JPH09162626A - Plane array antenna and monopulse radar equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the mass production of compact array antennas of plural systems consisting of serial and parallel feeder lines by arranging the antenna element strings formed on the serial feeder lines in such a way where these element strings interdigitate each other and almost at equal spaces. SOLUTION: A receiving antenna (plane antenna) 10 contains a dielectric substrate 22 that is placed on the surface of the antenna 10 to radiate the radio waves and a dielectric substrate 27 that is placed on the back side of the antenna 10. The antenna elements 24 are arranged in a matrix shape on the surface of the substrate 22, and the serial feeder lines 26 which connect in series the elements 24 in every string are provided on the back side of the substrate 22 together with a pair of parallel feeder lines 26a and 26b which perform the parallel feeding to the elements 24 in every string via the lines 26. Then such antennas 10 are arranged on the same plane, so that the whole or some of antenna element strings formed by the lines 26 interdigitate each other and almost at equal spaces.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar array antenna suitable for constituting a monopulse type radar device,
And a monopulse radar device using this antenna.

[0002]

2. Description of the Related Art Conventionally, it has been expected to realize an obstacle detection radar using radio waves as a transmission medium as a means for assisting a driver's vision in order to prevent a collision of a moving body such as an automobile. Further, in this type of radar device, it is possible to determine the horizontal position of an obstacle such as a vehicle traveling in front of the vehicle.
It is a very important technology for predicting the possibility of collision. Therefore, a monopulse radar device is considered to be effective as such a radar device for automobiles.

That is, the monopulse radar device transmits a predetermined radio wave to the outside, and the reflected wave reflected by the transmitted radio wave hitting a target is received by a pair of receiving antennas whose positions or beam directions are shifted, The position (direction, etc.) of the target is measured from the phase difference or amplitude difference of the received signals from each receiving antenna. Generally, it is used as an aircraft tracking radar. It is considered that it will function extremely effectively in a situation where there are many obstacles, such as the driving environment of a car, because the horizontal target can be distinguished with high accuracy by installing it horizontally. .

[0004]

However, conventionally, in the monopulse radar device, a large-sized antenna device such as a waveguide horn or a parabolic antenna, which is difficult to mass-produce, has been used as a receiving antenna. This is because the conventional monopulse radar device was developed for aircraft tracking, and there was no request for downsizing and mass production.
As described above, in order to mount the monopulse radar device as an obstacle detection radar on a moving body such as an automobile, the receiving antenna needs to be miniaturized and mass-produced, and the conventional monopulse radar device can be directly used as an obstacle detection radar. It could not be applied.

The present invention has been made in view of these problems, can be easily miniaturized and mass-produced, and is suitable for mounting a monopulse radar device as an obstacle detection radar on a moving body such as an automobile. An object of the present invention is to provide a planar array antenna and a monopulse radar device using the same.

[0006]

In order to achieve the above object, in the planar array antenna according to claim 1, the antenna elements arranged in a matrix form and a series provided for each column of the antenna elements. An antenna element array including two systems of array antennas each including a feed line and a parallel feed line that performs parallel feed for each row of antenna elements via the series feed line, and each array antenna is formed by the series feed line The array antennas are arranged on the same plane so that all the rows or some of the rows are alternately meshed at substantially equal intervals.

For this reason, in the planar antenna of the present invention, when the array antennas of two systems are arranged so that all the antenna element arrays are alternately meshed with each other, the spacing between the antenna element arrays in the array antennas of each system is arranged. An array antenna of two systems spatially displaced by a distance "d / 2" which is about half the distance d is constructed, and an array antenna of two systems is arranged so that a part of the antenna element rows alternately mesh with each other. In this case, in the array antennas of each system, the number n of gaps in which the antenna element rows of other array antennas are not arranged between the antenna element rows and the distance d between the antenna element rows.
Two array antennas are spatially displaced by a predetermined distance “n · d + d / 2” determined by

