JP2000059141A - Antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend the radar detection distance and to reduce the appearance frequency of a false target on the radar by combining the directivities of at least two adjacent beams almost in the same phase, setting the beam cross point between the combined antenna beams within a specific range dB, and constituting one or plural antenna beams. SOLUTION: An antenna 2 covers the radar coverage area with beams 3a to 3c emitted by primary radiators 12a to 12c. Then by a directivity combining circuit 13 and a beam control part 14, beams 3d and 3e are obtd. by combining the directivities of the adjacent beams 3a and 3b, and 3b and 3c almost in the same phase. Consequently, the level as the beam cross point of the combined beams 3d and 3e becomes about 1.6 db and is made lower than the level 3 db at the beam cross point of the original beams 3a to 3c and the antenna gain increases, so that the radar detection distance can be extended; and further the side lobe level drops and false radar targets are reducible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device for a base station of a radar device using a sequential roving method.

[0002]

2. Description of the Related Art Conventionally, in a base station antenna device of a radar device using a sequential lobing method,
There are a method of mechanically driving a single beam antenna to scan an antenna beam and a method of scanning a beam by electronically switching an antenna beam of a multi-beam antenna. This radar antenna device is described in detail in, for example, “Antenna Engineering Handbook” p184, edited by the Institute of Electronics, Information and Communication Engineers.

As a sequential roving type radar, a method of scanning a beam by electronically switching an antenna beam of a multi-beam antenna has advantages such as no mechanical drive unit and high-speed beam switching. Here, for convenience of explanation, a radar antenna device that performs sequential roving by electronically switching three beams will be described as an example. FIG. 9A shows this system, in which 1 is a radar device,
2 is an antenna, 3a to 3c are antenna beams radiated from the antenna 2, 4 is an automobile, 5 is an obstacle on the road such as a falling object from the automobile, 6 is a column for mounting the radar device 1, and a roadside. 1 shows an example of a system in which a radar device is installed on the upper side to detect an obstacle or the like on a road and warns or warns the driver of an obstacle ahead of the driver using an information display board or the like. FIG. 9B shows the radar device 1.
FIG. 7 is a schematic diagram showing the configuration of the first embodiment, wherein 7 is a transceiver, 8 is a switching circuit such as a switch, and 9 is a signal processing unit.

Next, the operation will be described. In FIG. 9B, a radio wave is generated from the transceiver 7 and guided to the antenna 2 via the switching circuit 8. Next, the antenna beam 3 a transmitted from the antenna 2 is reflected by the obstacle 5 and received again by the antenna 2, and is transmitted through the switching circuit 8 to the transceiver 7.
, And guides information such as the amplitude and beat frequency of the reflected wave to the signal processing unit 9. By sequentially switching the switching circuit 7, the antenna beams 3a to 3c can be switched, and by calculating (addition / subtraction) output signals of two adjacent beams, a sum signal Σ and a difference signal Δ are generated. ,
The position, relative speed, and the like of the obstacle 5 are measured by calculating a so-called discrete curve of Δ / Σ in the signal processing unit.

[0005] Further, as a configuration of the multi-beam antenna for electronically switching beams, a configuration having one or more reflecting mirrors and a plurality of primary radiators is used to switch a plurality of primary radiators. A so-called passive phased array that generates multiple beams by connecting a phase shift circuit to each radiating element of the array antenna and electronically controlling the excitation phase of each radiating element. There is a so-called active phased array system in which a phase shift circuit and a transmission / reception module are connected to each radiating element of an array antenna to electronically control the excitation amplitude and phase of each radiating element to generate a plurality of beams. Of the above, the antenna system using a reflector and a plurality of primary radiators has been conventionally used because it has a relatively simple configuration and can be configured at a low cost because it does not require a phase shifter or the like. . The configuration of the switching circuit 8 in this system is such that the primary radiators are sequentially switched using an organ pipe scanner or the like, or a beam forming circuit (BFN) is configured by a power combining / distributing circuit to connect each terminal of the BFN to each other. There is a configuration in which a switch is provided between the primary radiator and the primary radiator, and the switches are sequentially switched to switch the primary radiator.

