TWI733114B - Vehicle radar system and its design method - Google Patents

Abstract

The present invention is a vehicle radar system, which includes a first antenna array, a second antenna array, and a feed point, each antenna array includes at least one antenna, and the feed point is connected to each antenna through a transmission line , Where a straight line spacing L is maintained between any two adjacent antennas, which is greater than one-half of the wavelength λ of the wireless radiation signal (L>1/2λ), so that the radar system can generate dual-beam signals in different directions. Improve radar detection range.

Description

Vehicle radar system and its design method

The invention relates to a radar system, in particular to a vehicle radar system capable of generating dual beam signals.

With the improvement of the concept of automobile safety protection, even the unmanned vehicles that many manufacturers have invested in development in recent years require a comprehensive sensing mechanism, so the demand for automotive radars is increasing. In the more intuitive application part, the vehicle radar can be applied to the collision warning mechanism and the automatic emergency braking system. The wireless signal wave emitted by the radar system is used in conjunction with other sensors (such as image sensors) to determine the relationship between the vehicle and its surrounding vehicles. In relation to the relative situation, or the traffic condition of the vehicle in the direction of travel, once it is judged that an emergency response is needed, the driver can be reminded to slow down or be automatically forced to intervene in the control operation of the vehicle.

With the scanning and detection function of the vehicle radar, it can effectively compensate for the possible negligence of human judgment and improve driving safety. Therefore, the scanning ability of the vehicle radar is extremely important. The existing vehicle radar system mainly produces a single-direction radiation pattern, that is, it can only detect the presence of objects in a single direction. If you want to detect the front, rear, left, and right directions of the vehicle at the same time, it often requires multiple configurations. The vehicle-mounted radar can cover the required detection range, leading to problems such as increased costs, increased configuration complexity, and increased data calculations. Therefore, the detection capability of the vehicle-mounted radar system does need to be improved.

In view of the fact that the existing radar system can only detect objects in a single direction, the main purpose of the present invention is to provide a vehicle radar system that can generate dual beams with a single antenna system to expand the effective scanning range.

The vehicle radar system of the present invention includes: a first antenna array including at least one antenna; a second antenna array symmetrically arranged with the first antenna array, and the second antenna array At least one antenna is included, and the antenna in the second antenna array is parallel to the antenna in the first antenna array; a feed point is connected to the first antenna array and the second antenna array through a transmission line For each antenna, the wavelength of the signal transmitted on each antenna is λ; a straight line spacing L is maintained between two adjacent antennas, which is greater than half the wavelength λ of the wireless signal, and the distance between two adjacent antennas The phase difference Δψ of the transmission signal satisfies the following formula, so that the first antenna array and the second antenna array generate two signal beams:

The present invention only needs to control the relative distance L between the first antenna and the second antenna to be greater than one-half, and make the phase difference of the wireless signal on the first antenna and the second antenna meet the preset condition, the radar system It can generate dual-beam signals in different directions. When applied to a vehicle, it can sense both the rear area and the side area of the vehicle, thereby increasing the detection range of the vehicle radar.

10: The first antenna

20: second antenna

30: third antenna

40: Fourth antenna

50: feed point

60, 60a, 60b: transmission line

100: radar system

Fig. 1: A schematic diagram of the architecture of an embodiment of the vehicle radar system of the present invention.

2A~2C: schematic diagrams of different signal beams generated by a dipole antenna in the vehicle radar system of the present invention.

3A to 3C: schematic diagrams of different signal beams generated by a patch antenna in the vehicle radar system of the present invention.

Figure 4: Schematic diagram of the signal beam generated by the radar system of the present invention.

Figure 5: A schematic diagram of the present invention applied to a vehicle.

Please refer to FIG. 1, which is a schematic diagram of the structure of the radar system of the present invention. The radar system 100 can be used as a signal transmitting or signal receiving system, and includes a first antenna arranged on a substrate and arranged symmetrically along a central axis. Array and a second antenna array, each antenna array includes at least one antenna. In this example, the first antenna array includes a first antenna 10 and a second antenna 20, and the second antenna array includes A third antenna 30 and a fourth antenna 40. The first antenna 10, the second antenna 20, the third antenna 30, and the fourth antenna 40 are arranged in parallel, and the linear relative distance L between two adjacent antennas is equal in length and greater than the transmission signal wavelength (λ) One-half, that is, L>1/2 λ, for example, the linear relative distance L between the first antenna 10 and the second antenna 20 is greater than one-half of the transmission signal wavelength (λ), the second antenna 20 The linear relative distance L between the third antenna 30 and the third antenna 30 is also greater than one-half of the transmission signal wavelength (λ), so that the radar system can generate dual signal beams as shown in Figure 3, where the pointing angle of one signal beam is about At an angle of 30 degrees, the pointing angle of the other signal beam is about -60 degrees.

