna, etc. in this frequency band. Further, the applicant of the present application has applied for a patent for a transmitter and a modulator of this frequency band (Japanese Patent Application No. 5-52).
No. 607, unpublished at the time of filing this application).

[0004]

The electromagnetic waves in the 60 GHz band have a wavelength of about 5 mm in free space, and even if the conventional three-dimensional circuit or semiconductor integrated circuit is simply downsized, a practical transmitting / receiving device cannot be realized. . If a conventional horn antenna is used for a radar device mounted on a vehicle, a device in this frequency band cannot be obtained as a practical device because the shape is too small. Further, a transmitter / receiver having a simple structure and stable against vibration is required.

The present invention has been made against such a background, and an object thereof is to provide a millimeter wave transmitting / receiving apparatus having a simple circuit configuration and having a shape and a size suitable for mounting on an automobile. An object of the present invention is to provide a front end (transmission / reception end) of a 60 GHz band automotive radar device.

[0006]

A first aspect of the present invention is a millimeter wave transmitter / receiver, which is characterized by a millimeter wave oscillator and a non-radiative dielectric line for guiding the output of the oscillator. A first waveguide, an angle modulator inserted in the first waveguide, a circulator whose first terminal is coupled to the output end of the first waveguide, and a second terminal of the circulator. A combined transmit and receive antenna,
A frequency mixer coupled to the third terminal of the circulator; and a directional coupler for partially separating the signal traveling from the oscillator in the direction of the circulator through the first waveguide and coupling it to the carrier input of the frequency mixer. It's right there.

Here, the angle modulator is a frequency modulator or a phase modulator.

Further, a millimeter wave oscillator, a first waveguide composed of a non-radiative dielectric line for guiding the output of the oscillator, a frequency modulator inserted in the first waveguide, and the first waveguide. A circulator whose first terminal is coupled to the output end of the waveguide, a second waveguide which is coupled to the second terminal of this circulator and is constituted by a non-radiative dielectric line, and the other end of this second waveguide. An antenna connected to
A third waveguide coupled to the third terminal of the circulator and configured by a non-radiative dielectric line, a first frequency mixer coupled to the output end of the third waveguide, and the first conductor. A fourth directional coupler composed of a first directional coupler that partially separates a signal traveling from the oscillator to the circulator in the waveguide and a non-radiative dielectric line that guides the signal separated by the first directional coupler. A waveguide, a second frequency mixer coupled to the output of the fourth waveguide, and the fourth waveguide from the first directional coupler in the direction of the second frequency mixer. A second directional coupler for mutually coupling a traveling signal and a signal traveling through the third waveguide in the direction toward the first frequency mixer, the first frequency mixer and the second frequency coupler Frequency mixers set to form a balanced mixer with each other It can also be configured to be.

A second aspect of the present invention is a millimeter wave receiving apparatus, which is characterized by a waveguide constituted by a non-radiative dielectric line to which a received signal is supplied and a non-radiative wave from which a carrier wave is supplied. A waveguide constituted by an inductive line,
The two waveguides are provided with a directional coupler that couples the received signal and the carrier wave traveling in the two waveguides to each other, and two frequency mixers that are coupled to the output ends of the two waveguides. The mixers are set up to form an equilibrium mixer with each other.

Further, the two waveguides and the two frequency mixers are provided with a structure in which they are coupled through a gap (for example, corresponding to a half wavelength of a signal) and a non-radiative dielectric line piece provided respectively between them. The signal to noise ratio can be improved.

A third aspect of the present invention is a millimeter-wave transmitting / receiving antenna having a radiation surface which is formed of a non-radiative dielectric line and has a radiation surface formed at an angle in the signal traveling direction.

