JP2005094440A - Antenna system and radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and low antenna system reducing the mutual interference between planar antennas. <P>SOLUTION: A transmission antenna 6 is a planar antenna having a radiating element 6a and a power distribution circuit 6c for connecting a feeding point 6b to the radiating element 6a. A reception antenna 11 is the planar antenna having a radiating element 11a and a power distribution circuit 11c for connecting a feeding point 11b to the radiating element 11a. The transmission antenna 6 and the reception antenna 11 are formed on one surface of the same circuit board PC. In the transmission antenna 6 and the reception antenna 11, the power distribution circuits 6c, 11c in respective antennas are arranged between the radiating elements 6a, 11a of respective antennas. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an antenna device in which at least a pair of planar antennas each including a radiating element and a power distribution circuit are formed on one surface of the same circuit board, and a radar device including the antenna device.

In this type of antenna device, a plurality of planar antennas are formed on one surface of the same circuit board. As a result, the planar antennas are close to each other. As a result, how to reduce mutual interference between the planar antennas. It becomes a problem. In this regard, in the antenna device disclosed in Japanese Patent Laid-Open No. 4-140905, as shown in FIG. 1 of the same publication, the antenna substrate 1 between the planar antennas (between the transmitting antenna 2 and the receiving antenna 3). A radio wave absorber 7 made of a resin foam or the like impregnated with carbon or the like is provided on the top to absorb and attenuate radio waves from the transmitting antenna 2 to the receiving antenna 3.
Japanese Patent Laid-Open No. 4-140905 (page 2, FIG. 1)

  However, the conventional antenna device has the following problems. That is, in this antenna device, since the radio wave absorber 7 is disposed on the antenna substrate 1, the height of the antenna device itself increases by the height of the radio wave absorber 7. On the other hand, in recent years, an attempt has been made to mount a radar device on a moving body such as an automobile, and it is considered to use this type of antenna device on the radar device, but the mounting is performed on the moving body. An antenna device used in a radar device is required to be a small and low-profile type. However, in the conventional antenna device, since the height is increased by disposing the radio wave absorber 7 on the antenna substrate 1, it is difficult to use the radar device mounted on the moving body. There is a point.

  The present invention has been made in view of such problems, and a main object of the present invention is to provide an antenna device that is small and can reduce mutual interference between planar antennas while maintaining a low height. Another main object is to provide a radar apparatus provided with the antenna apparatus.

  In order to achieve the above object, in the antenna device according to the present invention, at least a pair of planar antennas each including a radiating element, a feeding point and a power distribution circuit that connects the radiating element are formed on one surface of the same circuit board, The planar antenna is configured such that the distribution circuit of each planar antenna is disposed between the radiating elements of each planar antenna. The power distribution circuit in the present invention refers to a circuit composed of a transmission line, an impedance converter, a distributor, a phase shifter, a line converter, and the like.

  In this case, it is preferable to form a ground conductor between the distribution circuits of the planar antennas on the one surface of the circuit board so as to partition the pair of planar antennas.

  Preferably, a ground conductor is formed around each planar antenna on the one surface of the circuit board so as to surround the pair of planar antennas.

  Furthermore, it is preferable to include another ground conductor formed on the other surface of the circuit board and connected to the ground conductor formed on the one surface of the circuit board via a plurality of through holes.

  The through holes are preferably formed at intervals of 1/4 or less of the wavelength of electromagnetic waves to be transmitted or received.

  Furthermore, the planar antenna can be configured to transmit or receive millimeter waves or quasi-millimeter waves.

  A radar apparatus according to the present invention includes the antenna apparatus described above, and is configured such that one of the pair of planar antennas functions as a transmission antenna and the other functions as a reception antenna.

  In this case, the radar apparatus outputs a modulation signal generation circuit that generates and outputs a modulation signal, a carrier wave generation circuit that generates a carrier wave, and outputs a high-frequency signal generated by modulating the carrier wave with the input modulation signal. A modulation circuit; a modulation signal extraction circuit that extracts the modulation signal from the high-frequency signal that is reflected by the measurement object of the high-frequency signal transmitted through the transmission antenna and received by the reception antenna; And a detection signal generation circuit that generates a detection signal capable of measuring the distance to the measurement object based on the modulation signal extracted by the modulation signal extraction circuit.