Therefore, the planar array antenna of the present invention is
For example, when it is used as a receiving antenna of a phase monopulse radar device, it is possible to detect the azimuth of the target by detecting the phase difference of the received signals obtained from the power supply terminals of the parallel power supply lines. That is, as shown in FIG. 5, the phase monopulse radar device has an antenna with the same directional characteristics (a parabolic antenna provided with a reflecting mirror is shown in the figure) A.
1, A2 are arranged in a state where they are slightly shifted in the horizontal direction, reflected radio waves from the same reflecting target Px are received by the respective antennas A1 and A2, and the direction of the reflecting target (from the phase difference of the received signals) Angle) θ is measured. Specifically, the phase difference of the received signal caused by the difference between the path lengths LA1 and LA2 of the radio waves from the reflecting target Px to the receiving points P1 and P2 of the antennas A1 and A2 is calculated. Letting φ be the distance between the antennas A1 and A2 be D, the wavelength of the radio wave be λ, and the direction angle of the reflecting target be θ, the direction θ of the reflecting target is obtained from the following relational expression (1).

Φ = (2π / λ) D · sin θ (1) Therefore, when constructing the phase monopulse radar device, basically, the antennas A1 and A2 having the same directivity characteristics are used.
It is necessary to simultaneously receive the reflected radio waves from the reflection target Px by using the above. However, according to the present invention, a predetermined planar array antenna determines the predetermined distance determined by the distance d between the antenna element rows of each system. Distance (“d / 2” or “n · d + d / 2”)
Since it is possible to construct an array antenna of two systems which are displaced by only the position, it can be used as a receiving antenna for a phase monopulse radar device.

In this case, unlike the conventional apparatus shown in FIG. 5, it is not necessary to dispose the two receiving antennas at different positions, and one plane array antenna is used to receive the receiving antennas of the phase monopulse radar apparatus. Therefore, the receiving antenna in the phase monopulse radar device can be easily downsized. Further, the planar array antenna does not need to be provided with a reflecting mirror or a waveguide, unlike the parabolic antenna or the waveguide horn that has been conventionally used as a receiving antenna of a monopulse radar device, so that mass production is facilitated. Since it can be mounted and is lightweight, it can be easily mounted on a moving body such as an automobile.

Further, when the phase monopulse radar device is constructed by using a pair of receiving antennas like the conventional device shown in FIG. 5, two receiving antennas are required.
The device becomes large, and the antenna distance D is limited by the antenna apertures of the antennas A1 and A2.
If the azimuth D becomes wider and the azimuth cannot be uniquely determined from the phase difference between the received signals, or conversely, if an antenna with a small antenna aperture is used for each of the antennas A1 and A2 to narrow the antenna gap. However, there is a problem that the maximum detection distance of the target becomes small, but according to the planar array antenna of the present invention, a pair of receiving antennas for a phase monopulse radar device can be realized with one planar array antenna, Since the distance between each pair of these receiving antennas can be set arbitrarily without being limited by the antenna aperture of the planar array antenna, the direction of the target can be changed without decreasing the antenna gain and thus the maximum detection distance of the target. It is possible to detect uniquely.

In the phase monopulse radar device, when the antenna distance D becomes wider, the direction of the target direction θ cannot be uniquely detected because the phase difference φ and the direction θ are within the receivable direction θ. This is because there is no one-to-one correspondence. In other words, as the antenna spacing D is larger, the value of the phase difference φ changes greatly with a slight change in the direction θ, and the range of the value of the phase difference φ exceeds ± π, and is folded.
This is because a plurality of azimuth values θ correspond to one phase difference value φ (see FIG. 6).

By the way, as a parallel feed line for feeding parallel power to each antenna element row in a two-system array antenna, the line length from the feed terminal to each row of antenna elements is set like a general parallel feed line. When all are the same, the directions of the radiation beams of the array antennas of the above-mentioned two systems will coincide. Then, when the directions of the radiation beams of the array antennas are matched in this way,
As described above, it can be used as a receiving antenna for a phase monopulse radar device that detects the azimuth of a target from the phase difference of received signals.

