KR101963384B1 - Antenna for radar - Google Patents

Abstract

The present invention relates to an antenna for radar, which comprises: a first array radiating signals in one direction; a second array radiating signals in a direction opposite to the first array; and a feed unit supplying signals to the first and second arrays. Each of the first array and the second array includes a plurality of first radiators and second radiators installed so as to radiate signals in opposite directions. In a non-radiating direction of the first and second radiators, a configuration in which parasite elements resonating at a frequency adjacent to the first and second radiators to implement a broadband effect is provided, thereby having a wide bandwidth of 4 GHz in the center frequency 79 GHz band, and improving the distance resolution.

Description

ANTENNA FOR RADAR "

The present invention relates to a radar antenna, and more particularly, to a radar antenna for transmitting a radar signal and receiving a radar signal reflected from an obstacle in the vicinity.

A radar sensor is a sensing means for measuring the distance, velocity, and angle information by transmitting a radio wave using a microwave and receiving a reflection signal reflected from the target.

Such a radar sensor may be a pulse radar (Pulsed Doppler Radar), a Frequency Modulated Continuous Wave (FMCW), a Stepped-Frequency Continuous Wave (SFCW) And a frequency shift keying (FSK) radar. The radar waveform is used to measure target information.

The applicant of the present invention has disclosed a radar sensor technology to many of the following Patent Documents 1 and 2 and has been patented and registered.

On the other hand, in-vehicle radars are classified as long range radar (LRR), middle range radar (MRR) and short range radar (SRR) or blind spot detection (BSD) .

Among them, the LRR and MRR for sensing the front of the vehicle mainly use the frequency of 77 GHz band, and the SRR or BSD for sensing the rear side of the vehicle uses the frequency of 24 GHz band.

An antenna applied to a radar sensor for a vehicle is designed to receive special characteristics when a complicated structure such as a chebyshov, binomial, or taylor is applied to an array antenna, Complex feeder circuits are needed. Therefore, there is a disadvantage that the development period such as the design and performance optimization of the array antenna having a complicated power supply circuit is prolonged.

Therefore, in order to solve the above problems due to the complexity of the design, the patch array antenna for the 24 ㎓ or 77 ㎓ band is designed such that the magnitude and phase of the current are uniformly input to each patch.

However, the array antenna having a uniform magnitude and phase of the current input to the patch exhibits a high side lobe level characteristic, which results in a problem that the sensing area is very uneven.

In addition, when the detection area of the radar detector is very narrow, there is a problem that it is difficult to generate a narrow and uniform width beam only by the radar algorithm because the side lobe level of the beam generated by the array antenna is high.

Accordingly, the applicant has disclosed and patented a radar antenna technology having high gain and low side lobe level characteristics in Patent Document 3 described below.

Korean Patent Registration No. 10-1513878 (issued on April 22, 2015) Korean Patent Registration No. 10-1505044 (issued on March 24, 2015) Korean Patent Registration No. 10-1841685 (Announcement on March 27, 2018)

However, in recent SRR or BSD, a frequency of 79 GHz band, which replaces the frequency band of 24 GHz, is mainly used.

Since the 79 GHz band has a bandwidth of 4 GHz which is wider than the 24 GHz band having a bandwidth of 250 MHz, the distance resolution (or range resolution) performance is excellent and accurate target detection can be performed at a close range.

In the case of the SRR using the 79 GHz band, it has a wide-angle characteristic as it detects a wide range in the azimuth direction from the near range.

The SRR using the 79GHz band with a wide beam width can be used as a front and rear radar for a vehicle, can detect a wide range of near targets at an intersection, and has a high distance resolution There are characteristics.

The distance resolution refers to the minimum distance difference that can be distinguished even when two targets in the same direction are approached in the radar.

This distance resolution can be calculated by Equation (1).

[Equation 1]

Here,? R is the distance resolution and BW is the bandwidth.

As can be seen from Equation (1), as the bandwidth increases, the distance resolution becomes smaller, and precise distance measurement becomes possible.

1 is a graph showing a radiation pattern of a conventional radar antenna using a frequency band of 79 GHz.

In the case of using the frequency band of 79 GHz having the wide bandwidth of 4 GHz, as shown in FIG. 1, as the center frequency is changed from 77 GHz to 81 GHz, There is a problem in that a deviation occurs while being rocked in the left and right direction without being fixed.

Thus, when using a wide bandwidth, the high-angle antenna pattern error must be small. In addition, the radar antenna design with wide wide angle characteristics should be designed to have a wide width of left and right beam and symmetrical characteristics with respect to the azimuth axis at 0 degree.

