Antenna structure, printed circuit board and radar sensor

Abstract

The embodiment of the invention provides an antenna structure, a printed circuit board and a radar sensor, which are strong in anti-interference capability and not easy to shake. The antenna structure is characterized in that a radiation layer comprises at least one radiation unit, the radiation unit is a dipole unit, and the polarization surface of the radiation unit and the wide beam surface of a directional diagram are not in the same horizontal direction; the feed layer is used for transmitting an input signal to each radiation unit, so that the radiation units emit electromagnetic wave signals. The antenna structure provided by the embodiment of the invention is smaller in size and high in directional diagram stability.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to, but are not limited to, the field of antenna packaging technology, and in particular, to an antenna structure, a printed circuit board, and a radar chip. Background Art

[0002] In recent years, automobiles have been developing towards intelligence and electrification. With the upgrade and evolution of the L2-level autonomous driving functions of automobiles, such as lane change assistance, automatic cruise, automatic parking, and emergency automatic braking, the vehicle installation rate of millimeter-wave corner radars has also increased rapidly. In order to meet the application requirements such as blind spot detection and collision avoidance warning, the corner radar needs to have the characteristic of a wide field of view (FOV). To meet the wide FOV requirement of the millimeter-wave corner radar, a wide-beam antenna needs to be used in the radar radio frequency front end. At the same time, for the stability of the radar detection performance, the antenna pattern needs to have strong stability and not be affected by the surrounding environment.

[0003] Currently, in order to achieve a wide-beam pattern, the antenna usually adopts the form of beamforming. However, the current wide-beam antenna is large in size and its pattern is easily affected. Summary of the Invention

[0004] Embodiments of the present disclosure provide an antenna structure, a printed circuit board, and a radar sensor, which have strong anti-interference ability and are not prone to jitter.

[0005] On the one hand, embodiments of the present disclosure provide an antenna structure, including: a feeding layer and a radiation layer arranged in a stacked manner, wherein the radiation layer includes at least one radiation unit, the radiation unit is a dipole unit, and the polarization plane of the radiation unit is not in the same horizontal direction as the wide-beam plane of its pattern; the feeding layer is used to transmit the input signal to each radiation unit for the radiation unit to emit an electromagnetic wave signal.

[0006] In an exemplary embodiment, each radiation unit includes two radiation branches located on the same metal layer, the two radiation branches are respectively connected to the feeding layer for feeding, the two radiation branches are symmetrically arranged and arranged along a first direction, and the extending direction of the radiation branch is the first direction or the opposite direction of the first direction.

[0007] In an exemplary embodiment, the current directions on the two radiation branches in the same radiation unit are the same, and the current directions on the radiation branches of different radiation units belonging to the same antenna structure are the same.

[0008] In an exemplary embodiment, when there are two or more radiation units, the radiation units are arranged in a first direction. In each radiation unit, one of the two radiation branches extends in the first direction, and the other extends in the opposite direction of the first direction. The current directions on all the radiation units are in the first direction or the opposite direction of the first direction.

[0009] In an exemplary embodiment, the maximum distance between the two radiation branches in one radiation unit is λ1 / 2, where λ1 is the air wavelength.

[0010] In an exemplary embodiment, the feeding layer is of SIW structure or microstrip line structure.

[0011] In an exemplary embodiment, when the feeding layer adopts an SIW structure, the feeding layer includes a first metal layer, a second metal layer, and a dielectric layer between the first metal layer and the second metal layer. Metal posts are provided on the dielectric layer and are respectively connected to the first metal layer and the second metal layer. The metal posts and the first metal layer and the second metal layer form a resonant cavity. The first metal layer is a grounding layer, and a slit communicating with the resonant cavity is provided at the corresponding position of each radiation unit on the second metal layer. Each radiation unit is fed through the slit.

[0012] In an exemplary embodiment, the two radiation branches on one radiation unit are connected to both sides of the corresponding slit on the second metal layer through two metal connectors, and one radiation branch is connected to one metal connector in a one-to-one correspondence.

[0013] In an exemplary embodiment, the metal connector is connected to the radiation branch at the edge of the radiation branch.

[0014] In an exemplary embodiment, the two metal connectors are symmetrically arranged on both sides of the slit with the slit as the center, and the two radiation branches respectively connected to the two metal connectors in a one-to-one correspondence extend away from the slit.

[0015] In an exemplary embodiment, the center-to-center spacing of adjacent slits is λ2, where λ2 is the dielectric wavelength of the dielectric layer.

[0016] In an exemplary embodiment, when the feeding layer adopts a microstrip line structure, the feeding layer includes a first metal layer, a second metal layer, and a dielectric layer between the first metal layer and the second metal layer. The first metal layer is provided with a feeder for feeding each radiation unit, and the second metal layer is a grounding layer.

