JP4506728B2 - Antenna device and radar - Google Patents

Description

  The present invention relates to an antenna device and a radar that can be applied to, for example, a vehicle-mounted radar.

Conventionally, Patent Document 1 discloses a radar including a planar array antenna having a high degree of freedom in arrangement of element antennas. The configuration of the radar disclosed in Patent Document 1 is shown in FIG.
As shown in FIG. 1, the radar 1 performs an antenna layer 2 having a planar array antenna 20, a transmission line layer 3 provided with a transmission line, a high-frequency circuit layer 4 equipped with a high-frequency circuit, and a digital beam forming process. A signal processing circuit layer 5 on which a signal processing circuit is mounted is provided.

An array antenna in which side lobes are suppressed is disclosed in Patent Document 2. The configuration of the array antenna disclosed in Patent Document 2 is shown in FIG.
This array antenna is intended to suppress side lobes without controlling the power supplied to a plurality of radiating elements (element antennas) from a feeding circuit. As shown in FIG. 2, the array antenna has radiating elements 11a and 11b, a feed line 12, and a matching impedance conversion line 13 formed on the surface of the dielectric substrate 10, and is in contact with the back surface of the dielectric substrate 10. A conductor film constituting the ground is formed. In addition, the microstrip-structured array antenna is configured in this way, and among the four radiating elements 11a and 11b, the element width of the inner two radiating elements 11b is made larger than the element width of the two outer radiating elements 11a. It is narrow. The array antenna power supply circuit 40 includes a branch circuit 41 and a transmission line 42, and distributes the power supply signal from the power supply terminal 30 to supply power to each of the radiating elements 11a and 11b.
JP-A-11-261332 JP 2000-269735 A

  In general, when a plurality of array antennas are arranged, there is a problem that the length of the feed line becomes long and the loss due to the feed line becomes large in the antenna arranged away from the feed unit.

  In the array antenna shown in Patent Document 1, the transmission line from the primary radiator is three-dimensionally configured so that approximately equal power is supplied to each element antenna, and each is approximately equidistant. It is configured as follows. In such a configuration, the deviation of the power radiated from each element antenna can be reduced, but the transmission line for the element antenna is formed over a plurality of layers, which causes a problem that the thickness of the device increases. .

  In the array antenna of Patent Document 2, a side lobe is suppressed by giving a distribution to the power supplied to each element antenna. The antenna gain and the side lobe level are in a trade-off relationship, and the antenna gain G is expressed by the following expression using the antenna aperture area S, the antenna efficiency η, and the wavelength λ.

G = (4πS / λ ² ) η
That is, to increase the antenna gain G, the antenna aperture area S must be increased when the antenna efficiency η and the wavelength λ are constant. That is, it is necessary to increase the number of antenna elements. The antenna efficiency η can be changed by controlling the power distribution supplied to each element antenna. However, when power is evenly supplied to each element antenna, the antenna efficiency η becomes η = 1 and becomes the maximum. In the case of Patent Document 2, the power supplied to each element antenna is distributed. As a result, even if it is effective for suppressing side lobes, the antenna efficiency η has a relationship of η <1, and the antenna gain G becomes small. In other words, the configuration of the array antenna disclosed in Patent Document 2 does not increase the overall antenna gain.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an antenna apparatus having a composite array antenna configuration in which a plurality of array antennas are arranged, in which the effective gain deviation of each array antenna is reduced, and a radar equipped with the antenna apparatus. .

  An antenna device according to the present invention includes a high-frequency circuit unit, a plurality of array antennas, and a plurality of transmission lines that connect the high-frequency circuit unit and the array antenna. Among these transmission lines, a transmission loss is relatively large. The number of elements of the array antenna connected to the transmission line is larger than the number of elements of the array antenna connected to the transmission line having a relatively small transmission loss.

  The number of elements of each array antenna is determined so that the effective gains of each array antenna including the loss due to the transmission line are equal to each other.

  The plurality of array antennas and the plurality of transmission lines are formed on the same substrate.

  Further, among the plurality of array antennas, an array antenna arranged at a position adjacent to the end of the substrate is a side radiation array antenna, and the other array antenna is a front radiation array antenna.

  Further, the directivity directions of the array antennas of the plurality of array antennas are made different from each other.

  The radar according to the present invention includes the antenna device having any one of the above-described configurations and a radar control unit that detects a target by transmitting and receiving a radio wave for detection by the antenna device.