  Preferably, the modulation signal generation circuit, the carrier wave generation circuit, the modulation circuit, the modulation signal extraction circuit, and the detection signal generation circuit are integrated into a module.

  According to the antenna device and the radar device of the present invention, at least a pair of planar antennas each including a radiating element and a power distribution point that connects the feeding point and the radiating element are formed on one surface of the same circuit board. By arranging a pair of planar antennas by arranging the power distribution circuit between the radiating elements of each planar antenna, the radiating elements in each planar antenna are kept small while maintaining a small height (small and low profile). Since the physical distance can be extended, the electromagnetic interference in the space between the radiating elements of each planar antenna can be weakened to reduce mutual interference between the planar antennas. As a result, the isolation characteristics between the planar antennas can be sufficiently improved.

  Further, according to the antenna device and the radar device according to the present invention, the ground conductor is formed between the power distribution circuits of the planar antennas on one surface of the circuit board so as to partition the pair of planar antennas. Not only electromagnetic coupling between the planar antennas in the space between the radiating elements, but also leakage waves (surface waves) propagating on the surface of the circuit board between the planar antennas are blocked by the ground conductor, thereby causing mutual interference between the planar antennas. Can be reduced. Therefore, the isolation characteristics between the planar antennas can be further improved.

  Furthermore, according to the antenna device and the radar device of the present invention, the ground conductor is formed around each planar antenna on one surface of the circuit board so as to surround the pair of planar antennas, so that the circuit is output from one planar antenna. Leakage of electromagnetic waves radiated outward from the outer edge side of the substrate to the other planar antenna can be blocked by the ground conductor to reduce mutual interference between the planar antennas. Therefore, the isolation characteristics between the planar antennas can be further improved.

  Further, according to the antenna device and the radar device of the present invention, the other ground conductor formed on the other surface of the circuit board and connected to the ground conductor formed on the one surface of the circuit board via the plurality of through holes. By limiting the leakage of the electromagnetic wave caused by the propagation of the electromagnetic wave in the parallel plate mode between the ground conductor formed on one surface of the circuit board and the other ground conductor formed on the other surface. Therefore, the isolation characteristics between the planar antennas can be further improved.

  In addition, according to the antenna device and the radar device according to the present invention, each through hole is formed at an interval equal to or less than ¼ of the wavelength of the electromagnetic wave to be transmitted or received. The leakage of the electromagnetic wave caused by the propagation of the electromagnetic wave in the parallel plate mode between other ground conductors formed on the surface can be more reliably regulated. In this case, an electromagnetic wave in the millimeter wave band or the quasi-millimeter wave band can be used as the electromagnetic wave for transmission or the electromagnetic wave for reception.

  Further, according to the radar apparatus of the present invention, the modulation signal generation circuit, the carrier wave generation circuit, the modulation circuit, the modulation signal extraction circuit, and the detection signal generation circuit are integrated into a module, thereby reducing the size of the radar apparatus as a whole. It is possible to improve mass productivity.

  The best mode of an antenna device and a radar device according to the present invention will be described below with reference to the accompanying drawings.

  First, the configuration of the radar apparatus 1 will be described with reference to the drawings.

  As shown in FIG. 1, the radar apparatus 1 includes a pulse generation circuit (a modulation signal generation circuit in the present invention) 2, a carrier wave generation circuit 3, a distribution circuit 4, a modulation circuit 5, an antenna apparatus AT, a mixer circuit (a modulation in the present invention). A signal extraction circuit) 12, an amplifier circuit 13, a comparator circuit 14, and a detection signal generation circuit 15, and is configured to generate a detection signal Sd that can measure the distance L between the measurement object (for example, a vehicle) 21. Yes. Further, in the radar apparatus 1, as an example, other components excluding the antenna apparatus AT (pulse generation circuit 2, carrier wave generation circuit 3, distribution circuit 4, modulation circuit 5, mixer circuit 12, amplifier circuit 13, comparator circuit 14 and The detection signal generation circuit 15) is integrated (modulated) by resin molding while mounted on a single circuit board (printed circuit board), and the module ML including the pulse generation circuit 2 and the antenna The device AT is connected by two coaxial cables CB1 and CB2.