However, in the amplitude monopulse radar device which detects the azimuth of the target from the amplitude difference of the received signals, it is necessary to shift the directions of the radiation beams of the two receiving antennas. If the line lengths up to the columns are all the same, it cannot be used as a receiving antenna of the amplitude monopulse radar device.

Therefore, when the planar array antenna of the present invention is used as a receiving antenna of an amplitude monopulse radar device, as described in claim 2, a pair of parallel feed lines constituting the array antennas of the above two systems respectively. Of these, at least one of the parallel feed lines may have a nonuniform line length from the feed terminal to each antenna element array so that the radiation beam center directions of the two-system array antennas deviate from each other by a predetermined angle.

That is, in the array antenna, the direction of the radiation beam can be changed by adjusting the length of the feed line for each antenna element and shifting the phase of the transmission / reception signal for each antenna element. When the planar array antenna of 1 is used as the receiving antenna of the amplitude monopulse radar device, the lines from the feed terminals of the parallel feed lines to the antenna element rows are arranged so that the center directions of the radiation beams of the two-system array antennas are deviated. Just adjust the length. Even when the planar array antenna of the present invention is configured as an antenna device for an amplitude monopulse radar device as described above, a receiving antenna of the amplitude monopulse radar device can be realized with one planar array antenna. It is possible to easily reduce the size of the receiving antenna in the radar device. In this case, only one of the pair of parallel feed lines may be adjusted in line length, or both line lengths may be adjusted.

As the antenna element, various antenna elements such as a plane patch and a slit antenna which have been conventionally used as a plane antenna can be used. Among them, the antenna element is as described in claim 3. Is formed by a plane patch, the plane array antenna can be mass-produced more easily. That is, since the planar patch can be easily manufactured by forming the microstrip line on the dielectric substrate, mass production of the planar array antenna can be realized more easily by forming the antenna element with the planar patch.

On the other hand, as in the present invention, the array antennas of the two systems are arranged on the same plane so that all rows or some rows of the antenna element rows forming the array antennas of the two systems are alternately meshed. In such a case, in the portion where the antenna element rows of the array antenna of each system are meshed with each other, the spacing between the antenna element rows becomes half of the normal one, and when the antenna elements are formed by a generally used circular planar patch, It is conceivable that the antenna elements of each system may overlap with each other and normal reception characteristics may not be obtained. Therefore, in such a case, as described in claim 4, it is preferable that each antenna element is formed of a half-wavelength resonator that is long in the column direction.

Next, in the monopulse radar device according to a fifth aspect of the present invention, the plane array antenna described above receives the reflected radio wave transmitted from the transmitting antenna and reflected by hitting an external target, and this plane array antenna receives the reflected radio wave. The direction of the target is detected based on the received signal obtained from the feed terminal of each parallel feed line of the array antenna. That is, in this monopulse radar device, the planar array antenna according to any one of claims 1 to 4 is used as a receiving antenna.

Therefore, according to the monopulse radar device of the present invention, unlike the conventional monopulse radar device, it is possible to detect the direction of the target without using two receiving antennas, and to detect a moving object such as an automobile. The radar device can be optimally installed and used as an obstacle detection radar.
Further, since the planar array antenna can be mass-produced and reduced in weight as described above, the monopulse radar device itself can be realized at low cost and can be easily attached to a moving body or the like.

By the way, the above planar array antenna is suitable for use as a receiving antenna of a monopulse radar device, since one antenna device constitutes an array antenna of two systems. If it is used only as, it is necessary to separately provide a transmitting antenna. However, since the two array antennas in the above planar array antenna are independent antenna devices, they can also be used individually as transmitting antennas.