  By increasing the number of elements of the array antenna connected to the transmission line having a relatively large transmission loss among the plurality of transmission lines to be larger than the number of elements of the array antenna connected to the transmission line having a relatively small transmission loss, each array Since the effective antenna gains of the antennas are equalized, the deviation of the gain between the array antennas is suppressed, and when applied to the radar, the deviation of the detection range using each array antenna is reduced.

  By determining the element antennas of the array antennas so that the effective gains of the array antennas including the loss due to the transmission line are equal to each other, the effective gains of the array antennas are more effectively aligned.

  By forming the plurality of array antennas and the plurality of transmission lines on the same substrate, the antenna device can be thinned as a whole.

  Further, an antenna device capable of directing a beam over a wide angle can be obtained by using a side-radiating array antenna as the array antenna at the substrate end and a front-radiating array antenna as the other array antenna.

  Further, an antenna device in which the beam is directed in a desired direction can be obtained by making the directivity directions of the array antennas of the plurality of array antennas different from each other.

  By configuring the radar using the antenna device having any one of the configurations described above, it is possible to detect a target with little gain variation for each direction.

<< First Embodiment >>
FIG. 3 is an exploded perspective view showing the configuration of the antenna device according to the first embodiment. This antenna device mainly has a laminated structure of an upper dielectric substrate 50 and conductor plates 60 and 70. Five array antennas 51, 52, 53, 54, and 55 are configured on the dielectric layer 50. The array antenna 51 includes element antennas (hereinafter simply referred to as “elements”) 511A, 511B,... 511I, and 512A, 512B,. Each element constitutes a micropatch antenna together with a ground electrode formed on the lower surface of the dielectric substrate 50. The adjacent elements of the elements 511A to 511I and 512A to 512I are connected by a microstrip line.

  Each of the array antennas 51 to 55 includes line conversion units 111 to 115, respectively. These line converters 111 to 115 are line converters between a waveguide and a microstrip line formed by the lower conductor plates 60 and 70. The microstrip line converted by the line conversion unit 111 in the array antenna 51 is branched into two so as to supply power to the elements 511A to 511I and 512A to 512I, respectively.

  The same applies to the other array antennas 52 to 55. However, the number of elements constituting the array antennas 51 and 55 is 18 respectively, the number of elements constituting the array antennas 52 and 54 is 16 pieces, and the number of elements constituting the array antenna 53 is 14 pieces.

  Grooves are formed on the inner surfaces of the conductor plates 60 and 70 (the surfaces where both face each other), and a plurality of waveguides are configured with the two conductor plates 60 and 70 being laminated. Waveguide grooves 71 to 75 are formed in the conductor plate 70. These waveguide grooves 71 to 75 and mirror symmetric waveguide grooves are also formed on the lower surface of the conductor plate 60, and five waveguides are configured in a state where the conductor plates 60 and 70 are laminated.

  A high-frequency circuit unit is formed below the region A of the conductor plate 70, and signal input / output with the high-frequency circuit is performed by a waveguide formed by the conductor plates 60 and 70. The conductor plate 60 has waveguide holes 61 to 65 connected to the five waveguides. These waveguide holes 61 to 65 correspond to the positions of the line converters 111 to 115 of the dielectric substrate 50, respectively.

  FIG. 4 is an exploded perspective view showing the configuration of the line converter. In FIG. 4A, an upper surface ground electrode 515, a via 516 conducting to the resonator electrode on the lower surface, and a microstrip line 517 extending therefrom are formed on the upper surface of the dielectric substrate 50. FIG. 4B is a bottom view of the dielectric substrate 50 (a perspective view with the top and bottom turned upside down). A resonator electrode 513 and a substantially entire lower surface ground electrode 514 are formed on the lower surface of the dielectric substrate 50. The ground electrodes on the upper and lower surfaces of the dielectric substrate 50 are conducted through vias around the resonator electrode 513. The resonator electrode 513 is opposed to the waveguide hole 61 formed in the conductor plate 60, and resonates by being coupled with the waveguide mode. This resonance signal is propagated in the mode of the microstrip line 517 through the via 516.

  As shown in FIG. 3, the line length of the waveguide that feeds power to the array antennas 51 to 55 from the high-frequency circuit section (lower area A) is shorter as the array antenna is arranged at the center, and away from both sides from there. The arranged array antenna becomes longer. Therefore, the number of elements of the array antennas 52 and 54 is larger than that of the central array antenna 53, and the number of elements of the array antennas 51 and 55 is larger than that of the array antennas 52 and 54. As a result, the effective antenna gains of the array antennas 51 to 55 are aligned.