[0017] In an exemplary embodiment, the two radiation branches on one radiation unit are connected to the feeder on the first metal layer through two metal connectors, and one radiation branch is connected to one metal connector in a one-to-one correspondence.

[0018] In an exemplary embodiment, the metal connector is connected to the radiating stub at the edge of the radiating stub.

[0019] In an exemplary embodiment, two radiating stubs in a radiating element are symmetrically arranged, the extending direction of the radiating stub is the same as or opposite to the arranging direction of the radiating elements, two metal connectors respectively corresponding to and connected to the two radiating stubs in a radiating element are symmetrically arranged with respect to the symmetry axis of the two radiating stubs, or the connection positions of the two metal connectors and the two radiating stubs are the same.

[0020] In an exemplary embodiment, the feeder for feeding a radiating element includes a main feeder and a feeder branch, the extending direction of the main feeder is the same as the arranging direction of the radiating elements, the feeder branch connects the main feeder and the metal connector to enable the main feeder to feed the radiating element, the length of the main feeder corresponding to each radiating element is Nλ3, where N is a positive integer greater than or equal to 1, and λ3 is the dielectric wavelength of the dielectric layer.

[0021] On the other hand, an embodiment of the present disclosure further provides a printed circuit board including the foregoing antenna structure.

[0022] On yet another aspect, an embodiment of the present disclosure further provides a radar sensor chip including the foregoing printed circuit board.

[0023] In the embodiment of the present disclosure, by using a dipole unit whose polarization plane and wide beam pattern plane of the radiation pattern are not in the same horizontal direction as the radiating element, the radiation pattern of the antenna is not easily affected by the surrounding environment and jitters. Compared with the wide beam scheme described above, the antenna structure of the embodiment of the present disclosure has a smaller size and high radiation pattern stability.

[0024] Other features and advantages of the present application will be described in the subsequent specification, and part of them will become obvious from the specification, or will be understood by implementing the present application. Other advantages of the present application can be realized and obtained by the solutions described in the specification and the drawings. Description of the Drawings

[0025] The drawings are used to provide an understanding of the technical solution of the present application, and constitute a part of the specification. They are used together with the embodiments of the present application to explain the technical solution of the present application, and do not constitute a limitation to the technical solution of the present application.

[0026] Figure 1 Schematic diagram of an antenna structure for implementing a wide beam using a feeding power divider;

[0027] Figure 2 Schematic diagram of an antenna structure for implementing a wide beam by adjusting the structure of the antenna element;

[0028] Figure 3Schematic diagram of an antenna structure according to an embodiment of the present disclosure;

[0029] Figure 4A Top view of an antenna structure according to an embodiment of the present disclosure;

[0030] Figure 4B is Figure 4A Cross-sectional view taken along the AA direction in

[0031] Figure 4C is Figure 4A Partial perspective view in

[0032] Figure 5 Horizontal plane radiation pattern of a wide-beam dipole antenna array according to an embodiment of the present disclosure;

[0033] Figure 6 Schematic diagram of a wide-beam dipole array antenna provided in this example disposed on a large-sized PCB;

[0034] Figure 7 Comparison diagram of horizontal plane radiation patterns when the antenna structure of this embodiment is disposed on PCB boards of different sizes;

[0035] Figure 8A Top view of another antenna structure according to an embodiment of the present disclosure;

[0036] Figure 8B is Figure 8A Cross-sectional view taken along the BB direction in

[0037] Figure 9 Top view of yet another antenna structure according to an embodiment of the present disclosure;

[0038] Figure 10A Top view of a radiation element;

[0039] Figure 10B Top view of another radiation element;

[0040] Figure 10C Top view of yet another radiation element;

[0041] Figure 11 Schematic diagram of a radar sensor provided by an embodiment of the present disclosure;

[0042] Figure 12 Schematic diagram of another radar sensor provided by an embodiment of the present disclosure. Detailed implementation manners

[0043] The present disclosure describes multiple embodiments, but the description is exemplary rather than restrictive, and it will be apparent to those of ordinary skill in the art that there can be more embodiments and implementation solutions within the scope encompassed by the embodiments described in the present disclosure. Although many possible combinations of features are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically restricted, any feature or element of any embodiment can be used in combination with any other feature or element in any other embodiment, or can replace any other feature or element in any other embodiment.

[0044] In the description of the present disclosure, unless otherwise specified, "multiple" has the same meaning as more than two, and "more than two" includes "two".