However, although a wide-angle antenna using 77 GHz frequency has been commercialized, the frequency bandwidth is limited to a maximum 1 GHz band, and there is no antenna considering the wide band characteristics of 77 GHz to 81 GHz.

As a result, SRR radar sensors of the 77GHz band, which are applied to the front and rear sides of Advanced Driver Assistance Systems (ADAS) applied to autonomous vehicles, Up to eight vehicles must be installed.

An object of the present invention is to provide a radar antenna having a wide bandwidth of 4 GHz in a frequency band of 79 GHz and improving distance resolution.

It is another object of the present invention to provide a radar antenna capable of preventing lateral deviation of an elevation beamwidth according to a change in center frequency in order to use a broadband in a radar antenna using a center frequency band of 79 GHz will be.

Another object of the present invention is to provide a radar antenna capable of maintaining symmetry in a wide azimuth beam width in order to expand a radar detection region.

It is another object of the present invention to provide a radar antenna capable of minimizing the number of radars installed in a vehicle.

According to an aspect of the present invention, there is provided a radar antenna comprising: a first array radiating a signal in one direction; a second array radiating a signal in a direction opposite to the first array; Wherein the first array and the second array each include a plurality of first radiators and a second radiator cross-mounted to radiate signals in opposite directions to each other, And a parasitic element that resonates at a frequency adjacent to the first and second radiators to realize a wide band is disposed in the first and second radiator non-radiation directions.

As described above, according to the antenna for radar of the present invention, it is possible to obtain an effect of improving the distance resolution by having a wide bandwidth of 4 GHz in the frequency band of 79 GHz at the center frequency.

According to the present invention, a multi-array antenna is designed in a radar antenna using a center frequency band of 79 GHz, and an effect of minimizing the height beam width can be obtained.

Further, according to the present invention, it is possible to prevent an occurrence of lateral deviation of the high-angle beam width according to the change of the center frequency for using the wide band.

Further, according to the present invention, when the wide azimuth beam width is designed to extend the radar detection area, the symmetry can be maintained.

As a result, according to the present invention, it is possible to design a wide-band and wide-angle antenna and detect a target with respect to an omnidirectional (360 degrees) area of the vehicle using a small number of radars, thereby minimizing the number of radars installed in the vehicle Can be obtained.

1 is a graph showing a radiation pattern of a radar antenna according to the prior art,
2 is a plan view of a radar antenna according to a preferred embodiment of the present invention,
FIG. 3 is a partially enlarged view of the radar antenna shown in FIG. 2,
FIG. 4 is a graph showing a radiation pattern of the radar antenna shown in FIG. 2,
5 is a graph showing the reflection loss of the radar antenna.

Hereinafter, a radar antenna according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a plan view of a radar antenna according to a preferred embodiment of the present invention, and FIG. 3 is a partially enlarged view of the radar antenna shown in FIG.

Hereinafter, terms indicating directions such as 'left', 'right', 'forward', 'rearward', 'upward' and 'downward' are defined as indicating respective directions based on the states shown in the respective drawings do.

2, a radar antenna 10 according to a preferred embodiment of the present invention includes a first array 20 for radiating signals in one direction, a second array 20 for radiating signals in the opposite direction to the first array 20, And a feeding part 40 for supplying signals to the first and second arrays 20 and 30.

The first array 20 and the second array 30 each include a plurality of first radiators 21 and second radiators 31 and the first and second radiators 21 and 31 are disposed in opposite directions Lt; RTI ID = 0.0 > a < / RTI > row.

Specifically, the first array 20 includes a plurality of first radiators 21 disposed on one straight line, and the second array 30 includes a plurality of first radiators 21 disposed between the plurality of first radiators 21 And includes a plurality of second radiators (31).

Here, the first radiator 21 and the second radiator 31 may be arranged symmetrically so as to radiate signals in opposite directions to each other.

A second radiator 31 may be disposed between each first radiator 21 and the first radiator 21 and the second radiator 31 may be provided in the same number.

On the other hand, the plurality of first and second radiators 21 and 31 form a radiation pattern of the antenna 10 for radar.

The plurality of first and second radiators 21 and 31 are arranged along the first and second feeder lines 41 and 42 of the feeder 40 to be described below, Signals are supplied to the radiators 21 and 31 from the radiating elements 41 and 42, respectively.