  As shown in FIGS. 1 and 2, the antenna device AT is configured to include a pair of planar antennas (a transmission antenna 6 and a reception antenna 11) formed with a conductor pattern on one surface (front surface) of one circuit board PC. ing. The transmitting antenna 6 is a so-called microstrip type patch antenna, and as shown in FIG. 2, one or more (four as an example) radiating elements 6a, 6a, 6a, 6a, a feeding point 6b, and each radiating element 6a. And a single power distribution circuit 6c for connecting the two. In this case, the power distribution circuit 6c is composed of a line (microstrip line) formed of a conductor pattern, and electrically connects one feeding point 6b and the four radiating elements 6a, 6a, 6a, 6a while matching them. Therefore, it functions as a transmission line, an impedance conversion circuit, a distributor, a phase shifter, and a line converter (including through holes as necessary) (the same applies to a power distribution circuit 11c described later). Similarly, the receiving antenna 11 is also a microstrip type patch antenna, and connects one or more (for example, four) radiating elements 11a, 11a, 11a, 11a to the feeding point 11b and each radiating element 11a. One power distribution circuit 11c is provided.

  Further, in the transmission antenna 6 and the reception antenna 11, the feeding points 6b and 11b of the antennas 6 and 11 are arranged between the distribution circuits 6c and 11c of the antennas 6 and 11, and the distribution circuits 6c and 11c of the antennas 6 and 11 are arranged. 11c is arranged between the radiating elements 6a and 11a of the antennas 6 and 11, respectively. However, with respect to the feeding points 6b and 11b, the feeding point 6b can be arranged on the radiation element 6a side in the power distribution circuit 6c (for example, between the two radiation elements 6a and 6a located in the middle in FIG. 2) The feeding point 11b can also be arranged on the radiation element 11a side of the power distribution circuit 11c (for example, between the two radiation elements 11a and 11a located in the middle in the figure). That is, in the antennas 6 and 11, it is an important requirement to arrange the distribution circuits 6c and 11c between the radiating elements 6a and 11a arranged on the outside of the circuit board PC (on the central portion side of the circuit board PC). . In other words, the antennas 6 and 11 have a physical distance between each radiating element 6a of the transmitting antenna 6 and each radiating element 11a of the receiving antenna 11 within a limited area of one circuit board PC. The radiating elements 6a and 11a are configured (arranged) so as to expand most, that is, so that the radiating elements 6a and 11a are spaced apart from each other. Further, as shown in the figure, a ground conductor 7 is disposed (formed) so as to surround each antenna 6 and 11 around each antenna 6 and 11. Further, as shown in FIG. 3, the ground conductor 7 is a planar (solid) conductor pattern (other ground conductor in the present invention, which is formed over almost the entire other surface (back surface) of the circuit board PC. , Also referred to as a “ground conductor”) 8 and a plurality of through holes 9, 9. In this case, as shown in FIGS. 2 and 3, the through-hole 9 is formed in the entire area of the ground conductor 7 along the extending direction of the ground conductor 7, and the distance d between the adjacent through-holes 9 and 9 is set. The length is ¼ or less of the wavelength of the electromagnetic wave transmitted and received by the antenna device AT. Further, as shown in FIG. 3, a pair of coaxial connectors CN1 and CN2 whose core wires are connected to the feeding points 6b and 11b through through holes (not shown) are arranged on the other surface of the circuit board PC, respectively. It is installed. The casings of the coaxial connectors CN1 and CN2 are connected to the ground conductor 8. The coaxial connectors CN1 and CN2 are connected to the coaxial connectors CN3 and CN4 attached to the ends of the coaxial cables CB1 and CB2, respectively. However, the present invention is not limited to this configuration. For example, the core wires of the coaxial cables CB1 and CB2 can be directly connected to the feeding points 6b and 11b by soldering or the like without using the coaxial connectors CN1 and CN2.