[0045] Beamforming is a signal processing technique used to change or optimize the radiation or reception characteristics of a transmission or reception antenna system. It adjusts the phase and amplitude of multiple antenna elements so that the transmitted (or received) signal forms a directional beam in a specific direction, thereby achieving enhanced signal transmission distance, reduced interference, and improved system capacity and performance. Beamforming can be implemented using a feed power divider or by adjusting the structure of the antenna unit. The antenna structure for implementing a wide beam using a feed power divider is as Figure 1 shown. By adjusting the size of the power divider, there are different phase and amplitude ratios between the three antenna branches, thereby achieving a wide beam pattern. The antenna structure for implementing a wide beam by adjusting the antenna unit structure is as Figure 2 shown. By adjusting the size of the antenna unit to generate reverse current, a wide beam antenna is achieved. The above two forms of wide beam antennas have large sizes, and at the same time, their patterns are easily affected by the surrounding environment such as the size of the printed circuit board (PCB), metal devices, etc., resulting in jitter and affecting the radar detection performance.

[0046] The inventors analyzed the above solutions and found that for the wide beam millimeter-wave radar antenna in the above solutions, since the wide beam plane of its pattern and the antenna polarization plane are in the same horizontal plane, the antenna pattern is easily affected by the surrounding environment and undergoes jitter and deformation.

[0047] Therefore, an embodiment of the present disclosure provides an antenna structure, as Figure 3 shown, including a stacked feed layer 10 and radiation layer 20. The radiation layer 20 includes at least one radiation unit 21, the radiation unit 21 is a dipole unit, and the polarization plane of the radiation unit 21 is not in the same horizontal direction as its pattern wide beam plane; the feed layer 10 is used to transmit the input signal to each radiation unit 21 for the radiation unit 21 to emit electromagnetic wave signals.

[0048] In the embodiments of the present disclosure, by using a dipole unit whose polarization plane and wide beam plane of the radiation pattern are not in the same horizontal direction as the radiation unit, the radiation pattern of the antenna is not easily affected by the surrounding environment and jitters. Compared with the wide beam scheme described above, the antenna structure size of the embodiments of the present disclosure is smaller, and the radiation pattern has high stability.

[0049] In an exemplary embodiment, the radiation unit may adopt the following structure: Each radiation unit 21 includes two radiation branches 211 located on the same metal layer. The two radiation branches 211 are respectively connected to the feeding layer 10 for feeding. The two radiation branches 211 are symmetrically arranged and arranged along a first direction ( Figure 3 the Y direction in the figure), and the extending direction of the radiation branch 211 is the first direction or the opposite direction of the first direction. The radiation branch 211 is used to emit electromagnetic wave signals. The above two radiation branches 211 form a dipole antenna unit. By using a dipole as the antenna radiation unit, since the polarization plane of the dipole antenna and its wide beam plane of the radiation pattern are not in the same horizontal direction, its radiation pattern is not easily affected by the surrounding environment and jitters, and has high stability.

[0050] In an exemplary embodiment, the current directions on the two radiation branches in the same radiation unit are the same, and the current directions on the radiation branches of different radiation units belonging to the same antenna structure are also the same. Setting the currents on all radiation branches to flow in the same direction can improve the radiation power.

[0051] In an exemplary embodiment, when there are two or more radiation units, the radiation units are arranged along the first direction (the Y direction in the figure). One of the two radiation branches in each radiation unit extends in the first direction, and the other extends in the opposite direction of the first direction. The current directions on all radiation units are the first direction or the opposite direction of the first direction. Setting multiple radiation units can improve the radiation efficiency and enhance the signal coverage.

[0052] In an exemplary embodiment, the feeding layer may adopt a substrate integrated waveguide (Substrate Integrated Waveguide, SIW) structure or be implemented by a microstrip line structure. In other examples, it may also be other structures as long as it can realize feeding to the radiation unit.

[0053] The following will be described separately.

[0054] Taking the feeding layer as an SIW structure as an example, it can be combined with Figures 4A to 4C, the feeding layer includes a first metal layer L1, a second metal layer L2, and a dielectric layer between the first metal layer and the second metal layer. The dielectric layer is provided with metal posts 111 respectively connected to the first metal layer L1 and the second metal layer L2. The metal posts 111 and the first metal layer L1 and the second metal layer L2 form a resonant cavity, and the first metal layer L1 is a grounding layer; the radiation layer is arranged on the side of the second metal layer away from the first metal layer, and a dielectric layer is also provided between the radiation layer and the second metal layer. The second metal layer L2 is provided with a slit 112 communicating with the resonant cavity at the corresponding position of each radiation unit 21, for providing an energy coupling path, and the radiation unit 21 arranged at the slit 112 can be fed through the slit 112.