At this time, if the power level at a so-called beam crossing point where adjacent antenna beams cross each other is high, the receiving sensitivity is improved, and the radar detection distance can be extended. In addition, if the beam width of each antenna beam can be increased, the angle measurement range can be increased accordingly.

[0007]

As described above, in the conventional multi-beam antenna apparatus, in order to generate a plurality of beams with a simple configuration using a reflector antenna, the plurality of beams are different from each other. A configuration in which excitation is performed by a primary radiator is often used. A horn antenna, a helical antenna, a microstrip antenna, or the like can be applied to the primary radiator. However, the horn antenna has a low mutual coupling, easy beam shape setting, and low loss. In many cases, is used as the primary radiator. For this reason, the multibeam antenna of this system will be described in detail below as an example, but the outline is also described in detail in, for example, “Antenna Engineering Handbook” edited by the Institute of Electronics, Information and Communication Engineers, pp. 178-180.

In order to improve the radar performance, the power level at the beam cross point can be increased by reducing the relative distance between adjacent beams or increasing the antenna beam width. A first approach to reducing the relative spacing between adjacent beams is to reduce the spacing between adjacent primary radiators without changing the focal length of the reflector. Reducing the spacing between the primary radiators leads to a decrease in the aperture diameter of the horn antenna.However, when the aperture diameter of the horn decreases, the primary beam blown from the horn antenna to the reflecting mirror surface becomes thicker. Power level (edge level) becomes high. Generally, in a reflector antenna, the edge level is often set to about −10 dB for higher efficiency and lower side lobe.
As described above, when the horn opening diameter decreases, the edge level increases to about −several dB, so that the efficiency decreases and the side lobe characteristics deteriorate. For this reason, although the beam interval can be narrowed, there is a problem that the radar detection distance is shortened due to a decrease in gain, and there is a problem that a pseudo target appears on the radar due to deterioration of side lobe characteristics.

On the other hand, the horn interval can be widened by increasing the focal length of the reflector, and the primary beam can be narrowed by increasing the horn aperture, but the angle at which the horn antenna looks at the reflector edge is small. Because
As a result of the beam focusing effect being canceled out, there is a problem that the edge level cannot be lowered. Further, increasing the focal length leads to an increase in the size of the antenna, and there is also a problem that the radar system cannot be downsized.

Further, in order to widen the antenna beam width, the aperture diameter of the reflecting mirror may be reduced, but there is a problem that the radar detection distance is shortened due to a decrease in gain. In addition, it is conceivable to use mirror surface modification technology to obtain an antenna with high gain and a wide beam width,
In general, an antenna using a modified mirror surface optimizes the performance of the beam from the primary radiator placed at the focal point, and the beam from the primary radiator defocused to obtain a multi-beam has large specular aberration. There is a problem that the performance is deteriorated. In addition, in order to obtain the effect of the mirror surface modification, it is generally necessary to make the size of the reflecting mirror 10 times or more the wavelength, and there is also a problem that the antenna becomes large. Was.

Further, as described above, since the horn opening diameter cannot be increased due to the limitation of the horn interval, the edge level of the reflecting mirror must be increased, so that the side lobe performance deteriorates and a pseudo target appears on the radar. There was a point. In addition, a high edge level means that, among radio waves radiated from the primary radiator, a large amount of power that is wasted without being blown to the reflecting mirror and is a so-called spillover power is large, and therefore, the antenna gain is reduced. There is a problem that the detection distance is shortened. In order to reduce this spillover, the aperture diameter of the reflector should be increased, but in this case, the antenna beam becomes narrower, the power level at the beam cross point decreases, and eventually the radar detection distance cannot be extended There was a problem.

As described above, the multi-beam antenna has more restrictions than the single-beam antenna.
The electrical performance of both gain and side lobes had to be sacrificed somewhat, and as a result, it was difficult to increase the power level at the beam cross point. The present invention has been made to solve such a problem, and will be described in detail below.