  As shown in FIG. 1, the pulse generation circuit 2 generates a pulse-like trigger signal STG and outputs it to the detection signal generation circuit 15, and also a pulse-like baseband signal (modulation signal) in synchronization with the trigger signal STG. STB is generated and output to the modulation circuit 5. As an example, the carrier wave generation circuit 3 continuously generates a carrier wave Sc of a predetermined frequency (for example, 24 GHz) in a quasi-millimeter wave band and outputs the carrier wave Sc to the distribution circuit 4. The distribution circuit 4 distributes the input carrier wave Sc to the modulation circuit 5 and the mixer circuit 12 and outputs them. The modulation circuit 5 is connected to the coaxial connector CN1 of the antenna device AT via the coaxial cable CB1 and the coaxial connector CN3. The modulation circuit 5 also modulates the carrier wave Sc with the input baseband signal STB to generate a high-frequency signal STR, and outputs the generated high-frequency signal STR to the antenna device AT via the coaxial cable CB1. To send from. On the other hand, the receiving antenna 11 is connected to the mixer circuit 12 via coaxial connectors CN2 and CN4 and a coaxial cable CB2. The receiving antenna 11 receives the high-frequency signal STR reflected by the vehicle 21 as the measurement object among the high-frequency signals STR transmitted via the transmitting antenna 6 and receives the high-frequency signal SRR via the coaxial cable CB2. Output to the mixer circuit 12.

  As shown in FIG. 1, the mixer circuit 12 mixes the input high-frequency signal SRR and the carrier wave Sc input from the distribution circuit 4 and down-converts the signal component corresponding to the baseband signal STB from the high-frequency signal SRR. Is extracted as a baseband signal SRB and output to the amplifier circuit 13. As shown in the figure, the amplifier circuit 13 amplifies the input baseband signal SRB and outputs it to the comparator circuit 14. The comparator circuit 14 compares the input baseband signal SRB with the reference voltage Vr, shapes the baseband signal SRB, and outputs the waveform to the detection signal generation circuit 15. Thereby, a noise component lower than the reference voltage Vr included in the baseband signal SRB is removed from the baseband signal SRB.

  The detection signal generation circuit 15 generates and outputs a detection signal Sd that can measure the distance to the vehicle 21 based on the trigger signal STG and the waveform shaped baseband signal SRB. Specifically, the detection signal generation circuit 15 includes, for example, an RS flip-flop, and outputs the RS flip-flop in synchronization with the input of the trigger signal STG (as an example, in synchronization with the rising edge of the trigger signal STG). The signal is set and synchronized with the input of the trigger signal STG by resetting the output signal of the RS flip-flop in synchronization with the input of the baseband signal SRB (for example, in synchronization with the rise of the baseband signal SRB). A detection signal Sd that rises and falls in synchronization with the input of the baseband signal SRB is generated.

  Next, the overall operation of the radar apparatus 1 will be described.

  In the radar apparatus 1, the pulse generation circuit 2 generates a trigger signal STG and outputs it to the detection signal generation circuit 15, and outputs a baseband signal STB generated in synchronization with the trigger signal STG to the modulation circuit 5. At this time, the detection signal generation circuit 15 starts generating the detection signal Sd in synchronization with the trigger signal STG input from the pulse generation circuit 2. Also, the modulation circuit 5 modulates the carrier wave Sc input from the distribution circuit 4 with the baseband signal STB input from the pulse generation circuit 2 to generate a high frequency signal STR and outputs it to the transmission antenna 6. Thereby, the high frequency signal STR is transmitted from the transmission antenna 6. At this time, as shown in FIG. 2, the transmission antenna 6 and the reception antenna 11 are arranged so that the distribution circuits 6c and 11c of the antennas 6 and 11 are located between the radiating elements 6a and 11a of the antennas 6 and 11, respectively. By being formed, the physical distance between the radiating elements 6a and 11a is defined to be as wide as possible under the condition that they are formed in the same circuit board PC. In addition, a ground conductor 7 is formed around the transmitting antenna 6 and the receiving antenna 11 so as to surround the antennas 6 and 11, respectively, and the ground conductor 7 is formed on the other surface of the circuit board PC. 8 and a plurality of through holes 9. Therefore, in this antenna device AT, leakage of electromagnetic waves radiated from the transmission antenna 6 to the reception antenna 11 (mutual interference between the transmission antenna 6 and the reception antenna 11) is reduced to an extremely small level.

  On the other hand, the receiving antenna 11 receives the high-frequency signal STR reflected by the vehicle 21 after a predetermined time T1 has elapsed from the output of the baseband signal STB (that is, the trigger signal STG) by the pulse generation circuit 2. In this case, the predetermined time T1 is required for the high-frequency signal STR to propagate a time for reciprocating the distance L between the radar apparatus 1 and the vehicle 21, that is, a distance (2 × L) that is twice the distance L. Means time.