[0055] In an exemplary embodiment, two radiation branches 211 on one radiation unit 21 are connected to both sides of the corresponding slit of the second metal layer L2 through two metal connectors 12, and one radiation branch 211 is connected to one metal connector 12 in a one-to-one correspondence. In the figure, each radiation branch 211 is connected to the feeding layer 10 through a metal connector 12. The metal connector 12 is used to receive the electrical signal of the feeding layer 10 and transmit it to the radiation branch 211. In the figure, the metal connector 12 is taken as an example of a metal post. In this example, the cross-section of the metal connector is circular. In other examples, the cross-section of the metal connector can be other shapes such as oval, square, rectangle, etc., and the present disclosure does not limit this. Specifically, a dielectric layer is provided between the second metal layer L2 and the radiation layer L3 of the feeding layer, and the metal connector is arranged in the dielectric layer. Exemplarily, in order to achieve in-phase slits and the dipole unit spacing is small, it is preferred that a material with a larger DK value can be used between the second metal layer and the third metal layer. For example, it can be set that 1λg≈0.5 - 0.8λ, where λg is the dielectric wavelength between the second metal layer and the third metal layer, and λ is the air wavelength in the resonant cavity.

[0056] Since the metal connector 12 is configured to transmit the electrical signal of the feeding layer 10, in order to ensure that the current directions on the two radiation branches 211 are the same, the metal connector 12 can be arranged to be connected to the radiation branch 211 at the edge of the radiation branch 211. For example, the orthographic projection of the metal connector 12 on the radiation branch 211 is located at the edge of the radiation branch.

[0057] In an exemplary embodiment, two metal connectors 12 respectively connected to two radiation branches 211 in one radiation unit 21 are symmetrically arranged on both sides of the slit with the slit as the center, and the two radiation branches respectively connected to the two metal connectors extend in directions away from the slit (see Figure 4A ).

[0058] In an exemplary embodiment, when multiple radiation units are provided, the center-to-center spacing of adjacent slots is λ / 2, where λ / 2 is the dielectric wavelength of the dielectric layer (i.e., λg in the previous text). This can ensure that the slots are in phase, and further ensure that the current directions on the dipole units are consistent, preventing grating lobes from appearing in the radiation pattern due to excessive slot spacing.

[0059] Taking the feeding layer as a microstrip line structure as an example, it can be combined with Figures 8A to 10C , the feeding layer includes a first metal layer L1, a second metal layer L2, and a dielectric layer between the first metal layer L2 and the second metal layer L2. The first metal layer L1 is provided with feed lines for feeding each radiation unit 21, and the second metal layer L2 is a ground layer. In this example, signal transmission is carried out through metal wires, and the wire arrangement is more flexible. Since there is no need to set up a resonant cavity, the overall size can be smaller.

[0060] Exemplarily, two radiation branches 211 on one radiation unit 21 are connected to the feed line of the first metal layer L1 through two metal connectors 12, and one radiation branch 211 is connected to one metal connector 12 in a one-to-one correspondence.

[0061] Since the metal connector 12 is configured to transmit the electrical signal of the feeding layer 10, in order to ensure that the current directions on the two radiation branches 211 are the same, the metal connector 12 can be set to be connected to the radiation branch 211 at the edge of the radiation branch 211.

[0062] In an exemplary embodiment, the two radiation branches 211 in one radiation unit 21 are symmetrically arranged, and the extending direction of the radiation branch 211 is the same as or opposite to the arrangement direction of the radiation unit 21. For example, the radiation unit 21 is arranged in the first direction, and the radiation branch 211 extends in the first direction or in the opposite direction of the first direction. The two metal connectors 12 respectively corresponding to the two radiation branches 211 in one radiation unit 21 are symmetrically arranged with respect to the symmetry axis (the symmetry axis along the X direction) of the two radiation branches 211, or the connection positions of the two metal connectors and the two radiation branches are the same, that is, the connection position of one metal connector and one radiation branch is the same as the connection position of the other metal connector and the other radiation branch. For example, each radiation branch has a first edge and a second edge in the Y direction. The first edge of the first radiation branch is far from the above symmetry axis, the second edge is close to the above symmetry axis, the first edge of the second radiation branch is close to the above symmetry axis, and the second edge is far from the above symmetry axis. The two metal connectors 12 are both located at the first edge of the radiation branch to which they are connected, or both are located at the second edge of the radiation branch to which they are connected.

[0063] In an exemplary embodiment, the feeder for feeding a radiation unit 21 includes a main feeder and a feeder branch. The extending direction of the main feeder is the same as the arrangement direction of the radiation units (for example, both are the first direction). The feeder branch connects the main feeder and the metal connector to feed the main feeder to the radiation unit. The length of the main feeder corresponding to each radiation unit is Nλ3, where N is a positive integer greater than or equal to 1, and λ3 is the dielectric wavelength of the dielectric layer. The dielectric layer in this example may be the same as or different from the dielectric layer in the SIW structure, that is, λ3 may be equal to λ2.

[0064] Regardless of the structure of the feeding layer, in order to ensure better electromagnetic wave transmission effect and ensure the stability of the current direction, the maximum distance between two radiation branches in a radiation unit is preferably λ1 / 2, where λ1 is the air wavelength.