[0013]

In order to solve the above-mentioned problems, an antenna device according to the first invention is provided with a plurality of antenna beam terminals, and a beam cross point between adjacent antenna beams is about 3 dB. In an antenna device in which a plurality of antenna beam intervals and beam widths are set such that the following formulas, at least two adjacent beams are directionally synthesized in substantially the same phase, and a beam cross point between the directionally synthesized antenna beams is obtained. Is set to be about 1 to 2 dB so that one or a plurality of antenna beams can be obtained.

An antenna device according to a second aspect of the present invention includes:
Each of at least three or more antenna beam terminals is connected to a switch, switches connected to at least two or more adjacent antenna beam terminals can be turned on at the same time, and switches connected to other antenna beam terminals are turned off. With this configuration, the directivity synthesis of the antenna beam is performed, and the combination of the antenna beam terminals is sequentially changed to switch the antenna beam that has been subjected to the directivity synthesis.

The antenna device according to a third aspect of the present invention includes:
The configuration is such that the switches connected to all the antenna beam terminals can be simultaneously turned on.

Further, an antenna device according to a fourth aspect of the present invention includes:
All antenna beam terminals are connected to a power distribution / combination circuit.

An antenna device according to a fifth aspect of the present invention includes:
An LNA is connected to each of at least three or more receiving antenna beam terminals, and LNAs connected to at least two or more adjacent receiving beam terminals can be simultaneously turned on, and LNs connected to other receiving antenna beam terminals can be simultaneously turned on.
A is configured to be in an OFF state, so that the directivity of the antenna beam is synthesized, and further, the combination of the antenna beam terminals is sequentially changed so that the antenna beam having the directivity synthesized can be switched. is there.

An antenna device according to a sixth aspect of the present invention includes:
A pin diode is connected to each of at least three or more receiving antenna beam terminals, and pin diodes connected to at least two or more adjacent receiving beam terminals can be simultaneously turned on, and connected to other receiving antenna beam terminals. A configuration in which the pin diode can be turned off to perform directivity synthesis of an antenna beam, and further, the combination of the antenna beam terminals is sequentially changed to switch the antenna beam subjected to the directivity synthesis. It is.

An antenna device according to a seventh aspect of the present invention includes:
An antenna beam terminal for radiating antenna beams arranged in two directions that are substantially orthogonal to each other is provided, and a plurality of antenna beams are arranged so that a beam cross point between adjacent antenna beams is about 3 dB. In the antenna device in which the interval and the beam width are set,
At least two adjacent beams arranged on one or both of the axes are directionally combined in substantially the same phase,
A beam cross point between the directionally synthesized antenna beams is set to be about 1 to 2 dB so that one or a plurality of antenna beams can be obtained on one or both of the arbitrary two axes. It is composed.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1A is a schematic configuration diagram showing a first embodiment of the present invention. In the drawings, reference numerals 1 to 6 are exactly the same as those of the above-mentioned conventional example. This shows an example of a system that detects an obstacle or the like and warns or warns the driver of an obstacle in front by using an information display board or the like, and shows an example in which antenna beams are arranged in a horizontal plane direction. FIG. 1B is a diagram showing a schematic configuration of the radar apparatus 1 and the antenna 2, wherein 10 is a main reflector, 11 is a sub-reflector, 12a to c are primary radiators, and 13 is a directivity combining circuit. ,
Reference numeral 9 denotes a signal processing unit, and 14 denotes a beam control unit.