In the embodiment of FIG. 1, a feeding point 50 is arranged on the same side of the first antenna 10 to the fourth antenna 40, and the feeding point 50 is connected to the end of each antenna through a transmission line 60, but in In other embodiments, the feeding point 50 can also be designed in other positions. The functions of these transmission lines 60 not only transmit signals, but also delay signals, which are equivalent to phase delay elements. As long as the extension length, shape, and material of the transmission line 60 are appropriately changed, the transmission signal can be transmitted to each antenna 10~ There is a phase difference Δψ between 40.

Please refer to FIGS. 2A to 2C. The first antenna 10 to the fourth antenna 40 are simulated by using 4 dipole antennas in the following. Assuming that the frequency of the transmission signal (operating frequency) is 3GHz, the wavelength is λ=100mm, and the distance L between two adjacent antennas 10-40 is set to 0.9 times the wavelength λ (L=0.9 λ=90mm). The phase difference (ψ) between adjacent antennas 10-40 can change the beam angle ( θ ). The relationship between the phase difference and the angle is as follows:

Taking the beam of Figure 2A as an example, in order to generate a 15-degree beam (θ=15 degrees), according to the above formula, the required phase difference ψ between adjacent antennas 10 to 40 can be calculated to be about 83.8 degrees (0.47 π ), therefore, when designing the antenna, taking the phase of the first antenna 10 as a reference point (zero degrees), the phase difference between the second antenna 20 and the first antenna 10 is about 83.8 degrees, and the third antenna 30 is relative to The phase difference of the first antenna 10 is 167.6 degrees, and the phase difference of the fourth antenna 40 relative to the first antenna 10 is 251.4 degrees, which can generate a beam as shown in FIG. 2A, wherein the angle of the main beam B1 is about 15 degrees. .

Taking the beam of Figure 2B as an example, in order to generate a 30-degree beam (θ=30 degrees), according to the above formula, the phase difference ψ required between adjacent antennas 10-40 can be calculated to be about 162 degrees (0.9 π ), therefore, when designing the antenna, taking the phase of the first antenna 10 as a reference point (zero degree), the phase difference between the second antenna 20 and the first antenna 10 is about 162 degrees, and the third antenna 30 is relative to The phase difference of the first antenna 10 is 324 degrees, and so on, so that a beam as shown in FIG. 2B can be generated, wherein the angle of the main beam B1 is about 30 degrees. Among them, the extension axis of the dipole antenna is shown by arrow A, because the dipole antenna is placed in the space for simulation in Figures 2A~2C, so the complete beam of the dipole antenna can be seen completely; In application, if the antenna is arranged on a substrate, the available beams are the two beams B1 and B2 indicated in the current figure.

Taking the beam of Figure 2C as an example, in order to generate a 30-degree beam (θ=45 degrees), according to the above formula, the required phase difference ψ between adjacent antennas 10-40 can be calculated to be about 229.1 degrees (1.27 π) Therefore, when designing the antenna, taking the phase of the first antenna 10 as a reference point (zero degree), the phase difference between the second antenna 20 and the first antenna 10 is about 229.1 degrees, and the third antenna 30 is relative to the first antenna. The phase difference of an antenna 10 is 458.2 degrees, and so on, so that a beam as shown in FIG. 2C can be generated, wherein the angle of the main beam B1 is about 45 degrees.

The above examples in Figures 2A~2C prove that when the phase difference ψ between adjacent antennas 10~40 is adjusted, the beam angle can be changed. Among them, the angle shown in Figure 2B is more conducive to the detection around the vehicle, that is, it conforms to the following Mode:

Among them, the relative opening angle of the main beam B1 and the side beam B2 is about 80-100 degrees.

Please refer to FIGS. 3A to 3C again. Four patch antennas are used to simulate the first antenna 10 to the fourth antenna 40 below. Assuming that the frequency (operating frequency) of the transmitted signal is 2.45GHz, the wavelength is λ=122.5mm, and the distance L between two adjacent antennas 10-40 is set to 0.9 times the wavelength λ (L=0.9 λ=110mm).

Taking the beam of Figure 3A as an example, in order to generate a 15-degree beam (θ=15 degrees), the phase difference ψ required between adjacent antennas 10-40 is about 83.8 degrees (0.47 π). Therefore, when designing the antenna When taking the phase of the first antenna 10 as a reference point (zero degrees), the phase difference of the second antenna 20 relative to the first antenna 10 is about 83.8 degrees, and the phase difference of the third antenna 30 relative to the first antenna 10 The difference is 167.6 degrees, and the phase difference of the fourth antenna 40 relative to the first antenna 10 is 251.4 degrees, which can generate a beam as shown in FIG. 3A, wherein the angle of the main beam B1 is about 15 degrees.