[0065] Hereinafter, taking the feeding layer adopting the SIW structure as an example for illustration. In this example, a plurality of dipole antenna units are arranged to form a dipole array to realize a wide-beam antenna. In this example, the radiation unit 21 includes a plurality of dipole antenna units, and each dipole antenna unit includes two radiation branches. In this example, the antenna structure includes three metal layers, and a dielectric layer is filled between the three metal layers. Among the three metal layers, the first metal layer L1, the second metal layer L2, and the metal posts between the first metal layer L1 and the second metal layer L2 form an SIW structure, which belongs to the feeding layer. The third metal layer L3 is the radiation layer, on which dipole antenna units are arranged. The antenna structure of this example will be described in detail below.

[0066] Figure 4A This is a top view of the antenna structure of this example. Figure 4B For Figure 4A the sectional view taken along the AA direction in Figure 4C For Figure 4A a partial perspective view. In this example, the feeding layer is an SIW structure. As Figures 4A to 4C shown, the L1 layer is a metal ground layer. A plurality of metal posts 111 respectively connected to the L1 layer and the L2 layer are arranged between the L1 layer and the L2 layer. The metal posts 111 and the L1 layer and the L2 layer form a resonant cavity for receiving electrical signals. The outside of the resonant cavity between the L1 layer and the L2 layer is filled with a dielectric layer, which can use the same dielectric as the dielectric layer between the L2 layer and the L3 layer. Figure 4AThe In position in the middle is the signal input port, and the top of the antenna structure in the Y direction is the short - circuit end. To feed the radiation unit, a slot 112 is opened at the corresponding position of each radiation unit in the L2 layer. The slot 112 cuts the surface current of the SIW (i.e., the surface of the L2 layer), couples the energy to the metal connector 12, and then feeds it to the radiation branch 211 of the dipole antenna unit in the L1 layer. In this example, the shape of the slot 112 is rectangular. In other examples, the slot can be other shapes such as square, parallelogram, trapezoid, circle, etc., as long as it can perform coupling feeding. The present disclosure does not limit this. In this example, the maximum distance D1 between the two radiation branches 211 in one radiation unit 21 is λ1 / 2, where λ1 is the air wavelength. Exemplarily, the center - to - center spacing D2 of adjacent slots is λ2, where λ2 is the dielectric wavelength of the dielectric layer between the L2 and L3 layers. This is because in order to ensure that the current directions on each dipole unit are the same, the slot needs to cut the in - phase current. And in order to ensure that the slots are in phase, the spacing between adjacent slots is set to λ2. If the slot spacing is too large, it may cause grating lobes to appear in the radiation pattern. In order to achieve in - phase slots and a small dipole unit spacing, it is preferred that a material with a larger DK value can be used between the L2 and L3 layers. For example, λ2 can be 1.25 to 2 times the air wavelength.

[0067] In this example, the radiation unit 21 is a dipole antenna unit, and one dipole antenna unit includes two radiation branches 211. To obtain a better coupling effect, the two metal connectors 12 connecting the dipole antenna unit 21 and the feeding layer are respectively arranged at the edges of the slot 112, that is, the two metal connectors 12 are arranged close to the slot 112. The two metal connectors 12 can be symmetrically arranged with the slot as the center. The radiation branch 211 is located in the L3 layer. The metal connector 12 can be located at one edge of the radiation branch 211 so that the current on this radiation branch is in the same direction. As Figure 4A shown, the two radiation branches 211 are symmetrically arranged with the slot as the center. In this example, the radiation branches are strip - shaped (rectangular), are respectively located on both sides of the slot 112, and extend away from the slot in the direction away from the position connected to the metal connector. In other examples, the radiation branches can be other shapes as long as the current directions on the radiation branches are the same. The maximum distance between the two radiation branches in one radiation unit is λ1 / 2, where λ1 is the air wavelength.

[0068] In this example, the dipole antenna unit is equivalent to an electric dipole. At this time, the polarization of this electric dipole is in the Y direction, and the antenna radiation pattern in the X direction is a wide beam. In the figures of this article, the X direction and the Y direction are perpendicular to each other. The horizontal plane radiation pattern of the wide - beam dipole antenna is as Figure 5 shown, the maximum gain is 13.3 dBi, and by Figure 5It can be seen that the beam width with a maximum gain of -3 dB covers ±55°, and the beam width with a maximum gain of -6 dB can cover ±70°. It can be seen that this dipole antenna can achieve the characteristics of high gain and wide beam. Since the polarization plane of this dipole is not in the same horizontal plane as the wide beam plane of the radiation pattern, the radiation pattern of the wide beam plane is not easily affected by the surrounding environment and is not prone to jitter. Figure 6 This is a schematic diagram of the wide beam dipole antenna of this example arranged on a large-sized PCB. Compared with being arranged on a small-sized PCB board, the distance on the right side of the wide beam dipole antenna is increased by 40 mm (≈10λ). Observe the changes in the radiation patterns of the wide beam dipole antenna when it is on a small-sized PCB and a large-sized PCB. Figure 7 For the comparison of the radiation patterns under two sizes, from Figure 7 It can be seen that after the size of the PCB board becomes larger, the radiation pattern does not jitter. It can be seen that the antenna structure provided in this embodiment can achieve a radiation pattern with a relatively wide beam. Using this antenna structure as the millimeter-wave radar antenna can not only achieve a radiation pattern with a relatively wide beam, but also has strong stability angle, which is more conducive to the stability of the detection performance of the millimeter-wave radar.

