JPH0693027B2 - Radar system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a radar system capable of detecting a target other than a sight distance or a mountain shadow, which cannot be detected by a conventional radar, by using a radar repeater. Is.

[Conventional technology]

In the conventional radar system, another independent radar is installed at a predetermined position and data is transmitted to a base station of information of this radar as a method for covering a dead area outside the sight distance or a mountain shadow. The method is adopted.

For example, as shown in Fig. 8, when the A radar is installed, the detection coverage area is the area shown by the broken line in the figure, but there are high mountains at points B, C, D, E in the coverage area. Then, a dead zone usually appears behind the points B, C, D, and E as indicated by the diagonal lines. Therefore, a method is adopted in which another independent radar is installed at each of the points B, C, D, and E, and the information is transmitted to the base station as data.

[Problems to be solved by the invention]

However, in the conventional method as described above, the cost is increased, and frequency allocation for arranging a large number of radars in close proximity becomes a problem. In the example of FIG. 8 described above, four radars having the same configuration as the base station are required, and it is necessary to secure four frequency bands different in frequency from the base station radar.

Furthermore, when the conventional method is examined, as shown in FIG. 8, the dead zone is usually rare in the entire circumference centered on B, C, D, and E, and the points A to B, C, D, and E In many cases, only the shadowed areas of the mountainous areas that are present in the dead zones. In this case,
As a relay radar installed at each point of B, C, D, E, B, C,
It is sufficient to install a radar that can detect only the fan-shaped part that occurs behind each point B, C, D, E when viewed from the point A where the radar is installed, as shown in FIG. It is uneconomical to install radars that can search all around C, D, E points. As described above, the drawbacks of the conventional method are summarized as follows.

A frequency band corresponding to the number of radars is required, which is a problem in radio administration.

At the point where the dead zones of B, C, D and E start, it is necessary to detect only a limited fan-shaped zone, while radars that can detect the omnidirectional direction should not be installed at each point of B, C, D and E. It is economical.

Further, since the radar capable of detecting the entire circumference as described above is configured to rotate the antenna all the way, the scale is large and uneconomical.

Further, such a radar is inconvenient to move, and is inconvenient to transport and install at a high place in a mountainous area.

The present invention has been made in view of the above points, and an object thereof is to obtain an economical radar system that is excellent in portability and mobility.

[Means for solving problems]

Therefore, the present invention incorporates the concept of a repeater in a communication device into the field of radar, and as can be seen from the above description, as a radar repeater, it is possible to search only a limited fan-shaped area, not the entire circumference, and it is portable. The purpose of this study was to find that a device with excellent mobility is desirable. If only a limited fan-shaped area is used, the frequency sweep electronic scanning antenna can be used to scan the beam easily without the need for an antenna rotation drive mechanism. Therefore, the portability and mobility are excellent. A radar repeater can be realized.

In the radar system according to the present invention, a main body radar capable of sweeping the frequency of the beam is installed in a base station, and a frequency beam scanning antenna capable of beam scanning by frequency sweep is provided at a required position within the detection range of the main body radar. Installed a radar repeater, and scanning the detection range by the beam of the main body radar, while the beam of the main body radar is directed in the direction of the radar repeater, the beam direction of the main body radar is fixed. , The beam frequency sweep of the main body radar is performed, the beam scanning of the antenna of the radar repeater is performed, and the detection range of the main body radar is expanded by the radar repeater.

[Action]

In the present invention, a radar repeater having a frequency beam scanning antenna capable of beam scanning by frequency sweep is arranged at a required position within the detection range of the main body radar capable of sweeping the frequency of the beam to detect the main body radar. Since the range is expanded by the radar repeater, a small antenna that can detect only a limited fan-shaped area can be used for the radar repeater instead of a large antenna that can detect all directions. The machine can be easily transported and installed. In addition, beam scanning at the radar repeater can be performed by frequency sweeping of the beam of the main body radar, so even if multiple radar repeaters are installed, the frequency band to be used is given to the main body radar of the base station. Only one frequency band is required, and there is no problem of frequency allocation, which is advantageous in radio administration.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an arrangement example of a radar repeater according to an embodiment of the present invention, in which a general radar is installed at a base station at point A, and a dead zone begins at a peak, B, C, D, E. A radar repeater is installed at each point.

