JP3780411B2 - Transceiver and radar device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmission / reception apparatus and a radar apparatus using high frequency waves such as a microwave band and a millimeter wave band.
[0002]
[Prior art]
Conventionally, for example, an RF unit of an in-vehicle millimeter wave radar is composed of an oscillator, a mixer, and an antenna. The oscillator generates a millimeter wave signal, and the antenna transmits the millimeter wave signal generated by the oscillator and receives the reflected signal from the target. The mixer mixes a part of the transmission signal with the received signal as a local signal, and outputs a signal of the frequency difference component as an intermediate frequency signal.
[0003]
FIG. 11 is a block diagram of an RF unit of a conventional millimeter wave radar using continuous waves. In FIG. 11, 100 is an oscillator, 101 is a circulator, and 102 is a non-reflective terminator connected to a predetermined port of the circulator 101. Reference numerals 106 and 107 denote couplers, and reference numerals 108 and 109 denote non-reflective terminators connected to predetermined ports of these couplers. 103 is a circulator, 104 is an antenna, and 105 is a mixer.
[0004]
The oscillator 100 includes a Gunn diode and its bias circuit, and generates a millimeter wave signal. The circulator 101 passes the return signal to the oscillator to the non-reflective terminator 102, absorbs the return signal by the non-reflective terminator 102, and causes the oscillator 100 to operate stably. Circulator 103 outputs a transmission signal to antenna 104 and outputs a reception signal from antenna 104 to mixer 105 side. The couplers 106 and 107 supply a part of the transmission signal to the mixer 105 as a Lo signal (local signal). The mixer 105 outputs the frequency component of the difference between the received signal and the local signal as an IF signal (intermediate frequency signal).
[0005]
However, in such a conventional radar apparatus, the couplers 106 and 107 are indispensable for extracting a part of the output signal of the oscillator 1 as a local signal.
[0006]
In view of this, in order to simplify the configuration of the entire apparatus and reduce the number of components, an apparatus that eliminates the need for the couplers 106, 107, etc. is proposed in Japanese Patent Laid-Open No. 10-41849. An example of the configuration is shown in FIG. Here, the passive element 110 is provided between the second port # 2 of the circulator 103 and the antenna 104. With this structure, a part of the signal propagated from the first port 1 # 1 to the second port # 2 of the isolator 103 is reflected by the passive element 110 and propagated from the second port # 2 toward the third port # 3. The This signal is given to the mixer 105 as a local signal. Therefore, the couplers 106 and 107 as shown in FIG.
[0007]
[Problems to be solved by the invention]
According to the structure shown in FIG. 11B, two couplers are unnecessary, which is advantageous in terms of reduction in size and weight and cost. However, the reflected signal given to the mixer 105 is not limited to the reflected signal from the passive element 110, and reflection occurs also in other impedance mismatched portions, so that the control is not always easy.
[0008]
An object of the present invention is to provide a transmission / reception apparatus and a radar apparatus which can supply a stable local signal to a mixer without providing a coupler or a passive element for generating a local signal as described above. is there.
[0009]
[Means for Solving the Problems]
The transmission / reception apparatus of the present invention includes a circulator that outputs an input signal from the first port to the second port and outputs an input signal from the second port to the third port, an oscillator, an antenna, and a mixer. In the transmitting / receiving device,
An oscillator is connected to the first port of the circulator, an antenna is connected to the second port, a mixer is connected to the third port, an oscillation signal is input to the first port of the circulator from the oscillator, and the first port To the third port is supplied as a local signal to the mixer.
[0010]
That is, a part of the transmission signal leaked and output from the first port to the third port of the circulator is given to the mixer as a local signal. With this structure, both the couplers 106 and 107 as shown in FIG. 11A and the passive element 110 shown in FIG. 11B are unnecessary.
[0011]
The circulator includes a ferrite part including a ferrite plate to which a DC magnetic field is applied by a magnet, and the first to third ports respectively coupled to the ferrite part, and the ferrite part and the ferrite part relatively shifting Rutotomoni the position of the ferrite portion in the state coupled position of the first to third ports are 120 ° rotationally symmetrical with respect to the first to third ports, by its displacement, the first Determine the amount of leakage signal from the port to the third port.