  The mixer circuit 12 extracts the baseband signal SRB by mixing the high frequency signal SRR input from the receiving antenna 11 and the carrier wave Sc. Next, the baseband signal SRB output from the mixer circuit 12 is amplified by the amplifier circuit 13, and after being shaped by the comparator circuit 14, is input to the detection signal generation circuit 15. Subsequently, the detection signal generation circuit 15 stops the output of the detection signal Sd by resetting the output signal of the RS flip-flop in synchronization with the input baseband signal SRB. Thereby, the detection signal generation circuit 15 outputs a detection signal Sd having a pulse width equivalent to the time T1. Thereafter, the external device uses the detection signal Sd output from the radar device 1 as it is, and based on the time half the pulse width (predetermined time T1) of the detection signal Sd and the speed of light, the radar device 1. And the distance L between the vehicle 21 and the vehicle 21 is calculated.

  Thus, according to the antenna device AT and the radar device 1, both antennas 6 and 11 are formed on one surface of the same circuit board PC so that the power distribution circuits 6c and 11c are located between the radiation elements 6a and 11a. As a result, the physical distance between the radiating elements 6a and 11a of the antennas 6 and 11 can be increased while reducing the size and height of the antenna device AT and thus the size of the radar device 1. The electromagnetic field coupling in the space between the eleven radiating elements 6a and 11a can be weakened to reduce the mutual interference between the antennas 6 and 11. Therefore, the isolation characteristics between the antennas 6 and 11 can be sufficiently improved.

  Further, a part 7a of the ground conductor 7 is formed so as to partition the antennas 6 and 11 between the feeding points 6b and 11b (distribution circuits 6c and 11c) of the antennas 6 and 11 on one surface of the circuit board PC. As a result, not only electromagnetic coupling between the antennas 6 and 11 in the space but also leakage waves (surface waves) propagating on the surface of the circuit board PC between the antennas 6 and 11 are caused by the part 7 a of the ground conductor 7. Can be blocked. Therefore, the isolation characteristics between the antennas 6 and 11 can be further improved. Further, the ground conductor 7 is formed around the antennas 6 and 11 on one surface of the circuit board PC so as to surround the antennas 6 and 11, so that the ground conductor formed on the outer edge of the circuit board PC on the radiation element 6a side is formed. 7 further blocks the leakage to the receiving antenna 11 of the electromagnetic wave output from the transmitting antenna 6 and radiated outward from the outer edge side of the circuit board PC, so that the isolation characteristics between the antennas 6 and 11 are further improved. be able to. Further, by forming another ground conductor 8 on the other surface of the circuit board PC and connecting the ground conductor 8 to the ground conductor 7 formed on one surface of the circuit board PC via a plurality of through holes 9, Through-hole 9 restricts leakage of electromagnetic waves caused by propagation of electromagnetic waves in a parallel plate mode between ground conductor 7 formed on one surface of circuit board PC and other ground conductors 8 formed on the other surface. Therefore, the isolation characteristics between the antennas 6 and 11 can be further improved. In particular, since the through holes 9 are formed at intervals of 1/4 or less of the wavelength of the electromagnetic wave transmitted from the transmission antenna 6, leakage of the electromagnetic wave in the parallel plate mode can be more reliably regulated.

  In addition, this invention is not limited to said structure. For example, in the antenna device AT described above, an example in which the ground conductor 7 is formed in an annular shape so as to surround the antennas 6 and 11 around the transmitting antenna 6 and the receiving antenna 11 has been described. However, the antenna device AT1 shown in FIG. As described above, the ground conductor 7 is formed in a strip shape so as to partition the antennas 6 and 11 only between the feeding points 6b and 11b (distribution circuits 6c and 11c) of the antennas 6 and 11 on one surface of the circuit board PC. The structure to form can also be employ | adopted. Even in this antenna device AT1, the physical distance between the radiating elements 6a and 11a of the antennas 6 and 11 is increased, and the electromagnetic coupling in the space between the radiating elements 6a and 11a of the antennas 6 and 11 is weakened. Thus, the mutual interference between the antennas 6 and 11 can be reduced, and the leakage wave (surface wave) propagating on the surface of the circuit board PC between the antennas 6 and 11 can be blocked by the ground conductor 7. Isolation characteristics between the antennas 6 and 11 can be sufficiently improved. In the antenna devices AT and AT1, the ground conductor 8 and the ground conductor 7 formed on the other surface of the circuit board PC are connected to each other through a plurality of through holes 9 formed in the entire area of the ground conductor 7 and maintained at the same potential. However, it is also possible to adopt a configuration in which the through-hole 9 is formed only in a part of the ground conductor 7 and both the ground conductors 7 and 8 are maintained at the same potential (ground potential). Further, it is possible to adopt a configuration in which both ground conductors 7 and 8 are regulated to the same potential by a method other than the through hole 9 (for example, jumper wire). Also in this configuration, by setting the ground conductors 7 and 8 to the same potential, leakage of the electromagnetic waves caused by propagation of the electromagnetic waves in the parallel plate mode between the ground conductors 7 and 8 can be regulated. .

