Antenna, antenna system and automobile

Abstract

The present disclosure belongs to the technical field of wireless communications, and provides an antenna, an antenna system and an automobile. The antenna comprises a main antenna, a parasitic antenna and a main board, the main antenna and the parasitic antenna both being located on the surface of the main board, and the plane where the main antenna is located and the plane where the parasitic antenna is located being in parallel and opposite to each other. A feed point of the main antenna is connected to a feed transmission line of the main board, and the parasitic antenna is connected to a second ground end of the main board, the difference value between the resonance frequency point of the main antenna and the resonance frequency point of the parasitic antenna being lower than a target threshold value. The antenna is applied to an automobile and serves as a communication antenna, such as a 4G communication antenna or a 5G communication antenna, of the automobile so as to achieve 4G or 5G broad bandwidth coverage, such as full-bandwidth coverage. In addition, the antenna can also improve the degree of out-of-band rejection and the anti-pilot-frequency interference characteristic.

Description

Antennas, antenna systems and automobiles

[0001] This disclosure claims priority to Chinese patent application number 202311160190.9, filed on September 8, 2023, entitled “Antenna, Antenna System and Automobile,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to the field of wireless communication technology, and in particular to an antenna, an antenna system, and a car. Background Art

[0003] With the rapid development of intelligent connected technology and the advent of the fifth generation mobile networks (5G), it has become possible to connect cars to the Internet of Everything (IoE) with high traffic, low latency and high speed.

[0004] Among them, the vehicle-mounted antenna is the core component that enables the vehicle to communicate with the outside world, and is usually arranged on the top of the vehicle, for example, in the roof luggage rack.

[0005] However, due to the limited height of the luggage rack, the size of the vehicle-mounted antenna will be limited. Since the radiation frequency of the antenna is related to the size of the antenna, it will be difficult for the vehicle-mounted antenna to achieve 5G wide-band coverage.

[0006] Summary of the Invention

[0007] The present disclosure provides an antenna, an antenna system, and a car. The antenna, when applied to a car, can achieve 5G wide-band coverage. The technical solution is as follows:

[0008] In a first aspect, an antenna is provided, comprising a main antenna, a parasitic antenna, and a mainboard;

[0009] The main antenna and the parasitic antenna are both located on the surface of the mainboard, and the plane where the main antenna is located is parallel to the plane where the parasitic antenna is located, and the positions are opposite;

[0010] The feeding point of the main antenna is connected to the feeding transmission line of the mainboard, and the parasitic antenna is connected to the second ground terminal of the mainboard;

[0011] The difference between the resonant frequency of the main antenna and the resonant frequency of the parasitic antenna is smaller than a target threshold.

[0012] In the embodiments disclosed herein, the difference between the resonant frequency of the main antenna and the resonant frequency of the parasitic antenna can be the absolute value of the absolute difference, specifically the absolute value of the difference between the resonant frequency of the main antenna and the resonant frequency of the parasitic antenna. For example, if the resonant frequency of the main antenna is f1 and the resonant frequency of the parasitic antenna is f2, then the difference between the resonant frequency of the main antenna and the resonant frequency of the parasitic antenna is |f1-f2|.

[0013] Alternatively, the difference between the resonant frequency of the main antenna and the resonant frequency of the parasitic antenna may be the absolute value of the relative difference, specifically the percentage between the absolute value of the difference between the resonant frequency of the main antenna and the resonant frequency of the parasitic antenna and the midpoint between the two. For example, if the resonant frequency of the main antenna is f1 and the resonant frequency of the parasitic antenna is f2, then the difference between the resonant frequency of the main antenna and the resonant frequency of the parasitic antenna is,

[0014] Then, if the difference between the resonant frequencies of main antenna 1 and parasitic antenna 2 is the absolute value of the absolute difference, the target threshold is a frequency value. If the difference between the resonant frequencies of main antenna 1 and parasitic antenna 2 is the absolute value of the relative difference, the target threshold is a percentage.

