JP2000065912A - Array antenna and its using method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate installation and maintenance of line-side facilities, and to reduce its size, weight, and cost. SOLUTION: Radiating elements belonging to an upper left quarter part out of those used as line-side antennas are connected to a position judging circuit connecting terminal 30-1, radiating elements belonging to upper right quarter to a position judging circuit connecting terminal 30-2, radiating elements belonging to lower left quarter part to a position judging circuit connecting terminal 30-3, and radiating elements belonging to lower right quarter part to a position judging circuit connecting terminal 30-4 respectively. A sum beam and a difference beam are formed by rat races 32-X and 32-Y in respect of X-axis and Y-axis respectively, and the phases of the sum beam and the difference beam are compared by phase detectors 34-X and 34-Y.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an array antenna having a plurality of radiating elements and a method of using the same.

[0002]

[Prior art and its problems] ETC (Electronic Toll)
Collection) system is a system that automatically imposes a toll on vehicles using a toll road, and uses wireless communication between a wireless device provided on the roadside and a wireless device mounted on a vehicle. For example, as shown in FIG. 7, a bridge structure 10 is provided across a road, and a roadside antenna 12 connected to a roadside radio (not shown) is provided on the bridge structure 10.
Is provided. On the other hand, the vehicle-mounted radio 16 is mounted on the vehicle 14. The area indicated by 100 in the figure is an area where wireless communication can be performed between the roadside wireless device and the on-board wireless device 16, that is, a communication area by the roadside antenna 12.
In the example of this figure, a road surface having a length of about 5 m and a width of about 3 m is covered. Further, for example, an optical vehicle detector 18 is provided near the front edge and the rear edge of the communication area 100,
These vehicle detectors 18 can detect entry of the vehicle into the communication area 100 and exit of the vehicle from the communication area 100.

When the vehicle 14 enters the communication area 100,
A predetermined communication procedure such that the roadside apparatus receives a signal from the vehicle-mounted wireless apparatus 16 by the roadside antenna 12 is executed. When this communication procedure is executed, the vehicle 14 (strictly, a user or an owner thereof) is charged in a form such as a settlement by communication via a communication system (not shown). On the other hand, the vehicle detector 18 detects entry and exit of the vehicle. Therefore, by comparing the result of the communication using the roadside antenna 12 with the result of the detection using the vehicle detector 18, the vehicle 14 for which the wireless automatic charging by the ETC system has been performed and the vehicle 14 for which the automatic charging has not been performed ( For example, it is possible to discriminate and detect the vehicle (vehicle not equipped with the vehicle-mounted radio 16). This discrimination processing (and communication with the outside)
Is performed by a processing device (not shown). This processing device may be provided on the roadside, or may be provided at a remote place via a communication line.

[0004] The roadside antenna 12 can be realized by, for example, a flat microstrip array antenna as shown in FIG. The array antenna shown in this figure has a configuration in which 32 radiating elements are arranged in a matrix of 4 rows × 8 columns. Each radiating element includes a patch 20 which is a circular conductor formed on the surface of the array antenna, and a through hole 22 provided corresponding to each patch. The through hole 22 is an element feed point for the radiating element, and a line 26 for connecting each element feed point 22 to the feed end 24 is arranged and formed on the back surface of the array antenna. The feeding end 24 is connected to the roadside wireless device (particularly, a high-frequency circuit portion thereof) by the roadside antenna 12.
Is a part where a terminal (connector) for connecting is connected or arranged. Normally, as shown in this figure, the line 26 and the power distribution unit 28, which is a branch thereof, are arranged and formed so that the reception outputs of the respective radiating elements are combined (added) in phase, and the directivity of each radiating element is determined. Is synthesized.