Therefore, when this planar array antenna is used in a monopulse radar device, as described in claim 6, a circulator is connected to the power supply terminal of one of the parallel power supply lines, and a transmission signal is input through this circulator. By taking out the received signal, the array antenna receiving power from the parallel feed line can be operated as an antenna device for both transmission and reception. And in this case, since it is not necessary to separately provide a transmitting antenna, the configuration of the monopulse radar device is further simplified,
It becomes possible to realize the monopulse radar device at a lower cost.

Next, the monopulse radar device detects the azimuth of the target from the phase difference or the amplitude difference between the pair of received signals. As described above, the monopulse radar device is mounted on a moving body or the like to detect an obstacle. For use as a radar, it is preferable to be able to detect the distance between the target and the moving body and the relative speed between the target and the moving body. Therefore, when the monopulse radar device of the present invention is used as an obstacle detection radar, as described in claim 7, the signal generation means generates a predetermined continuous wave as a transmission signal to detect a target. On the side of the target detecting means for performing homodyne detection of the pair of received signals received by the plane array antenna, from the detected signal, not only the direction of the target but also the distance and speed can be detected. Good.

That is, conventionally, as a CW radar for detecting the distance and the relative speed of a target using a continuous wave (CW), a signal (FM-CW) frequency-modulated by a triangular wave is transmitted and the received signal is Frequency conversion (homodyne detection) is performed on the transmitted signal, and the frequency converted signal (detection signal)
FM-CW to calculate the distance and relative velocity from the target to the target
Radar or two signals with different frequencies are transmitted, and the received signals are homodyne detected for each signal to detect the frequency change (Doppler frequency component) of the signal caused by the Doppler effect, and from the detection result, the target There are known two-frequency CW radars and the like for obtaining the distance and relative speed between the CW and the
If the radar system is used to detect the distance and the relative speed, the obstacle can be detected better. If the monopulse radar device is mounted on a moving body such as an automobile, It becomes possible to further improve the running safety of the body.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION An obstacle detection radar according to an embodiment of the present invention will be described below. First, FIG. 2 is a block diagram showing the configuration of the obstacle detection radar of this embodiment. The obstacle detection radar of the present embodiment is mounted on a moving body such as an automobile, detects an obstacle (target) existing in front of or behind the moving body, and the moving body may collide with the obstacle. A warning is issued to the driver to inform the driver of the fact, and the receiving antenna 10 is provided with a plane array antenna having two array antennas.

In the obstacle detection radar of this embodiment, the reception radio wave transmitted from the transmission antenna 6 is reflected by the reception radio wave reflected by an external obstacle.
It is configured as a phase monopulse radar device that detects the direction of an obstacle from the phase difference of the received signals, but not only the function as such a phase monopulse radar, but also from the received signals. FM that detects the distance to the obstacle and the relative speed to the obstacle
-Has a function as a CW radar.

That is, as shown in FIG. 2, the obstacle detection radar of this embodiment is an electronic control unit (hereinafter referred to as ECU) 2 for obtaining the azimuth, distance and relative speed of the obstacle from the received signal.
0, a control voltage (triangular wave) output from the ECU 20, and a voltage control oscillator 2 whose oscillation frequency gradually increases / decreases according to the control voltage, and an output signal from the voltage control oscillator 2 as a transmission signal. Directionality for inputting to the power supply terminal of the transmitting antenna 6 and radiating a transmitting radio wave whose frequency gradually increases and decreasing in a triangular wave form from the transmitting antenna 6 and distributing the transmitting signal to the power distributor 12 side at a predetermined ratio. Outputs (that is, reception signals) from the power supply terminals A and B of the combiner 4 and the array antennas that form the reception antenna 10 are received at RF terminals, respectively, and the transmission signals distributed by the power distributor 12 are transmitted to the LO terminals. Then, by mixing the respective signals, the received signal is frequency-converted (homodyne detection) into an intermediate frequency signal (hereinafter referred to as an IF signal) having a difference frequency between the two signals. Circuit 14a, 14b, a pair of IF circuits 16a, 16b for amplifying the IF signals output from the mixer circuits 14a, 14b, and an alarm for notifying a driver or the like of the danger by receiving alarm output information from the ECU 20. The device 18 is provided.

