CN118299832A - Antenna device - Google Patents

Abstract

The embodiments of the present disclosure relate to an antenna device, including a substrate; an antenna unit array, including: a substrate; an antenna unit array, including: a central antenna unit, arranged at the center of the top of the substrate; and at least two surrounding antenna units, arranged at the top of the substrate and arranged around the central antenna unit; a plurality of metal spacers, arranged at the top of the substrate and inside the substrate; a plurality of clearance areas, arranged inside and at the bottom of the substrate; and a plurality of feed parts, arranged on the antenna units in the antenna unit array. According to the antenna device of the present disclosure, it has higher phase stability and channel isolation, thereby being able to effectively position the accuracy.

Description

Antenna device

Technical Field

Various embodiments of the present disclosure generally relate to antenna devices.

Background technique

With the increasing pressure of urban traffic and the demand for green travel, bicycles and other two-wheeled vehicles have gradually become common means of transportation. In recent years, shared vehicles have been favored by many people for their low-carbon, environmentally friendly and convenient parking characteristics. However, with the popularization of shared vehicles, a large number of shared vehicles are parked randomly after use, seriously affecting the passage of pedestrians or other vehicles. Orderly and standardized parking has become an urgent problem to be solved.

At present, the traditional method is to use ultrasonic technology or GPS positioning technology to achieve the problem of fixed-point parking of shared vehicles. However, the above positioning methods may fail to locate or have poor positioning accuracy in scenes such as buildings or trees blocking the parking space. Therefore, a high-precision positioning solution is needed.

Summary of the invention

In view of the above problems, the present disclosure provides an antenna device.

According to a first aspect of the present disclosure, there is provided an antenna device, comprising: a substrate; an antenna unit array, comprising: a central antenna unit, arranged at the center of the top of the substrate; and at least two surrounding antenna units, arranged at the top of the substrate and around the central antenna unit; a plurality of metal spacers, arranged at the top of the substrate and inside the substrate; a plurality of clearance areas, arranged inside and at the bottom of the substrate; and a plurality of feed parts, arranged on the antenna units in the antenna unit array.

According to a second aspect of the present disclosure, there is provided a parking device for a shared vehicle, comprising: an antenna device according to the first aspect of claim 1, the antenna device being configured to communicate with an antenna module provided on the shared vehicle to determine an orientation of the shared vehicle relative to the antenna device.

According to the antenna device disclosed in the present invention, the influence of the change of the polarization state of the electromagnetic wave on the angle estimation can be eliminated, and at the same time, the phase stability and channel isolation are higher, and the positioning accuracy is improved. At the same time, the design adopts a square antenna, which occupies a small area while ensuring the signal strength.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific embodiments of the present disclosure will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG1 is a schematic diagram of positioning of an antenna device according to an embodiment of the present disclosure;

FIG2 is a top view of an antenna device according to an embodiment of the present disclosure;

FIG3 is a schematic diagram of the polarization direction of the antenna device according to an embodiment of the present disclosure;

FIG4 is a schematic diagram of a circuit structure of an antenna device according to an embodiment of the present disclosure;

FIG5 is a simulated amplitude diagram of an antenna device according to an embodiment of the present disclosure; and

FIG. 6 is a simulated phase pattern of the antenna device according to an embodiment of the present disclosure.

Detailed ways

The embodiments of the present disclosure will now be described in detail in conjunction with the accompanying drawings. It should be noted that similar components or functional kits may be indicated by the same reference numerals in the accompanying drawings. The accompanying drawings are intended only to illustrate the embodiments of the present disclosure and are not intended to be limiting. Those skilled in the art may derive alternative technical solutions from the following description without departing from the spirit and scope of protection of the present disclosure.

In the description of the present disclosure, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present disclosure.