FIG. 2 shows a block diagram of each radar repeater. In the figure, 1 is a relay receiving antenna for receiving a signal from a base station (main body radar), 2 is a relay receiver, 3 is a power amplifier, 4 is a transmission / reception switch, and 5 is a radar antenna.
The beam can be scanned by frequency sweep. Reference numeral 6 is a radar receiver for receiving and processing a signal returned from the radar antenna 5 and reflected back from the target, 7 is a relay transmitter for transmitting the signal from the target to the main body radar, and 8 is a relay It is a transmitting antenna.

Next, the operation will be described.

The radar installed at the point A scans the beam all around, but when the beam is directed in the B, C, D, and E directions, the beam is stopped for a certain period of time and the frequency is swept. When pointing in a direction other than points B, C, D, and E, the beam is rotated to operate as a normal radar. And within the range of the broken line (excluding the shaded part)
Detect the goal of.

When the beam is directed in the directions of points B, C, D and E, the radar of point A irradiates the beam to the radar repeater for a certain period. As a result, the beam irradiates the relay receiving antenna 1 of the radar repeater, so that the transmission signal of the base station radar is transmitted to the relay receiver 2.
Is amplified by the power amplifier 3 and is radiated into the air from the radar antenna 5 via the transmission / reception switch 4.

The radar antenna 5 is composed of an array antenna as shown in FIG. 3, and a transmission line called a meandering feed 52, which has a linearly changing phase with respect to a frequency change, is used between the array elements 51. ing. Therefore, when the frequency of the signal from the base station radar changes, the same operation as the phased array antenna is performed and the beam is scanned.

The radio waves radiated from the radar antenna 5 are beam-scanned within an area corresponding to the shaded area in FIG. Then, the signal returned from the target and returned is received again by the radar antenna 5 and is sent back to the base station radar through the transmission / reception switch 4, the radar receiver 6, the relay transmitter 7, and the relay transmission antenna 8.

The base station radar receives this signal and displays it on the indicator. At this time, however, it is necessary to display the points B, C, D, and E in FIG. ), When the beam of the base station radar is directed to each of B, C, D, and E signals, the bright line sweep of the fan-shaped area is swept from the points corresponding to B, C, D, and E on the indicator. I do. That is, in the enlarged view of FIG. 4 (b), the bright line starts from point A and reaches point B, and the direction is changed from point B to the direction in which the antenna of the radar repeater is pointing, and The sweep is repeated to the point A after returning to point A.

5 (a) and 5 (b) are examples of sweep waveforms when target detection in the B direction is performed. FIG. 5 (a) shows distance direction bright line sweep waveforms, and FIG. 5 (b) shows azimuth direction bright line sweep waveforms. Indicates. C, D,
It can be considered that the case of E point is similar to this. In the azimuth direction bright line sweep waveform, the section corresponding to T _{A to} T _A + T _B is a sweep with B, C, D, and E as the origins. Figure 6 (a)
(B) is an enlargement of the time axis of the sweep waveform of FIGS. 5 (a) and (b). In these figures, θ _A is the azimuth angle of point _B , θ _B is the fan-shaped scan angle with point B as the origin, and θ _B ′ is A
Sector scan angle with the origin point, R _A is the distance from point A to point B, R _B is sector scanning distance from point B, T _A is represented by 2R _A / C,
The time (C is the speed of light) that the radio wave makes a round trip to R _A , T _B is represented by 2R _B / C, the time that the radio wave makes a round trip to R _B , and T _R is the radar repetition period.