[0012]
Further, as the circulator, from the state bond position is 120 ° rotationally symmetrical of the first to third ports for the ferrite portion and the ferrite portion, by the structure of the ferrite portion in the rotational asymmetrical , or with a material placement constituting the ferrite portion to the non-rotationally symmetrical, its by rotational asymmetry, determine the amount of leakage signal from the first port to the third port.
[0013]
Further, as the circulator, the DC magnetic field applied to the ferrite is made non- rotationally symmetric from the state where the ferrite portion and the coupling position of the first to third ports to the ferrite portion are 120 ° rotationally symmetric. together, determine the amount of that to the non-rotational symmetry Therefore, the leakage signal from the first port to the third port.
[0014]
In addition, the circulator may be configured such that the first to third ports are coupled to the ferrite portion from a state where the first and third ports are coupled to the ferrite portion at 120 ° rotational symmetry. while position to a non-rotationally symmetrical, depending on the non-rotational symmetry, or, while the non-congruent at least one of the first to third three-port, by its non-congruence, the leakage Determine the amount of signal.
[0015]
A radar apparatus according to the present invention includes a transmission / reception apparatus having any one of the structures described above, and a control unit that detects a target based on transmission signals and reception signals from the transmission / reception apparatus.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
A radar transmitting / receiving apparatus and a radar apparatus according to a first embodiment will be described with reference to FIGS.
FIG. 1A is a block diagram illustrating a configuration of a radar transceiver device, and FIG. 1B is a block diagram illustrating a configuration of a radar device. In FIG. 1, 100 is an oscillator, 101 is a circulator, 102 is a non-reflective terminator, 111 is an asymmetrical circulator, 104 is an antenna, and 105 is a mixer. Reference numeral 200 denotes a control unit. The components other than the control unit 200 are connected via a high-frequency transmission line.
[0017]
The oscillator 100 includes a VCO that is frequency-modulated by a modulation signal from the control unit 200. The control unit 200 modulates the oscillation frequency of the oscillator 100 into, for example, a triangular wave shape. The circulator 101 propagates the oscillation signal to the circulator 111 side and propagates the reflected signal from the circulator 111 side to the non-reflection terminator 102. That is, the circulator 101 and the non-reflection terminator 102 constitute an isolator. The circulator 111 propagates the oscillation signal to the antenna 104 as a transmission signal. Further, the circulator 111 propagates the reception signal from the antenna 104 to the mixer 105. The mixer 105 mixes the received signal Rx and the local signal Lo to convert them to an intermediate frequency signal IF, and supplies it to the control unit 200. The control unit 200 detects the relative distance and relative speed of the target based on the frequency control signal for the oscillator 100 and the IF signal output from the mixer 105, and outputs the result to the host device.
[0018]
The amount of leakage from the first port # 1 to the third port # 3 of the circulator 111 with asymmetric characteristics shown in FIG. 1 is −10 dB, the amount of leakage from the second port # 2 to the first port # 1, and the third port If the amount of leakage from # 3 to the second port # 2 is -20 dB, and the level of the signal input to the first port # 1 of the circulator 111 via the circulator 101 is 10 dBm, it is given to the mixer 105 The level of the local signal Lo is 0 dBm.
[0019]
FIG. 2 is a diagram illustrating the relationship between the input signal strength to the mixer 105 and the conversion loss of the mixer 105. In general, a single mixer exhibits a certain conversion loss if the input signal strength is 0 dBm or more, but if the input signal strength is smaller than that, the conversion loss increases. Therefore, as in the above example, if the intensity of the oscillation signal input to the circulator 111 is 10 dBm or more, the leakage amount from the first port # 1 to the third port # 3 of the circulator 111 is set to −10 dB. The mixer 105 is supplied with a local signal Lo of 0 dBm or more, and can be mixed with low conversion loss.