In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present disclosure, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

In the present disclosure, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

In the present disclosure, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

As mentioned above, in traditional positioning technology, there are two positioning schemes: (1) Ultrasonic positioning, which mainly uses the reflection ranging method to determine the position of the object through methods such as multilateral positioning. The ultrasonic positioning system consists of a main rangefinder and several receivers. The main rangefinder can be placed on the target to be measured, and the receiver is fixed in an indoor environment. During positioning, a signal of the same frequency is transmitted to the receiver, which is then reflected and transmitted to the main rangefinder after receiving it. The distance is calculated based on the time difference between the echo and the transmitted wave, thereby determining the position. (2); and (2) Bluetooth beacon positioning, which uses the trilateral measurement principle. The device side uses ibeacon or private Beacon broadcasting to send Beacon signals. The receiver is usually a mobile phone. It reversely determines its own location based on the signal strength and device ID number received from the broadcasting device and the coordinate map drawn in advance.

The defects of traditional solutions are: (1) Ultrasonic waves are greatly affected by multipath effects and non-line-of-sight propagation, and the ultrasonic frequency is affected by the Doppler effect and temperature. It also requires a lot of basic hardware facilities and is costly. (2) Bluetooth Beacon positioning is easily affected by environmental/human interference, and the positioning accuracy is relatively low. Environmental factors such as human or vehicle metal shielding can affect the actual antenna field pattern and the Bluetooth positioning accuracy, making it difficult to achieve accurate parking in actual operations.

According to the scheme of the present disclosure, a low-cost antenna device is proposed for positioning. The antenna device includes: a substrate; an antenna unit array, including: a central antenna unit, arranged at the center of the top of the substrate; and at least two surrounding antenna units, arranged at the top of the substrate and arranged around the central antenna unit; a plurality of metal spacers, arranged at the top and inside of the substrate; a plurality of clearance areas, arranged inside and at the bottom of the substrate; and a plurality of feed parts, arranged on the antenna units in the antenna unit array. According to the antenna device of the present disclosure, it has higher phase stability and channel isolation, thereby enabling effective positioning accuracy.

First, the principle of positioning the antenna device of the present disclosure is explained below with reference to FIG1. As shown in FIG1, multiple receiving antennas 110-1 and 110-2 are placed adjacent to each other, and the antennas may be the antenna device according to the present disclosure. Although two antennas are shown in the figure, any number of antennas may be arranged as needed, and the present disclosure does not limit this.

The radio waves emitted by a single transmitter will arrive at different antennas 110-1 and 110-2 at different phases. From the above phase difference, the direction from which the radio wave was emitted can be calculated. Since the angle is determined relative to the receiver, this method is called arrival angle estimation (AOA, ANGLE OF ARRIVAL). The opposite is called departure angle estimation (AOD, ANGLE OF DEPARTURE). Assuming that the incident signal does not change frequency during the measurement (i.e., unmodulated) and the distance between the receiving antennas is less than half the wavelength, the phase difference clearly determines the angle of incidence. In this method, the tag (such as the antenna on the shared bicycle to be located) transmits an unmodulated narrowband signal for a specific time. The locator samples the received signal on multiple antennas. Assume that two antennas 110-1 and 110-2 are used. If the incident signal arrives at these antennas at an oblique angle of incidence, a phase difference ψ will be generated, because the wavefront propagates at the speed of light c, and it takes more time to reach the farther antenna. Since the wavelength of 2.4 GHz is around λ = 0.125 m, this phase shift can be converted to the distance between the wavefront and the more distant antenna and is determined by the following equation (1):

If the receiver is far enough from the transmitter (at least 3-4 wavelengths), the wavefront is assumed to be flat. In this case, the angle of incidence can be easily determined from this distance (Δ) by trigonometric functions according to equation (2):

Where d is the distance between the antennas. After determining the incident angle θ, the position of the object to be located relative to the antenna can be determined. This technology can also be called AOA/AOD Bluetooth positioning technology. The device described in the present disclosure below can adopt the above-mentioned AOA/AOD Bluetooth positioning technology for positioning, but it can also adopt other methods for positioning, and the present disclosure does not limit it here.