Next, the operation will be described. FIG. 2 (a),
(B) shows the radiation pattern of the antenna 2 on the horizontal plane. As shown in the figure, the horizontal direction of the antenna is configured such that the radar coverage can be covered by three beams 3a to 3c radiated from the three primary radiators 12a to 12c shown in FIG. The beam cross point of the adjacent antenna is set to be about 3 dB. For example, as shown in FIG. 2A, the directivity combining circuit 13 and the beam control unit 14 perform directivity combining of the adjacent beams 3a and 3b in substantially the same phase to obtain a combined beam 3d. As the directivity synthesis means constituting the directivity synthesis circuit,
Since it is only necessary to be able to combine antenna beams in almost the same phase, use a power distribution / combination circuit using a coupler, hybrid, etc., and set the feed line length to a predetermined value or insert a phase shifter, etc. As a result, the electric length between each primary radiator and the transmitter / receiver can be made substantially equal to each other.
It may be performed in the F system, or may be performed in the digital system in the signal processing unit or the beam control unit.

Here, the multi-beam antenna according to the first embodiment of the present invention is used as a transmitting antenna,
A case where beam combining is performed in an RF system will be described as an example, and for convenience of description, FIG. 2A shows only the antenna beams 3a, 3b, and 3d. For example, when the directivity synthesis circuit is configured by a coupler, the transmission power is reduced by about half by the coupler to the primary radiator 12.
a and 12b. In the example of the conventional multi-beam antenna, a switch or the like is inserted between the coupler and the primary radiator, and the antenna beams 3a and 3b are switched and used by switching the switch. There is a problem that the power is reduced by half every time the light passes, and as a result, the power of the antenna beam is reduced. Since the antenna beams 3a and 3b emitted from the primary radiators 12a and 12b are directionally combined in substantially the same phase, the respective main beams are directionally combined in the same phase, and the output at the beam cross point is 6 dB. It rises and becomes the peak of the antenna beam 3d that has undergone directivity synthesis.
In general, the side lobe of the antenna beam changes in phase with respect to the main beam phase, the first side lobe has an opposite phase, the second side lobe has the same phase, and so on. In portions other than the point, the directivity of the main beam of the beam 3a and the first side lobe of the beam 3b are combined in opposite phases, and similarly, the first side lobe of the beam 3a and the main beam of the beam 3b are directed in opposite phases. The main beam 3d that is directionally synthesized and consequently directionally synthesized is not a trapezoidal beam but the original beam 3a,
The resulting pencil beam has a peak gain about 3 dB higher than that of the pencil beam 3b. Also, as shown in FIG. 2, the first side lobe of the beam 3a and the second side lobe of the beam 3b are directionally synthesized in opposite phases, and similarly, the side lobes are always directional in opposite phases. Since the beams are synthesized, the side lobe level is lower than that of the original beams 3a and 3b. Further, the beam 3e is obtained by similarly performing directivity synthesis of the beams 3b and 3c. FIG.
As shown in (b), the level of the beam cross point of the beams 3d and 3e obtained by the directivity synthesis is about 1.6 dB, which is higher than the level of the beam cross point of the original beams 3a to 3c of about 3 dB. In addition, since the antenna gain is also increased, there is an effect that the radar detection distance can be extended. In addition, the beams 3d and 3e obtained by the directional synthesis are used.
Are lower than the original side lobe levels of the beams 3a to 3c, so that the radar false target can be reduced.

In a case where the conventional multi-beam antenna is constituted by an organ pipe scanner or the like,
Although the transmission power propagates to one primary radiator almost as it is, if the transmission power is changed to propagate the transmission power to two primary radiators, the antenna beams 3a and 3b radiated from the primary radiators 12a and 12b can be changed. However, since the antenna beams 3a and 3b are directionally combined in substantially the same phase, the respective main beams are directionally combined in the same phase, and the output at the beam cross point is It rises by 6 dB and becomes the peak of the antenna beam that has undergone directivity synthesis. That is, the level of the beam cross point is reduced by 6 dB from the peak level of the original beams 3a and 3b, and the peak of the directionally synthesized antenna beam is now 6 due to the directivity matching according to the present invention.
As a result, a pencil beam having substantially the same gain as the original beams 3a and 3b and a wide beam width is obtained. Further, the side lobes of the antenna beam are always directionally synthesized in the opposite phase with each other according to the same principle as described above.
The side lobe level is lower than a and 3b. By obtaining such a beam, the effects of improving the radar detection distance and reducing the radar false target can be obtained.