[0069] The above example is described by taking an antenna structure including four dipole antenna units as an example. In other embodiments, an antenna structure may include one or two or three or more than four dipole antenna units. The above antenna structure can be arranged on a PCB board, and two or more (including two) antenna structures can be arranged on one PCB board to form an antenna structure array.

[0070] In addition to using SIW for feeding, the wide beam dipole antenna structure can also be fed by a microstrip line. The following takes the implementation of the feeding layer with a microstrip line structure as an example for description. In this example, multiple dipole antenna units are arranged to form a dipole antenna structure, and a wide beam antenna can be realized. The same as the previous example, the antenna structure includes three metal layers, and a dielectric layer is filled between the three metal layers. The radiation unit 21 includes multiple dipole antenna units, and each dipole antenna unit includes two radiation branches. Different from the above example, in this example, the metal connector 12 is located between the L1 layer and the L3 layer and is used to transmit energy to the radiation layer. In this example, the feeding layer 10 includes the feeder on the L1 layer and the ground wire on the L2 layer, and the feeding layer 10 is connected to the radiation layer 20 through the metal connector 12 arranged between the L1 and L3 layers, and the radiation layer 20 includes the L3 layer. Figure 8A This is the top view of the antenna structure of this example. Figure 8B For Figure 8A the cross-sectional view along the BB direction in. For clear illustration, the feeder on the L1 layer is shown in Figure 8A In this example, the feeder is located on the L1 layer, and the L2 layer serves as the metal ground layer ( Figure 8A(not shown in the figure). Energy can be directly transmitted to the dipole antenna element through the feeder and the metal connector 12. The feeder for feeding one dipole antenna element includes a main feeder and a feeder branch. The extending direction of the main feeder is the same as the arrangement direction of the radiation elements. The feeder branch connects the main feeder and the metal connector to feed the main feeder to the radiation elements. The length D3 of the main feeder corresponding to each radiation element is Nλ3, where N is a positive integer greater than or equal to 1, and λ3 is the dielectric wavelength of the dielectric layer between L1 and L2. In this example, the dielectric of the dielectric layer between L1 and L2 and the dielectric layer between L2 and L3 can be the same. In this instance, Figure 8B The slot 112 in is used to insulate the metal connector 12 from the ground layer L2.

[0071] In the scheme of using the SIW structure to implement the feeding layer, in order to ensure the electromagnetic wave propagation speed, a material with a lower dielectric constant can be selected for the dielectric layer. Compared with the scheme of using the SIW structure to implement the feeding layer, in the antenna structure using the microstrip line structure to implement the feeding layer, a material with a larger dielectric constant can be selected for the dielectric layer, which can reduce the cost.

[0072] In this example, in order to ensure that the current directions on the radiation branches are the same, the length of one dipole antenna element, i.e., D1 in the figure, can be set to λ1 / 2. In this example, the length D3 of the main feeder feeding one radiation element along the Y direction can be λ3, where λ3 is the dielectric wavelength. Figure 8A The arrow on the microstrip line in indicates the current direction. Since the current reverses every 1 / 2 wavelength, D3 is preferably λ3. In other examples, D3 can be Nλ3. At this time, the length of D1 can be adjusted accordingly, as long as the current directions on the two radiation branches in the same dipole antenna element are the same, and the current directions on the radiation branches of different dipole antenna elements belonging to the same antenna structure are the same.

[0073] In another example, the wiring of the microstrip line can be as Figure 9 shown. In other examples, the microstrip line can also adopt other wirings, as long as the current directions on the two radiation branches in the same dipole antenna element are the same, and the current directions on the radiation branches of different dipole antenna elements belonging to the same antenna structure are the same.

