Millimeter wave antenna and millimeter wave radar

Abstract

The utility model discloses a millimeter wave antenna and a millimeter wave radar, and relates to the technical field of in-vehicle monitoring, and the millimeter wave antenna comprises a grounding layer, a base layer and a radiation structure. The grounding layer is used for being laid or embedded in the ground. The base layer is stacked above the grounding layer, in the vertical direction, the middle position of the base layer is partially hollowed out to form a hollowed-out position, and the hollowed-out position is used for containing the grounding part; the radiation structure is arranged right above the base layer, the radiation structure comprises a feed layer, a plurality of feeder lines and a plurality of antennas, the feed layer is arranged above the base layer and is located right above the hollow position, each feeder line is at least partially embedded into the feed layer, the plurality of antennas are correspondingly and electrically connected with the plurality of feeder lines, and each antenna and the hollow position are arranged in a staggered manner in the horizontal direction; wherein the feed layer is provided with a plurality of via holes around each feed line, and each via hole penetrates through the feed layer and a part of the base layer and is used for being electrically connected with the grounding part; according to the technical scheme provided by the utility model, the antenna is convenient to arrange and has larger antenna bandwidth.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of automobile, especially a kind of millimeter wave antenna and millimeter wave radar. BACKGROUND

[0002] With the continuous development of the fifth generation communication technology, millimeter wave band (mm-wave band) gradually enters people's field of vision, and derives many new technologies. Millimeter wave band has ultra-wide bandwidth, lower delay, higher unlimited transmission speed, and is mainly used in vehicle-mounted radar monitoring field. Millimeter wave radar mostly adopts multi-layer PCB (Printed Circuit Board) structure design, which is divided into antenna layer and device layer on the top layer.

[0003] In the face of complex environment in the car, the antenna of the existing in-car detection radar mostly adopts the design of microstrip antenna, and adopts the MIMO form of multiple transmission and multiple reception. Since the theoretical bandwidth of microstrip antenna is not large, only about 5-8%, it cannot meet the accuracy requirements of millimeter wave radar during detection, so array form is often used to increase the bandwidth of the antenna. However, for small and compact radar installed in the car, the antenna in array form is a great challenge to PCB with small board size, greatly increasing the difficulty of other device layout.

[0004] Therefore, how to increase the bandwidth of the antenna while reducing the difficulty of other device layout has become a technical problem to be solved by the technical personnel in the field. UTILITY MODEL CONTENT

[0005] The main purpose of the utility model is to provide a kind of millimeter wave antenna and millimeter wave radar, which aims to increase the bandwidth of the antenna while reducing the difficulty of other device layout.

[0006] To achieve the above purpose, the millimeter wave antenna provided by the utility model includes a ground layer, a base layer and a radiation structure. The ground layer is used to lay or embed on the ground. The base layer is stacked above the ground layer. In the vertical direction, the middle part of the base layer is partially hollowed out to form a hollow position, which is used to accommodate the grounding part. The radiation structure is arranged directly above the base layer. The radiation structure includes a feed layer, multiple feed lines and multiple antennas. The feed layer is stacked above the base layer and located directly above the hollow position. Each feed line is at least partially embedded in the feed layer. The multiple antennas are electrically connected to the multiple feed lines, and each antenna is arranged horizontally offset from the hollow position. The feed layer has multiple vias around each feed line. Each via penetrates the feed layer and part of the base layer to electrically connect with the grounding part.

[0007] In an embodiment, the base layer includes a first dielectric layer, a second dielectric layer, and at least one intermediate dielectric layer; the first dielectric layer is arranged below the grounding portion and in contact with the grounding layer; the second dielectric layer is arranged above the grounding portion and attached to the bottom of the feed layer, the second dielectric layer is used to integrate the circuit structure of the millimeter wave antenna and is penetrated by the via; the intermediate dielectric layer is arranged between the first dielectric layer and the second dielectric layer and below the plurality of antennas to form a hollow position with the first dielectric layer and the second dielectric layer at the grounding portion.