The specific structure of the antenna device of the present disclosure is described in detail below with reference to Figures 2 to 3. Figure 2 shows a top view of the antenna device according to an embodiment of the present disclosure. As shown in Figure 2. The antenna device includes: a substrate 210; an antenna unit array, including: a substrate; an antenna unit array, including: a central antenna unit 205, arranged at the center of the top of the substrate; and at least two surrounding antenna units 206, arranged at the top of the substrate and arranged around the central antenna unit 205; a plurality of metal isolation members 203-1, 203-2, 203-3 and 203-4, arranged at the top of the substrate and inside the substrate; a plurality of clearance areas 204-1 and 204-2, arranged inside and at the bottom of the substrate; and a plurality of feed sections 201-1, 201-2 and 202, arranged on the antenna units in the antenna unit array.

Although the central antenna unit 205 and at least two surrounding antenna units 206 shown in the top view 200 are square. It can be understood that each antenna unit can have a different shape as needed. Although the top view 200 is shown to include 1 central antenna unit and 6 surrounding antenna units, and the various elements in the figure are arranged symmetrically with respect to the diameter of the circular substrate, this is merely exemplary, and a different number of antenna units and different arrangements can be set as needed. It should be noted that in the present disclosure, the substrate has a height, and the top, inside and bottom refer to three different heights along the height of the substrate. Although not shown in the figure, it can be understood that the elements in the antenna are arranged in layers along the height of the substrate.

In some embodiments, the central antenna unit and the surrounding antenna units are square antenna units of the same size and shape. The inventors have found that the square antenna unit can further optimize the performance of the antenna.

In some embodiments, the antenna units are all patch antennas. Since the rod antenna used in the traditional antenna has a "tire" shape antenna gain pattern, the phase change is more drastic when the pitch angle is 0°, resulting in poor test accuracy. By using a patch antenna, the antenna gain pattern changes from omnidirectional to directional, which can cover the area to be positioned directly above the array, making the measurement positioning more accurate.

Alternatively, in some embodiments, the antenna units are all microstrip antennas. Dipole antennas and monopole antennas are used in traditional antennas. Monopole antennas cannot be well applied to direction finding systems because of the coupling with the ground plane and the poor phase performance between the monopole and the antenna. Dipole antennas need to be isolated from the ground due to differential feeding, and the ground has a greater impact on the antenna. If the distance to the ground plane is too far or too close, it will affect the phase of the electromagnetic wave reflected back to the antenna and the antenna efficiency. The above problems can be solved by using microstrip antennas, making positioning more accurate.

Additionally or alternatively, in some embodiments, at least one of the central antenna unit and the surrounding antenna units is shaped as a square patch antenna unit of the same size and shape. Experimental data shows that when all antenna units are shaped as square patch antenna units of the same size and shape, the performance of the antenna is further improved.

The size of the substrate and the antenna unit can be further defined to optimize the performance of the antenna. In some embodiments, the distance between adjacent surrounding antenna units in at least two surrounding antenna units is equal, and the distance is no greater than half of the wavelength corresponding to the highest frequency electromagnetic wave emitted or received by the antenna device. For example, the straight-line distance between the geometric centers of two adjacent square or other shaped (e.g., circular) antennas is no greater than half of the wavelength corresponding to the highest frequency electromagnetic wave emitted or received by the antenna device. Alternatively, in some embodiments, the substrate is a circular substrate, and each surrounding antenna unit is arranged so that the diagonal connecting line of each surrounding antenna unit is in the radial direction of the circular substrate. For example, the diagonal of the square antenna unit or the radius of the circular antenna unit coincides with the radius of the circular substrate.

Additionally or alternatively, in some embodiments, the radius of the circular substrate may be 100 mm, but substrates with different radii may also be provided as required, and the present disclosure is not limited thereto.

By adopting one or more of the above dimensions and arrangements, the influence of the change in the polarization state of the electromagnetic wave on the angle estimation can be eliminated, and the positioning accuracy can be improved. At the same time, the design adopts a square antenna, which occupies a small area while ensuring the signal strength.

It can be understood that there is interference between the antennas, and an isolator can be arranged between the antennas to prevent the antennas from interfering with each other. In some embodiments, a first metal isolator 203-1 can be arranged on the top of the substrate around the central antenna unit, and the first metal isolator is suitable in shape to isolate the central antenna unit from at least two surrounding antenna units. It can be understood that the shape of the first metal isolator substantially depends on the arrangement and number of at least two surrounding antennas. For example, as shown in Figure 2, the first metal isolator is hexagonal. By providing the first metal isolator, the isolation between the central antenna unit and the outer antenna units can be improved.