[0020]
Incidentally, assuming that the conventional circulator with the same amount of leakage between the three ports is used as the circulator 111 shown in FIG. 1, and the isolation is 20 dB, the input signal strength to the first port # 1 Is 10 dBm, only a -10 dBm local signal Lo is supplied to the mixer 105 and does not operate as a mixer. Similarly, if a circulator with the same amount of leakage between the three ports and an isolation between the ports of 15 dB is used and the signal intensity input to the first port # 1 is increased to 15 dBm, the mixer 105 is supplied with a local of 0 dBm. A signal is supplied. For this reason, the mixer 105 functions temporarily. However, since the isolation between the first port # 1 and the second port # 2 and the isolation between the second port # 2 and the third port # 3 are poor, it functions as a transmission / reception device and a radar due to the occurrence of noise or the like. do not do.
[0021]
Next, the configuration of the asymmetrical circulator 111 will be described with reference to FIGS. The transmission line used here is a non-radiative dielectric line (NRD guide), and the circulator is configured to be compatible with the NRD guide.
First, FIGS. 3 and 4 show the configuration of a symmetric circulator in which the isolation between three ports is equal.
[0022]
FIG. 3 is an exploded perspective view of the main part of the circulator. 4A is a top view of the conductor plate 2, and FIG. 4B is a top view in a state where the dielectric strips 3a, 3b, and 3c are placed on the conductor plate 2 together with the ferrite plate 7. FIG. In the figure, reference numerals 1 and 2 denote conductor plates, and the opposing surfaces constitute conductor planes that are substantially parallel. The conductor plate 2 has three side walls 17 projecting, and when overlapped with the conductor plate 1, a space is formed through which the dielectric strips 3a, 3b, 3c pass in a region sandwiched between two adjacent side walls. . Grooves 14b, 15a, 15b, and 15c into which the dielectric strips are fitted are formed on the lower surface of the conductor plate 1 and the upper surface of the conductor plate 2. The main portions of the dielectric strips 3a, 3b, 3c extend radially from the central portion, and are provided with connecting portions 16 that connect adjacent dielectric strips at the central portion. Reference numerals 6 and 7 denote disc-shaped ferrite plates, which are arranged so as to be fitted into the connecting portions 16 of the three dielectric strips.
[0023]
In the conductor plate 2, a space portion 8 that extends in the surface direction of the conductor plate 2 is formed around the periphery of the ferrite plate 7.
[0024]
With the structure described above, the ferrite portion is configured by the three space portions 8 and the region including the ferrite plates 6 and 7 surrounded by the space portions 8.
[0025]
FIG. 5 is a top view showing a state in which the dielectric strips 3a, 3b, 3c are placed together with the ferrite plate 7 on the conductor plate 2 similar to the portion shown in FIG. In the example shown in FIG. 5A, the dielectric strip 3b extends from the center among the three space portions 8, 8, 8 'spreading in the surface direction of the conductor plate 2 around the ferrite plate 7 is disposed. The space portion 8 'on the opposite side, that is, the side sandwiched between the dielectric strips 3a and 3c is formed smaller than the other two space portions 8.
[0026]
With this structure, the center frequency of the frequency band showing irreversible characteristics is raised between the first port # 1 and the third port # 3. As a result, in the operating frequency band, the isolation (leakage amount) in the reverse direction from the third port # 3 to the first port # 1 side is set to about −10 dB. For the first port # 1 to the second port # 2, and the second port # 2 to the third port # 3, for example, high isolation of about −20 dB is ensured, for example.
[0027]
In the example shown in FIG. 5B, of the three connecting portions 16, 16, 16 'that connect the three dielectric strips 3a, 3b, 3c, the connecting portion that connects the dielectric strips 3a-3c. 16 'part is formed thicker than the other connection part 16. As shown in FIG. This structure ensures sufficient isolation from the second port # 2 to the first port # 1 and isolation from the third port # 3 to the second port # 2, while ensuring sufficient isolation from the first port # 1 to the first port # 2. The isolation to 3 port # 3 is reduced by a predetermined amount.
