CN106953157B - An antenna device for a radar sensor - Google Patents

Abstract

The invention discloses an antenna device for a radar sensor, which comprises a printed circuit board, and more than one group of antenna units are arranged on the bottom board of the printed circuit board, and each group of antenna units includes a receiving antenna and a transmitting antenna, and the top layer board of the printed circuit board The radio frequency circuit is arranged on the top, and each group of antenna units is respectively arranged on both sides of the bottom board, and a feed transmission unit is also arranged on the bottom board, and the feed transmission unit connects the feed point of the antenna unit to the area where the radio frequency circuit is located on the bottom board. The direction extends to the position of the target feed point, and the through hole extends from the target feed point to the top layer board and then connects with the radio frequency circuit. The invention has the advantages of simple and compact structure, simple feeding and transmission wiring, low cost and small volume of the device.

Description

Antenna device for radar sensor

technical field

The invention relates to the technical field of millimeter wave radar, in particular to an antenna device used for a radar sensor in millimeter wave radar.

Background technique

The electromagnetic wavelength emitted by millimeter-wave radar is usually a few millimeters. For the same antenna size, the millimeter-wave antenna has a narrower beam and higher gain, and it has higher angle and distance measurement accuracy, so it is widely used in various fields Among them, typical application areas such as automotive active safety and regional safety protection. The millimeter-wave radar transmits high-frequency electromagnetic waves through the transmitting antenna, and then receives the echo signal of the target through the receiving antenna, and then outputs the information of the target through circuits such as frequency mixing, zero-IF amplification, intermediate frequency amplification, AD sampling, and signal processing. The single-send and single-receive millimeter-wave radar using the FM continuous wave system can obtain the speed information of the target, and the multi-receive antenna can also obtain the angle information of the target.

As the main component of the millimeter wave radar, the radar sensor covers the area to be protected through the radiation of the antenna. An important parameter that characterizes the radiation characteristics of the antenna is the radiation pattern of the antenna. The main beam of the radiation pattern is the beam, and the beams of the transmitting antenna and the receiving antenna determine the detection area of the radar sensor. In practical applications of millimeter-wave radar sensors, such as regional perimeter protection, the transmitting antenna is usually required to have a narrow beam and high-gain radiation characteristics. In the existing millimeter-wave radar antenna, the transmitting antenna and the receiving antenna usually adopt a single feeding method, and the feeding points of the transmitting antenna and the receiving antenna are located on both sides of the center line of the radio frequency circuit board, and then the transmitting antenna and the receiving antenna The feed point is directly transmitted to the two feed ports of the radio frequency circuit through the feed transmission structure. However, in the above-mentioned millimeter-wave radar antenna, the distance between the feed point of the transmitting antenna and the receiving antenna and the two feed ports of the radio frequency circuit is usually relatively long, and the direct transmission from the transmitting antenna and the receiving antenna to the radio frequency processing circuit will make the feed The transmission line is too long, resulting in complex wiring of the transmission line in the antenna device, which in turn makes the entire circuit board bulky and not compact, and also increases the cost of the millimeter-wave radar sensor.

Contents of the invention

The technical problem to be solved by the present invention is: aiming at the technical problems existing in the prior art, the present invention provides an antenna device for radar sensors with simple and compact structure, simple feeding and transmission wiring, low device cost and small volume .

In order to solve the problems of the technologies described above, the technical solution proposed by the present invention is:

An antenna device for a radar sensor, comprising a printed circuit board, more than one group of antenna units are arranged on the bottom plate of the printed circuit board, each group of antenna units includes a receiving antenna and a transmitting antenna, and the printed circuit board A radio frequency circuit is arranged on the top layer board of each group, and each group of antenna units is respectively arranged on both sides of the bottom board, and a feed transmission unit is also arranged on the bottom board, and the feed transmission unit connects the antenna unit The feed point on the bottom layer extends to the position of the target feed point in the direction of the area where the radio frequency circuit is located, and is connected to the radio frequency circuit after extending from the target feed point to the top layer via a hole.

As a further improvement of the present invention: each group of antenna units corresponds to an end-fed antenna unit composed of an end-fed antenna and a center-fed antenna unit composed of a center-fed antenna, and the feed point of the end-fed antenna unit is connected to the The feed transmission unit, the feed point of the mid-feed antenna unit extends to the top layer board through a hole and is connected to the radio frequency circuit.