The ECU 20 includes a CPU, a ROM,
Mainly composed of a microcomputer composed of RAM and the like, and according to a preset program, in the procedure described later,
A function as an FM-CW radar and a phase monopulse radar is realized. The power distributor 12 transmits the transmission signal input from the directional coupler 4 to each of the mixer circuits 14a and 14a.
Power is distributed to b in the same phase.

Next, the structure of the receiving antenna 10 which is the main part of the present invention will be described. In FIG. 1, (a) shows the receiving antenna 10 as seen from the front side that radiates radio waves, and (b) shows a column for explaining one antenna element section 29 shown by a dotted line in the figure below. The cross-sectional state when cut in the direction is shown.

As shown in FIG. 1, the receiving antenna 10 has a first dielectric substrate 22 arranged on the front surface side that radiates radio waves.
And a second dielectric substrate 27 arranged on the back side thereof, and the antenna elements 24 are arranged in a matrix on the front side of the first dielectric substrate 22.

The antenna element 24 has m rows and 2 · m columns (8 rows and 16 rows in this embodiment), where the rows in the vertical direction and the rows in the horizontal direction when the receiving antennas 10 are viewed from the front side. The antenna elements 24 are arranged in a matrix of rows and columns, and each of the antenna elements 24 is composed of a half-wavelength resonator formed of a microstrip line (in other words, a planar patch) elongated in the row direction. Further, the arrangement intervals of the respective antenna elements 24 are such that the interval of each column is half the normal array interval and the interval of each row is the normal array interval.

On the back surface side of the first dielectric substrate 22 on which the antenna elements 24 are arranged, a series feed line 26 for connecting the antenna elements 24 in series for each column and a series feed line 26 are provided. Of the connected antenna elements 24 in each row, a pair of parallel power feeds for feeding parallel power in the same phase to the antenna elements in the odd rows and the antenna elements in the even rows, which are grouped into one row from the left side, respectively. Tracks 26a, 26
b is provided, and the second dielectric substrate 27 is laminated on the back surface side of the first dielectric substrate 22 with the feed line interposed therebetween. On the side surface of the second dielectric substrate 27 opposite to the feed line (that is, the rear surface side of the receiving antenna 10), the ground conductor 28 is provided on the entire surface.

In the receiving antenna 10 of the present embodiment having such a configuration, the antenna elements 24 in the odd columns are fed from the feeding terminal A in the same phase via the parallel feed line 26a, and the antennas in the even columns are supplied. Power is supplied to the element 24 from the power supply terminal B through the parallel power supply line 26b in the same phase. Then, in each column, series power is fed by the electromagnetic coupling method via the series feed line 26.

Therefore, the receiving antenna 10 of this embodiment is
Two arrays of array antennas are provided: an array antenna formed by the odd-numbered column antenna elements that are fed from the parallel feed lines 26a and 26b and an array antenna formed by the even-numbered column antenna elements 24.
The reception signals received by the array antennas can be captured from the power supply terminals A and B of the parallel power supply lines 26a and 26b.