By the way, as described above, the roadside antenna 1
By comparing the result of the communication using the vehicle 2 with the result of the detection using the vehicle detector 18, a vehicle 14 (hereinafter, referred to as an “ETC vehicle”) for which the automatic charging by the ETC system has been performed, A vehicle that has not been controlled (hereinafter, referred to as a “non-ETC vehicle”) can be determined and detected. However, when the ETC vehicle and the non-ETC vehicle enter the communication area 100 simultaneously or in sequence, the vehicle detector 1
It is impossible with the above-described system to identify which of the plurality of vehicles whose entry has been detected by E.8 is an ETC vehicle and which is a non-ETC vehicle. As a device for solving this problem, Mituno et al.
We have proposed a configuration in which an azimuth finder is further arranged on 0,
Nishimura et al. Have proposed a configuration in which a narrow beam antenna is further arranged on the bridge structure 10.

Mitsuno et al .: "Method of measuring arrival angle of radio wave and communication vehicle discrimination system", Atsushi Mitsuno and Yoshihiko Kuwahara, NEC Technical Report,
Vol. 50, no. 7, pages 147 to 155, Nishimura et al .: "Position estimation of communication vehicle in automatic charging system using reception-only antenna", IEICE General Conference, 1998, SB-1-4, pages 689 to 689. 690 pages.

[0007] The proposals by Mitsuno et al. And the proposal by Nishimura et al.
Apart from this, since a device for azimuth detection is provided on the bridge structure 10, it is difficult to install and maintain it, and there is a problem that the shape, weight, and price increase.

[0008]

SUMMARY OF THE INVENTION One of the objects of the present invention is to eliminate the need to provide a device for azimuth detection separately from a roadside antenna, to achieve easy installation and maintenance of roadside facilities and to reduce the shape, weight and price. Is to do.

In order to achieve such an object, in the array antenna according to the present invention, first, the connection relation between a plurality of radiating elements is improved. That is, in the prior art shown in FIG. 8, all the radiating elements are connected by lines and their reception outputs are in-phase combined. However, in the present invention, a plurality of radiating elements are divided into a plurality of groups according to their arrangement. For each group, the radiating elements are connected by a line or the like so that the received outputs of the radiating elements are combined in phase.

In the present invention, secondly, the combined reception output from each group is subjected to in-phase and out-of-phase combination using a device such as a rat race, so that the difference between the combined reception output relating to the sum beam (in-phase combination) is obtained. A combined reception output related to the beam (negative-phase combining) is generated. By comparing the phase of the combined reception output of the sum beam and the combined reception output of the difference beam, the position of the signal source (in the system of FIG. 7, the ETC vehicle that has entered the communication area and has communicated). Or, the azimuth can be detected.

As described above, according to the present invention, the connection relationship between the radiating elements is modified, and the sum / difference beam is formed using a rat race or the like so that the position of the signal source can be determined. Is integrated into the array antenna (roadside antenna). Therefore, it is not necessary to provide a direction detection device separately from the roadside antenna.
Weight and price reductions are achieved.

The present invention can be applied to an array antenna having a configuration in which radiating elements are arranged one-dimensionally and to an array antenna having a two-dimensional arrangement. That is, in the array antenna according to the first configuration of the present invention, (1) a plurality of radiating elements arranged along a predetermined axis, and (2) a sum beam is formed on a plane parallel to the axis. Means for in-phase combining the reception outputs of some of the plurality of radiating elements and the reception outputs of some of the other radiating elements; and (3) a difference beam is formed in a plane parallel to the axis. Means for combining the reception outputs of some of the plurality of radiating elements and the reception outputs of some of the other radiating elements in opposite phases; and (4) a signal source based on the signal obtained by the in-phase combining. Means for generating an output signal indicating the received signal from the controller, and (5) comparing the phase of the signal obtained by the in-phase synthesis with the signal obtained by the anti-phase synthesis to determine the position of the signal source on the axis. Means for generating a position determination signal to indicate And it features. The array antenna according to the second configuration of the present invention includes: (1) a plurality of radiating elements arranged in a matrix along a first axis and a second axis intersecting the first axis;
Means for in-phase combining the received output of some of the radiating elements and the received output of some of the other radiating elements so that a sum beam is formed in a plane parallel to the first axis; (3) The reception outputs of some of the plurality of radiating elements and the reception outputs of some of the other radiating elements are out of phase so that a difference beam is formed on a plane parallel to the first axis. (4) receiving output of some of the plurality of radiating elements and receiving output of some of the other radiating elements so that a sum beam is formed in a plane parallel to the second axis. And (5) receiving outputs of some of the plurality of radiating elements and the other of the plurality of radiating elements so that a difference beam is formed in a plane parallel to the second axis. (6) means for synthesizing the received output in reverse phase; Means for generating an output signal indicating the received signal from the signal source by synthesizing the signals obtained by the synthesizing with each other, and (7) a signal obtained by the in-phase synthesizing with respect to each of the first and second axes. Means for generating a position determination signal indicating the position of the signal source in the plane defined by the first and second axes by comparing the phase of the signal with the signal obtained by the inverse phase synthesis. It is characterized by.