[0015] The solution shown in the present disclosure is that the antenna includes a main antenna and a parasitic antenna, which are arranged relative to each other. The excitation signal of the main antenna is introduced by the feeder, and the excitation signal of the parasitic antenna is introduced by coupling with the electromagnetic field of the main antenna. The main antenna and the parasitic antenna are coupled with each other, which can broaden the bandwidth of the antenna. Then, the antenna is used in a car as a communication antenna for the car, such as a 4G communication antenna or a 5G communication antenna, and can achieve 4G or 5G wide bandwidth coverage, or even full bandwidth coverage.

[0016] In addition, the antenna can also improve the out-of-band suppression and the anti-frequency interference characteristics. For example, the antenna can improve the out-of-band suppression of the GNSS antenna, so that even if the GNSS antenna and the antenna described in this embodiment are arranged together, such as both arranged in the shark fin or both arranged in the luggage rack, the interference of the GNSS antenna on the antenna described in this embodiment can be reduced.

[0017] In a possible implementation, the feeding point of the main antenna is connected to the inner conductor of the feeding transmission line of the mainboard, the outer conductor of the feeding transmission line is connected to the first ground terminal of the mainboard, and the first ground terminal and the second ground terminal are shared.

[0018] The solution shown in the present disclosure is that the common ground can eliminate the invalid resonant mode excited after the main antenna and the parasitic antenna are coupled, thereby slowing down the efficiency drop rate of the effective resonant mode. For example, after the main antenna and the parasitic antenna are coupled, they can excite the effective resonant mode 2 and the invalid resonant mode 3. The resonance points corresponding to these two resonant modes are relatively close. If the invalid resonant mode 3 is eliminated by the common ground, then, since the resonant point 3 is not at the corresponding minimum point in the radiation efficiency characteristic diagram, the radiation loss will not drop rapidly from the resonant point 2 to the resonant point 3. Therefore, eliminating the invalid resonant mode 3 can reduce the rate of decrease of the radiation loss of the resonant mode 2, that is, slow down the efficiency drop rate of the resonant mode 2.

[0019] In a possible implementation, the main antenna is a monopole antenna, and the parasitic antenna is a loop antenna.

[0020] The monopole antenna disclosed in the present disclosure is an antenna that can excite a specific wavelength line mode after an excitation signal is input thereto. For example, a resonant mode of a 1 / 4 wavelength line mode can be excited after an excitation signal is input thereto.

[0021] A loop antenna, also known as a loop antenna, is a structure consisting of a metal conductor wound into a specific shape, such as a circle, square, or triangle, with the two ends of the conductor serving as output terminals. When an excitation signal is input to the loop antenna, a resonant mode at a specific wavelength, such as a half-wavelength ring mode, is excited.

[0022] In a possible implementation, the starting end of the main antenna is a feeding point, and both ends of the parasitic antenna are connected to the second ground terminal of the mainboard;

[0023] The distance between the starting end of the main antenna and the end of the parasitic antenna is less than a first value, and the distance between the end of the main antenna and the middle position of the parasitic antenna is less than a second value.

[0024] In the scheme shown in this disclosure, the main antenna is a monopole antenna. The starting point is the location of strong current, corresponding to the strong magnetic field, and the end is the location of weak current, corresponding to the strong electric field. For the parasitic antenna, the ends are the locations of strong current, corresponding to the strong magnetic field, and the middle is the location of weak current, corresponding to the strong electric field.

[0025] Then, when adjusting the coupling degree between the main antenna and the parasitic antenna, the starting end of the main antenna can be adjusted to be closer to the end of the parasitic antenna, and the end of the main antenna can be adjusted to be closer to the middle position of the parasitic antenna.

[0026] The solution shown in the present disclosure can adjust the resonant frequency and bandwidth after mutual coupling by adjusting the degree of coupling between the main antenna and the parasitic antenna, thereby achieving wide bandwidth coverage of the antenna.

[0027] The solution shown in the present disclosure can also adjust the position of the out-of-band radiation null point by adjusting the degree of coupling between the main antenna and the parasitic antenna.

[0028] In a possible implementation, the main antenna is a monopole antenna, and the parasitic antenna is a monopole antenna.