  Furthermore, when it is sufficient to improve the isolation characteristics between the antennas 6 and 11 obtained by increasing the physical distance between the radiating elements 6a and 11a of the antennas 6 and 11, the antenna device AT2 shown in FIG. As described above, a configuration in which the ground conductor 7 is not formed at all on the surface of the circuit board PC can be adopted.

  In the above configuration, an example in which two planar antennas (the transmitting antenna 6 and the receiving antenna 11) are formed on one circuit board PC has been described. However, the number of planar antennas is not limited to two, but three. Of course, the present invention can be applied to the antenna device formed as described above. For example, in an antenna device in which three or more planar antennas are formed, one of them is formed as a transmission antenna and the remaining planar antennas are formed as reception antennas.

  Further, each of the antenna devices AT, AT1, AT2, etc. described above can be applied not only to the radar device 1 using the module ML having the above-described configuration but also to the radar device 31 using the module ML1 having the configuration shown in FIG. it can. In this case, the module ML1 includes a pulse generation circuit (modulation signal generation circuit in the present invention) 32, a carrier generation circuit 3, a distribution circuit 4, a modulation circuit 5, a distribution circuit 33, an antenna device AT, and a synthesis as shown in FIG. A circuit 34, a mixer circuit 12, an amplifier circuit 13, a comparator circuit 14, and a detection signal generation circuit 35 are provided. In addition, the same code | symbol is attached | subjected about the component same as the component of module ML, and the overlapping description is abbreviate | omitted. The pulse generation circuit 32 generates and outputs a modulation signal STB. The distribution circuit 33 distributes the high frequency signal STR generated by the modulation circuit 5 and outputs it to the transmission antenna 6 and the synthesis circuit 34. The synthesis circuit 34 synthesizes the input high-frequency signal STR and the high-frequency signal SRR and outputs the synthesized high-frequency signal STR to the mixer circuit 12. In this case, the synthesis circuit 34 outputs the high frequency signal STR output from the distribution circuit 33 to the mixer circuit 12 as the high frequency signal SRR1, and is reflected by the vehicle 21 in the high frequency signal STR transmitted via the transmission antenna 6. The high-frequency signal STR input via the receiving antenna 11 is output to the mixer circuit 12 as a high-frequency signal SRR2. The detection signal generation circuit 35 is configured to include an RS flip-flop, and is input with two pulse-like baseband signals SRB1 and SRB2 (hereinafter collectively referred to as input signals) separated by a time proportional to the distance to the vehicle 21. In other words, the output signal of the RS flip-flop is set and reset by “baseband signal SRB”) to generate and output a detection signal Sd that can measure the distance to the vehicle 21.

  Next, the overall operation of the radar apparatus 31 will be described. First, the modulation circuit 5 modulates the carrier wave Sc input from the distribution circuit 4 with the baseband signal STB input from the pulse generation circuit 32 to generate a high-frequency signal STR and outputs it to the distribution circuit 33. The distribution circuit 33 distributes the input high frequency signal STR and outputs it to the transmission antenna 6 and the synthesis circuit 34. Thereby, the high frequency signal STR is transmitted from the transmission antenna 6. At this time, the high frequency signal STR from the distribution circuit 33 is first input to the combining circuit 34, and then the high frequency signal STR reflected by the vehicle 21 passes through the receiving antenna 11 after a predetermined time T1 has elapsed. input. In this case, the predetermined time T1 means a time during which the high-frequency signal STR travels back and forth the distance L between the radar device 31 and the vehicle 21.