The sweep described above has more complicated movement than the conventional radar sweep, but can be realized by an XY deflection type indicator.

As described above, in this embodiment, since the radar repeater having the frequency sweep electronic scanning antenna is arranged at the mountain top where the dead zone of the main body radar of the base station starts, the radar repeater can detect the omnidirectional direction. Instead of a large antenna, a small antenna that can detect only a limited fan-shaped area can be used. Therefore, the repeater can be made compact and lightweight, and its maneuverability and portability are improved. Also, by simply sweeping the frequency of the beam from the main unit radar, the beam of radio waves re-radiated from the repeater can be scanned, and therefore the frequency band need only be one wave given to the main unit radar of the base station, The problem of frequency allocation can also be solved.

In the above embodiment, the dead zone countermeasures within the base station radar detection station have been described, but this method is naturally used as means for enabling detection outside the sight distance of the base station radar and beyond the radar performance limit. Can also be applied.

FIG. 7 is its application, can not be detected only up to R _A is a base station radar, F, G, H, ..., at a radar repeater to each point of M, further R _M increase the maximum detection distance It is an example to make.

〔The invention's effect〕

As described above, according to the radar system of the present invention, the base station is provided with the main body radar capable of sweeping the frequency of the beam, and the beam is swept by the frequency sweep to a predetermined position within the detection range of the main body radar. By installing a radar repeater with a frequency beam scanning antenna that can be scanned and extending the detection range of the main body radar by the radar repeater, the radar repeater can be made compact and lightweight, and its maneuverability,
The portability can be improved. Further, since the beam of the antenna of the repeater can be electronically scanned by the radio wave of the radar of the base station, even if a plurality of repeaters are installed, the frequency band need be only one wave given to the base station.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the radar system of the present invention, and FIG.
FIG. 4 is a block diagram showing the configuration of the radar repeater, FIG. 3 is a principle diagram of a radar antenna of the radar repeater, and FIG.
FIG. 4A is a diagram showing a display state of an indicator in a radar system according to an embodiment of the present invention, FIG. 4B is a partially enlarged view thereof, and FIGS. 5A and 5B are distance directions, FIG. 6 (a) and FIG. 6 (b) show the azimuth line sweep waveform, respectively.
FIGS. 7A and 7B are enlarged views of the time axis, FIG. 7 is a view showing another embodiment of the present invention, and FIG. 8 is a view showing a conventional radar system. 1 ... Relay receiving antenna, 2 ... Relay receiver, 3 ...
… Power amplifier, 4 …… Transmission / reception switch, 5 …… Radar antenna, 6 …… Radar receiver, 7 …… Relay transmitter, 8 ・ ・ ・
… A relay transmitting antenna.

Claims (2)

[Claims] 1. A base station is provided with a main body radar having a structure capable of sweeping the frequency of the beam, and a frequency beam scanning antenna capable of beam scanning by frequency sweeping at a required position within the detection range of the main body radar. A radar repeater with a main body radar is installed, and the beam of the main body radar scans the detection range, and the beam direction of the main body radar is fixed when the beam of the main body radar is directed toward the radar repeater. so,
A radar system characterized in that a frequency sweep of a beam of a main body radar is performed to perform beam scanning of an antenna of the radar repeater, and a detection range of the main body radar is expanded by the radar repeater. 2. The radar repeater includes a relay receiver for receiving a high frequency pulse signal from the radar main body, and transmitting means for power-amplifying the received high frequency pulse signal to supply power to the frequency beam scanning antenna. A receiving means for receiving the signal re-radiated from the frequency beam scanning antenna and reflected from the target; a transmitting / receiving switch for connecting the transmitting means to the antenna during transmission and connecting the receiving means to the antenna during reception; The radar system according to claim 1, wherein a portable radar repeater having a relay transmitter for amplifying a received signal from a target and transmitting the signal to the main body radar is used.