Next, the control operation executed in the ECU 20 in order for the obstacle detection radar of this embodiment to function as a phase monopulse radar and an FM-CW radar will be described. First, the ECU 20 outputs a control voltage, which changes in a triangular wave shape, to the voltage controlled oscillator 2 by using a predetermined voltage generation circuit, so that the FM modulation in which the frequency gradually increases or decreases in the triangular wave shape from the voltage controlled oscillator 2. Output a signal. Then, a transmission radio wave corresponding to this FM modulated signal (transmission signal) is transmitted from the transmission antenna 6, and when there is an obstacle outside, the transmission radio wave hits the obstacle and is reflected, and the reflected radio wave is incident on the reception antenna 10. To do. In the receiving antenna 10, the reflected radio waves are respectively received by a pair of array antennas composed of the antenna elements 24 in the odd-numbered columns and the antenna elements 24 in the even-numbered columns, and the received signals are the parallel feeding lines 26a, 26b. Is output from each of the power supply terminals A and B. And each of these received signals is
The mixer circuits 14a and 14b mix (homodyne detection) the transmission signal currently being transmitted and convert it into an IF signal,
After being further amplified by the IF circuits 16a and 16b, the ECU
It is input to 20.

Then, the ECU 20 makes the IF circuits 16a, 1
It is well known that either one of the received signals (IF signals) input from 6b is frequency-analyzed by a high-speed Ferrier conversion method, etc., and the distance to the obstacle reflecting the transmitted radio waves and the relative speed of the obstacle are measured. Measuring the direction (angle) of the external obstacle by executing the measurement operation as the FM-CW radar and comparing the phases of a pair of received signals received by the receiving antenna 10 from each IF signal. A measurement operation as a well-known phase monopulse radar is executed.

Then, the ECU 20 determines whether or not there is a risk that the moving body will collide with the obstacle based on the measurement result, that is, the distance to the obstacle, the relative speed with respect to the obstacle, and the direction of the obstacle. When there is a risk of collision, the alarm device 18 is operated to inform the driver or the like to that effect.

The alarm device 18 receives the alarm output information from the ECU 20 to inform the driver of the danger, and the alarm device 18 is provided with a buzzer or the like for generating a predetermined alarm sound. Although it may be used, the safety can be further enhanced by using, for example, a voice synthesizing device which issues a voice message indicating the direction of the obstacle according to the detection result.

As described above, in the obstacle detecting radar for a mobile body of this embodiment, in order to realize the function as the phase monopulse radar, the receiving antenna 10 is a parabolic antenna or a waveguide as in the conventional case. Instead of using a pair of receiving antennas such as horns, a planar array antenna having the function of an array antenna of two systems is provided. Therefore, only one receiving antenna 10 needs to be mounted on the moving body, and the device can be downsized and the mountability on the moving body can be improved. Further, since the receiving antenna 10 is a planar array antenna, it does not require a reflecting mirror or a waveguide, and can be easily mass-produced and reduced in weight. Therefore, the radar device can be realized at low cost and can be attached to an arbitrary position of the moving body, so that the versatile radar device can be realized.

Furthermore, according to the receiving antenna 10 of this embodiment, a pair of array antennas for a phase monopulse radar device can be constructed by one plane array antenna, and the distance between the pair of array antennas is the antenna element 24. Since the distance is one row (half the distance between the array antennas of one system) and can be made extremely smaller than the antenna aperture, the antenna gain and thus the maximum detection distance of the target are not reduced, and It is possible to uniquely detect the direction.

Further, the obstacle detection radar of this embodiment has not only a function as a simple phase monopulse radar device but also a function as an FM-CW radar, so that not only the direction of the obstacle but also the obstacle is detected. Distance and relative velocity can also be detected. As a result, the possibility of collision with an obstacle can be determined with higher accuracy, and the traveling safety of an automobile or the like can be further enhanced.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment and can take various modes. For example, in the above embodiment, the receiving antenna 10 in which the antenna elements 24 are arranged in a matrix of 8 rows and 16 columns has been described. However, regarding the number of rows and the number of columns, the characteristics of the antenna to be used (frequency of transmitted and received radio waves, Radiation beam width, antenna gain, etc.)
May be set appropriately according to the conditions.