[0028]
In the example shown in FIG. 5, the structure of the ferrite portion composed of the three space portions 8 and the region surrounded by the space portions 8 is asymmetrical, but the material arrangement constituting the resonator may be asymmetrical. . For example, in FIG. 4B, a material having a higher relative dielectric constant than the other connecting portions 16 is used for the connecting portions 16 between the dielectric strips 3a to 3c. Thereby, the leakage amount from the first port # 1 to the third port # 3 is set.
[0029]
FIG. 6 is a diagram showing a structure in which the irreversible characteristics are made asymmetric by other structures, and an isolation characteristic (reverse pass characteristic) of a circulator having the structure. However, FIG. 6 shows only the positional relationship between the three dielectric strips 3 a, 3 b, 3 c and the ferrite plate 6. In the example shown in FIG. 5, among the three ports formed by the three dielectric strips, the angular interval between adjacent ports is equal to 120 degrees, but the angular interval is unequal as shown in FIG. 6. By setting the interval, the amount of leakage signal from the first port # 1 to the third port # 3 is determined.
[0030]
6A shows an example in which the angular intervals between the three ports are equally spaced, and FIG. 6B shows an example in which the angular intervals are not evenly spaced. In this way, by increasing the angle between the first port # 1 and the third port # 3, the reverse pass characteristic S31 from the first port # 1 to the third port # 3 is changed between the other two ports. The reverse direction passage characteristics S12 and S23 are different from each other.
[0031]
FIG. 7 shows the positional relationship between the ferrites 6 and 7 provided in the ferrite part and the permanent magnets 18 and 19 that apply a DC magnetic field thereto. However, in the example shown in FIG. 7, the dielectric strip, the support portions of the ferrite plates 6 and 7, and the conductor plate are omitted in the drawing. In the example shown in (A), the central axes of the permanent magnets 18 and 19 coincide with the central axes of the ferrite plates 6 and 7. On the other hand, in the example shown in (B), both are arrange | positioned so that the central axis of the permanent magnets 18 and 19 and the central axis of the ferrite plates 6 and 7 may differ. With this structure, the DC magnetic field applied to the ferrite plates 6 and 7 is rotationally asymmetric, and the isolation characteristics between the ports are also asymmetric.
[0032]
By utilizing this characteristic change, in the above example, the first port to the third port are sufficiently secured while ensuring sufficient isolation from the second port to the first port direction and from the third port to the second port direction. What is necessary is just to define asymmetry so that the amount of leaks to a predetermined amount may become.
[0033]
Next, the structure of the circulator used in the radar transceiver according to the second embodiment is shown in FIG. This circulator is a waveguide type circulator using waveguides 30a, 30b, and 30c as transmission lines. A ferrite plate 6 applies a DC magnetic field to the ferrite plate 6 in a direction perpendicular to the paper surface by a permanent magnet (not shown).
[0034]
In the example shown in FIG. 8A, a disk-shaped ferrite plate 6 is used, and the center axis of the three waveguides 30a, 30b, 30c intersects with a position shifted in a predetermined direction parallel to the paper surface. By arranging, the isolation characteristic between the three ports is made asymmetric.
[0035]
Further, in the example shown in FIG. 8B, for example, a rectangular plate-shaped ferrite plate 6 is used as the ferrite plate 6 without using a regular polygonal plate shape or a disk shape having a multiple of 3 corners. This makes the isolation characteristic between the three ports asymmetric. At this time, for example, the ferrite plate 6 is disposed with the central axis of the waveguide 30b of the second port # 2 as the axis of line symmetry. As a result, the isolation between the first port # 1 and the second port # 2 and the isolation between the second port # 2 and the third port # 3 are made equal, and between the first port # 1 and the third port # 3. Is a different characteristic from those of the above.
[0036]
Next, the configuration of the circulator used in the radar transceiver according to the third embodiment will be described with reference to FIGS.
This circulator is a microstrip line type circulator. FIG. 9A is a plan view of a dielectric substrate provided in the microstrip line type circulator. The dielectric substrate 20 is formed with a circular center conductor 21 and a microstrip line having a correction capacitance conductor 22 in the middle. A disk-shaped ferrite plate is disposed above and below the dielectric substrate 20 so as to sandwich the central conductor 21, and a permanent magnet that applies a DC magnetic field to the ferrite plate is further disposed on the outer side thereof.