Further, by using the rat race, a circuit for forming a sum beam (in-phase combining) and a circuit for forming a difference beam (out-of-phase combining) can be downsized. The array antenna according to the third configuration of the present invention includes: (1) a plurality of radiating elements arranged in a matrix in up, down, left, and right directions;
And a second input terminal, and a first and a second output terminal, from the first output terminal a signal obtained by in-phase combining a signal input from the first input terminal and a signal input from the second input terminal, A first and a second rat race respectively outputting a signal subjected to the reverse phase synthesis from a second output terminal; and (3) a signal outputted from a first output terminal of the first rat race and a first signal of the second rat race. Means for generating an output signal indicating a received signal from the signal source by combining the signal output from the output end, and (4) a means provided for each of the first and second rat races, First and second phases for generating a position determination signal indicating a two-dimensional position of a signal source by comparing phases of a signal output from a first output terminal and a signal output from a second output terminal of the rat race. A plurality of radiating elements, comprising: The radiating element disposed in the upper half is disposed at the first input end of the first rat race, the radiating element disposed in the lower half is disposed at the second input end of the first rat race, and is disposed on the left half. The radiating element is connected to the first input terminal of the second rat race, and the radiating element disposed on the right half is connected to the second input terminal of the second rat race.

A typical application of the array antenna according to the present invention is for communication with a signal source in an ETC system or the like and detection of the direction of the signal source. The method for using an array antenna according to the fourth configuration of the present invention is such that the array antenna of the present invention is installed on the roadside such that a predetermined section on the road is the communication area, and the array antenna is used to move within the predetermined section. A signal wirelessly transmitted from a body is received to generate the output signal and the position determination signal.
The method for using an array antenna according to the fifth configuration of the present invention includes:
Further, by comparing the output of a vehicle detector that detects the entry of the vehicle into the communication area with a position determination signal from the array antenna, detecting a vehicle that is not performing communication via the array antenna. It is characterized by.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. Note that the same or common components as those of the related art shown in FIGS. 7 and 8 are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 shows the configuration of an array antenna according to an embodiment of the present invention, particularly the arrangement of the line 26 and the power distribution unit 28 on the back surface thereof. In this embodiment, a radiating element having the same structure as that of the prior art shown in FIG. 8 is used, and the arrangement of the patches 20 on the surface is also the same. As is apparent from FIG.
The two radiating elements are divided into four groups, each containing eight radiating elements. That is, the power supply terminal 24 in the prior art
, Four connection terminals 30-1 to 30-4
Are provided, and each of the position determination circuit connection terminals 30-1 to 30-3
Eight radiating elements are connected to 0-4, respectively. In particular, the position determination circuit connection end 30-1 is located at the upper left in the figure, 2 rows × 4 columns = 8 radiating elements, and the position determination circuit connection end 30-2 is located at the upper right, 2 rows × 4 columns. = 8 radiating elements, the position judging circuit connection end 30-3 is 2 rows × 4 columns = 8 radiating elements located at the lower left in the figure, and the position judging circuit connection end 30-4 is at the lower right in the figure. Each of the radiating elements is connected to 8 rows × 4 columns = 8 radiating elements. Each of the position determination circuit connection terminals 30-1 to 30-4 is connected to each of the eight connected terminals.
A signal appears in which the received outputs of the radiating elements are combined in phase.