In some other embodiments, the second metal isolator 203-2 can be set on the top of the substrate, between adjacent surrounding antenna units among at least two surrounding antenna units, and the second metal isolator can improve the isolation between adjacent surrounding antenna units. Alternatively, in some other embodiments, a third metal isolator 203-3 can be set on the top of the substrate, on the radially outer side of the surrounding antenna unit among at least two surrounding antenna units, and the third metal isolator can improve the phase uniformity of the directional pattern of the antenna unit. Additionally or alternatively, a fourth metal isolator 203-4 can be set inside the substrate and on the outermost side in the radial direction of the substrate, and the fourth metal isolator can improve the phase uniformity of the directional pattern of the antenna unit.

The four types of metal spacers can be metal copper foil, but can also be any other suitable material. The shapes of the four types of metal spacers can be the shapes shown in Figure 2, that is, the first metal spacer is a hexagon, and the second metal spacer can be a branch spacer extending from the first metal spacer. The third metal spacer can be a semicircular spacer that surrounds a pair of right-angled sides of the surrounding antenna unit. The fourth metal spacer can be a ring that is embedded in the interior of the substrate along the circumference of the circular substrate.

The inventors have found that the size and shape of the metal isolation member can match the shape and size of the antenna unit, which can further improve the phase stability and channel isolation, thereby effectively improving the positioning range and positioning accuracy of the antenna.

In order to prevent the antenna unit from being interfered with by other electronic components or other antenna units or metal devices, resulting in a decrease in radiation characteristics, a clearance area needs to be set on the substrate. In some embodiments, multiple first clearance areas 204-1 can be set inside the substrate and radially adjacent to the surrounding antenna units. The first clearance area can be small and adjacent to the surrounding antenna units. In some embodiments, multiple second clearance areas 204-2 can be set at the bottom of the substrate and at the outermost side of the substrate in the radial direction, and the second clearance area can be larger. The ratio of the area of the first clearance area and the second clearance area to the area of the substrate can be shown in Figure 2. It can be understood that different antennas need to be configured with clearance areas of different sizes. The inventor found that by setting the clearance area shown in the area ratio in Figure 2, a compromise between the signal-to-noise ratio and the size of the antenna device can be achieved. That is, the signal-to-noise ratio is maximized while ensuring the smallest size. The inside and bottom of the substrate, except for the first clearance area and the second clearance area, can all be metal copper foil, but other elements may also be included, and the present disclosure is not limited here.

The basic structure of the antenna device is described above, and the feeding part and polarization direction of the antenna unit are described below in conjunction with Figure 3. Figure 3 shows a schematic diagram of the polarization direction of the antenna device according to an embodiment of the present disclosure.

First, referring to the surrounding antenna units, the multiple feeds include multiple pairs of first feeds 201-1 and 201-2, each pair of first feeds is arranged in the circumference of each surrounding antenna unit of at least two surrounding antenna units, so that each surrounding antenna unit has a different polarization direction, and the feeding mode of the multiple pairs of first feeds is side feeding. The surrounding antenna units are orthogonally polarized antenna units. In some embodiments, as shown in FIG2, when the antenna unit is a square, the first feed is arranged on the adjacent right-angled sides of each surrounding antenna unit of at least two surrounding antenna units.

Continuing to refer to the central antenna unit, the multiple feeding portions include a second feeding portion 202, which is arranged on the central antenna unit, and the feeding mode of the second feeding portion is bottom feeding, and the central antenna unit is a circularly polarized antenna unit.

As shown by the arrows in Figure 3, the six circularly arranged surrounding antenna units are orthogonally polarized antenna units, and the electromagnetic waves they transmit/receive have two mutually orthogonal linear polarization directions. The surrounding antenna unit at the center is a circularly polarized antenna unit, and the electromagnetic waves it transmits/receives are right-handed/left-handed circularly polarized. The feeding point of each antenna unit corresponds to a different linear polarization radiation direction, and the linear polarization direction of this example covers six different polarization directions. By arranging the feed part and the feeding method of the feed part as described above, the phase stability of the antenna can be further improved, thereby effectively improving the positioning range and positioning accuracy of the antenna.