[0037]
And the center conductor 21, constituting a ferrite plate and the therefore the ferrite portion of the upper and lower. Of the three ports # 1, # 2 and # 3 by the microstrip line coupled to the ferrite portion, the line of a predetermined port portion is not congruent. This causes an asymmetry in the isolation characteristics. That is, the line widths of the microstrip lines of the ports # 1, # 2, and # 3 (particularly, the line widths of the portions drawn from the central conductor 21) are w1, w2, and w3, respectively. By setting the line widths w1, w2, and w3, the irreversible characteristics are made asymmetric.
[0038]
FIG. 9B shows the isolation characteristics when the line widths w1 and w2 shown in FIG. 9A are equalized and the ratio of w2 and w3 is changed. Here, the black circle is the isolation characteristic from the second port # 2 to the first port # 1, and the white circle is the isolation characteristic from the first port # 1 to the third port # 3. Thus, as the w3 / w2 ratio is decreased, the isolation from the first port # 1 toward the third port # 3 decreases. That is, the amount of signal leakage increases. Such asymmetry of the isolation characteristic is due to the fact that the coupling state is different when an asymmetric microstrip line is connected to the ferrite portion.
[0039]
FIG. 10 is a diagram showing another configuration of the dielectric substrate. In the example shown in (A), a notch d is provided in a part of the outer edge of the center conductor 21. In the example shown in (B), the protrusion p is provided at a predetermined location on the outer edge of the center conductor 21. In the example shown in (C), a conductor deletion portion h is provided in the vicinity of the outer edge portion of the center conductor 21. With these structures, the rotational symmetry of the ferrite part including the central conductor 21 is broken, and as a result, the isolation between predetermined ports is weakened, and the amount of signal leakage in the reverse direction is set to a predetermined amount.
[0040]
In the example shown in FIG. 10D, the angular intervals between the three ports drawn out from the center conductor 21 are non-uniform. In this example, θ13> θ12 = θ23. Thereby, the rotational symmetry of the ferrite part is broken, and the amount of signal leakage between predetermined ports is determined.
[0041]
【The invention's effect】
According to the present invention, a part of the transmission signal leaked and output from the first port to the third port of the circulator is supplied to the mixer as a local signal. An element becomes unnecessary. Therefore, it is possible to reduce the size and weight, reduce the cost, provide a stable local signal to the mixer, and obtain a transmission / reception apparatus with little characteristic variation. Furthermore, a radar device having the transmission / reception device and having a small size, light weight, low cost, and stable characteristics can be obtained.
[0042]
Further, according to the present invention, the relative ferrite portion and the ferrite portion first to third port coupled position 120 ° from the state that is rotationally symmetrical to the position of the ferrite part and the first to third port relatively shifted Rutotomoni respect, by its displacement, by determining the amount of leakage signal from the first port of the circulator to the third port, it can be easily configured the circulator.
[0043]
Further, according to the present invention, by the structure of ferrite portion in the rotation asymmetric or as to the material placement constituting the ferrite portion to the non-rotationally symmetrical, by their non-rotational symmetry, the first port of the circulator, The circulator can be easily configured by determining the amount of the leakage signal from to the third port.
[0044]
Further, according to the present invention, as well as a DC magnetic field applied to the ferrite rotationally asymmetric, depending on the non-rotational symmetry, by determining the amount of leakage signal from the first port to the third port, the circulator Easy to configure.
[0045]
Further, according to the present invention, as well as the coupling position of the first through third ports for the ferrite portion to the non-rotationally symmetrical, its rotational asymmetry Accordingly, or, the first to third three The circulator can be easily configured by making at least one of the ports non-congruent and determining the amount of leakage signal from the first port to the third port by the non- congruity.
