JP3572603B2 - Radar equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a radar device having an array antenna, and more particularly to a radar device suitable for DBF (digital beam forming).
[0002]
[Prior art]
The DBF radar device includes a receiving antenna including a plurality of element antennas. A mixer is provided for each reception channel for each element antenna, and in each mixer, a part of a transmission signal is mixed as a local signal with a reception signal received for each channel. In the case of an FM-CW radar device using an FM-CW (frequency modulated continuous wave) as a transmission signal, a beat signal for each reception channel is obtained by this mixing.
[0003]
After each beat signal is A / D-converted, the signal processing circuit unit performs FFT processing and DBF processing. In the DBF processing, since the reception beam can be directed to a desired direction, step scanning is achieved by shifting the directions one after another. For the direction in which the receiving beam is directed, the distance and speed of the target are detected, and the data is integrated to detect the target.
[0004]
By the way, as a method of supplying a part of the transmission signal to the mixer of each reception channel, a method using a multi-stage power distributor as described in “Electronic scanning antenna” of JP-A-3-143104 is used. There is. First, a part of a transmission signal is divided into two parts by a first-stage power divider. In the second stage, two power dividers are prepared, and the power dividers are coupled to the two outputs of the first stage power divider, respectively, and each is divided into two. As a result, a total of four divided transmission signals are obtained. Hereinafter, similarly, the number of distributions is increased to a required number, and the output of the final stage is connected to the mixer of each reception channel.
[0005]
[Problems to be solved by the invention]
According to this conventional transmission signal distribution method, it is necessary to increase the number of power distributors as the number of reception channels increases. The increase in the number of power distributors has resulted in an increase in the size of the device, and it has been difficult to apply it to applications that require small size and light weight. In other words, in a vehicle-mounted radar device, etc. where it is important to be small and lightweight, the number of receiving channels must be limited due to size restrictions, and radar detection with high resolution must be abandoned. Had occurred.
[0006]
[Means for Solving the Problems]
The radar device of the present invention has been made to solve such a problem,
A directional coupler array, a mixer array, a receiving antenna array, a transmission signal generator, a transmission antenna, and a signal processing circuit are provided.
[0007]
Here, the directional coupler array includes a large number of cross-shaped directional couplers in which the first waveguide and the second waveguide are orthogonal to each other across a common wall in which a coupling hole is formed. Waveguides are continuous, and one opening of each second waveguide is arranged on the same plane. The mixer array is configured by arranging a plurality of mixers having one input end facing the opening of each second waveguide and the other input end located on the opposite side.
[0008]
The receiving antenna array is one in which a plurality of element antennas connected to the other input terminal of each mixer are arranged, and the transmission signal generator is connected to one opening end of the first waveguide. . The transmitting antenna is connected to the other open end of the first waveguide, and the signal processing circuit is configured to input each output signal of the plurality of mixers and perform a target detection process.
[0009]
According to this radar device, the number of mixers and the number of directional couplers increase with an increase in the number of reception channels (number of transmission antennas for reception). However, since these are all arranged in an array, they are ordered. The device can be stored in a compact form, and the size of the device can be suppressed.
[0010]
In particular, when the element antennas are two-dimensionally arranged to perform two-dimensional beam scanning, the mixer and the cross-shaped directional coupler are also two-dimensionally arranged, and the integration rate is further improved.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a diagram showing a circuit configuration of a radar device according to one embodiment of the present invention. This radar apparatus is an FM-CW radar apparatus that uses a transmission signal obtained by applying frequency modulation (FM) to a continuous wave (CW), and is a DBF radar apparatus that performs digital beam forming processing.
[0012]
The transmission signal generator 11 includes a voltage controlled oscillator (VCO) having a center frequency of f0 (for example, 60 GHz) and a modulator for applying a modulation voltage to the VCO, and outputs a modulated wave (transmission signal) of f0 ± ΔF. Output. The transmission signal is radiated from the transmission antenna 13.
[0013]
A directional coupler array 12 is provided between the transmission signal generator 11 and the transmission antenna 13, and the directional coupler array 12 includes n directional couplers 12-1 to 12-n. Have been.
[0014]
The receiving antenna array 14 includes n element antennas 14-1 to 14-n, and each element antenna is connected to one input terminal of n mixers 15-1 to 15-n forming the mixer array 15. It is connected.
[0015]
Output terminals of the directional couplers 12-1 to 12-n are connected to the other input terminals of the mixers 15-1 to 15-n, and a part of the transmission signal output from the transmission signal generator 11 is connected. Is supplied to the mixers 15-1 to 15-n via the directional couplers 12-1 to 12-n.
[0016]
Each of the mixers 15-1 to 15-n mixes a part of a transmission signal as a local signal with a reception signal received by the element antennas 14-1 to 14-n. As a result, the received signal is down-converted into a beat signal.
[0017]
The signal processing circuit 16 receives beat signals for the respective reception channels from the mixers 15-1 to 15-n, performs A / D conversion on the beat signals, performs FFT processing and DBF processing, and executes distance, speed, and azimuth of the target. Is detected.