[0008] In an embodiment, the effective dielectric constant of the second dielectric layer and the first dielectric layer is ε, 3.8≤ε≤4.2.

[0009] In an embodiment, the dielectric constants of the first dielectric layer, the second dielectric layer, and the intermediate dielectric layer are the same.

[0010] In an embodiment, the material of the first dielectric layer includes a first semi-solid sheet, the material of the second dielectric layer includes a second semi-solid sheet, and the intermediate dielectric layer is formed by extruding the first semi-solid sheet and the second semi-solid sheet.

[0011] In an embodiment, the first dielectric layer, the second dielectric layer, and the grounding layer are projected to coincide in the up-down direction.

[0012] In an embodiment, the material of the feed layer includes at least one of copper and copper-aluminum composite material.

[0013] In an embodiment, the distance between every two adjacent antennas is d, the wavelength of the electromagnetic wave emitted by the antenna is λ, and d=λ / 2.

[0014] In an embodiment, among the plurality of antennas, part of the antennas are used to emit electromagnetic waves, and another part of the antennas are used to receive electromagnetic waves, and the plurality of antennas are arranged in an array.

[0015] The utility model also proposes a kind of millimeter wave radar, the millimeter wave radar includes millimeter wave antenna and antenna cover, millimeter wave antenna includes grounding layer, base layer and radiating structure;Grounding layer is used to lay or embed in ground;Base layer is stacked above grounding layer, in up-down direction, the middle position of base layer is partially hollow to form hollow position to accommodate grounding portion;Radiating structure is arranged directly above base layer, and radiating structure includes feed layer, multiple feed lines and multiple antennas, feed layer is stacked above base layer and located directly above hollow position, each feed line is at least partially embedded in feed layer, multiple antennas are electrically connected with multiple feed lines, and each antenna and hollow position are arranged staggered in horizontal direction;Wherein, multiple vias are formed around each feed line in feed layer, each via penetrates feed layer and part of base layer, to be electrically connected with grounding portion, antenna cover is covered in millimeter wave antenna.

[0016] The feeding layer beside the feeder line is provided with a via hole, and the via hole is electrically connected with the grounding part, so that the grounding part is used as a reference ground, the base layer provided with the hollow position forms a thinner medium substrate of the feeder line, the thickness of the medium substrate of the feeder line is the distance from the top of the hollow position to the top of the feeding layer, so that the size of the via hole can be smaller, thereby facilitating the layout of the circuit structure, and the ground can be used as the reference ground to form a thicker medium substrate of the antenna assembly, the thickness of the medium substrate of the antenna assembly is the distance from the top of the feeding layer to the grounding layer, so that the reference ground and the thicker medium substrate of the antenna assembly are arranged at intervals, so that the millimeter wave antenna is convenient to layout and has a larger antenna bandwidth. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical scheme in the embodiments of the present application or the prior art, the drawings needed to be used in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained according to the structures shown in the drawings without creative labor for those skilled in the art.

[0018] Figure 1 The structure schematic diagram of the millimeter wave antenna provided by the present application is shown in the embodiment.

[0019] Figure 2 The structure schematic diagram of the millimeter wave antenna provided by the present application is shown in the embodiment. Figure 1 The top view schematic diagram of the millimeter wave antenna is shown in the embodiment.

[0020] Figure 3 The S parameter comparison diagram of the millimeter wave antenna provided by the present application is shown in the embodiment.

[0021] Figure 4 The antenna directional diagram of the millimeter wave radar provided by the present application is shown in the embodiment.

[0022] BRIEF DESCRIPTION OF DRAWINGS

[0023] 100, millimeter wave antenna; 1, grounding layer; 2, base layer; 21, first dielectric layer; 22, second dielectric layer; 23, intermediate dielectric layer; 2A, hollow position; 3, radiation structure; 31, feeder line; 32, antenna; 33, feeding layer.