In the present embodiment, the parallel feed lines 26a and 26b in the receiving antenna 10 have been described as being capable of feeding power to the antenna elements 24 in the corresponding column in the same phase. This is because the center direction of the radiation beam from the antenna is made to coincide with the direction orthogonal to the dielectric substrate 22 to realize a highly accurate phase monopulse radar, and the amplitude for detecting the direction of the obstacle from the amplitude difference of the received signals. When realizing a monopulse radar, for example, of the parallel feed lines 26a and 26b, for the parallel feed line 26a that feeds the antenna elements 24 in odd columns, the feed line extending from the feed terminal A to the left column The line length of the feed line extending from the feed terminal A to each column is set so that the path length and the line length are increased, and conversely, the antenna elements 24 in even columns are fed with power. The column feed line 26b,
The line length of the power supply line extending from the power supply terminal B to each column may be set such that the line length of the power supply line extending from the power supply terminal B to the right side column is longer.

That is, in the amplitude monopulse radar, it is necessary to shift the center directions of the radiation beams of the antenna device to be used from each other, but if this is done, the two systems formed by the antenna elements in the odd and even rows, respectively. The center direction of the radiation beam from the array antenna can be shifted horizontally by a predetermined angle, and an amplitude monopulse radar can be realized well. Further, it is possible to realize a phase monopulse radar device using the antenna device having this configuration, and it is also possible to realize a monopulse radar device that detects the direction of the target from both the amplitude difference and the phase difference of the received signals. .

Further, in the present embodiment, the transmission radio wave is configured to be transmitted using the transmission antenna 6 dedicated to transmission. However, as shown in FIG. 3, the transmission radio wave output from the directional coupler 4 is generated. Via the circulator 32, the power feeding terminal A (or B) of one of the transmitting and receiving antennas 30 configured similarly to the receiving antenna 10 of the above embodiment.
The received signal output from the power supply terminal A may be input to the RF terminal of the mixer circuit 14a via the circulator 32.

By doing so, it becomes possible to transmit the transmission radio wave by using the array antenna formed by the odd-numbered columns of antenna elements 24 shown in FIG. 1, and the transmission antenna 6 is separately provided. However, an obstacle detection radar having the same function as that of the above-described embodiment can be configured, and the configuration of this radar device can be further simplified and realized at low cost.

The obstacle detecting radar shown in FIG. 3 has the plane shown in FIG. 1 by removing the transmitting antenna 6 from the obstacle detecting radar of the above-mentioned embodiment shown in FIG. 2 and providing a circulator 32 instead. The array antenna is operated as the transmission / reception antenna 30, and other configurations are exactly the same as those in the above-described embodiment,
The other parts are denoted by the same reference numerals and the description thereof is omitted.

Furthermore, in the above embodiment, as the receiving antenna 10, the antenna elements 24 are arranged in a matrix of m rows and 2 · m columns, and all the antenna elements are arranged in odd-numbered column antenna elements and even-numbered column antenna elements. Divided into groups and
Each group is provided with a plurality of series feed lines that feed series to the antenna elements of each column and a parallel feed line that feeds parallel to each column, and feed power from two feed terminals A and B respectively. Two possible array antennas 10
All the antenna element rows of A and 10B mesh with each other alternately, and the distance D between the array antennas 10A and 10B is half the distance between the antenna element rows in the array antennas 10A and 10B of each system. The obstacle detection radar using the schematic diagrams a1 and a2 shown in FIG. 4) has been described. However, in the planar array antenna of the present invention, all the antenna element rows of the two array antennas 10A and 10B are alternately arranged. You don't have to be in mesh.

That is, the planar array antenna of the present invention is
As in the receiving antenna 10 'shown in FIGS. 4 (b1) and 4 (b2), a part of the antenna element array of the two-system array antennas 10A' and 10B 'capable of feeding from the two feeding terminals A and B, respectively. (6 rows out of all 8 rows in the figure) mesh with each other alternately, and between the left and right antenna element rows (left in the figure
The antenna element rows of the other array antenna may not be arranged in the first and second rows and between the second and third rows on the right side.