[0074] In the above example, in one radiation element, the two radiation branches are symmetrically arranged. The axis of symmetry is a straight line that bisects the interval between the two radiation branches in the Y direction and extends in the X direction. The metal connector is located at the edge of the radiation branch and away from the other radiation branch. In other examples, the position of the metal connector can be adjusted, for example Figure 10A 、 Figure 10B and Figure 10CAs shown, as long as the current directions on the two radiation branches in the same dipole antenna unit are the same, and the circuit directions on the radiation branches of different dipole antenna units belonging to the same antenna structure are the same. In this example, the radiation branch extension refers to the extension direction of the radiation branch starting from the connection position with the metal connector. In Figure 10A the two radiation branches extend in opposite directions, and in Figure 10B and Figure 10C the two radiation branches extend in the same direction.

[0075] Feeding with a microstrip line only requires adjusting the feeder length to make the current directions on all radiation branches of the antenna structure the same, and a dipole antenna array with high gain and wide beam can be achieved. This dipole antenna array can be used as a millimeter-wave radar antenna array. Compared with the antenna structure fed by SIW, the feeding method using a microstrip line can make the spacing between radiation units in the antenna structure adjustable, and the pitch beam design has a higher redundancy.

[0076] The above example is described with an antenna structure including four dipole antenna units as an example. In other embodiments, an antenna structure may include one or two or three or more than four dipole antenna units. The above antenna structure can be arranged on a PCB board, and two or more (including two) antenna structures can be arranged on one PCB board to form an antenna structure array. When the antenna structure of the feeding layer is realized by a microstrip line structure to form an antenna structure array, since the feeding is realized by a metal wire, compared with the antenna structure fed by SIW structure, the interference between adjacent antenna structures is less, so the arrangement between antenna structures can be more compact and the adjustment is relatively flexible.

[0077] The embodiment of the present disclosure also provides a printed circuit board, including the antenna structure described in any of the above embodiments.

[0078] The embodiment of the present disclosure also provides a radar sensor chip, including the antenna structure described in any of the above embodiments. The radar sensor chip, as Figure 11 shown, may include a signal receiving module, a signal transmitting module and a clock source. Among them, the signal transmitting module is used to transmit an electromagnetic wave signal through a transmitting antenna based on the reference frequency provided by the phase-locked loop in the clock source; the signal receiving module uses a receiving antenna to receive the echo formed by being reflected by a target object, and performs down-conversion processing based on the reference frequency provided by the phase-locked loop in the clock source to generate and output an intermediate frequency signal.

[0079] Optionally, in the exemplary embodiment of the present disclosure, the frequency-modulated continuous wave signal is a millimeter-wave signal, so that the electronic device can be applied to fields such as autonomous driving, industrial automation, smart home appliances and security inspection.

[0080] AsFigure 12 As shown, in an exemplary embodiment, the radar sensor may further include an analog-to-digital conversion module and a signal processing module. Among them, the signal receiving module generates and outputs an intermediate frequency signal to the analog-to-digital conversion module, and after being processed by the analog-to-digital conversion module, it is transmitted to the signal processing module. The signal processing module is used to perform signal processing on the digital signal output by the analog-to-digital conversion module.

[0081] Figure 11 and Figure 12 The transmitting antenna and the receiving antenna in

[0082] Exemplarily, the signal transmitting module generates a chirp signal in accordance with a preset continuous frequency modulation method; obtains a radio frequency transmitting signal through frequency doubling processing, and feeds it to the transmitting antenna to transmit a corresponding detection signal wave. When the detection signal wave is reflected by an object, an echo signal wave is formed. The echo signal wave is converted into a radio frequency receiving signal through the receiving antenna. The signal receiving module is used to perform down-conversion, filtering, analog-to-digital conversion, etc. on the radio frequency receiving signal by using the radio frequency transmitting signal to output a baseband digital signal representing the difference frequency between the detection signal wave and the echo signal wave. The signal processing module is used to extract measurement information from the baseband digital signal through signal processing and output corresponding measurement data. Among them, the signal processing includes performing digital signal processing calculations such as phase, frequency, and time domain on at least one path of the to-be-processed signal provided by at least one path of receiving antennas. The measurement data includes at least one of the following: distance data for representing the relative distance of at least one detected obstacle; speed data for representing the relative speed of at least one detected obstacle; angle data for representing the relative angle of at least one detected obstacle, etc.

[0083] Optionally, the frequency modulation continuous wave signal is a millimeter wave signal, and the radar sensor may be an AiP millimeter wave radar chip integrated with an antenna. In other embodiments of the present disclosure, the radar sensor may also be other types of radar chips, and the present disclosure does not limit this.

[0084] The millimeter wave radar antenna adopting the antenna structure of the embodiment of the present disclosure has a smaller size, not only has a wide beam characteristic, but also has high directivity pattern stability, which can improve the radar performance.