As a further improvement of the present invention: the position of the transmission terminal of the feed transmission unit can be located in the designated area where the radio frequency circuit is located when extending the via hole of the target feed point to the top layer board.

As a further improvement of the present invention: the end-fed antenna unit includes a plurality of parallel-connected end-fed array antennas, and the center-fed antenna unit includes a plurality of parallel-connected center-fed array antennas.

As a further improvement of the present invention: the center-fed antenna unit and the radio frequency circuit are arranged on the same side of the printed circuit board.

As a further improvement of the present invention: the position of the center-fed antenna unit is such that when the feed point via hole of the center-fed antenna unit is extended to the top layer board, it can be within the specified area where the radio frequency circuit is located.

As a further improvement of the present invention: the end-fed antenna unit includes a first main feed network in the horizontal direction, a plurality of first sub-feed networks with the same structure and in the vertical direction, the first main feed network The left and right parts are symmetrical with respect to the feeding points at the ends, and the microstrip antenna array elements in the upper part and the microstrip antenna array elements in the lower part of the first sub-feeding network are symmetrical.

As a further improvement of the present invention: the center-fed antenna unit includes a second main feed network in the horizontal direction, a plurality of second sub-feed networks with the same structure and in the vertical direction, the second main feed network The left and right parts and the upper and lower parts are respectively symmetrical with respect to the feeding point in the middle part, and the microstrip antenna array elements in the upper part in the second sub-feed network are symmetrical and opposite in phase to the microstrip antenna array elements in the lower part, and the second sub-feeding network A transmission line is also provided at the feeding point of the upper part of the feed network to keep the upper part and the lower part of the second sub-feed network fed in the same phase.

As a further improvement of the present invention: the feed transmission unit is a feed transmission line.

As a further improvement of the present invention: the bottom plate is also provided with a high-frequency substrate, and the antenna unit and the feeding transmission unit are printed on the high-frequency substrate.

Compared with the prior art, the present invention has the advantages of:

1) The present invention is used for the antenna device of the radar sensor, and each group of antenna units is respectively arranged on both sides of the printed circuit board, which can increase the isolation between the high-frequency transceiver circuits, thereby improving the detection sensitivity of the radar sensor, and at the same time transmit The unit extends the feed point of the antenna unit on the bottom board to the area where the radio frequency circuit is located, so that the extended target feed point can be close to the radio frequency circuit, and then directly extends from the target feed point to the top board through holes and connects with the radio frequency circuit. The circuit connection can shorten the transmission line between the bottom antenna unit and the top radio frequency circuit in the antenna device, and at the same time make the transmission wiring simple, effectively reduce the volume of the device and reduce the cost of the device;

2) The antenna device used in the radar sensor of the present invention further adopts different feeding methods for the transmitting antenna and the receiving antenna, which can increase the flexibility of the antenna device and improve the System resource utilization; at the same time, for the end-fed antenna unit, by connecting the feed transmission unit, the feed point of the end-fed antenna unit is extended on the bottom board to the direction of the area where the radio frequency circuit is located to the target feed point, directly from the target feed point The via hole extends to the top layer board. For the mid-feed antenna unit, the feed point via hole is directly extended to the top layer board. Combining different feeding methods can shorten the transmission line between the antenna unit and the radio frequency circuit, making the transmission wiring simple;

3) The present invention is used for the antenna device of the radar sensor. Each group of antenna units adopts the end-fed antenna unit and the center-fed antenna unit. The feed antenna unit and the radio frequency circuit are arranged on the same side, and at the same time, the position of the target feed point of the feed transmission unit transmission terminal and the feed point of the middle feed antenna unit is located in the designated area where the radio frequency circuit is located after the hole extends to the top layer board Inside, the length of the transmission line from the antenna unit at the bottom layer to the radio frequency circuit at the top layer can be shortened to the greatest extent, greatly reducing the complexity of the transmission wiring of the antenna device, and making the structure of the antenna device compact.

Description of drawings

FIG. 1 is a schematic diagram of the structure and principle of the antenna device used in the radar sensor in this embodiment.

Fig. 2 is a schematic diagram of the specific structure of the antenna unit in this embodiment.

Fig. 3 is a schematic structural diagram of the feed network of the elevation plane of the end-fed antenna unit in this embodiment.

Fig. 4 is a schematic structural diagram of the azimuth plane feeding network of the end-fed antenna unit in this embodiment.