[0029] In a possible implementation, the starting end of the main antenna is a feeding point, and the starting end of the parasitic antenna is connected to the second ground terminal of the mainboard;

[0030] The distance between the starting end of the main antenna and the starting end of the parasitic antenna is less than a third value, and the distance between the ending end of the main antenna and the ending end of the parasitic antenna is less than a fourth value.

[0031] In the solution shown in this disclosure, the main antenna is a monopole antenna. The starting point is the location of strong current, corresponding to the strong magnetic field, and the ending point is the location of weak current, corresponding to the strong electric field. For the parasitic antenna, the starting point connected to the motherboard is the location of strong current, corresponding to the strong magnetic field, and the ending point is the location of weak current, corresponding to the strong electric field.

[0032] Then, when adjusting the coupling degree between the main antenna and the parasitic antenna, the starting end of the main antenna can be adjusted to be closer to the starting end of the parasitic antenna, and the ending end of the main antenna can be adjusted to be closer to the ending end of the parasitic antenna.

[0033] The solution shown in the present disclosure can adjust the resonant frequency and bandwidth after mutual coupling by adjusting the degree of coupling between the main antenna and the parasitic antenna, thereby achieving wide bandwidth coverage of the antenna.

[0034] The solution shown in the present disclosure can also adjust the position of the out-of-band radiation null point by adjusting the degree of coupling between the main antenna and the parasitic antenna.

[0035] In a possible implementation, the main antenna is a loop antenna, and the parasitic antenna is a loop antenna or a monopole antenna.

[0036] In a possible implementation, the main antenna includes a first branch and a second branch;

[0037] One end of the first branch is vertically located on the surface of the main board, and the other end is connected to the second branch. The width of the second branch is greater than that of the first branch.

[0038] In the solution shown in the present disclosure, the second branch is relatively wide, so there are multiple current paths distributed on the second branch. Although the electrical lengths corresponding to these current paths are almost the same, they are also slightly different. Different electrical lengths stimulate different resonant frequencies. Then, multiple different electrical lengths stimulate multiple close but different resonant frequencies, which is beneficial to broaden the bandwidth of the antenna.

[0039] In a possible implementation, the main antenna further includes a first matching branch;

[0040] There is a distance between the second branch and the main board, the first matching branch is fixed to the main board and is located on one side of the first branch and between the second branch and the main board;

[0041] Capacitance is formed between the first matching branch and the edges of the first branch that are close to each other, and / or between the first matching branch and the edges of the second branch that are close to each other.

[0042] In the solution shown in the present disclosure, capacitance can be formed between the first matching branch and the edges of the first branch that are close to each other, and / or between the edges of the first matching branch and the second branch that are close to each other. The capacitance formed can be used to adjust the impedance matching between the antenna and the feeder to reduce the return loss and improve the radiation efficiency of the antenna.

[0043] In a possible implementation, the second branch section includes a first branch and a second branch, and the first branch and the second branch are arranged side by side along the width direction of the second branch section;

[0044] One end of the first branch is connected to one end of the second branch, and the other end of the first branch and the other end of the second branch are both connected to the first branch node.

[0045] In the solution shown in the present disclosure, since the second branch is relatively wide, the second branch can be hollowed out so that the second branch includes a hollow area and the first branch and the second branch located on the left and right sides of the hollow area.

[0046] The second branch includes a separate first branch and a second branch. Then, the current distributed in the first branch can excite an electromagnetic wave of one resonant frequency, and the current distributed in the second branch can excite an electromagnetic wave of another resonant frequency, thereby increasing the number of resonant frequencies of the antenna and broadening the bandwidth of the antenna by increasing the number of resonant frequencies.

[0047] In a possible implementation, the main antenna includes a first radiating arm, a second radiating arm, and a third radiating arm;

[0048] One end of the first radiation arm is vertically located on the surface of the mainboard, and the other end is vertically connected to one end of the second radiation arm. The other end of the second radiation arm is vertically connected to one end of the third radiation arm.

[0049] In the solution shown in the present disclosure, the first radiating arm is arranged vertically relative to the mainboard, the second radiating arm is arranged horizontally relative to the mainboard, and the third radiating arm is arranged vertically relative to the mainboard. The arrangement of the three radiating arms of the main antenna is conducive to reducing the height and width, making the structure of the main antenna more compact.