The plurality of radiators may be made of a conductive material containing at least one of silver (Ag), palladium (Pd), platinum (Pt), copper (Gu), gold (Au), and nickel (Ni)

Meanwhile, as shown in FIGS. 2 and 3, between the first and second radiators 21 and 31, in order to increase the bandwidth of the radar antenna 10, A device 50 may be provided.

The parasitic element 50 is formed in a substantially quadrangular pattern in the space between the first radiator 21 and the second radiator 31 and resonates at a frequency adjacent to the first and second radiators 21 and 31 to be broadened .

However, when a parasitic element is provided for each non-radiating slot direction, the length of the radar antenna is unnecessarily long, and manufacturing cost increases.

Therefore, in this embodiment, only one parasitic element 50 is disposed between the first and second radiators 21 and 31, as shown in Fig.

Thus, the first and second radiators 21 and 31 share one parasitic element 50 disposed therebetween.

Thus, according to the present invention, one parasitic element is disposed between the first and second radiators and shared with each other, thereby minimizing the length of the radar antenna and reducing manufacturing cost.

 As described above, according to the present invention, the parasitic elements disposed between the first and second radiators are disposed in a shared manner, so that the entire length of the antenna can be minimized by efficiently utilizing the limited space for designing the radar antenna.

It is preferable that the radar antenna 10 has a center frequency set to 79 GHz as performance deviation or performance deterioration occurs in a high frequency band.

In general, the width of the main radiating element and the parasitic element are designed to be smaller than the vertical length of each element.

In the present embodiment, the widths of the first and second radiators 21 and 31 are smaller than the lengths of the first and second radiators 21 and 31, .

The width of the parasitic element 50 may be designed to be slightly larger than the length of the parasitic element 50. [

In order to realize a wide band characteristic, the first and second radiators 21 and 31 and the parasitic element 50 are designed to be located near the resonance frequency, and the first and second radiators 21 and 31 Electromagnetic Coupling (Coupling) The length of the parasitic element 50 fed can be designed to be about 0.5?.

In order to separate the resonance frequencies of the two devices, the two devices are designed to differ in length.

In general, the resonance length of the patch is 0.5 lambda and the length of the two elements can be designed within the range of 0.4 lambda to 0.6 lambda.

2, the feeder 40 includes a first feeder line 41 for supplying a signal to a plurality of first radiators 21 provided in the first array 20, a plurality of first feeders 41 provided in the second array 30, The second feeder line 42 for supplying a signal to the second radiator 31 and the one end of the first and second feeder lines 41 and 42 are connected to the first and second feeder lines 41 and 42 And a feeding point 43 for supplying a signal.

1, each of the first radiators 21 of the first array 20 is connected to a first connection line 44 and a second connection line 44 is connected to the first transmission line 41. The first transmission line 41 is disposed on one side of the first array 20, To the first feeder line (41).

The second feeder line 42 is disposed on one side of the second array 30 and on the right side as viewed in Figure 1 and each second radiator 31 of the second array 30 is connected to the second connection line 45, To the second feeder line (42).

On the other hand, as the first and second radiators 21 and 31 are disposed in an alternate arrangement, the radiation pattern in the wide angle direction, i.e., the azimuth angle direction, of the single antenna is asymmetric.

That is, when the feeder line is disposed on one side with respect to the first and second radiators 21 and 31, asymmetry occurs with respect to the azimuthal beam width of 0 degree.

Therefore, in this embodiment, the first and second feeder lines 41 and 42 are disposed on both sides of the first and second radiators 21 and 31, and the first and second feeder lines 41 and 42 are connected to the first and second connection lines 44 and 45, The power supply circuit is implemented.

As described above, according to the present invention, asymmetry of the radiation pattern of the radiation beam can be eliminated by applying the structure of supplying power from the right and left sides of the first and second arrays having an asymmetric structure.

First and second stubs 46 and 47 may extend upwardly from the upper ends of the first feeder line 41 and the second feeder line 42, respectively.

The first and second stubs 46 and 47 can reduce the power supplied to the first and second arrays 20 and 30 to provide an effect of suppressing side lobes.

In addition, the first and second stubs 46, 47 can help regulate the power ratio supplied to the first and second arrays 2, 30.

For example, the lengths of the first and second stubs 46 and 47 may be designed to be 0.25? Of the center frequency.

In this embodiment, since the power feeding circuit is designed to be zigzag for wide angle right and left symmetry of the radiation angle beam width and the phases of signals fed to each patch must be the same, the length of the first and second feed line 41, lt; / RTI >

Meanwhile, the feed point 43 and the first and second feeder lines 41 and 42 may be connected by the first and second branch lines 48 and 49, respectively.