FIG. 5 is a schematic structural diagram of a feeding network of a center-fed antenna unit in this embodiment.

Fig. 6 is a schematic structural diagram of an azimuth-plane feed network of the center-fed antenna unit in this embodiment. .

Fig. 7 is a schematic diagram of the radiation pattern results of the end-fed antenna unit in this embodiment.

Fig. 8 is a schematic diagram of the radiation pattern results of the center-fed antenna unit in this embodiment.

Legend: 1. Bottom board; 11. Antenna unit; 111. End-fed antenna unit; 112. Center-fed antenna unit; 12. Feed transmission unit; 2. Top board; 21. Radio frequency circuit.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

As shown in Figures 1 and 2, the antenna device used in the radar sensor in this embodiment includes a printed circuit board, and the bottom plate 1 of the printed circuit board is arranged with more than one group of antenna units 11, and each group of antenna units 11 includes a receiving antenna and a transmitting antenna. , the top layer board 2 of the printed circuit board is arranged with a radio frequency circuit 21 for processing high-frequency signals, and the top layer board 2 is also provided with a signal processing circuit, etc., and each group of antenna units 11 is respectively arranged on both sides of the printed circuit board, and the bottom board 1 is also provided with a feed transmission unit 12, the feed transmission unit 12 extends the feed point of the antenna unit 11 on the bottom board 1 to the position of the target feed point in the direction of the area where the radio frequency circuit 21 is located, and the target feed point The via hole extends to the top layer board 2 and is connected to the radio frequency circuit 21 .

In this embodiment, each group of antenna units 11 is respectively arranged on both sides of the printed circuit board, that is, the transmitting antenna and the receiving antenna are distributed on both sides of the center line of the high-frequency printed board at a certain interval, which can increase the isolation between the high-frequency transceiver circuits. Further, the detection sensitivity of the radar sensor is improved, and at the same time, the feed point of the antenna unit 11 is first extended on the bottom plate 1 to the direction of the area where the radio frequency circuit 21 is located through the feed transmission unit 12, so that the extended target feed point can be close to the radio frequency circuit 21, and then directly extend from the target feed point to the top layer board 2 and then connect to the radio frequency circuit 21, which can shorten the transmission line between the bottom antenna unit 11 and the top layer radio frequency circuit 21 in the antenna device, and at the same time make the transmission wiring simple and effectively reduce the The volume of the device is small and the required cost of the device is reduced.

As shown in Figure 1, each group of antenna units 11 in this embodiment specifically corresponds to an end-fed antenna unit 111 composed of an end-fed antenna and a center-fed antenna unit 112 composed of a center-fed antenna. The end-fed antenna unit 111 has an end portion Feed point (first feed point), center-fed antenna unit 112 has a middle feed point (second feed point), end-fed antenna unit 111, and center-fed antenna unit 112 are all printed on the bottom layer of the high-frequency printed board On the board 1, the end-fed antenna unit 111 includes a plurality of parallel-connected end-fed array antennas for radiating high-frequency transmission signals, that is, the transmitting antenna, and the center-fed antenna unit 112 includes a plurality of parallel-connected center-fed array antennas, It is used to receive the echo signal reflected on the target, which is the receiving antenna. The transmitting antenna and the receiving antenna in each group of antenna units 11 can be specifically set as an antenna of an end-fed feeding mode, and the other is an antenna of a center-fed feeding mode according to actual needs. The transmitting antenna and the receiving antenna adopt different feeding methods, which can increase the flexibility of the antenna device and improve the utilization rate of system resources compared with the traditional antenna device using a single feeding method.

In this embodiment, the feed point of the end-fed antenna unit 111 is specifically connected to the feed transmission unit 12, wherein the starting end of the feed transmission unit 12 is connected to the feed point of the end-fed antenna unit 111, and the transmission terminal is the target feed point so that the end feed point (the first feed point) of the end-fed antenna unit 111 extends to the target feed point (the third feed point) on the bottom board 1 toward the area where the radio frequency circuit 21 is The position of the feed point) is extended from the third feed point via the hole to the top layer board 2 and then connected to the radio frequency circuit 21; the middle feed point (second feed point) of the mid-feed antenna unit 112 is directly extended to the top layer through the hole The board 2 is connected with the radio frequency circuit 21 afterward.