[Brief description of the drawings]
FIG. 1 is a block diagram of a radar transmitting / receiving device and a radar device according to an embodiment. FIG. 2 is a diagram showing a relationship of conversion loss to input signal intensity of a mixer used in the device. FIG. 4 is a top view of the lower conductor plate of the circulator. FIG. 5 is a top view of the lower conductor plate of the circulator having another configuration. FIG. 6 is a positional relationship between the ferrite plate and the three dielectric strips. FIG. 7 is a diagram showing a positional relationship between a ferrite plate and a magnet. FIG. 8 is a diagram showing a configuration of a circulator according to the second embodiment. FIG. 9 is a diagram showing the third embodiment. FIG. 10 is a diagram showing a configuration and characteristics of a circulator used in the radar transceiver device. FIG. 10 is a diagram showing another configuration example of the isolator. Block diagram showing the configuration of a device [Description of symbols]
1, 2-conductor plate 3-dielectric strip 6, 7-ferrite plate 8-space 12-recess 14, 15-groove 16-connection 17-side wall 18, 19-magnet 20-dielectric substrate 21-center conductor 22-Correction capacitance conductor 30-Waveguide 100-Oscillator 101-Circulator 102-Reflection terminator 103-Circulator 104-Antenna 105-Mixers 106, 107-Coupler 108, 109-Reflection terminator 110-Passive element 111 -Circulator 200-Control unit

Claims (6)

A millimeter-wave or microwave-band circulator that outputs an input signal from the first port to the second port and an input signal from the second port to the third port, and a millimeter-wave band to the first port of the circulator Or an oscillator that inputs a transmission signal in the microwave band, and an antenna that receives the transmission signal from the second port of the circulator and receives a reception signal due to reception of a reflected wave from a target to the second port of the circulator , In a transmission / reception apparatus comprising: a mixer that mixes a local signal having the same frequency as the transmission signal and the reception signal output from the third port of the circulator to output an intermediate frequency signal ;
By reducing the isolation from the first port to the third port of the circulator by a predetermined amount from the isolation from the second port to the first port and from the third port to the second port, transceiver apparatus that provide to the mixer leakage signal leaking to the third port as said local signal. The circulator includes a ferrite portion including a ferrite plate to which a DC magnetic field is applied by a magnet, and the first to third ports respectively coupled to the ferrite portion. The ferrite portion and the first portion with respect to the ferrite portion third coupling position of the port shifted relative positions of the ferrite portion in the state is 120 ° rotationally symmetrical with respect to the first to third ports Rutotomoni, by its displacement, said first The transmission / reception apparatus according to claim 1, wherein an amount of a leakage signal from the port to the third port is determined. The circulator includes a ferrite portion including a ferrite plate to which a DC magnetic field is applied by a magnet, and the first to third ports respectively coupled to the ferrite portion. The ferrite portion and the first portion with respect to the ferrite portion 1 from the third state binding position is 120 ° rotationally symmetrical port, by the structure of the ferrite portion in the rotation asymmetric, or with a material placement constituting the ferrite portion to the non-rotational symmetry The transmission / reception apparatus according to claim 1, wherein an amount of a leakage signal from the first port to the third port is determined by the non-rotational symmetry . The circulator includes a ferrite portion including a ferrite plate to which a DC magnetic field is applied by a magnet, and the first to third ports respectively coupled to the ferrite portion. The ferrite portion and the first portion with respect to the ferrite portion from state 1 to the bonding position of the third port is 120 ° rotationally symmetrical, with the DC magnetic field applied to the ferrite rotationally asymmetric, depending on the non-rotational symmetry, third from the first port The transmission / reception apparatus according to claim 1, wherein an amount of a leak signal to the port is determined. The circulator includes a ferrite portion including a ferrite plate to which a DC magnetic field is applied by a magnet, and the first to third ports respectively coupled to the ferrite portion. The ferrite portion and the first portion with respect to the ferrite portion 1 from the third state binding position is 120 ° rotationally symmetrical ports, as well as the coupling position of the first through third ports for the ferrite portion to the non-rotationally symmetrical, depending on its rotational asymmetry Or at least one of the first to third three ports is made non-congruent, and the amount of leakage signal from the first port to the third port is determined by the non-congruity. 1. The transmission / reception device according to 1. A radar apparatus comprising: the transmission / reception apparatus according to any one of claims 1 to 5; and a control unit that detects a target by using the transmission signal and the reception signal by the transmission / reception apparatus.

Images