[0012]

The oscillation output generated from the Gunn diode resonates with the metal strip resonator to a desired stable oscillation frequency within 50 to 70 GHz, more specifically 59 to 65 GHz. The oscillator output propagates through the non-radiative dielectric line and reaches the modulator. The modulator is one in which a variable capacitance diode is mounted on a non-radiative dielectric and is orthogonally inserted into a non-radiative dielectric line. The variable capacitance diode is an element whose capacitance changes with voltage.
Due to the change, a part of the output signal propagated to the non-radiative dielectric line is reflected, and the signal returning to the oscillator side changes with the capacitance of the variable capacitance diode. As a result, the oscillation frequency of the output of the oscillator changes and is modulated.

The signal thus modulated is radiated as a radio wave from the antenna. Further, the same signal as that radiated from the antenna is branched by the directional coupler and input to the frequency mixer as a local oscillation signal. If there is no obstacle in the radiation direction of the radio wave, the local oscillation signal input to the frequency mixer is output without being affected by other signals. However, if there is an obstacle, the radio wave reflected by the obstacle returns to the antenna. The returned signal is input to the frequency mixer. The local oscillator signal of the frequency mixer is affected by this returned signal. Therefore, the waveform of the output signal of the frequency mixer is deformed as compared with the case where the returned signal does not exist. By observing the deformation state of the output signal, the position of the obstacle existing in the radiation direction of the radio wave and the relative speed to the obstacle can be detected.

As a result, it is possible to realize a millimeter wave transmitter / receiver having a shape and size suitable for mounting on an automobile with a simple circuit configuration. This millimeter wave transmission / reception device can be applied to the front end of a 60 GHz band automotive radar device.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention.

The present invention is a millimeter wave transmission / reception device, which is characterized by a millimeter wave oscillator 1 and a first waveguide 11 composed of a non-radiative dielectric line for guiding the output of the millimeter wave oscillator 1. , A frequency modulator 4 inserted in the first waveguide 11, a circulator 6 having a first terminal coupled to an output end of the first waveguide 11, and a second terminal of the circulator 6. Transmitted and received antenna 7
The frequency mixer 9 coupled to the third terminal of the circulator 6 and the first waveguide 11 are connected to the millimeter wave oscillator 1
To a circulator 6 from which a part of the signal traveling is separated and coupled to the carrier input of the frequency mixer 9 with directional couplers 5 and 8.

Next, the structure of the apparatus of the present invention will be described with reference to FIGS. FIG. 2 is a plan view of the apparatus according to the present invention. FIG. 3 is a perspective view of the apparatus according to the present invention. A millimeter wave transmitter / receiver which is an embodiment of the present invention comprises a millimeter wave oscillator 1, a first waveguide 11 constituted by a non-radiative dielectric line for guiding the output of the millimeter wave oscillator 1, and the first waveguide. 11 is composed of a frequency modulator 4 inserted in 11, a circulator 6 having a first terminal coupled to the output end of the first waveguide 11, and a non-radiative dielectric line coupled to a second terminal of the circulator. The second waveguide 12, the antenna 7 connected to the other end of the second waveguide, and the third waveguide 13 which is coupled to the third terminal of the circulator 6 and is constituted by a non-radiative dielectric line. When,
A first frequency mixer 91 coupled to the output end of the third waveguide 13 and a first direction for partially separating a signal traveling through the first waveguide 11 from the millimeter wave oscillator 1 toward the circulator 6. To the output end of the fourth waveguide 14 and a fourth waveguide 14 constituted by a non-radiative dielectric line for guiding the signal separated by the first directional coupler 5 The second frequency mixer 92, the fourth waveguide 14, and the signal traveling from the first directional coupler 5 in the direction of the second frequency mixer 92 and the third waveguide 13. A second directional coupler 8 for mutually coupling a signal traveling in the direction toward the first frequency mixer 91, and the first frequency mixer 91 and the second frequency mixer 92 are balanced with each other. It is set up to form a mixer. The device according to the embodiment of the present invention is manufactured as a prototype for use as a front end of a radar device mounted on an automobile.