In this embodiment, the feed transmission unit 12 is a feed transmission line, that is, the feed point of the antenna unit 11 first passes through a section of feed transmission line and then transfers to the position of the target feed point, and then directly extends from the target feed point through the hole Connect to the feeding point of the radio frequency circuit 21 after reaching the top layer board 2 . Referring to Fig. 1, the first feed point of the end-fed antenna unit 111 and the second feed point of the center-fed antenna unit 112 are arranged on both sides of the bottom plate 1 of the printed circuit board (PCB printed board) to handle radar high-frequency The radio frequency circuit 21 of the signal is laid out in the lower right corner area of the top layer board 2 of the PCB printed board. A very long transmission line connected to the feeding point of the radio frequency circuit 21 will cause complicated routing of the transmission line on the back of the printed board, and even interfere with the entire circuit layout of the printed board, making the antenna structure not compact. In this embodiment, by setting the feed transmission unit 12 on the bottom board 1, the feed transmission unit 12 transitions the feed transmission of the first feed point of the end-fed antenna unit 111 to the third feed point of the bottom board 1, Furthermore, through the hole to the top layer board 2, it is connected to the feed point of the radio frequency circuit 21, so that the feed transmission wiring between the feed port of the end-fed antenna unit 111 and the radio frequency circuit 21 is simple, and the structure of the antenna device is compact.

In this embodiment, each group of antenna units 11 corresponds to an end-fed antenna unit 111 and a center-fed antenna unit 112, so that the transmitting antenna and the receiving antenna adopt different feeding methods. 12 Extend the first feeding point of the end-fed antenna unit 111 to the third feeding point on the bottom board 1 toward the area where the radio frequency circuit 21 is located, and extend from the third feeding point directly to the top board 2 through a hole. To feed the antenna unit 112, the feed point via hole is directly extended to the top layer board 2, and the transmission line between the antenna unit 11 and the radio frequency circuit 21 can be shortened by combining different feeding methods, so that the transmission wiring is simple.

In this embodiment, the position of the transmission terminal of the feed transmission unit 12 is such that when the via hole of the target feed point is extended to the top layer board 2, it can be located in the designated area where the radio frequency circuit 21 is located. The holes extend to the top plate 2. As shown in Figure 1, the position of the transmission terminal of the feed transmission unit 12 in this embodiment is the position of the third feed point, and the third feed point extends to the top-layer board 2 through the hole and is located at the designated place where the radio frequency circuit 21 is located. In the area A, the area A is a rectangular area with the position of the radio frequency circuit 21 as the center, so that the transmission and wiring from the third feeding point to the radio frequency circuit 21 can be facilitated, and the length of the transmission line can be shortened. The size and structure of area A can be set according to actual needs.

In this embodiment, the center-fed antenna unit 112 and the radio frequency circuit 21 are arranged on the same side of the printed circuit board, so that the transmission distance from the center-fed antenna unit 112 to the radio frequency circuit 21 is short, which is convenient for wiring. In combination with the above-mentioned end-fed antenna unit After 111 is extended to the third feed point through the feed transmission unit 12, it is extended from the third feed point to the top board 2 and connected to the radio frequency circuit 21, which can make the overall transmission line of the antenna device short and the transmission wiring simple.

In this embodiment, the position of the center-fed antenna unit 112 is such that when the feed point of the center-fed antenna unit 112 is extended to the top layer board 2 through the via hole, it can be located in the designated area where the radio frequency circuit 21 is located. The center-fed antenna unit 112 Specifically, the feeding point directly extends to the top layer board 2 through the metallized via hole and then connects with the radio frequency circuit 21 . As shown in Figure 1, the feed point (second feed point) of the antenna unit 112 in this embodiment, the via hole extends to the top layer board 2 and is located in the designated area A where the radio frequency circuit 21 is located, where the area A is as follows The position of the radio frequency circuit 21 is a rectangular area at the center, so that transmission and wiring from the second feed point to the radio frequency circuit 21 can be facilitated, and the length of the transmission line can be shortened.

With the above structure, each group of antenna units 11 corresponds to an end-fed antenna unit 111 and a center-fed antenna unit 112. The end-fed antenna unit 111 extends the feed point to the direction of the radio frequency circuit 21 through the feed transmission unit 12, and the center-fed antenna unit 112 is arranged on the same side as the radio frequency circuit 21, and at the same time, the position of the target feed point of the transmission terminal of the feed transmission unit 12 and the feed point of the mid-feed antenna unit 112 is located where the radio frequency circuit 21 is after the hole extends to the top layer board 2 In the specified area, the length of the transmission line from the antenna unit 11 on the bottom layer to the radio frequency circuit 21 on the top layer can be shortened to the greatest extent, greatly reducing the complexity of transmission wiring, thereby making the antenna device compact in structure, reducing the volume of the antenna device and the required cost.