<< Second Embodiment >>
FIG. 5 is an exploded perspective view of the antenna device according to the second embodiment. This antenna device mainly has a laminated structure of a dielectric substrate 80 and a conductor plate 90. The dielectric substrate 80 constitutes a slot array for five array antennas 81-85.

  The slot array may be configured by using a conductor plate instead of the dielectric substrate 80 and forming a slot in the conductor plate.

  A ground electrode is formed on substantially the entire bottom surface of the dielectric substrate 80, and a slot array is formed. For example, slots 811A, 811B,... 811J and 812A, 812B,. Similarly, the other array antennas 82 to 85 are each formed with a plurality of slot arrays.

  Waveguide grooves 911, 912, 921, 922, 931, 932, 941, 942, 951, and 952 are formed in the conductor plate 90, respectively. In addition, waveguide holes 91, 92, 93, 94, and 95 are formed at the end of the waveguide groove in region A, respectively.

  In the state where the dielectric substrate 80 is laminated on the conductor plate 90, the ground electrode formed on the lower surface of the dielectric substrate 80 and the waveguide groove formed on the conductor plate 90 act as a waveguide. A signal is propagated (powered) by a waveguide connected to the high-frequency circuit section below the area A, and acts as a slot array antenna by the slots 811A to 812J.

  Also in this case, the transmission line length from the high-frequency circuit section is shorter at the center of the array antennas 81 to 85 and becomes longer as it moves away from both sides. The number of slots of the outer array antennas 81 and 85 is further increased. As a result, the effective antenna gains of the array antennas 81 to 85 are aligned.

<< Third Embodiment >>
FIG. 6 is an exploded perspective view of the antenna device according to the third embodiment. This antenna device mainly has a laminated structure of a dielectric substrate 100 and a conductor plate 110. The dielectric substrate 100 constitutes a slot array for the five array antennas 101 to 105.

  The slot array may be configured by using a conductor plate instead of the dielectric substrate 100 and forming a slot in the conductor plate.

  On the lower surface of the dielectric substrate 100, a ground electrode is formed on substantially the entire surface, and a slot array is formed. For example, slots 1011A, 1011B,... 1011J and 1012A, 1012B,.

  In the example shown in FIG. 5, the region A that is a connection portion with the high-frequency circuit unit is arranged at the end of the conductor plate. However, in the example shown in FIG. 6, the central portion (region A) of the conductor plate 110 is It is a connection part with the high frequency circuit part in the lower surface. Along with this, the waveguide grooves 1111 to 1152 of the conductor plate 110 are formed so as to spread from the central portion (region A) of the conductor plate 110. Further, in the slot array of the dielectric substrate 100, each slot is formed at a position avoiding the central portion.

  Others are the same as those shown in FIG. The slots of each of the array antennas 101 to 105 are determined according to the transmission line length from the high frequency circuit section below the area A. Also in this case, the length of the transmission line from the high frequency circuit section is shorter at the center of the array antennas 101 to 105 and becomes longer as it goes away from both sides. The number of slots of the outer array antennas 101 and 105 is further increased. As a result, the effective antenna gains of the array antennas 101 to 105 are aligned.

<< Fourth Embodiment >>
FIG. 7 is an exploded perspective view of the antenna device according to the fourth embodiment. In the antenna apparatus shown in FIG. 3, all of the five array antennas are array antennas having a micropatch antenna as an element. However, in the antenna apparatus shown in FIG. Array antennas 121 and 125 located at both ends of 120 are side radiation type array antennas. These side-emitting array antennas 121 and 125 are linear end-phi antennas 121A, 121B,... 121K and 125A, 125B,. The remaining array antennas 122 to 124 are micropatch array antennas similar to those shown in FIG.

  Each of the array antennas 121 to 125 includes line conversion units 111 to 115, respectively. These line converters 111 to 115 are line converters between a waveguide and a microstrip line formed by lower conductor plates 130 and 140.

  Grooves are formed in the inner surfaces of the conductor plates 130 and 140 (the surfaces where both face each other), and a plurality of waveguides are formed in a state where the two conductor plates 130 and 140 are laminated. Waveguide grooves 141 to 145 are formed in the conductor plate 140. These waveguide grooves 141 to 145 and mirror symmetric waveguide grooves are also formed on the lower surface of the conductor plate 130, and five waveguides are configured in a state where the conductor plates 130 and 140 are laminated.