[0050] In a possible implementation, the total height of the main antenna is equal to the total height of the parasitic antenna, and the total width of the main antenna is equal to the total width of the parasitic antenna.

[0051] In the solution shown in the present disclosure, the total height of the main antenna is equal to or nearly equal to the total height of the parasitic antenna, and the total width of the main antenna is equal to or nearly equal to the total width of the parasitic antenna, which is beneficial for making full use of the space size of the main antenna and the parasitic antenna.

[0052] In one possible implementation, the antenna also includes a dielectric plate, which is located vertically on the surface of the main board, the main antenna is located on the first surface of the dielectric plate, and the parasitic antenna is located on the second surface of the dielectric plate, and the first surface and the second surface of the dielectric plate are relative to each other.

[0053] In the solution shown in the present disclosure, the dielectric plate is located vertically on the surface of the main board, and the main antenna and the parasitic antenna can be printed on two opposite surfaces of the dielectric plate. For example, the main antenna is located on the first surface of the dielectric plate, and the parasitic antenna is located on the second surface of the dielectric plate.

[0054] In the solution shown in the present disclosure, the main antenna and the parasitic antenna are arranged on two opposite surfaces of the dielectric plate, which can improve the vibration resistance of the antenna. Therefore, when the antenna is used in a car, the degree of shaking of the antenna with the car can be reduced.

[0055] In a second aspect, an antenna system is provided, comprising a radio frequency circuit and the antenna described in the first aspect, wherein the radio frequency circuit is configured to enable the antenna to transmit and receive wireless signals.

[0056] According to a third aspect, a car is provided, comprising the antenna system according to the second aspect.

[0057] In a possible implementation, the antenna is located in a luggage rack of the car.

[0058] In the solution shown in the present disclosure, the antenna can be located in the luggage rack on the left side of the car body, or in the luggage rack on the right side of the car body, or in both the luggage rack on the left side and the luggage rack on the right side of the car body.

[0059] In one possible implementation, the radio frequency circuit is arranged in the telematics processor T-BOX of the car, the T-BOX is located in the back seat of the car and close to the tail of the tire, and the luggage rack where the antenna is located and the T-BOX are located on the same side of the car body.

[0060] In the solution shown in this disclosure, the T-BOX is located in the back seat of the car, close to the rear of the tire. In addition, the luggage rack where the antenna is located is located on the same side of the car body as the T-BOX. This makes the antenna and T-BOX close in distance. As a result, the signal cable harness is shorter, which can effectively reduce the link loss caused by the cable, thereby improving the system efficiency of the vehicle antenna.

[0061] In a possible implementation, the antenna is located in a shark fin of the car. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] FIG1 is a schematic structural diagram of an antenna provided by the present disclosure;

[0063] FIG2 is a schematic diagram of current distribution for exciting a quarter wavelength line mode provided by the present disclosure;

[0064] FIG3 is a schematic diagram of current distribution for exciting a 1 / 2 wavelength ring mode provided by the present disclosure;

[0065] FIG4 is a schematic structural diagram of a main antenna provided by the present disclosure, which is a monopole antenna;

[0066] FIG5 is a schematic structural diagram of a parasitic antenna provided by the present disclosure, which is a loop antenna;

[0067] FIG6 is a schematic structural diagram of an antenna provided by the present disclosure;

[0068] FIG7 is a schematic diagram of the distribution of multiple current paths on a main antenna provided by the present disclosure;

[0069] FIG8 is a schematic structural diagram of a main antenna with a hollowed-out area provided by the present disclosure;

[0070] FIG9 is a schematic structural diagram of a main antenna with matching branches provided by the present disclosure;

[0071] FIG10 is a schematic structural diagram of a main antenna provided by the present disclosure;

[0072] FIG11 is a schematic structural diagram of a parasitic antenna provided by the present disclosure;

[0073] FIG12 is a schematic structural diagram of an antenna provided by the present disclosure;

[0074] FIG13 is a graph showing return loss characteristics of the antenna shown in FIG12 provided by the present disclosure;