  The combining circuit 34 combines the high-frequency signal SRR input from the receiving antenna 11 and the high-frequency signal STR input from the distribution circuit 33 and outputs the combined signal to the mixer circuit 12. The mixer circuit 12 extracts the baseband signal SRB by mixing the input high-frequency signal SRR1 and high-frequency signal SRR2 with the carrier wave Sc. In this case, as shown in FIG. 6, as the baseband signal SRB, a baseband signal SRB1 corresponding to the high frequency signal SRR1 and a baseband signal SRB2 corresponding to the high frequency signal SRR2 are arranged in this order at intervals of a predetermined time T1. Extracted. Next, the baseband signal SRB output from the mixer circuit 12 is amplified by the amplifier circuit 13, shaped by the comparator circuit 14, and then input to the detection signal generation circuit 35. Subsequently, the detection signal generation circuit 35 sets the output signal of the RS flip-flop in synchronization with the input of the baseband signal SRB1 corresponding to the high frequency signal SRR1 (as an example, in synchronization with the rise of the baseband signal SRB1), Synchronize with the input of the baseband signal SRB1 by resetting the output signal of the RS flip-flop in synchronization with the input of the baseband signal SRB2 corresponding to the high frequency signal SRR2 (as an example, in synchronization with the rise of the baseband signal SRB2). Then, a detection signal Sd that rises and falls in synchronization with the input of the baseband signal SRB2 is generated. Thereafter, in the same manner as in the radar apparatus 1, the external apparatus uses the detection signal Sd output from the radar apparatus 31 as it is, and is a time that is ½ of the pulse width (predetermined time T1) of the detection signal Sd. The distance L between the radar device 31 and the vehicle 21 is calculated based on the speed of light and the speed of light.

  According to the radar apparatus 31, the distribution circuit 33 is provided between the modulation circuit 5 and the transmission antenna 6, and the high frequency signal STR is output to the synthesis circuit 34 together with the transmission antenna 6. By combining the signal STR and the high-frequency signal SRR from the receiving antenna 11 and outputting them to the mixer circuit 12, each circuit in the radar device 31 (modulation circuit 5, mixer circuit 12, amplification) is compared with the radar device 1. Without including the delay time in the circuit 13 and the comparator circuit 14), it is possible to measure the measurement time starting from the transmission time of the high frequency signal STR and ending with the reception time of the high frequency signal STR reflected by the vehicle 21. . Therefore, the detection signal Sd having a pulse width equivalent to the time required for the high-frequency signal STR to travel back and forth between the radar device 31 and the vehicle 21 (distance L), that is, the time required to propagate a distance twice as long as the distance L. Can be generated more accurately. As a result, the distance L between the radar device 31 and the vehicle 21 can be calculated immediately and accurately and easily based on the time half the pulse width (predetermined time T1) of the detection signal Sd and the speed of light. it can.

  In the above-described modules ML and ML1, the example in which the mixer circuit 12 is used as an example of the modulation signal extraction circuit has been described. However, a detection circuit or a low-pass filter circuit may be used instead of the mixer circuit 12. Further, the example in which the pulse generation circuits 2 and 32 are used as an example of the modulation signal generation circuit that generates the baseband signal STB (modulation signal) has been described. However, instead of the pulse generation circuits 2 and 32, a rectangular-wave modulation signal is used. Any modulation signal generation circuit that can generate the signal can be employed. In the radar apparatus 1 described above, the pulse generation circuit 2, the carrier generation circuit 3, the distribution circuit 4, the modulation circuit 5, the mixer circuit 12, the amplification circuit 13, the comparator circuit 14, and the detection signal generation circuit 15 are integrated (modularized). In the radar device 31, the pulse generation circuit 32, the carrier wave generation circuit 3, the distribution circuit 4, the modulation circuit 5, the distribution circuit 33, the synthesis circuit 34, the mixer circuit 12, the amplification circuit 13, the comparator circuit 14, and the detection signal Although the generation circuit 35 is integrated (modularized), an integrated (modularized) configuration including the antenna device AT (AT1, AT2) may be employed. According to this configuration, the radar device as a whole can be further downsized. The pulse generation circuit 2 and the like are preferably modularized in order to reduce the size of the radar devices 1 and 31 as a whole. However, if modularization is not required, individual circuits are mounted on a circuit board. The radar apparatus 1 can also be configured. In the above configuration, the carrier wave generation circuit 3 has been described by taking as an example a configuration in which the carrier wave Sc having a predetermined frequency in the quasi-millimeter wave band is continuously generated. However, the antenna devices AT, AT1, AT2 according to the present invention are described. Of course, the present invention can also be applied to a radar apparatus using an electromagnetic wave having a millimeter-wave band frequency (for example, 76 GHz).