[0085] The present disclosure includes and contemplates combinations with features and elements known to those of ordinary skill in the art. The disclosed embodiments, features, and elements of the present disclosure may also be combined with any conventional features or elements to form unique inventive solutions defined by the claims. Any feature or element of any embodiment may also be combined with features or elements from other inventive solutions to form another unique inventive solution defined by the claims. Accordingly, it should be understood that any feature shown and / or discussed in the present disclosure may be implemented alone or in any suitable combination. Thus, the embodiments are not limited except as defined by the appended claims and their equivalents. Additionally, various modifications and alterations may be made within the scope of the appended claims.

Claims

1. An antenna structure, characterized in that, Comprising: A feeding layer and a radiation layer arranged in a stacked manner, wherein the radiation layer includes at least one radiation unit, the radiation unit is a dipole unit, and the polarization plane of the radiation unit is not in the same horizontal direction as the wide beam plane of its radiation pattern; the feeding layer is used to transmit the input signal to each radiation unit for the radiation unit to emit electromagnetic wave signals.

2. The antenna structure according to claim 1, characterized in that, Each of the radiation units includes two radiation branches located on the same metal layer, the two radiation branches are respectively connected to the feeding layer for feeding, the two radiation branches are symmetrically arranged and arranged along a first direction, and the extending direction of the radiation branch is the first direction or the opposite direction of the first direction.

3. The antenna structure according to claim 2, wherein The current directions on the two radiation branches in the same radiation unit are the same, and the current directions on the radiation branches of different radiation units belonging to the same antenna structure are all the same.

4. The antenna structure according to claim 2, wherein When there are more than two radiation units, the radiation units are arranged along the first direction, one of the two radiation branches in each radiation unit extends in the first direction, and the other extends in the opposite direction of the first direction, and the current directions on all the radiation units are the first direction or the opposite direction of the first direction.

5. The antenna structure according to claim 2, wherein The maximum distance between the two radiation branches in one radiation unit is λ1 / 2, where λ1 is the air wavelength.

6. The antenna structure according to claim 2, wherein The feeding layer is a SIW structure or a microstrip line structure.

7. The antenna structure according to claim 6, characterized in that, The feeding layer adopts a SIW structure, the feeding layer includes a first metal layer, a second metal layer and a dielectric layer between the first metal layer and the second metal layer, the dielectric layer is provided with metal posts respectively connected to the first metal layer and the second metal layer, the metal posts and the first metal layer and the second metal layer form a resonant cavity, the first metal layer is a grounding layer, and the second metal layer is provided with a slit communicating with the resonant cavity at the corresponding position of each radiation unit, and the radiation unit is fed through the slit.

8. The antenna structure according to claim 7, wherein The two radiation branches on one radiation unit are connected to both sides of the corresponding slit of the second metal layer through two metal connectors, and one radiation branch is connected to one metal connector in a one-to-one correspondence.

9. The antenna structure according to claim 8, characterized in that The metal connector is connected to the radiation branch at the edge of the radiation branch.

10. The antenna structure according to claim 9, wherein, The two metal connectors are symmetrically arranged on both sides of the slit with the slit as the center, and the two radiation branches respectively connected to the two metal connectors in a one-to-one correspondence extend away from the slit.

11. The antenna structure according to claim 7, characterized in that, The center distance between adjacent slits is λ2, where λ2 is the dielectric wavelength of the dielectric layer.

12. The antenna structure according to claim 6, wherein, The feeding layer adopts a microstrip line structure, the feeding layer includes a first metal layer, a second metal layer and a dielectric layer between the first metal layer and the second metal layer, the first metal layer is provided with a feeder for feeding each radiation unit, and the second metal layer is a grounding layer.

13. The antenna structure according to claim 12, characterized in that, The two radiation branches on one radiation unit are connected to the feeder of the first metal layer through two metal connectors, and one radiation branch is connected to one metal connector in a one-to-one correspondence.

14. The antenna structure according to claim 13, wherein, The metal connector is connected to the radiation branch at the edge of the radiation branch.

15. The antenna structure according to claim 14, wherein, Two radiation branches in a radiation element are symmetrically arranged, and the extending direction of the radiation branches is the same as or opposite to the arrangement direction of the radiation elements. Two metal connectors respectively connected to the two radiation branches in a radiation element are symmetrically arranged with respect to the symmetry axis of the two radiation branches, or the connection positions of the two metal connectors to the two radiation branches are the same.

16. The antenna structure according to claim 13, characterized in that, The feeder for feeding a radiation element includes a main feeder and a feeder branch. The extending direction of the main feeder is the same as the arrangement direction of the radiation elements. The feeder branch connects the main feeder and the metal connector to enable the main feeder to feed the radiation element. The length of the main feeder corresponding to each radiation element is Nλ3, where N is a positive integer greater than or equal to 1, and λ3 is the dielectric wavelength of the dielectric layer.

17. A printed circuit board, characterized in that, It includes the antenna structure according to any one of claims 1-16.

18. A radar sensor chip, characterized in that, It includes the antenna structure according to any one of claims 1-16.

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