Next, the operation of the apparatus of the present invention will be described. The Gunn diode 30 of the millimeter wave oscillator 1 resonates with the metal strip resonator 2 and oscillates a radio wave of 60 GHz.
The oscillated radio wave is modulated into a triangular wave through the high dielectric constant sheet 3 and the frequency modulator 4 inserted in the first waveguide 11 (for details of the frequency modulator, see Japanese Patent Application No. 5-0.
52607, unpublished at the time of filing this application). This modulated radio wave is
Distributed in the direction. In the device of the present embodiment, the gap between the first waveguide 11 and the directional coupler 5 is 0.1 mm.

One of the distributed radio waves is supplied to the second waveguide 12 via the circulator 6, and further supplied to the antenna 7. The other is used as a mixer local signal of the second frequency mixer 92 via the fourth waveguide 14. The radio wave supplied to the antenna 7 is radiated into space. When an obstacle is present, the radio wave is reflected, supplied again to the third waveguide 13 via the antenna 7 and the circulator 6, and used as a mixer local signal of the first frequency mixer 91. Also, the third waveguide 1
A part of the signal supplied to 3 is guided to the fourth waveguide 14 by the second directional coupler 8, and the second frequency mixer 9
2 is also supplied. In the device of the present embodiment, the gap between the third waveguide 13 and the directional coupler 8 is 0.2 mm.
As a result, the first frequency mixer 91 and the second frequency mixer 92 form a balanced mixer, and an IF (intermediate frequency) signal is output as reflection information. Further, the coupling between the first and second frequency mixers 91 and 92 and the third and fourth waveguides 13 and 14 is performed via a gap. In the device of the present invention, this gap is set to 2.2 mm.
And By using a balanced mixer, even-order (2
The non-linear noise of the (4th, 4th) order is canceled and the signal-to-noise ratio is improved as a whole. Further, since the distance between the upper and lower metal plates is half a wavelength or less, even harmonics do not occur. The structure of this embodiment is simple because no bias voltage is supplied to the diodes forming the balanced mixer.

Next, referring to FIG. 4, the presence / absence of an obstacle and the IF
The relationship with signals will be described. FIG. 4 is a diagram showing the relationship between the presence or absence of an obstacle and the IF signal. In FIG. 4, the horizontal axis represents the IF signal frequency, and the vertical axis represents the IF signal level. Figure 4 (a)
Shows the IF signal when there is no obstacle in the radiation direction of the radio wave. The waveform is almost flat over about 1 MHz to 5 MHz. FIG. 4B shows an IF signal when an obstacle exists 20 m ahead of the radio wave radiation direction. A high level waveform appears just above 2 MHz. FIG. 4C shows the IF when an obstacle exists 30 m and 47 m ahead of the radio wave radiation direction.
Shows the signal. A little over 3MHz and 4M
A high level waveform appears between Hz and 5 MHz. When the millimeter wave transmitting / receiving device of the device of the embodiment of the present invention is used as the front end of the radar device, it is possible to detect the distance of the obstacle in the radiation direction of the radio wave and the relative speed to itself by the situation of these waveforms. it can.

Next, various characteristics of the apparatus of the present invention will be described with reference to FIGS. FIG. 5 is a diagram showing the relationship among the metal strip resonator length, the oscillation frequency, and the transmission output. The horizontal axis represents the length of the metal strip resonator (mm), and the vertical axis represents the oscillation frequency (GHz) and the transmission output (mW). The transmission output takes a maximum value when the length of the metal strip resonator exceeds 2.25 mm, which is about 160 mW. The oscillation frequency at this time is about 59 GHz to 61 GHz.
Is. In the device of the present invention, the metal strip resonator length was set to 2.25 mm.

FIG. 6 is a diagram showing frequency modulation characteristics of the frequency modulator 4. The horizontal axis represents the varactor diode bias voltage, and the vertical axis represents the frequency modulation width and output. 200
A nearly linear modulation characteristic with an output of 50 mW or more was obtained over MHz.