FIG4 shows a schematic diagram of the circuit structure of an antenna device according to an embodiment of the present disclosure. As shown in FIG4, the antenna device includes a power module 450, a Bluetooth module 440, a radio frequency switch module 430 and a plurality of phase shifter modules 420-1, 420-2, 420-3 and 420-4, which are arranged at the bottom of the substrate and are electrically connected in sequence. The radio frequency switch module is coupled to the corresponding antenna units 410-1, 410-2, 410-3 and 410-4 in the plurality of surrounding antenna units of the central antenna unit via the corresponding phase shifter modules in the plurality of phase shifter modules. The radio frequency switch module can be controlled by the Bluetooth module to control the corresponding antenna unit to transmit or receive signals. The corresponding phase shifter module can be controlled by the Bluetooth module to change the phase of the signal transmitted or received by the corresponding antenna unit.

Adjacent modules can be connected through RF feeders or metalized through-holes. During the operation of the antenna, the Bluetooth module controls the RF switch/phase shifter to select different radiation units to transmit/receive Bluetooth signals. The locator and the tag obtain each other's information through the handshake protocol, and then the Bluetooth module calculates the relative position of the locator and the tag based on the received amplitude/phase information.

Figures 5A to 5B show simulated amplitude diagrams of the antenna device according to an embodiment of the present disclosure. Figures 6A to 6D show simulated phase patterns of the antenna device according to an embodiment of the present disclosure. From the perspective of the phase fluctuation in the horizontal plane, the closer the antenna spacing is, the greater the mutual coupling is, and the greater the phase fluctuation is. Under the same spacing conditions, the amplitude pattern of the square patch antenna is relatively uniform, the antenna isolation is better than -20dB, and the phase fluctuation is less than 10°. When the substrate is smaller, the ±5° wave width is larger, and the phase fluctuation is larger. When the substrate is larger, the ±5° wave width is smaller, and the phase fluctuation is smaller. It can be seen from Figures 5 and 6 that the above-mentioned antenna device has a higher phase stability, which makes the positioning more accurate.

The present disclosure also proposes a parking device for a shared vehicle, comprising: according to the antenna device described above, the antenna device can communicate with the antenna module arranged on the shared vehicle to determine the orientation of the shared vehicle relative to the antenna device. The positioning antenna has higher phase stability and channel isolation, which can effectively improve the Bluetooth AOA positioning accuracy. In addition, benefiting from the reasonable arrangement and the characteristics of the square patch antenna, the Bluetooth antenna is small in size, low in cost, and easy to promote and apply.

It will be appreciated by those skilled in the art that the above description is provided for the purpose of illustration and not limitation. It will be appreciated by those skilled in the art that the present disclosure may be implemented in other implementations that depart from these specific details. Furthermore, in order not to obscure the present disclosure, unnecessary details of known functions and structures are omitted in the current description.

Although specific embodiments have been illustrated and described herein, those skilled in the art will recognize that the specific embodiments shown may be replaced with any arrangement intended to achieve the same purpose, and that the disclosure has other applications in other environments. This application is intended to cover any changes or variations of the disclosure. The appended claims should never be construed as limiting the scope of the disclosure to the specific embodiments described herein.

The solutions described in this specification and the embodiments, if they involve the processing of personal information, will be processed on the premise of having a legal basis (such as obtaining the consent of the subject of personal information, or being necessary for the performance of a contract, etc.), and will only be processed within the scope of regulations or agreements. If a user refuses to process personal information other than the necessary information for basic functions, it will not affect the user's use of basic functions.