[0024] The implementation, functional characteristics and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0025] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described, obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0026] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship, movement condition, etc. between the components in a certain posture, and if the certain posture changes, the directional indications will also change accordingly.

[0027] In addition, if the embodiments of the present application involve descriptions of "first", "second", etc., the descriptions of "first", "second", etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of indicated technical features. Therefore, the features limited by "first" and "second" can explicitly or implicitly include at least one of the features. In addition, "and / or" or "and / or" appearing throughout the text means that the three parallel schemes are included, for example, "A and / or B" includes A scheme, or B scheme, or A and B simultaneously satisfy the scheme. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection required by the present application.

[0028] In the face of the complex environment in the vehicle, the existing antenna of the in-vehicle detection radar mostly adopts the design of microstrip antenna, and adopts the MIMO form of multiple transmission and multiple reception. Since the theoretical bandwidth of the microstrip antenna is not large, only about 5-8%, it cannot meet the precision requirements of the millimeter wave radar during detection, and therefore an array form is often used to increase the bandwidth of the antenna. However, for the small and compact radar installed in the vehicle, the antenna in the array form is a great challenge to the PCB with small board size, greatly increasing the difficulty of layout of other devices.

[0029] In the related art, the PCB antenna structure is obtained by laminating the top layer, the dielectric layer and the ground layer from top to bottom, the dielectric layer is provided with a via hole for connecting the top layer and the ground layer, wherein the via hole is related to the thickness of the PCB antenna structure, the greater the thickness of the dielectric layer, the greater the thickness of the PCB antenna structure of the millimeter wave radar, the greater the aperture of the via hole, and the greater the via hole occupies the space of other circuit structures, therefore, when selecting the aperture of the via hole, the size of the components on the PCB antenna structure and the pin pitch need to be considered, if the size of the components is small and the pin pitch is tight, then the smaller blind hole aperture is more suitable.

[0030] The thickness of the antenna substrate directly affects the bandwidth of the antenna, and the calculation formula of the antenna bandwidth BW is as follows:

[0031]

[0032] Wherein, f2, f1 respectively represent the highest working frequency and the lowest working frequency, f r is the center of the working frequency. The bandwidth of the microstrip antenna can be described by the quality factor Q when the microstrip antenna resonates. The Q factor is the sum of all quality factors related to the loss of the antenna, including the power dissipated in the patch due to the loss of the metal conductor and the substrate, and the power loss due to radiation. The bandwidth of the antenna can also be described by the following formula:

[0033]

[0034] Wherein,

[0035] In the formula, h is the thickness of the antenna dielectric substrate, ε r (w) is the effective dielectric constant of the antenna. It can be seen that by increasing the thickness of the antenna substrate, the purpose of increasing the bandwidth of the antenna can be achieved.

[0036] Therefore, if the dielectric layer of the antenna structure is too thick, the via hole will be too large, which will affect the layout of the PCB structure, and if the dielectric layer is too thin, the bandwidth of the antenna will be small.

[0037] Based on this, the utility model provides a kind of millimeter wave antenna 100.

[0038] Please refer to Figure 1 With Figure 2In an embodiment of the utility model, this ground layer 1 is used to lay or embed in ground, base layer 2 is stacked on the top of ground layer 1, in the up-down direction, the middle part position of base layer 2 is partially hollowed out to form hollow position 2A, hollow position 2A is used to accommodate grounding part, radiation structure 3 is set on the top of base layer 2, radiation structure 3 includes feed layer 33, multiple feed lines 31 and multiple antennas 32, feed layer 33 is stacked on the top of base layer 2 and is located on the top of hollow position 2A, each feed line 31 is at least partially embedded in feed layer 33, multiple antennas 32 are electrically connected with multiple feed lines 31 correspondingly, and each antenna 32 is set in horizontal direction with hollow position 2A staggered, wherein, feed layer 33 is provided with multiple via holes around each feed line 31, each via hole penetrates feed layer 33 and the partial base layer 2, to be electrically connected with grounding part.