In this embodiment, the antennas in each group of antenna units 11 are specifically array antennas. The array antennas can be patch antenna array antennas or slot antenna arrays. The polarization mode of the array element can be oblique polarization, horizontal polarization, vertical polarization or circular polarization, etc.; the beam of the radiator is specifically a narrow beam, and the beam is specifically set to the half-power lobe width in the azimuth plane is less than the first preset threshold (20 degrees in this embodiment), and the half-power lobe width of the beam in the elevation plane is less than the second preset threshold (15 degrees in this embodiment), so that when a higher antenna gain is obtained At the same time, it can also make the radar detection width not spread too wide when it is far away from the radar, which can meet the application requirements of narrow beam and high gain required for regional perimeter protection.

In this embodiment, the beams of each group of antenna units 1 are the main beams of the radiation pattern, and the other beams except the main beam are side lobes. The maximum level of the signal is smaller than the third preset threshold (specifically 18dB in this embodiment), so as to greatly reduce the interference from other targets outside the main beam.

As shown in Figures 2, 3, and 4, the end-fed antenna unit 111 in this embodiment includes a first main feed network A11 in the horizontal direction, a plurality of first sub-feed networks A12 with the same structure and in a vertical direction, and the first sub-feed network A12 in the vertical direction. The left and right parts of a main feed network A11 are symmetrical with respect to the end feed point (the first feed point), and the microstrip antenna array elements in the upper part and the microstrip antenna array elements in the lower part of the first sub-feed network Element symmetry. This embodiment specifically includes a first main feed network A11 in the horizontal direction and five second sub-feed networks A12 with the same structure in the vertical direction. Since the antenna array adopts the end-fed feeding mode, the first main feed network A11 is left-right symmetrical about the first feed point; the microstrip antenna array element has good radiation performance, low profile and low cost, and is easy to integrate with high-frequency signal processing circuits. The end-fed antenna unit 111 of this embodiment specifically includes 40 microstrip antennas Array elements, each microstrip antenna array element is connected to each other through a microstrip line, and finally connected to the first main feed network A11, the energy fed from the feed point of the end-fed antenna unit 111 is distributed to the 40 microstrip antenna array elements, and radiate out in the form of horizontal polarization. The pattern of the horizontal plane is mainly determined by the distribution ratio of the first main feed network A11, and the pattern of the vertical plane is mainly determined by the distribution ratio of the first sub-feed network. The distribution ratio of A12 is determined, and the sidelobe levels on both surfaces are taken as -20dB on average in this embodiment. The number of microstrip antenna elements in the rectangular array structure of the end-fed antenna unit 111 can also be specifically set according to parameters such as the main lobe width and gain of the radar.

As shown in Fig. 3, the first main feeding network A11 is described in detail by taking the left half A21 of the first main feeding network A11 as an example. A21 transforms the energy of the first feeding point by the The specified ratio is distributed to the sub-feed network A211~A213 in the same phase. At the same time, a period of impedance matching is performed before the first feed point enters the first main feed network A11, and the input impedance matching at the first feed point is kept as specified. Size (50 ohms in this embodiment), the specified current ratio distributed to the three sub-feed networks can be calculated according to the sidelobe level (-20dB in this embodiment) according to Taylor's formula, from left to right The distribution ratio of the sub-feeding network is specifically 0.54:0.83:1.

As shown in Figure 4, the first sub-feeding network A12 of this embodiment has 8 microstrip antenna elements and impedance transformation lines in total, wherein each antenna element is connected in series and is symmetrical up and down, and the antenna element is both a radiation element and a It is an impedance transformation line, which can not only radiate electromagnetic wave energy but also play the role of impedance matching. Taking the lower part A13 of the first sub-feed network A12 as an example, A13 distributes the energy input from the array port of the first main feed network A11 to the four antennas in a specified proportion and in phase through impedance transformation lines A121-A124 In the array element, the specified current ratio allocated to the four antenna array elements can be calculated according to the sidelobe level (in this embodiment, -20dB) according to the Taylor formula. The distribution ratio of the sub-feed network from bottom to top Specifically, it is 0.54:0.67:0.86:1.