FIG. 2 shows an example of a multi-beam antenna in which the horizontal plane is composed of three beams. However, a multi-beam antenna device composed of three or more beams is used to direct adjacent beams in the same manner as described above. You may comprise so that synthesis | combination is possible. Although the figure shows an example of a two-mirror antenna, a one-mirror antenna or three or more reflecting mirrors may be used. Further, a horn antenna, a helical antenna, a microstrip antenna or the like can be applied as the primary radiator, and the present invention is effective without depending on the type of the primary radiator. Further, the antenna type according to the present invention is not limited to the reflector antenna, and the same effect can be obtained if the beam cross point between the adjacent antenna beams is set to about 3 dB.
The present invention is also effective for a planar antenna or the like. The vertical plane beam is not shown in the figure, but in addition to the pencil beam, which simplifies the antenna configuration, the antenna has a cosecant square characteristic capable of compensating for attenuation due to distance, so that the radar coverage can be substantially reduced. Beam irradiation can be performed with a uniform power density.

Embodiment 2 FIG. 3 is a schematic diagram showing a second embodiment of the present invention. In the figure, primary radiators 12a to 12c are connected to switches 15a to 15c, respectively.
And the power distribution / combination circuit 16 is connected to the transceiver 7. Further, the electrical length of a line from the primary radiator to the transceiver via the switch is set to be substantially equal. In the antenna device configured as described above, power combining can be performed by simultaneously turning on the switches connected to at least two or more adjacent antenna beam terminals. Since the electrical length of the line from the primary radiator to the transceiver is set to be almost equal, the radio waves radiated from each primary radiator are synthesized in directivity with almost the same phase,
The gain can be improved, the beam width can be widened, the level of the beam cross point can be improved, and the side lobe level can be reduced by exactly the same principle as in the first embodiment of the present invention.

A specific example in which the antenna device according to the second embodiment of the present invention is applied to a radar device using a sequential roving method will be described with reference to FIG. The antenna beams radiated from the primary radiators 12a to 12c of the antenna are the beams 3a to 3b shown in FIG.
It is exactly the same as c, and at a certain timing,
The switches 12a and 12b are turned on, and 12c
Is turned off, so that the beam 3 that is
Obtain d. At another timing, the switches 12b and 12c are turned on and the switch 12a is turned off, thereby obtaining a beam 3e with directional synthesis.
By sequentially switching the switches in this manner, two beams 3d and 3e are formed, and the outputs of these two beams are processed in the signal processing unit 9 in exactly the same procedure as in the past, thereby functioning as a radar. be able to. At this time, as described above, the level of the beam cross point between the two beams 3d and 3e has increased to about 1 to 2 dB, so that the detection distance performance can be improved, and since the side lobe level has decreased, False targets can also be reduced.

Although FIG. 3 shows a configuration in which the transmitting and receiving antennas are shared, the effect of the present invention does not change even if the transmitting and receiving antennas are separately configured. In addition, the power combining / distributing circuit 16 can be configured using a conventional technique such as a coupler or a hybrid. Although FIG. 3 shows a two-mirror antenna as an example, the present invention is effective without depending on the number of reflectors of the antenna.
Further, as the primary radiator of the reflector antenna, a helical antenna, a microstrip antenna, or the like may be used in addition to the horn antenna shown in the figure. In addition, the above-mentioned switch is an RF switch such as a mechanically driven waveguide switch or an electronic switch using an FET (field effect transistor) or the like.
As long as the power can be turned on / off, it does not depend on the switching mode. Further, the antenna type according to the present invention is not limited to the reflector antenna, and the same effect can be obtained if the beam cross point between adjacent antenna beams is set to about 3 dB. The present invention is also effective against the above. Further, the case where the number of antenna beams is three has been described as an example, but the same effect can be obtained by sequentially switching the switches even in the case of three or more.