  Further, in the above-described modules ML and ML1, in order to facilitate understanding of the present invention, the polarity of each signal such as the modulation signal STB is made positive, and the detection signal generation circuits 15 and 35 are input signals. The configuration in which the RS flip-flop is set and reset in synchronization with the rise of the signal has been described as an example, but it is needless to say that the polarity of the signal between the components can be arbitrarily defined. The detection signal generation circuits 15 and 35 may be configured to generate the negative detection signal Sd by resetting and setting the RS flip-flop in synchronization with the rising of the input signal. Further, the arrangement of the amplifier circuit 13 and the comparator circuit 14 is not essential, and can be appropriately arranged according to the level of the baseband signal SRB, the S / N ratio, and the like. Of course, circuits such as an amplifier circuit and a filter can be appropriately disposed between the circuits or between the circuits and the antennas.

1 is a block diagram showing a configuration of a radar apparatus 1. FIG. It is the top view seen from the one surface side of circuit board PC which forms antenna apparatus AT. It is the top view seen from the other surface side of circuit board PC which forms antenna apparatus AT. It is the top view seen from the one surface side of circuit board PC which forms antenna apparatus AT1. It is the top view seen from the one surface side of circuit board PC which forms antenna apparatus AT2. 2 is a block diagram showing a configuration of a radar apparatus 31. FIG.

Explanation of symbols

1,31 Radar device 2,32 Pulse generation circuit (modulation signal generation circuit)
DESCRIPTION OF SYMBOLS 3 Carrier wave generation circuit 5 Modulation circuit 6 Transmitting antenna 6a, 11a Radiating element 6b, 11b Feeding point 6c, 11c Distribution circuit 7, 8 Ground conductor 9 Through hole 11 Receiving antenna 12 Mixer circuit 15, 35 Detection signal generation circuit AT, AT1, AT2 antenna device PC circuit board

Claims (9)

At least a pair of planar antennas each including a radiating element and a power feeding point and a power distribution circuit connecting the radiating elements are formed on one surface of the same circuit board,
The pair of planar antennas is an antenna device configured such that the power distribution circuit of each planar antenna is disposed between the radiating elements of each planar antenna.   The antenna device according to claim 1, wherein a ground conductor is formed between the power distribution circuits of the planar antennas on the one surface of the circuit board so as to partition the pair of planar antennas.   The antenna device according to claim 1, wherein a ground conductor is formed around each planar antenna on the one surface of the circuit board so as to surround the pair of planar antennas.   The other ground conductor formed on the other surface of the circuit board and connected to the ground conductor formed on the one surface of the circuit board via a plurality of through holes. Antenna device.   The antenna device according to claim 4, wherein each through hole is formed at an interval of ¼ or less of a wavelength of an electromagnetic wave to be transmitted or received.   The antenna device according to claim 1, wherein the planar antenna is configured to be capable of transmitting or receiving millimeter waves or quasi-millimeter waves.   A radar apparatus comprising the antenna apparatus according to claim 1, wherein one of the pair of planar antennas functions as a transmission antenna and the other functions as a reception antenna.   A modulation signal generation circuit that generates and outputs a modulation signal; a carrier generation circuit that generates a carrier wave; a modulation circuit that outputs a high-frequency signal generated by modulating the carrier wave with the input modulation signal; and the transmission antenna. A modulation signal extraction circuit that extracts the modulation signal from the high-frequency signal that is reflected by the measurement object and received by the receiving antenna from the high-frequency signal transmitted via the signal, and extracted by the modulation signal extraction circuit The radar apparatus according to claim 7, further comprising: a detection signal generation circuit that generates a detection signal capable of measuring a distance to the measurement object based on the modulation signal.   The radar apparatus according to claim 8, wherein the modulation signal generation circuit, the carrier wave generation circuit, the modulation circuit, the modulation signal extraction circuit, and the detection signal generation circuit are integrated into a module.

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