  FIG. 8 is a plan view of one element of the array antennas 121 and 125 shown in FIG. This element is provided with radiation electrodes 611 and 612 having a dipole configuration, and a waveguide electrode 616 disposed parallel to the front thereof. Ground electrodes 610 are formed on the lower surfaces of the feeding electrode 615 and the balanced transmission electrodes 613 and 614, and these serve as a microstrip line. The radiation electrodes 611 and 612 are fed with balanced transmission electrodes 613 and 614 and a feeding electrode 615. Since the path lengths of the two balanced transmission electrodes 613 and 614 branched from the feeding electrode 615 are shifted by ½ wavelength, the radiation electrodes 611 and 612 are fed in opposite phases.

  This element is a linear array end-phi antenna having a Yagi-Uda antenna structure. Therefore, the radiation patterns of the array antennas 121 and 125 shown in FIG. 7 are directed to the side of the dielectric substrate 120.

<< Fifth Embodiment >>
FIG. 9 is an exploded perspective view of the antenna device according to the fifth embodiment. In the example shown in FIG. 3, the waveguide is routed around the five array antennas 51 to 55, but in the example of FIG. 9, the transmission line for feeding is routed by the microstrip line. That is, five array antennas 151 to 155 are formed on the dielectric substrate 150, and the line conversion units 111 to 115 are concentrated on the end of the dielectric substrate 150. Signal transmission is performed on the strip line.

  Correspondingly, waveguide holes 61 to 65 are formed in the conductor plate 160. A high-frequency circuit unit that inputs and outputs signals through the waveguide holes 61 to 65 is provided below the region A of the conductor plate 160.

  The transmission line length from the high-frequency circuit section is shorter at the center of the array antennas 151 to 155 and becomes longer as the distance from the both sides increases. The number of elements of the outer array antennas 151 and 155 is further increased. Thereby, the effective antenna gains of the array antennas 151 to 155 are aligned.

<< Sixth Embodiment >>
FIG. 10 is an exploded perspective view showing the configuration of the antenna device according to the sixth embodiment. In this antenna device, a line conversion unit that connects to a high-frequency circuit unit is arranged at the center of the antenna device.

  The dielectric substrate 170 includes five array antennas 171 to 175, and the line conversion units 111 to 115 are concentrated on the central portion of the dielectric substrate 170, and the microstrip line from the line conversion units 111 to 115 to each array antenna. Signal transmission.

  Correspondingly, waveguide holes 61 to 65 are formed in the conductor plate 180. A high-frequency circuit unit that inputs and outputs signals through the waveguide holes 61 to 65 is provided below the region A of the conductor plate 180.

  The length of the transmission line from the high-frequency circuit section is shorter at the center of the array antennas 171 to 175 and becomes longer as the distance from the both sides increases. The number of elements of the outer array antennas 171 and 175 is further increased. As a result, the effective antenna gains of the array antennas 171 to 175 are aligned.

<< Seventh Embodiment >>
FIG. 11 is a perspective view of an antenna device according to the seventh embodiment, and FIG. 12 shows an example of directivity characteristics by each array antenna.

  In FIG. 11, a dielectric substrate 190 includes five array antennas 191 to 195. Of these array antennas, the array antennas 191 and 195 located at both ends of the dielectric substrate 190 are side-emitting array antennas, and the remaining three array antennas 192 to 194 are front-emitting array antennas. 7 differs from the antenna device shown in FIG. 7 in that the line conversion units 111 to 115 are concentrated in the center of one side of the dielectric substrate 190, and the microstrip line 201 extends from the line conversion units 111 to 115. That is, power is fed through -205, and the feeding phases to the array antennas 192 and 194 are different. That is, by branching at a predetermined location of the microstrip line 202, a phase difference is provided to the feeding phase with respect to the two array antenna portions 192-1 and 192-2 constituting the array antenna 192. Similarly, by branching at a predetermined location of the microstrip line 204, a phase difference is given to the feeding phase with respect to the two array antenna portions 194-1 and 194-2 constituting the array antenna 194. On the other hand, the power feeding phases to the two array antenna units 193-1 and 193-2 constituting the array antenna 193 are made equal by dividing the microstrip line 203 equally at predetermined locations.

  With such feeding, the central array antenna 193 is fed in the same phase to the two array antenna units 193-1 and 193-2, and the front direction of the antenna device is indicated by a radiation pattern RP3 in FIG. Directivity is better. In addition, the array antennas 192 and 194 are respectively fed with phase difference to the two rows of array antenna units, and have directivity in the tilt direction with respect to the front of the antenna device as indicated by radiation patterns RP2 and RP4 in FIG. Is suitable. Further, the side radiation type array antennas 191 and 195 have directivity toward the side of the antenna device as indicated by radiation patterns RP1 and RP5 in FIG.