Position determination circuit connection terminals 30-1 to 30-4
Are connected to the power supply terminal 24 and, consequently, to the roadside device via the position determination circuit shown in FIG. This position determination circuit has a rat race 32-X and a phase detector 34-X corresponding to the X axis and a rat race 32-Y and a phase detector 34-Y corresponding to the Y axis in FIG. . Rat races 32-X and 32-Y are annular (or arc-shaped)
And the terminals 1 to 4 drawn out from this line. The terminals 1 to 4 are arranged at an interval d as shown in FIG. When a signal having a wavelength λ such that d = λ / 4 is input from the terminals 1 and 3, a signal obtained by in-phase combining these signals appears at the terminal 2. This is terminal 1
This is because the difference between the line length between the terminals 2 and the line length between the terminals 3 and 2 is an integral multiple of the wavelength? Also, a signal subjected to the reverse phase synthesis appears at the terminal 4. This is because the difference between the line length between the terminal 1 and the terminal 4 and the line length between the terminal 3 and the terminal 4 is an integral multiple of the wavelength λ + λ / 2 regardless of whether the line is short or short. In the present embodiment, the rat races 32-X and 32-Y are designed so that the in-phase synthesis and the out-of-phase synthesis are performed at the wavelength used for wireless transmission from the vehicle 14.

In the circuit shown in FIG. 2, the signal appearing at the position judging circuit connection terminal 30-1 and the signal appearing at the position judging circuit connection terminal 30-1
-2 is synthesized in-phase with the signal appearing at -2.
A signal input to terminal 1 of X and appearing at position determination circuit connection terminal 30-3 and position determination circuit connection terminal 30-4
The line 36 is formed so that the signal appearing in the line 3 is in-phase synthesized and input to the terminal 3 of the rat race 32-X.
Therefore, the signal input to the terminal 1 of the rat race 32-X is a reception signal by 2 rows × 8 columns = 16 radiating elements located in the upper half in FIG. 1, and the signal input to the terminal 3 is , 2 rows × 8 columns = 16 radiating elements located in the lower half of FIG. As a result, Rat Race 3
At the 2-X terminal 2, a signal (see FIG. 4) related to the sum beam in a plane including the X axis in FIG. 1 appears. At the terminal 4 of the rat race 32-X, a signal (see FIG. 4) relating to the difference beam in a plane including the X axis in FIG. 1 appears.

In the circuit shown in FIG. 2, the signal appearing at the position judging circuit connection end 30-1 and the signal appearing at the position judging circuit connection end 30-3 are further in-phase synthesized to form a terminal of the rat race 32-Y. 1 and a signal appearing at the position determination circuit connection terminal 30-2 and the position determination circuit connection terminal 3
The signals appearing in 0-4 are synthesized in phase with the rat race 32
The line 36 is formed so as to be input to the −Y terminal 3. Therefore, the signal input to the terminal 1 of the rat race 32-Y is 4 rows × 4 columns = 16 located in the left half in FIG.
The signals input to the terminal 3 are received signals by 4 radiating elements = 4 rows × 4 columns = 16 radiating elements located in the right half of FIG. As a result, a signal (see FIG. 4) relating to the sum beam in a plane including the Y axis in FIG. 1 appears at the terminal 2 of the rat race 32-Y. The terminal 4 of the rat race 32-Y has a signal related to a difference beam in a plane including the Y axis in FIG. 1 (see FIG. 4).
Appears.