FIG. 7 is a diagram showing the characteristics of the directional coupler.
The horizontal axis represents the frequency of the input signal, and the vertical axis represents the output signal level of the directional coupler. FIG. 8 is a diagram showing a measurement arrangement of directional coupler characteristics. The output signal S21 with respect to the input signal S11 shown in FIG. 8 was measured. The gap between the waveguide 31 and the directional coupler 32 was measured as 1.0 mm. 60GH
An output signal S21 was obtained in which the input signal S11 was attenuated by −3.25 dB at z.

FIG. 9 is a diagram showing insertion loss characteristics of the circulator 6. FIG. 10 is a diagram showing the isolation characteristic of the circulator 6. FIG. 11 shows a circulator 6
FIG. 6 is a diagram showing a measurement arrangement of insertion loss characteristics and isolation characteristics of FIG. In FIG. 9, the horizontal axis represents the frequency of the input signal (GH
z) and the insertion loss level (dB) on the vertical axis. This measurement result was measured by the measurement arrangement shown in FIG.
A mode suppressor is connected to each of the three terminals of the circulator 6, a non-reflection terminal is connected to one of the terminals, and tetrafluoroethylene resin pieces A and B are connected to the other two terminals, respectively. . The input signal S11 shown by the solid line was supplied from the tetrafluoroethylene resin piece A shown in FIG. 11, and the output signal S21 shown by the solid line was measured in the tetrafluoroethylene resin piece B. An insertion loss of -0.5 dB at 60.25 GHz was measured.

In FIG. 10, the horizontal axis represents the frequency of the input signal (GH
z), and the vertical axis shows the isolation level. This measurement result was measured by the measurement arrangement shown in FIG.
The input signal S22 indicated by the broken line is supplied from the tetrafluoroethylene resin piece B shown in FIG.
The output signal S12 indicated by the broken line was measured. 60.5G
An isolation of -29.94 dB at Hz was obtained. Also, about 3.5G centered on 60.5GHz
Isolation was obtained in the Hz band.

FIG. 12 is a diagram showing a horizontal radiation pattern of the antenna 7. The horizontal axis shows the horizontal radiation angle,
Radiation level is plotted on the vertical axis. As a result, it was measured to have a wide directivity with a beam width of 22 ° in the 90 ° direction, that is, forward. This is an angle sufficient to detect a vehicle or the like that is installed in an automobile and traveling ahead.

FIG. 13 is a diagram showing a radiation pattern of the antenna 7 in the vertical direction. Taking the vertical radiation angle on the horizontal axis,
Radiation level is plotted on the vertical axis. As a result, it was measured to have a wide directivity with a beam width of 26.5 ° in the 90 ° direction, that is, in the forward direction. This is also an angle sufficient to detect a vehicle traveling ahead and the like.

FIG. 14 is a diagram showing the conversion loss characteristic of the balanced mixer. The horizontal axis represents the IF frequency and the vertical axis represents the conversion loss level. The conversion loss level increases as the IF frequency increases. The range is about -7.5 dB to -14 dB, and below 5 MHz is about -8 dB, which is a practically sufficient value. The conversion loss is further improved by taking the IF matching.

Although the embodiment of the present invention has been described as a structure for performing modulation by a frequency modulation system, a structure for modulating this by a phase modulation system can be similarly realized. Although a triangular wave is selected as the modulation signal in the above embodiment, this can be generally pulse modulation. The device of the present invention is
If necessary, it can be used for communication as PCM modulation.

[0030]

As described above, according to the present invention, it is possible to realize a millimeter wave transmitting / receiving apparatus having a simple circuit configuration and having a shape and size suitable for mounting on an automobile. The present invention is 60
It can be applied to the front end of a radar device for automobiles in the GHz band.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view of an apparatus according to an embodiment of the present invention.

FIG. 3 is a perspective view of an apparatus according to an embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between the presence / absence of an obstacle and an IF signal.

FIG. 5 is a diagram showing a relationship among a metal strip resonator length, an oscillation frequency, and a transmission output.

FIG. 6 is a diagram showing frequency modulation characteristics of a frequency modulator.

FIG. 7 is a diagram showing directional coupler characteristics.