Embodiment 3 FIG. 4 is a schematic view of an antenna beam for illustrating the embodiment of the present invention. In the figure, 3a to 3c denote antenna beams generated by respective primary radiators, and 3d denotes an antenna beam after synthesis. The configuration of the antenna is exactly the same as that of the second embodiment shown in FIG. 2, and is characterized in that all switches connected to the respective antenna beam terminals can be simultaneously turned on. In the conventional sequential roving antenna device, the radar coverage is covered by sequentially switching the pencil beams 3a to 3c. However, in the antenna device according to the third embodiment of the present invention, all of the switches are turned on and the antenna is turned on. One fan beam can be obtained by directionally combining the beams in substantially the same phase.

When the antenna device according to the third embodiment of the present invention is applied to a sequential roving type antenna, for example, the above-mentioned antenna device is used for both transmission and reception, and all the switches are turned on at the timing of transmission. This makes it possible to cover a wide range of the radar coverage area with one fan beam. At the timing of reception, the switch is appropriately switched to select one narrow beam, or two or more beams are selected. As in the second embodiment of the present invention, by directionally combining and selecting and using a beam having a high gain and a low side lobe, the receiving antenna beam is electronically scanned,
A radar target can be detected. In a conventional antenna, it is impossible to realize an antenna having extremely different gain and beam width as described above with one antenna. Therefore, two antennas are required for transmission and reception. According to the present invention, transmission and reception can be shared by one antenna, and the size of the radar device can be reduced.

Embodiment 4 FIG. 5 is a schematic configuration diagram showing an embodiment of the present invention. In the figure, the primary radiators 12a to 12c are directly connected to a power distribution / combination circuit. Embodiment 4 of the present invention
Unlike the antenna device according to the third embodiment of the present invention, the antenna device according to the third embodiment always combines the directivity of the antenna beams radiated from all the primary radiators in substantially the same phase, thereby providing one simple configuration with a simpler configuration. You can get a fan beam. Embodiment 2 or 3 and 4 of the present invention
The difference from this is only the presence or absence of a switch, and the antenna design can be shared. Therefore, a multi-beam antenna and a fan-beam antenna can be easily formed and separated. Also, by using the antenna device according to the fourth embodiment of the present invention in combination with a mechanical drive unit capable of rotating the antenna device itself, the antenna device can be used as a radar device using a fan beam.

Embodiment 5 FIG. 6 is a schematic configuration diagram showing a fifth embodiment of the present invention.
2a to 2c are connected to LNAIs 7a to 7c, respectively, the LNA is connected to a power combining circuit 16, and the power combining circuit 16 is connected to a receiver 18. Furthermore, the electrical length of the line from the primary radiator to the receiver via the LNA is set to be substantially equal. In the antenna device configured as described above, by simultaneously turning on the LNAs connected to at least two or more adjacent antenna beam terminals, the primary radiation connected to the LNA that has been turned on is set. It is possible to combine the power of the antenna beam of the radiator, but since the electrical length of the line from the primary radiator to the receiver is set to be almost equal as described above, from each primary radiator The emitted radio waves are directionally combined in substantially the same phase, so that the beam width can be increased and the side lobe level can be reduced. The multi-beam antenna device according to the fourth embodiment of the present invention is characterized in that the LNA is used for two purposes, power amplification and power switching, as described above. Can be achieved.

Embodiment 6 FIG. FIG. 7 is a schematic configuration diagram showing Embodiment 6 of the present invention, in which each primary radiator 1
2a-c are detectors 19a-19 such as pin diodes, respectively.
c. Furthermore, the electrical length of the line from the primary radiator to the detector is set to be substantially equal, and the pin diode is turned ON / OFF.
By turning it off, the directivity of the antenna beam is synthesized. The multi-beam antenna device according to the fifth embodiment of the present invention is characterized in that a detector such as a pin diode is used for two purposes, that is, detection and power switching, as described above. Can be achieved.