[0039] The utility model discloses the feed layer 33 of feed line 31 is provided with via hole, and via hole is electrically connected with grounding part, so as to take grounding part as reference ground, and the base layer 2 of hollow setting forms the medium substrate of thinner feed line 31, and the thickness of the medium substrate of feed line 31 is the distance from the top of hollow position 2A to the top of feed layer 33, so the size of via hole can become smaller, thereby facilitating the layout of circuit structure, and can take ground as reference ground and form the medium substrate of thicker antenna assembly, and the thickness of the medium substrate of antenna assembly is the distance from the top of feed layer 33 to ground layer 1, so, the reference ground of interval arrangement and thicker antenna assembly medium substrate make millimeter wave antenna 100 convenient layout has greater antenna bandwidth simultaneously.

[0040] It should be noted that the grounding part is used to connect with the ground as the reference ground, and its formation method has many kinds, in order to realize its close setting in hollow position 2A and facilitate installation, the ground layer of existing PCB antenna structure can be partially corroded, the remaining ground layer forms the grounding part, the top layer forms the radiation structure 3, and the medium layer forms the upper part of base layer 2.

[0041] In an embodiment of the present application, the base layer 2 comprises a first dielectric layer 21, a second dielectric layer 22 and at least one intermediate dielectric layer 23; the first dielectric layer 21 is arranged below the grounding portion and in contact with the grounding layer 1; the second dielectric layer 22 is arranged above the grounding portion and attached to the bottom of the feeding layer 33, and the second dielectric layer 22 is used to integrate the circuit structure of the millimeter wave antenna and is penetrated by the via hole; the intermediate dielectric layer 23 is arranged between the first dielectric layer 21 and the second dielectric layer 22 and below the plurality of antennas 32, so as to form a hollow position with the first dielectric layer 21 and the second dielectric layer 22 in the grounding portion. In this way, the hollow position 2A can be formed by the first dielectric layer 21, the second dielectric layer 22 and the intermediate dielectric layer 23 with a common industrial thickness, and a standard plate is used, which is convenient to process; the layered arrangement can share external pressure, and the overall compression resistance and deformation resistance can be enhanced through reasonable layered layout, so as to prevent local deformation or damage of the dielectric layer.

[0042] Specifically, the thickness of the first dielectric layer 21 is set to 0.127 mm, the thickness of the intermediate dielectric layer is set to 0.035 mm, and the thickness of the second dielectric layer 22 is set to 0.092 mm, that is, the dielectric substrate thickness of the feed line 31 is 0.127 mm, and the dielectric substrate thickness of the antenna assembly is 0.254 mm.

[0043] In an embodiment of the present application, the effective dielectric constant of the second dielectric layer 22 and the first dielectric layer 21 is ε, and 3.8≤ε≤4.2. In this way, a relatively stable electric field environment can be provided, the scattering and absorption of electromagnetic energy can be reduced, and the transmission efficiency can be improved.

[0044] Specifically, the material of the base layer 2 can be selected from but not limited to PTFE (polytetrafluoroethylene), epoxy resin, hydrocarbon resin and other modified materials.

[0045] In an embodiment of the present application, the dielectric constants of the first dielectric layer 21, the second dielectric layer 22 and the intermediate dielectric layer 23 are the same, which can ensure that the electric field is uniformly distributed in the entire area, thereby improving the performance and precision of the device.

[0046] In an embodiment of the present application, the material of the first dielectric layer 21 comprises a first semi-solid sheet, the material of the second dielectric layer 22 comprises a second semi-solid sheet, and the intermediate dielectric layer 23 is formed by extruding the first semi-solid sheet and the second semi-solid sheet. In this way, the semi-solid sheet in the form of glue can better fill the gap, thereby improving the performance and precision of the device.