In the circuit shown in FIG. 2, terminal 2 of rat race 32-X and terminal 2 of rat race 32-Y
Are connected to the power supply terminal 24. At the power supply terminal 24, a signal appears in which the reception outputs of the 32 radiating elements in FIG. This signal is supplied to the roadside apparatus. The terminals 2 and 4 of the rat race 32-X are connected to the phase detector 34-X, and the terminals 2 and 4 of the rat race 32-Y are connected to the phase detector 34-Y. The phase detector 34-X compares the phase of the signal (X axis, sum beam) output from the terminal 2 of the rat race 32-X with the phase of the signal (X axis, difference beam) output from the terminal 4 of the rat race 32-X. , X-axis, a signal indicating whether the signal has come from above or below is generated. The phase detector 34-Y is
The signal output from the terminal 2 of the rat race 32-Y (Y
By comparing the phase of the signal (Y-axis, difference beam) with the signal (Y-axis, difference beam) output from the terminal 4 with respect to the Y-axis,
A signal indicating whether the signal has arrived from the left or right is generated. By these signals generated by the phase detectors 34-X and 34-Y, the signals are 2 (up and down) × 2 (left and right) =
It is possible to know which of the four directions has arrived. In a roadside radio (not shown) or a processing device connected thereto, the signal from the vehicle detector 18 is compared with the signals from the phase detectors 34-X and 34-Y, so that they are simultaneously or successively arranged. It identifies which of the plurality of vehicles that have entered the communication area 100 is the ETC vehicle 14 and which is a non-ETC vehicle.

As described above, in the present embodiment, the connection relationship between the radiating elements is changed, and a so-called phase monopulse signal is generated on the X axis and the Y axis by the rat races 32-X and 32-Y. ET
The detection function for the direction of the C vehicle 14 is
To simplify installation and maintenance, downsize roadside facilities,
Weight reduction and price reduction are achieved. That is, it is not necessary to separately provide a device for direction detection, and it is also possible to reduce the mechanical strength of the crosslinked structure 10, that is, to form the crosslinked structure 10 with a thin and light material or an inexpensive material / structure. Become.

FIGS. 5 and 6 show another embodiment of the present invention. In this embodiment, the position determination circuit connection terminal 30-4 in the above-described embodiment is omitted, and the lower 16 radiating elements in FIG. It is connected to the circuit connection end 30-3. The terminal 1 of the rat race 32-X has connection terminals 30-1 and 30-2 for the position determination circuit, the terminal 3 has the connection terminal 30-3 of the position determination circuit, and the terminal 1 of the rat race 32-Y has the terminal. The position determination circuit connection terminal 30-1 is connected to the terminal 3 and the position determination circuit connection terminal 30-2 is connected to the terminal 3. With such a configuration, it is possible to know from which of the two (upper and lower) × 2 (left and right) = four directions the signal has arrived, as in the embodiment shown in FIGS. Further, the circuit scale becomes smaller.

In the above description, as a preferred embodiment of the present invention, radiating elements are arranged along the X axis and the Y axis orthogonal thereto, and the direction of arrival of a signal is determined for both the X axis and the Y axis. The form was mentioned. However, the present invention is also applicable to a configuration in which radiating elements are arranged along two axes that are not orthogonal (non-parallel). The present invention can also be realized as a configuration in which the direction of arrival of a signal is determined for only one axis. There is no particular limitation on the type, structure, number, and the like of the radiating elements.

Further, in the system shown in FIG. 7, one roadside antenna 12 is provided on the bridge structure 10, and the roadside antenna 12 covers the road. The present invention can also be implemented in a system in which a plurality of roadside antennas 12 are provided, and the roadside antennas 12 share the roadside. The roadside antenna 12 does not need to be disposed on the bridge structure 10, and may be disposed on the top of another type of structure, for example, an inverted L-shaped structure. The operating principle, structure, arrangement, and the like of the vehicle detector 10 are not particularly limited.

[Brief description of the drawings]

FIG. 1 is a back view of an array antenna showing an element connection relationship in a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a position determination circuit according to the embodiment.

FIG. 3 is a diagram showing a configuration of a rat race.

FIG. 4 illustrates a sum / difference beam.

FIG. 5 is a rear view of an array antenna showing a connection relation of elements according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a position determination circuit in this embodiment.