Embodiment 7 FIG. 8 is a schematic configuration diagram showing a seventh embodiment of the present invention. In the drawing, reference numerals 12a to 12e denote primary radiators, and as shown in FIG.
a, 12b, 12c are arranged in a horizontal plane, while
The primary radiators 12d, 12c, 12e are arranged in a vertical plane. Also, an example is shown in which each primary radiator is connected to pin diodes 19a to 19e, and the other configuration is exactly the same as that of the fifth embodiment. In the multi-beam antenna device configured as described above, two adjacent beams of the primary radiators arranged in a horizontal plane are directionally combined by ON / OFF of the pin diode, thereby achieving high gain and beam width. And two antenna beams having low side lobes can be formed. Similarly, by performing the same directivity synthesis using the primary radiators arranged in the vertical plane, two antenna beams having a high gain, a wide beam width, and a low side lobe are formed on the horizontal and vertical planes of the antenna. With the combined beams formed on the horizontal plane and the vertical plane, the radar detection distance can be extended, the angle measurement accuracy can be improved, and false targets can be reduced.

By simultaneously turning on all the primary radiators arranged in the horizontal plane, one fan beam having a wide beam width can be obtained as in the third embodiment of the present invention. The same applies to the vertical plane. Although the figure shows an example using a pin diode, a switch may be used as the directivity combining means as in the second embodiment of the present invention, or as in the fifth embodiment of the present invention. LNA may be used. Although FIG. 1 shows an example of a 5-beam multi-beam antenna, the present invention is effective regardless of the number of antenna beams.

[0035]

According to the first aspect of the present invention, a plurality of adjacent antenna beams arranged in any one axis direction are directionally combined in substantially the same phase, thereby expanding an equivalent beam width.
It has the effect of improving the gain and obtaining low sidelobe characteristics.By applying the antenna according to the present invention to a sequential lobing type radar, it is possible to improve the angle measurement accuracy of the radar, improve the detection distance, and reduce the pseudo target. Three effects can be obtained simultaneously.

According to the second aspect of the present invention, a switch is connected to each antenna beam terminal, and these switches are turned on / off by a beam control unit to perform beam synthesis, thereby simplifying the configuration of the antenna. The effect is as follows.

According to the third aspect of the present invention, since the switches connected to all the antenna beam terminals can be turned on at the same time, a fan beam having a wide beam width can be obtained. Further, since the beam width of one antenna can be arbitrarily changed, beams having different characteristics can be arbitrarily formed in transmission and reception, and the radar device can be downsized.

According to the fourth invention, all the antenna beam terminals are connected to the power distribution / combination circuit,
There is an effect that a fan beam with a wide beam width can be obtained with a simpler configuration.

According to the fifth aspect of the present invention, the LNA is connected to each of the receiving antenna beam terminals, so that the noise characteristics of the antenna can be improved, and ON / OFF of the LNA can be achieved.
By performing beam combining according to the above, there is an effect that the configuration of the antenna can be simplified and high reliability can be achieved.

According to the sixth aspect of the present invention, the detectors are connected to the respective receiving antenna beam terminals, and the beam composition is performed by turning on / off the detectors, thereby simplifying the configuration of the antenna. This has the effect of reducing costs.

According to the seventh aspect of the present invention, a plurality of antenna beams arranged in any two directions substantially orthogonal to each other are directionally combined in substantially the same phase, thereby providing an equivalent beam in the two axes. There is an effect that the beam width is increased, the gain is improved, and low side lobe characteristics are obtained. By applying the antenna according to the present invention to a sequential lobing type radar, three effects of improving the angle measurement accuracy, improving the detection distance, and reducing the pseudo target can be simultaneously obtained in any two axial directions of the radar.

[Brief description of the drawings]

FIG. 1 is a first embodiment of an antenna device according to the present invention;
FIG.

FIG. 2 is a diagram showing an antenna beam after directivity synthesis with an original antenna beam.

FIG. 3 is a second embodiment of the antenna device according to the present invention;
FIG.

FIG. 4 is a third embodiment of the antenna device according to the present invention;
FIG. 3 is a diagram showing an antenna beam for indicating the above.