[0047] In an embodiment of the present application, the first dielectric layer 21, the second dielectric layer 22 and the grounding layer 1 are projected and overlapped along the up-down direction. In this way, the overall thickness of the millimeter wave antenna 100 is uniformly arranged, and adverse effects caused by the overall inclined millimeter wave antenna 100 are prevented.

[0048] In an embodiment of the present application, the material of the power supply layer 33 includes at least one of copper and copper-aluminum composite material.

[0049] In an embodiment of the present application, the interval distance between each two adjacent antennas 32 is d, the wavelength of the electromagnetic wave emitted by the antenna 32 is λ, and d = λ / 2. The multiple antennas 32 are placed at equal intervals along the half wavelength to form an antenna array, which can achieve high gain and good directivity, which helps to concentrate the signal in a specific direction for transmission, improves the transmission efficiency and coverage range of the signal, and enhances the detection ability and resolution of the target.

[0050] In an embodiment of the present application, among the multiple antennas 32, part of the antennas 32 are used to emit electromagnetic waves, and another part of the antennas 32 are used to receive electromagnetic waves, and the multiple antennas 32 are arranged in an array. The array-arranged antennas can realize spatial multiplexing and beamforming, effectively improve the data rate, signal reliability and anti-interference ability, and at the same time improve the spectrum efficiency and coverage range.

[0051] In an embodiment of the present application, the material of the grounding layer 1 is a good conductor material. Specifically, the material of the grounding layer 1 is copper, and the grounding layer 1 is laid on the ground or a groove opened on the ground and solidified to form the grounding layer 1.

[0052] In an embodiment of the present application, for the near-distance in-vehicle millimeter wave radar application scenario, the antenna operating frequency is designed in the 58-64GHz frequency band, the MIMO antenna form is adopted to increase the ranging and angle measurement accuracy of the antenna, and the base layer 2 based on the dielectric constant of about 4 is adopted. Among them, the thickness of the first dielectric layer 21 is set to 0.127mm, the thickness of the intermediate dielectric layer is set to 0.035mm, and the thickness of the second dielectric layer 22 is set to 0.092mm, that is, the dielectric substrate thickness of the feed line 31 is 0.127mm, and the dielectric substrate of the antenna assembly is 0.254mm.

[0053] Comparing the reflection coefficient S of the present embodiment with that of the millimeter wave antenna 100 without hollowing and with the same thickness, the results shown in Figure 3 are obtained, wherein S11 is the one-port reflection coefficient, indicating the matching condition of the antenna and the transmission line with an impedance of 50 ohms, and the smaller the reflection coefficient is, the better; the horizontal axis is the frequency of the antenna, with the unit of GHz; the vertical axis is the S11 parameter value of the antenna, with the unit of dB; the solid curve represents the S11 parameter of the embodiment, and the dashed line represents the S11 parameter of the millimeter wave radar without hollowing and with the same thickness; S11≤–10dB, and the reflection coefficient of –10dB indicates that 90% of the incident power is transmitted to the antenna for emission.

[0054] From Figure 3It can be known that the antenna bandwidth of the embodiment is 58-65GHz, and the bandwidth of the antenna can be greatly increased without changing the size of the antenna layout.

[0055] Since the antenna uses the scene in the vehicle detection, the requirement for the gain is small, but the requirement for the beam range is large, therefore, the utility model also provides a kind of millimeter wave radar, and the specific structure of millimeter wave radar refers to the above embodiment, since millimeter wave radar adopts all technical solutions of the above all embodiments, therefore, at least have all beneficial effects brought by the technical solutions of the above embodiments, hereinafter, it is not repeated. Wherein, the radome is covered in the millimeter wave antenna 100. Thus, by depressing maximum gain, millimeter wave radar obtains greater beam angle, and it is beneficial to detect wider range in vehicle.

[0056] Further, the radome adopts PBT material, and the PBT material has high strength, fatigue resistance, size stability and small creep.