FIG. 8 is a diagram showing a measurement arrangement of directional coupler characteristics.

FIG. 9 is a diagram showing insertion loss characteristics of a circulator.

FIG. 10 is a diagram showing isolation characteristics of a circulator.

FIG. 11 is a diagram showing a measurement arrangement of insertion loss characteristics and isolation characteristics of a circulator.

FIG. 12 is a diagram showing a horizontal radiation pattern of an antenna.

FIG. 13 is a diagram showing a radiation pattern in the vertical direction of the antenna.

FIG. 14 is a diagram showing conversion loss characteristics of a balanced mixer.

[Explanation of symbols]

 1 millimeter wave oscillator 2 metal strip resonator 3 high dielectric constant sheet 4 frequency modulator 5, 8, 32 directional coupler 6 circulator 7 antenna 9 frequency mixer 11 first waveguide 12 second waveguide 13 third Waveguide 14 Fourth Waveguide 20 Aluminum Plate 30 Gunn Diode 31 Waveguide 91 First Frequency Mixer 92 Second Frequency Mixer A, B Tetrafluoride Ethylene Resin Piece

Claims (5)

[Claims] 1. A millimeter wave oscillator (1), a first waveguide (11) composed of a non-radiative dielectric line for guiding the output of the oscillator, and an angle modulator inserted in the first waveguide. (4), a circulator (6) having its first terminal coupled to the output end of the first waveguide (11), a transmitting / receiving antenna (7) coupled to the second terminal of this circulator, and A frequency mixer (9) coupled to the third terminal of the circulator (6) and the first waveguide (1)
A millimeter wave characterized by comprising a directional coupler (5, 8) for partially separating the signal traveling from 1) from the oscillator (1) in the direction of the circulator (6) and coupling it to the carrier input of this frequency mixer. Transceiver. 2. A millimeter wave oscillator (1), a first waveguide (11) composed of a non-radiative dielectric line for guiding the output of the oscillator, and a frequency modulator inserted in the first waveguide. (4), a circulator (6) whose first terminal is coupled to the output end of the first waveguide (11), and a first radiator which is coupled to the second terminal of the circulator and comprises a non-radiative dielectric line. A second waveguide (12), an antenna (7) connected to the other end of the second waveguide, and a third non-radiative dielectric line coupled to the third terminal of the circulator (6). Waveguide (13) and a first frequency mixer (9) coupled to the output end of the third waveguide.
1), a first directional coupler (5) for partially separating a signal traveling through the first waveguide (11) from the oscillator (1) toward the circulator (6), and the first directional coupler. A fourth waveguide (14) composed of a non-radiative dielectric line for guiding the signals separated by the coupler, and a second frequency mixer (92) coupled to the output end of the fourth waveguide. , A signal traveling through the fourth waveguide (14) from the first directional coupler (5) toward the second frequency mixer (92) and the third waveguide (13) through the third waveguide (13). A second directional coupler (8) for mutually coupling a signal traveling in the direction toward the first frequency mixer (91), the first frequency mixer (91) and the second frequency Millimeter wave transmitter / receiver characterized in that the mixers (92) are set to form a balanced mixer with each other. apparatus. 3. A waveguide (13) composed of a non-radiative dielectric line to which a received signal is supplied and a waveguide (14) composed of a non-radiative dielectric line to which a carrier wave is supplied.
And a directional coupler (8) for mutually coupling a received signal and a carrier wave propagating through the two waveguides (13, 14) and an output end of the two waveguides (13, 14), respectively. Two frequency mixers (91, 9
2) and two frequency mixers (91, 92)
Are set so as to form a balanced mixer with each other. 4. The millimeter according to claim 3, further comprising a structure in which the two waveguides (13, 14) and the two frequency mixers (91, 92) are coupled to each other through a gap provided therebetween. Wave receiver. 5. A millimeter-wave transmitting / receiving antenna having a radiation surface formed of a non-radiative dielectric line and having a radiation surface formed at an angle to the signal traveling direction.