[0075] FIG14 is a diagram showing the radiation efficiency characteristics of the antenna shown in FIG12 provided by the present disclosure;

[0076] FIG15 is a diagram showing system efficiency characteristics of the antenna shown in FIG12 provided by the present disclosure;

[0077] FIG16 is a schematic diagram of current distribution for exciting a quarter wavelength line mode provided by the present disclosure;

[0078] FIG17 is a schematic diagram of current distribution for exciting a 1 / 4 wavelength line mode provided by the present disclosure;

[0079] FIG18 is a schematic structural diagram of an antenna provided by the present disclosure;

[0080] FIG19 is a schematic diagram of current distribution on a main antenna and a parasitic antenna provided by the present disclosure, wherein (a) is a front view and (b) is a top view;

[0081] FIG20 is a schematic diagram of current distribution on a main antenna and a parasitic antenna provided by the present disclosure, wherein (a) is a front view and (b) is a top view;

[0082] FIG21 is a schematic diagram of current distribution on a main antenna and a parasitic antenna provided by the present disclosure, wherein (a) is a front view and (b) is a top view;

[0083] FIG22 is a graph showing return loss characteristics of an antenna provided by the present disclosure;

[0084] FIG23 is a diagram showing the radiation efficiency characteristics and system efficiency characteristics of an antenna provided by the present disclosure;

[0085] FIG24 is a schematic structural diagram of an antenna provided by the present disclosure installed in a luggage rack;

[0086] FIG25 is a schematic structural diagram of an antenna mainboard provided by the present disclosure located in a metal base of a luggage rack.

[0087] Explanation of Reference Numerals: 1. Main antenna; 11. First radiating arm; 12. Second radiating arm; 13. Third radiating arm; 14. First matching branch; 15. Second matching branch; 111. First branch; 112. Second branch; 121. First inclined branch; 122. Horizontal branch; 123. Second inclined branch; 1120. Hollow region; 1121. First branch; 1122. Second branch. 2. Parasitic antenna. 3. Mainboard; 31. First ground plane; 32. Second ground plane. DETAILED DESCRIPTION

[0088] Although the description of the present disclosure will be introduced in conjunction with some embodiments, this does not mean that the features of this application are limited to the embodiments. On the contrary, the purpose of introducing the application in conjunction with the embodiments is to cover other options or modifications that may be extended based on the claims of the present disclosure. In order to provide an in-depth understanding of the present disclosure, the following description will contain many specific details. The present disclosure can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present disclosure, some specific details will be omitted in the description. It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other unless there is a conflict.

[0089] In the embodiments of the present disclosure, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first," "second," "third," or "fourth" may explicitly or implicitly include one or more of the features.

[0090] In the embodiments of the present disclosure, "and / or" is simply a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the related objects are in an "or" relationship.

[0091] In the description of the embodiments of the present disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation" and "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. The directional terms mentioned in the embodiments of the present disclosure, such as "up", "down", "left", "right", etc., are only reference to the directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present disclosure, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present disclosure.

[0092] This embodiment relates to a car antenna, which is used to achieve communication between the vehicle and a base station. The antenna is usually arranged in a shark fin on the roof or in a roof luggage rack. However, due to the limited height of the shark fin and the luggage rack, the size of the antenna will be limited, and the radiation frequency of the antenna is related to the size of the antenna. For example, the radiation frequency and the size of the antenna are negatively correlated, which makes it difficult for the antenna to achieve wide frequency band coverage.

[0093] The antenna provided in this embodiment, when used in a car, can broaden the antenna's operating bandwidth to achieve wide-band coverage. In addition, the antenna can also improve out-of-band interference suppression to resist interference from out-of-band adjacent frequencies.

[0094] The antenna may be a transmitting antenna, a receiving antenna, or a transceiver antenna, which is not specifically limited in this embodiment.

[0095] The antenna may specifically be an antenna for a cellular mobile communication system, such as a 4th generation mobile network (4G) antenna or a 5th generation mobile network (5G) antenna. The antenna may also be a communication antenna for wireless local area networks (WLAN), vehicle-to-everything (V2X) technology, or Bluetooth low energy (BLE).