FIGS. 7A and 7B are diagrams showing an outline of the ETC system. FIG. 7A is a side view (partial cross section), and FIG. 7B is a top view.

8A and 8B are diagrams illustrating a configuration of an array antenna according to the related art, in which FIG. 8A illustrates a front surface, and FIG. 8B illustrates a rear surface.

[Explanation of symbols]

12 roadside antenna, 14 ETC vehicle, 18 vehicle detector, 20 patches, 22 element feeding point (through hole), 24 feeding end, 30-1 to 30-4 position determination circuit connection end, 32-X, 32-Y rat Race, 34-
X, 34-Y phase detector, 100 communication area.

Claims (5)

[Claims] 1. A plurality of radiating elements arranged along a predetermined axis, and reception outputs of some of the plurality of radiating elements such that a sum beam is formed in a plane parallel to the axis. Means for in-phase combining the reception outputs of the other radiating elements, and the reception outputs of some of the plurality of radiating elements and the other so that a difference beam is formed in a plane parallel to the axis. Means for synthesizing the received output of some of the radiating elements in antiphase, means for generating an output signal indicating a received signal from the signal source based on the signal obtained by in-phase synthesis, and a signal obtained by in-phase synthesis. Means for generating a position determination signal indicating the position of the signal source on the axis by comparing the phase of the signal obtained by the reverse phase synthesis. 2. A plurality of radiating elements arranged in a matrix along a first axis and a second axis intersecting the first axis, wherein a sum beam is formed in a plane parallel to the first axis. Means for in-phase combining the reception outputs of some of the plurality of radiating elements and the reception outputs of some of the other radiating elements, wherein a difference beam is formed in a plane parallel to the first axis. Means for combining the reception outputs of some of the radiating elements and the reception outputs of the other radiating elements out of phase with each other; and forming a sum beam in a plane parallel to the second axis. Means for in-phase combining the reception outputs of some of the plurality of radiating elements and the reception outputs of some of the other radiating elements, such that a difference beam is formed in a plane parallel to the second axis. The reception output of some of the plurality of radiating elements and the other Means for synthesizing the reception output of the radiation element in opposite phase, and synthesizing the signals obtained by the in-phase synthesis for each of the first and second axes with each other to generate an output signal indicating the reception signal from the signal source. Means for performing the phase comparison between the signal obtained by the in-phase synthesis and the signal obtained by the antiphase synthesis with respect to each of the first and second axes, thereby defining the first and second axes. Means for generating a position determination signal indicating the position of the signal source in the plane. 3. A signal input from a first input terminal having a plurality of radiating elements arranged in a matrix in up, down, left, and right directions, and first and second input terminals and first and second output terminals, respectively. A first and a second rat race for outputting, from a first output terminal, a signal obtained by in-phase combining a signal inputted from the second input terminal and a signal inputted from the second input terminal; Means for combining the signal output from the first output of the rat race and the signal output from the first output of the second rat race to generate an output signal indicative of a received signal from the signal source; The signal output from the first output terminal and the signal output from the second output terminal of the corresponding rat race are provided for each of the first and second rat races. Position determination signal indicating two-dimensional position First and second phase detectors for generating a signal, wherein a radiating element disposed in an upper half of the plurality of radiating elements is disposed in a first input end of the first rat race and in a lower half. Radiating element is the second in the first rat race
At the input end, the radiating element arranged at the left half is connected to the first input end of the second rat race, and the radiating element arranged at the right half is connected to the second input end of the second rat race. An array antenna. 4. The array antenna according to claim 1, wherein a predetermined section on the road is a communication area thereof, and the array antenna is installed on the road side, and the array antenna transmits a radio signal from a moving object existing in the predetermined section. A method for receiving a signal and generating said output signal and said position determination signal. 5. The method according to claim 4, wherein an output of a vehicle detector that detects the entry of the vehicle into the communication area is collated with a position determination signal from the array antenna, so that the array antenna is used. Detecting a vehicle that is not performing communication via the communication device.