[0018]
FIG. 2 is a perspective view showing the appearance of the radar apparatus, and FIG. 3 is a perspective view showing the appearance of the directional coupler array 12.
[0019]
The directional coupler array 12 includes n (here, n = 18) cross-shaped directional couplers arranged in an array. The cruciform directional coupler is formed by making two rectangular waveguides orthogonal to each other across a common wall having a slit as a coupling hole, and receives an input from one waveguide (first waveguide). The transmitted radio wave travels in one direction in the other orthogonal waveguide (second waveguide).
[0020]
As shown in FIG. 3, the directional coupler array 12 includes array elements 37 to 39 in which six cross-shaped directional couplers are connected, which are stacked in three stages. Each array element is composed of a lower structure 32 forming a first waveguide 34, an upper structure 31 forming a second waveguide 35, and a signal coupling plate 33 sandwiched between both structures. .
[0021]
In the lower structure 32, one waveguide 34 extending in the longitudinal direction is formed, and this waveguide 34 is one of the six cross-directional directional couplers (the first waveguide). Tube). In the upper structure 31, six waveguides 35 are formed at substantially equal intervals in a direction perpendicular to the waveguides 34, and each waveguide 35 is the other waveguide in the cross-shaped directional coupler. (Second waveguide).
[0022]
As shown in FIG. 4, the signal coupling plate 33 is provided with a slit at a portion serving as a common wall between the first waveguide 34 and each of the second waveguides 35. The slits 41 and 42 each have a cross shape, and are arranged at positions symmetrical to each other on a diagonal line of the common wall. Since each of the slits 41 and 42 has a cross shape, the radio wave input to the first waveguide 34 travels in a predetermined direction in each second waveguide 35. In addition, by providing two slits 41 and 42, the coupling degree is increased.
[0023]
The first waveguide 34 of the array element 37 and the first waveguide 34 of the array element 38 are connected by the side waveguide 22, and the first waveguide 34 of the array element 38 and the first waveguide 34 of the array element 39 are connected. The one waveguide 34 is connected by the side waveguide 21. The output terminal of the transmission signal generator 11 is connected to the other end (the left side in the drawing) of the first waveguide 34 of the array element 37, and the other end of the first waveguide 34 of the array element 39 (the left end). A horn-type transmitting antenna 13 is connected to the right side of the drawing). As a result, the transmission signal generator 11 and the transmission antenna 13 are connected by one waveguide, and 18 directional couplers are provided on the way.
[0024]
It should be noted that the traveling directions of the radio waves in the second waveguide 35 when the transmission signal is output from the transmission signal generator 11 are all in the same direction (forward), and the radio wave intensity is almost equal. The slits 41 and 42 are adjusted.
[0025]
An antenna array 14 is provided in front of the directional coupler array 12 via a mixer array 15. A dummy load 23, which is a ferrite plate, is provided behind the directional coupler array 12.
[0026]
The mixer array 15 includes 18 balanced mixers 15-1 to 15-n (n = 18) which are respectively arranged to face the 18 second waveguides 35, and one input terminal of each mixer is connected to one of the input ends. It is connected to each waveguide 35.
[0027]
Further ahead of the mixer array 15, a receiving antenna array 14 having 18 horn-type element antennas 14-1 to 14-n (n = 18) is provided. Each element antenna is connected to the other input terminal of each mixer of the mixer array 15.
[0028]
An output terminal of each mixer of the mixer array 15 is connected to a signal processing circuit 16, which receives a beat signal for each element antenna from each mixer and performs A / D conversion processing, FFT processing, and DBF processing. Run and detect targets.
[0029]
In this embodiment, the element antennas are arranged two-dimensionally, but may be arranged one-dimensionally.
[0030]
【The invention's effect】
As described above, according to the radar apparatus of the present invention, a local signal is supplied to each reception channel without using a power divider by arraying all the receiving element antennas, mixers, and directional couplers. Therefore, the size of the apparatus can be reduced. As a result, for example, a high-resolution on-vehicle radar device can be realized.
[Brief description of the drawings]
FIG. 1 is a diagram showing a circuit configuration of a radar device according to an embodiment of the present invention.
FIG. 2 is a perspective view showing its external structure.
FIG. 3 is a perspective view showing the external structure of a directional coupler array.
FIG. 4 is a perspective view showing a signal coupling plate of the directional coupler array.
[Explanation of symbols]
11: transmission signal generator, 12: directional coupler array, 13: transmission antenna, 14: reception antenna array, 15: mixer array, 16: signal processing circuit.

Claims (2)

A first waveguide and a second waveguide are provided with a large number of cross-shaped directional couplers orthogonal to each other across a common wall having a coupling hole, wherein each of the first waveguides is continuous; A directional coupler array in which one opening of each second waveguide is arranged in the same plane;
A mixer array in which a plurality of mixers having one input end facing the opening of each of the second waveguides and the other input end located on the opposite side,
A receiving antenna array in which a plurality of element antennas connected to the other input terminal of each of the mixers are arranged,
A transmission signal generator connected to one open end of the first waveguide;
A transmitting antenna connected to the other open end of the first waveguide;
A signal processing circuit that receives each output signal of the plurality of mixers and performs a target detection process. The radar device according to claim 1, wherein the plurality of element antennas are two-dimensionally arranged.

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