Claims (19)

1. An antenna device, comprising Substrate; Antenna element array, comprising: a central antenna unit disposed at the center of the top of the substrate; and at least two peripheral antenna units disposed on top of the substrate and surrounding the central antenna unit; a plurality of metal spacers disposed on the top of the substrate and inside the substrate; a plurality of clearance areas disposed in the interior and bottom of the substrate; and A plurality of feeding parts are arranged on the antenna units in the antenna unit array. 2. The antenna device according to claim 1, wherein the plurality of metal spacers include a first metal spacer, which is arranged on the top of the substrate around the central antenna unit, and the first metal spacer is suitable in shape to isolate the central antenna unit from the at least two surrounding antenna units. 3 . The antenna device according to claim 2 , wherein the plurality of metal spacers include a second metal spacer disposed between adjacent surrounding antenna units among the at least two surrounding antenna units and disposed on top of the substrate. 4. The antenna device according to any one of claims 2 to 3, wherein the plurality of metal isolation members include a ring-shaped third metal isolation member, which is radially arranged on the outside of the surrounding antenna unit among the at least two surrounding antenna units and is arranged on the top of the substrate. 5 . The antenna device according to claim 4 , wherein the plurality of metal spacers include a fourth ring-shaped metal spacer disposed inside the substrate and disposed at the outermost side in a radial direction of the substrate. 6. The antenna device according to claim 1, wherein the distance between adjacent surrounding antenna units among the at least two surrounding antenna units is equal, and the distance is not greater than half of the wavelength corresponding to the highest frequency electromagnetic wave emitted or received by the antenna device. 7 . The antenna device according to claim 1 , wherein the plurality of clearance areas include a plurality of first clearance areas, and the plurality of first clearance areas are disposed inside the substrate and are disposed adjacent to surrounding antenna units in a radial direction. 8 . The antenna device according to claim 7 , wherein the plurality of clearance areas include a plurality of second clearance areas disposed at the bottom of the substrate and disposed at the outermost sides in a radial direction of the substrate. 9. The antenna device according to claim 1, wherein the multiple feeding parts include multiple pairs of first feeding parts, each pair of first feeding parts is arranged on the circumference of each surrounding antenna unit of the at least two surrounding antenna units, so that each surrounding antenna unit has a different polarization direction, and the feeding method of the multiple pairs of first feeding parts is side feeding. 10 . The antenna device according to claim 1 , wherein the plurality of feeders include a second feeder, the second feeder is provided on the central antenna unit, and a feeding method of the second feeder is bottom feeding. 11 . The antenna device according to claim 1 , wherein the central antenna unit is a circularly polarized antenna unit, and the at least two surrounding antenna units are orthogonally polarized antenna units. 12 . The antenna device according to claim 1 , wherein at least one of the central antenna unit and the peripheral antenna units is square in shape. 13. The antenna device according to claim 12, wherein the substrate is a circular substrate, and each of the at least two peripheral antenna units is arranged so that a line connecting two diagonal corners of a square of each peripheral antenna unit extends in a radial direction passing through the center of the circular substrate. 14. The antenna device according to claim 12, wherein the side length of each peripheral antenna unit is equal to half of the wavelength corresponding to the highest frequency electromagnetic wave emitted or received by the antenna device. 15 . The antenna device according to claim 2 , wherein the number of central antenna elements in the antenna element array is one, the number of peripheral antenna elements is six, and the shape of the first metal spacer is a hexagon. 16. The antenna device according to claim 1 further comprises a power module, a Bluetooth module, a radio frequency switch module and a plurality of phase shifter modules which are arranged at the bottom of the substrate and are electrically connected in sequence, and the radio frequency switch module is respectively coupled to the central antenna unit and the corresponding antenna units of the at least two surrounding antenna units via the corresponding phase shifter modules of the multiple phase shifter modules. 17 . The antenna device according to claim 16 , wherein the radio frequency switch module is controlled by the Bluetooth module to control the corresponding antenna unit to transmit or receive signals. 18. The antenna device according to claim 16, wherein the corresponding phase shifter module is controlled by the Bluetooth module to change the phase of the signal transmitted or received by the corresponding antenna unit. 19. A parking device for a shared vehicle, comprising: The antenna device according to any one of claims 1 to 18, the antenna device is configured to communicate with an antenna module provided on a shared vehicle to determine the orientation of the shared vehicle relative to the antenna device.