In this case, although the aperture surface of the entire planar array antenna becomes large, the distance D between the array antennas 10A and 10B should be increased as compared with the case where all the antenna element rows are alternately meshed. You can Therefore, according to the present invention, by arbitrarily setting the number of antenna element rows in which the two-system array antennas are alternately meshed, the interval between the two-system array antennas can be arbitrarily set, and the phase monopulse radar When used as an antenna device for the device, there is also an effect that the antenna interval can be optimally set according to the required target detection characteristics.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of a receiving antenna (planar array antenna) according to an embodiment.

FIG. 2 is a block diagram showing a configuration of an obstacle detection radar according to an embodiment.

FIG. 3 is a block diagram showing a configuration of an obstacle detection radar that uses the planar array antenna shown in FIG. 1 as a transmitting / receiving antenna.

4A and 4B are explanatory diagrams schematically showing the planar array antenna shown in FIG. 1 and a modification thereof, respectively.

FIG. 5 is a set-up diagram illustrating a principle of detecting a target in a phase monopulse radar device.

FIG. 6 is an explanatory diagram illustrating a change in reception characteristics caused by the size of an antenna interval in the phase monopulse radar device.

[Explanation of symbols]

2 ... Voltage-controlled oscillator 4 ... Directional coupler 6 ... Transmission antenna 10 ... Reception antenna 12 ... Power distributor 14a,
14b ... Mixer circuit 16a, 16b ... IF circuit 18 ... Alarm device 20
... ECU 22 ... first dielectric substrate 24 ... antenna element 2
6 ... Serial feeding line 26a, 26b ... Parallel feeding line 27 ... Second dielectric substrate 28 ... Ground conductor A, B ... Feeding terminal 30 ... Transmitting / receiving antenna 32 ... Circulator

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication H01Q 21/28 H01Q 25/02 25/02 G01S 13/93 Z

Claims (7)

[Claims] 1. An antenna element arranged in a matrix, a series feed line provided for each column of the antenna element, and parallel feed for each column of the antenna element via the series feed line. A parallel feed line and two array antennas each including the parallel feed line are provided, and in the array antennas of the two lines, all or some of the array of antenna elements formed by the series feed line are alternately arranged at substantially equal intervals. A planar array antenna characterized in that the array antennas are arranged on the same plane so as to mesh with each other. 2. A pair of parallel feed lines respectively constituting the two-system array antennas, wherein at least one of the parallel feed lines has a non-uniform line length from a feed terminal to each antenna element row, and the two feed lines are arranged. 2. The planar array antenna according to claim 1, wherein the center directions of the radiation beams of the array antenna are shifted from each other by a predetermined angle. 3. The planar array antenna according to claim 1, wherein each antenna element is formed by a planar patch. 4. The planar array antenna according to claim 3, wherein each of the antenna elements is formed of a half-wavelength resonator that is long in the column direction. 5. A monopulse radar device equipped with the planar array antenna according to claim 1, further comprising: signal generating means for generating a transmission signal and causing the transmission antenna to transmit the signal. The reflected radio wave transmitted from the antenna is reflected by the external target, which is reflected by the planar array antenna, and based on the received signal obtained from the feed terminals of the parallel feed lines of the planar array antenna, the target signal is received. A monopulse radar device comprising: a target detection unit that detects the direction of the. 6. A circulator connected to a feed terminal of one parallel feed line of the planar array antenna for inputting a transmission signal from the signal generating means to the feed terminal and taking out a received signal from the feed terminal. The monopulse radar device according to claim 5, wherein an array antenna provided on the side to which the circulator is connected is used for both transmission and reception. 7. The signal generating means generates a predetermined continuous wave as a transmission signal, and the target detecting means homodyne-detects the received signal, and detects the direction and distance of the target from the detected signal. And a velocity are detected, The monopulse radar device according to claim 5 or 6.