<< Eighth Embodiment >>
FIG. 13 is a block diagram showing a configuration of a main part of a radar according to the eighth embodiment.
The signal processing unit 302 controls the antenna device 301 to direct the beam in a predetermined direction. In addition, the signal processing unit 302 generates a control voltage for forming a transmission beam based on the FMCW detection process and supplies the control voltage to the VCO 303. The VCO 303 generates a transmission signal in which the frequency is continuously changed in a triangular shape in time series according to a given control voltage. The coupler 304 outputs the input transmission signal to the circulator 305 and supplies a part of it to the mixer 306 as a local signal. The circulator 305 outputs the transmission signal from the coupler 304 to the antenna device 301.
The antenna device 301 is the antenna device shown in the above embodiments.

  The circulator 305 outputs a reception signal from the antenna device 301 to the mixer 306. The mixer 306 generates a beat signal by mixing the local signal from the coupler 304 and the received signal from the circulator 305 and outputs the beat signal to the LNA 307. The LNA 307 amplifies the beat signal and gives it to the A / D converter 308. The A / D converter 308 performs A / D conversion on the amplified beat signal and provides it to the signal processing unit 302. Based on the digitized beat signal, the signal processing unit 302 calculates the relative speed, the relative distance, and the like of the target using a known FMCW data processing method.

  In such a configuration, since the antenna device 301 is small, the radar can also be miniaturized. Further, since the gain of the antenna device 301 is high, a radar having a wide detection range and high detection performance can be configured.

  The present invention is not limited to the FMCW radar and can be applied to other types of radar in the same manner. Further, the present invention is applicable not only to radar but also to wireless communication devices.

It is a perspective view of the radar shown by patent document 1. FIG. 10 is a plan view of an array antenna disclosed in Patent Document 2. FIG. It is a disassembled perspective view of the antenna device which concerns on 1st Embodiment. It is a figure which shows the structure of the track | line conversion part of the antenna apparatus. It is a disassembled perspective view which shows the structure of the antenna apparatus which concerns on 2nd Embodiment. It is a disassembled perspective view which shows the structure of the antenna device which concerns on 3rd Embodiment. It is a disassembled perspective view which shows the structure of the antenna apparatus which concerns on 4th Embodiment. It is a top view which shows the structure of the element of the antenna apparatus. It is a disassembled perspective view which shows the structure of the antenna device which concerns on 5th Embodiment. It is a disassembled perspective view which shows the structure of the antenna device which concerns on 6th Embodiment. It is a disassembled perspective view which shows the structure of the antenna device which concerns on 7th Embodiment. It is a figure which shows the example of the radiation pattern of the antenna apparatus. It is a block diagram which shows the structure of the radar which concerns on 8th Embodiment.

Explanation of symbols

51 to 55, 81 to 85, 101 to 105, 121 to 125, 151 to 155, 171 to 175, 191 to 195, array antenna 50, 80, 100, 120, 150, 170, 190-dielectric substrate 60, 70 , 90, 110, 130, 140, 160, 180-conductor plates 61-65, 91-95-waveguide holes 71-75-waveguide grooves 513-resonator electrodes 514-bottom ground electrodes 515-top ground electrodes 516-via 517-microstrip line 111-115-line converter 511,512-element 911,912,921,922,931,932,941,942,951,952-waveguide groove 811,812-slot 611 612-Radiation electrode 201-205-Microstrip line

Claims (6)

A high-frequency circuit unit, a plurality of array antennas, and a plurality of transmission lines connecting the array antenna to the high-frequency circuit unit,
Among the plurality of transmission lines, an antenna in which the number of elements of the array antenna connected to a transmission line having a relatively large transmission loss is larger than the number of elements of the array antenna connected to a transmission line having a relatively small transmission loss. apparatus.   The antenna device according to claim 1, wherein the number of elements of each array antenna is determined so that an effective gain of each array antenna of the plurality of array antennas including a loss due to the transmission line is equal to each other.   The antenna device according to claim 1, wherein the plurality of array antennas and the plurality of transmission lines are formed on the same substrate.   4. The array antenna arranged at a position adjacent to the end of the substrate among the plurality of array antennas is a side-emitting array antenna, and the other array antenna is a front-emitting array antenna. Antenna device.   The antenna device according to any one of claims 1 to 4, wherein directivity directions of the array antennas of the plurality of array antennas are different from each other. A radar comprising the antenna device according to any one of claims 1 to 5 and a radar control unit that detects a target by transmitting and receiving a radio wave for detection by the antenna device.

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