The first and second branch lines 48 and 49 may be provided in a slanting structure in which the first and second branch lines 48 and 49 are inclined toward the lower ends of the first and second feeder lines 41 and 42 with respect to the feed point 43, respectively.

As described above, according to the present invention, by arranging the first and second branch lines in a diagonal structure, the horizontal area of the lower end of the feeding part can be minimized to vertically align the beam center in the high angle direction, The peak can be adjusted to 0 degrees, and the side lobe level of the broadband signal can be minimized.

On the other hand, in general, when designing an antenna, a specific center frequency is selected and designed.

Therefore, in the case of the wide band like the 79 GHz band described in this embodiment, the center frequency is designed to be 79 GHz, and the center frequency is varied by 77 GHz to 81 GHz through simulation.

4 and 5, simulation results of a radar antenna according to a preferred embodiment of the present invention will be described.

FIG. 4 is a graph showing the radiation pattern of the radar antenna shown in FIG. 2, and FIG. 5 is a graph showing the return loss of the radar antenna.

5A to 5D show graphs of antenna gains according to power and angles at 77 GHz to 80 GHz, respectively.

5 (a) to 5 (d), the radar antenna 10 according to the present embodiment suppresses the level of the side lobe to -10 dB or less in the entire 77 GHz to 80 GHz band, And the level difference between the side lobes is maintained at about 20 dB or more.

As shown in FIG. 6, the radar antenna 10 according to the present embodiment can be confirmed to satisfy S11 = -10 dB or less in the entire band of 77 GHz to 81 GHz due to the influence of the feed line.

Accordingly, the present invention satisfies S11 = -10 dB or less for a wide bandwidth of 77 GHz to 81 GHz, so that a transmission signal can be effectively propagated through a transmission antenna.

Through the above process, the present invention has a wide bandwidth of 4 GHz in the frequency band of 79 GHz and can improve the distance resolution.

In addition, the present invention can design a multi-array antenna in a radar antenna using a center frequency band of 79 GHz, and minimize an elevation beam width.

In addition, the present invention can prevent a left-right deviation of a high-angle beam width according to a center frequency change for using a wideband.

In addition, the present invention can maintain symmetry in the case of designing a wide azimuth beam width to extend the radar detection area.

As described above, the present invention can minimize the number of radars installed in a vehicle by designing a wide-band and wide-angle antenna and detecting a target in an omnidirectional (360 degrees) area of the vehicle using a small number of radars .

Although the invention made by the present inventors has been described concretely with reference to the above embodiments, the present invention is not limited to the above embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

The present invention is applied to an antenna technology for a radar having broadband and wide angle characteristics having a wide bandwidth.

10: Antenna for radar
20: first array 21: second emitter
30: second array 31: second emitter
40: feeding part 41, 42: first and second feeding lines
43: feed point 44, 45: first and second connection lines
46, 47: first and second stubs 48, 49: first and second branch lines
50: parasitic element

Claims (5)

A first array including a plurality of first radiators for radiating signals in one direction,
A second array comprising a plurality of second radiators emitting a signal in a direction opposite to the first array,
A power feeder for supplying a signal to the first and second arrays,
And a parasitic element disposed in a non-radiation direction of the first and second radiators,
Wherein the first and second radiators are installed so as to cross each other along one row to radiate signals in opposite directions to each other,
Wherein the parasitic element resonates at a frequency adjacent to the first and second radiators to implement a wide band and is disposed one by one between the first and second radiators so that the first and second radiators share,
Wherein the power feeder is a first feeder line for supplying a signal to a plurality of first radiators provided in the first array,
A second feed line for supplying a signal to a plurality of second radiators provided in the second array,
And a feeding point connected to one end of the first and second feeder lines for supplying a signal to the first and second feeder lines,
Wherein the first and second radiators are respectively supplied with signals from the first and second feeder lines via a zigzag feed structure connected through first and second connection lines,
And first and second stubs extending from the upper ends of the first and second feeder lines are formed to reduce power supplied to the first and second arrays, respectively, so as to suppress the side lobe. delete delete delete The method according to claim 1,
The feed point and the first and second feeder lines are connected by first and second branch lines,
Wherein the first and second branch lines are each provided in a slanting structure in which the first and second branch lines are inclined toward the lower ends of the first and second feeder lines with respect to the feed point.

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