Taking the beam of Figure 3B as an example, in order to generate a 30-degree beam (θ=30 degrees), the phase difference ψ required between adjacent antennas 10-40 is about 162 degrees (0.9 π). Therefore, when designing the antenna When taking the phase of the first antenna 10 as a reference point (zero degree), the phase difference between the second antenna 20 and the first antenna 10 is about 162 degrees, and the phase difference between the third antenna 30 and the first antenna 10 is about 162 degrees. The difference is 324 degrees, and so on, so that a beam as shown in FIG. 3B can be generated, where the angle of the main beam B1 is about 30 degrees, and the other beam B2 has an angle with the main beam B1. According to FIG. 2B and FIG. 3B, it can be understood that even if the frequency of the transmission signal (operating frequency) is different, as long as the phase difference ψ between the antennas 10-40 is controlled, the desired dual-beam signal can be generated.

Taking the beam of Figure 3C as an example, in order to generate a 30-degree beam (θ=45 degrees), the phase difference ψ required between adjacent antennas 10-40 is about 229.1 degrees (1.27 π). Therefore, when designing the antenna , Taking the phase of the first antenna 10 as a reference point (zero degrees), the phase difference of the second antenna 20 relative to the first antenna 10 is about 229.1 degrees, the phase difference between the third antenna 30 and the first antenna 10 is 458.2 degrees, and so on, so that a beam as shown in FIG. 3C can be generated, wherein the angle of the main beam B1 is about 45 degrees.

According to the applicant’s No. I616064 "High-precision Analytical Method for Calculating the Direction of Arrival Angle Using the Wave’s Arrival Phase and Time Difference", it can be understood that when the relative distance between the two wave sensors is greater than one-half of the wavelength, The signal wave will have more than two directional angles. Applying the concept of the patent to the present invention, it can be obtained that there is another signal beam B2 in the vehicle radar of the present invention, and the present invention uses dual signal beams B1 and B2 to detect the environment around the vehicle.

Please refer to Figures 4 and 5, because each radar system 100 can independently generate beams B1 and B2 geometry as shown in Figure 4, when the radar system of the present invention is set to be applied to a vehicle, it can be placed on the left and rear of the vehicle and A group of radar systems 100 are set on the right rear. As shown in FIG. 5, each group of radar systems 100 detects the traffic behind and to the side of the vehicle, and can detect whether there is an object within the coverage of the dual beam signal. For example, when a vehicle is driving or changing lanes, the radar system 100 can assist in detecting whether other adjacent vehicles are approaching at the back of the vehicle or on the left and right sides. The radar system 100 of the present invention can also be installed at the front left or front right of the vehicle to detect the traffic state in front of the vehicle.

10: The first antenna

20: second antenna

30: third antenna

40: Fourth antenna

50: feed point

60, 60a, 60b: transmission line

70: Transmission signal

L: relative distance

D: Delay distance

Claims (9)

A vehicle radar system includes: a substrate; a first antenna array, which is arranged on the substrate and includes at least one antenna; a second antenna array, which is arranged on the substrate and is connected to the first antenna; The antenna array is arranged symmetrically, the second antenna array includes at least one antenna, and the antenna in the second antenna array is parallel to the antenna in the first antenna array; a feed point is connected to the antenna through a transmission line For each antenna in the first antenna array and the second antenna array, the wavelength of the wireless signal transmitted on each antenna is λ; a straight line spacing L is maintained between two adjacent antennas, which is larger than the wireless signal One-half of the wavelength λ, and the phase difference ψ of the wireless signal between two adjacent antennas satisfies the following formula, so that the first antenna array and the second antenna array generate two signal beams:

The vehicle radar system according to claim 1, wherein the feed point is connected to one end of each antenna through a transmission line. The vehicle radar system according to claim 1, wherein each of the first antenna array and the second antenna array has an antenna. The vehicle radar system according to claim 1, wherein each of the first antenna array and the second antenna array has two antennas. The vehicle radar system according to claim 1, wherein the angle between the two signal beams generated by the first antenna array and the second antenna array is 80-100 degrees. The vehicle radar system according to any one of claims 1 to 5, wherein each antenna in the first antenna array and the second antenna array is a dipole antenna. The vehicle radar system according to any one of claims 1 to 5, wherein each antenna in the first antenna array and the second antenna array is a flat-chip antenna. A design method of a vehicle radar system includes: arranging a plurality of antennas at equal intervals on a substrate to maintain a distance L between two adjacent antennas, wherein the wireless signals transmitted on the antennas have a wavelength λ, The distance L is greater than one-half of the wavelength λ; the phase difference ψ of the wireless signal between two adjacent antennas is controlled, so that the antennas generate two signal beams, wherein the angle θ of the main beam and the phase difference ψ conforms to the following formula:

, Where θ = 30°. As described in claim 8, the design method of the vehicle radar system, wherein the angle between the two signal beams is 80-100 degrees.

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