FIG. 5 is a fourth embodiment of the antenna device according to the present invention;
FIG.

FIG. 6 is a diagram illustrating a fifth embodiment of the antenna device according to the present invention;
FIG.

FIG. 7 shows an antenna device according to a sixth embodiment of the present invention;
FIG.

FIG. 8 is a seventh embodiment of the antenna device according to the present invention;
FIG.

FIG. 9 is a schematic configuration diagram showing a radar system having a conventional multi-beam antenna.

[Explanation of symbols]

1 radar device, 2 antennas, 3 antenna beams,
4 car, 5 obstacles, 6 pillars, 7 transceiver, 8
Switching circuit, 9 signal processing unit, 10 main reflector, 11
Sub-reflector, 12 primary radiator, 13 directional synthesis circuit,
14 beam control unit, 15 switch, 16 power distribution / combination circuit, 17 LNA, 18 receiver, 19 detector.

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 5J021 AA05 AA06 AB04 AB06 AB07 BA01 CA01 CA06 DB04 EA02 FA01 FA02 FA25 FA26 FA31 FA32 GA01 GA05 GA08 HA02 HA04 JA07 5J070 AD01 AD07 AD10 AE01 AF01 AG04 AG07

Claims (7)

[Claims] A plurality of antenna beam terminals are provided,
In an antenna device in which a plurality of antenna beam intervals and beam widths are set so that a beam cross point between adjacent antenna beams is about 3 dB, directivity of at least two or more adjacent antenna beams is substantially the same. An antenna, wherein one or a plurality of antenna beams are obtained by combining and setting an equivalent beam width so that a beam cross point between the directionally synthesized antenna beams is about 1 to 2 dB. apparatus. 2. The antenna device according to claim 1, wherein each of at least three or more antenna beam terminals is connected to a switch, and said switches connected to at least two or more adjacent antenna beam terminals are simultaneously turned on. 2. A beam combining or beam distribution is performed by turning off the switch connected to the antenna beam terminal of (a), and the antenna beam is switched by sequentially changing a combination of the antenna beam terminals. Antenna device. 3. The antenna device according to claim 1, wherein all the switches connected to all antenna beam terminals are simultaneously turned on to obtain a single beam antenna. 4. The antenna device according to claim 1, wherein all antenna beam terminals are connected to a power distribution / combination circuit to obtain a single beam antenna.
The antenna device as described in the above. 5. In the above antenna apparatus, each of at least three or more receiving antenna beam terminals is LN
A (Low Noise Amplifier), and simultaneously turn on the respective LNAs connected to at least two or more adjacent receiving antenna beam terminals.
And combining the receiving antenna beam terminals by changing the combination of the receiving antenna beam terminals while sequentially switching the receiving antenna beam terminals by turning off the LNAs connected to the other receiving antenna beam terminals. Item 4. The antenna device according to any one of Items 1 to 3. 6. In the above antenna device, each of at least three or more receiving antenna beam terminals is connected to a detector such as a pin diode, and each of at least two or more receiving antenna beam terminals is connected to at least two adjacent receiving antenna beam terminals. The beam combining is performed by simultaneously turning on the detectors such as the pin diodes and turning off the detectors such as the pin diodes connected to the other receiving antenna beam terminals, and sequentially combining the receiving antenna beam terminals. The antenna device according to claim 1, wherein the receiving antenna beam is switched by changing the distance. 7. A plurality of antenna beam terminals for radiating antenna beams arranged in directions of arbitrary two axes substantially orthogonal to each other are provided, and a beam cross point between each adjacent antenna beam is approximately In an antenna device in which a plurality of antenna beam intervals and beam widths are set so as to be 3 dB, at least two adjacent antenna beams arranged in one or both of the two axes are substantially in phase. Directivity synthesis is performed, and an equivalent beam width is set so that a beam cross point between the directionally synthesized antenna beams is about 1 to 2 dB. The antenna device according to claim 1, wherein the antenna device is obtained in one or both of them.