[0057] In an embodiment of the utility model, please refer to Figure 4 , Figure 4 is the pattern of millimeter wave radar. In the figure, the horizontal coordinate is the radiation angle of radar, unit: degree;The vertical coordinate represents the gain of radar, unit: dBi. The direction Figure 1 Generally, it is a three-dimensional 3D pattern in free space, and in engineering, it is usually described by maximum radiation direction surface. For microstrip antenna, the direction pattern of E plane and H plane is usually measured. It can be seen that the 3dB beam width of radar is 66 ° in horizontal direction and 50 ° in vertical direction. Since the radar uses the scene in the vehicle detection, the requirement for the gain is small, but the requirement for the beam range is large, by depressing maximum gain, the antenna can obtain greater beam angle, and it is more beneficial to detect larger range in vehicle.

[0058] The above-mentioned is only the exemplary embodiment of the utility model, and does not limit the patent range of the utility model, and any equivalent structural transformation made by using the utility model specification and drawing contents, or direct / indirect application in other related technical fields is included in the patent protection range of the utility model.

Claims

1. A millimeter wave antenna, characterized by, The application relates to a millimeter wave antenna, comprising: a ground layer, which is laid or embedded on the ground; a base layer, which is stacked above the ground layer, and the middle part of the base layer is partially hollowed out in the up-down direction to form a hollowed-out position, which is used to accommodate a grounding part; a radiation structure, which is arranged directly above the base layer and comprises a feed layer, a plurality of feed lines and a plurality of antennas, the feed layer is stacked above the base layer and located directly above the hollowed-out position, each feed line is at least partially embedded in the feed layer, a plurality of antennas are electrically connected with a plurality of feed lines, and each antenna is arranged horizontally offset from the hollowed-out position; wherein the feed layer is provided with a plurality of through holes around each feed line, each through hole penetrates the feed layer and part of the base layer to be electrically connected with the grounding part. The base layer comprises:

2. The millimeter wave antenna of claim 1, wherein, a first dielectric layer, which is arranged below the grounding part and in contact with the ground layer; a second dielectric layer, which is arranged above the grounding part and attached to the bottom of the feed layer, the second dielectric layer is used to integrate the circuit structure of the millimeter wave antenna and is penetrated by the through hole; and at least one intermediate dielectric layer, which is arranged between the first dielectric layer and the second dielectric layer and below a plurality of antennas to form a hollowed-out position with the first dielectric layer and the second dielectric layer in the grounding part. The effective dielectric constant of the second dielectric layer and the first dielectric layer is epsilon, 3.8 <= epsilon <= 4.

2.

3. The millimeter wave antenna of claim 2, wherein, The dielectric constants of the first dielectric layer, the second dielectric layer and the intermediate dielectric layer are the same.

4. The mmWave antenna of any of claims 2-3, wherein, The material of the first dielectric layer comprises a first semi-solid sheet, the material of the second dielectric layer comprises a second semi-solid sheet, and the intermediate dielectric layer is formed by extruding the first semi-solid sheet and the second semi-solid sheet.

5. The millimeter wave antenna of claim 4, wherein, The first dielectric layer, the second dielectric layer and the ground layer are projected to coincide in the up-down direction.

6. The millimeter wave antenna of claim 2, wherein, The material of the feed layer comprises at least one of copper and copper-aluminum composite material.

7. The millimeter wave antenna of claim 1, wherein, The interval distance between each adjacent two antennas is d, the wavelength of the electromagnetic wave emitted by the antenna is lambda, and d = lambda / 2.

8. The millimeter wave antenna of claim 1, wherein, Among a plurality of antennas, part of the antennas are used to emit electromagnetic waves, and the other part of the antennas are used to receive electromagnetic waves, and a plurality of antennas are arranged in an array.

9. The millimeter wave antenna of claim 1, wherein, The application relates to a millimeter wave antenna, comprising:

10. A millimeter wave radar, characterized by, a millimeter wave antenna according to any one of claims 1-9; and a radome, which covers the millimeter wave antenna. ​ ​

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