As shown in Figures 2, 5, and 6, the feed antenna unit 112 in this embodiment includes a second main feed network B11 in the horizontal direction, a plurality of second sub-feed networks B12 with the same structure and a vertical direction, and the second sub-feed network B12 in the vertical direction. The left and right parts, upper and lower parts of the main feed network B11 are respectively symmetrical with respect to the middle feed point (second feed point), and the microstrip antenna array element in the upper part of the second sub-feed network B12 and the microstrip antenna in the lower part The array elements are symmetrical and have opposite phases, and a transmission line is provided at the feed-in point of the upper part of the second sub-feed network to keep the upper part and the lower part of the second sub-feed network fed in the same phase. This embodiment specifically includes one main feed network B11 in the horizontal direction and five sub-feed networks B12 with the same structure in the vertical direction. The points are symmetrical up and down, left and right, and the second sub-feed network B12 is up-and-down symmetrical. At the same time, the phases of the upper and lower parts of the second sub-feed network B12 are opposite, and a semi-conductive wavelength transmission line is added at the feeding point of the upper part. To keep the upper and lower antenna array elements fed in the same phase; in this embodiment, the feed antenna unit 112 is consistent with the end-fed antenna unit 111, and specifically includes 40 microstrip antenna array elements, and each microstrip antenna array element passes through a microstrip line are connected to each other, and finally connected to the second main feed network B11, the energy fed in from the second feed point of the mid-feed antenna unit 112 is distributed to the 40 microstrip antenna array elements according to the calculated ratio, and is horizontally The polarization mode is radiated out, the pattern of the horizontal plane is mainly determined by the distribution ratio of the second main feed network B11, and the pattern of the vertical plane is mainly determined by the distribution ratio of the second sub-feed network B12. In this embodiment, the two planes The sidelobe level on the average is taken as -20dB. The number of microstrip antenna elements in the rectangular array structure of the center-fed antenna unit 112 can also be specifically set according to parameters such as the main lobe width and gain of the radar.

As shown in Figure 5, taking the left half part B21 of the second main feed network B11 as an example, B21 distributes the energy of the second feed point to three sub-feeders in a specified proportion and in phase through impedance transformation lines B2121-B2124 In the electrical network, and the input impedance matching at the second feed point is a specified size (in this embodiment, 50 ohms is used), the specified current ratio distributed to the three sub-feed networks can be determined according to the sidelobe level (in this embodiment Take -20dB for example) Calculated according to Taylor's formula, the distribution ratio of the feeder network from left to right is specifically 0.54:0.83:1.

As shown in Figure 6, the second sub-feeding network B12 of this embodiment specifically has 8 microstrip antenna array elements and impedance transformation lines, the upper part of the 4 antenna array elements are connected in series, and the lower part of the 4 antenna array elements are connected in series, The antenna array elements in the upper and lower parts are connected in parallel and are symmetrical. The antenna array elements are not only radiation array elements but also impedance transformation lines, so that they can not only radiate electromagnetic wave energy but also play an impedance matching role. Taking the upper part B13 of the second sub-feed network B12 as an example, B13 distributes the energy input from the array port of the second main feed network B11 to the four antennas in a specified proportion and in phase through impedance transformation lines B121-B124 In the array element, the specified current ratio allocated to the four antenna array elements can be calculated according to the sidelobe level (-20dB in this embodiment) according to the Taylor formula, and the distribution ratio of the sub-feed network from bottom to top is specific It is 0.54:0.67:0.86:1.

7 shows the radiation pattern of the end-fed antenna unit 111 obtained in the specific embodiment of the present invention, wherein the solid line represents the radiation pattern of the elevation plane, and the dotted line represents the radiation pattern of the azimuth plane. It can be seen from the figure that the half-power lobe width of the radiation pattern of the antenna device adopting the above-mentioned structure in the elevation plane can reach 13.5°, the side lobe level is less than -17dB, and the half-power wave width of the radiation pattern of the azimuth plane is less than -17dB. The lobe width is 20º, and the sidelobe level is less than -23dB.

Fig. 8 shows the radiation pattern of the mid-fed antenna unit 112 obtained in the specific embodiment of the present invention, wherein the solid line represents the radiation pattern of the elevation plane, and the dotted line represents the radiation pattern of the azimuth plane. It can be seen from the figure that the half-power lobe width of the radiation pattern of the antenna adopting the above-mentioned structure in the elevation plane can reach 12.5°, the side lobe level is less than -19.7dB, and the half-power wave width of the radiation pattern of the azimuth plane is The lobe width is 19.7º, and the sidelobe level is less than -19.2dB. That is to say, the above-mentioned antenna device of this embodiment can make the antenna structure compact, the transmission wiring is simple, the device volume and cost are small, and at the same time, it can ensure that the antenna has narrow beam, high gain and small side lobe, and meets the application requirements of regional perimeter protection, etc. .

In this embodiment, a high-frequency substrate is further provided on the bottom board 1 , and the antenna unit 11 and the feeding transmission unit 12 are all printed on the high-frequency substrate.

The above-mentioned antenna device for radar sensors in this embodiment is suitable for millimeter-wave radar sensors, especially for anti-collision millimeter-wave height sensors.

The above are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims (9)

1. An antenna device for a radar sensor, comprising a printed circuit board, more than one group of antenna units (11) are arranged on a bottom layer board (1) of the printed circuit board, each group of antenna units (11) comprises a receiving antenna and a transmitting antenna, and a radio frequency circuit (21) is arranged on a top layer board (2) of the printed circuit board, and the antenna device is characterized in that: each group of antenna units (11) is respectively arranged on two sides of the bottom plate (1), a feed transmission unit (12) is further arranged on the bottom plate (1), and the feed transmission unit (12) extends a feed point of the antenna unit (11) to a position of a target feed point on the bottom plate (1) towards the direction of the area where the radio frequency circuit (21) is located, and the feed point extends to the top plate (2) from a target feed point through hole and then is connected with the radio frequency circuit (21); each group of antenna units (11) is respectively and correspondingly an end feed antenna unit (111) formed by an end feed antenna and a middle feed antenna unit (112) formed by a middle feed antenna, a feed point of the end feed antenna unit (111) is connected with the feed transmission unit (12), a feed point via hole of the middle feed antenna unit (112) extends to the top layer board (2) and then is connected with the radio frequency circuit (21), and a beam of a radiator of each group of antenna units (11) is a narrow beam.

2. An antenna device for a radar sensor according to claim 1, characterized in that: when the transmission terminal of the feed transmission unit (12) is located at a position where the target feed point via hole extends to the top board (2), the feed transmission unit can be located in a designated area where the radio frequency circuit (21) is located.

3. An antenna device for a radar sensor according to claim 2, characterized in that: the end-fed antenna unit (111) comprises a plurality of end-fed array antennas connected in parallel, and the center-fed antenna unit (112) comprises a plurality of center-fed array antennas connected in parallel.

4. An antenna device for a radar sensor according to claim 1 or 2 or 3, characterized in that: the center feed antenna unit (112) is arranged on the same side of the printed circuit board as the radio frequency circuit (21).

5. An antenna device for a radar sensor according to claim 4, characterized in that: the position of the center-feed antenna unit (112) is that the feed point via hole of the center-feed antenna unit (112) extends to the top board (2)

Can be located in a designated area where the radio frequency circuit (21) is located.

6. An antenna device for a radar sensor according to claim 1 or 2 or 3, characterized in that: the end feed antenna unit (111) comprises a first main feed network in the horizontal direction and a plurality of first sub feed networks which have the same structure and are in the vertical direction, the left part and the right part of the first main feed network are symmetrical relative to the end feed point, and microstrip antenna elements at the upper part and microstrip antenna elements at the lower part of the first sub feed network are symmetrical.

7. An antenna device for a radar sensor according to claim 6, characterized in that: the middle feed antenna unit (112) comprises a second main feed network in the horizontal direction and a plurality of second branch feed networks in the vertical direction, wherein the left part, the right part, the upper part and the lower part of the second main feed network are respectively symmetrical relative to the middle feed point, microstrip antenna elements at the upper part of the second branch feed network are symmetrical and opposite in phase with microstrip antenna elements at the lower part, and a transmission line is further arranged at the feed position at the upper part of the second branch feed network so as to keep in-phase feed of the upper part and the lower part of the second branch feed network.

8. An antenna device for a radar sensor according to any one of claims 1-3, characterized in that: the feed transmission unit (12) is a feed transmission line.

9. An antenna device for a radar sensor according to any one of claims 1-3, characterized in that: the high-frequency substrate is further arranged on the bottom plate (1), and the antenna unit (11) and the feed transmission unit (12) are printed on the high-frequency substrate.

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