[0096] For example, the antenna may be a 4G full-band antenna or a 5G full-band antenna. This embodiment does not limit the type of antenna.

[0097] Before introducing this solution, the terms involved are first introduced.

[0098] The resonant frequency, also known as the resonant frequency or resonant point, is generally the center frequency of the desired operating frequency band. It is the frequency at which the current and voltage of the antenna reach their maximum values. At this frequency, the antenna has the highest radiation efficiency and can convert electrical energy into electromagnetic waves and transmit them out.

[0099] Bandwidth is also the operating frequency band of the antenna, generally covering the resonant frequency. It usually refers to the frequency range where the return loss is less than a certain dB value. For example, the frequency range where the return loss is less than -5dB can be defined as the bandwidth of the antenna.

[0100] Return loss refers to the ratio of the reflected power to the incident power at the antenna connector, reflecting the impedance matching characteristics between the antenna and the feeding transmission line. For example, the better the impedance matching between the antenna and the feeding transmission line, the smaller the return loss.

[0101] In the return loss characteristic diagram of this embodiment, the return loss is represented by a negative value. Then, the smaller the return loss, the better the impedance matching characteristic of the antenna. A return loss of 0 dB corresponds to the worst impedance matching.

[0102] Radiation efficiency refers to the ratio of the energy radiated by the antenna to the energy transmitted into the antenna. The energy not radiated is mainly lost by the antenna itself.

[0103] System efficiency, also known as antenna efficiency, refers to the ratio of the antenna's radiated power to the input power provided by the feeder. The energy not radiated by the antenna is partly reflected back and partly lost by the antenna itself.

[0104] The radiation zero point is the frequency point that theoretically neither radiates electromagnetic waves nor receives electromagnetic waves. In practice, the loss at the radiation zero point is relatively large and the efficiency is relatively low. In the efficiency characteristic diagram, the radiation zero point corresponds to the minimum point.

[0105] The structure of the antenna provided by this embodiment will be described below.

[0106] The antenna provided in this embodiment mainly increases the resonant modes of the antenna through electromagnetic field coupling between the main antenna and the parasitic antenna, thereby achieving the purpose of widening the antenna bandwidth.

[0107] As shown in Figure 1 , the antenna includes a main antenna 1, a parasitic antenna 2, and a motherboard 3. Both the main antenna 1 and the parasitic antenna 2 are located on the surface of the motherboard 3. For example, both the main antenna 1 and the parasitic antenna 2 are vertically soldered to the surface of the motherboard 3. Continuing with Figure 1 , the planes on which the main antenna 1 and the parasitic antenna 2 are located are parallel and opposite to each other.

[0108] In one example, the antenna may also include a dielectric plate, which is located vertically on the surface of the main board 3. The main antenna 1 and the parasitic antenna 2 can be printed on two opposite surfaces of the dielectric plate. For example, the main antenna 1 is located on the first surface of the dielectric plate, and the parasitic antenna 2 is located on the second surface of the dielectric plate.

[0109] In another example, the antenna may not include a dielectric plate, and both the main antenna 1 and the parasitic antenna 2 are metal sheets.

[0110] It should be noted that the main antenna 1 and the parasitic antenna 2 are arranged on two opposite surfaces of the dielectric plate, which can improve the anti-vibration performance of the antenna. Therefore, when the antenna is used in a car, the degree of shaking of the antenna with the car can be reduced.

[0111] In one example, the main antenna 1 is an active conductive element in a radio antenna and is connected to the radio frequency circuit via a feed transmission line (referred to as the feed line). For example, the feed point of the main antenna 1 is connected to the feed line on the mainboard 3. The feed line is typically a coaxial line including an inner conductor and an outer conductor. Therefore, the feed point of the main antenna 1 is connected to the inner conductor of the feed line, while the outer conductor of the feed line is connected to the first ground terminal of the mainboard 3 for grounding.

[0112] In one example, the parasitic antenna 2 is a passive conductive element in a radio antenna and is not connected to a feeder line. The excitation signal of the parasitic antenna 2 is introduced through electric field coupling and magnetic field coupling with the main antenna 1.

[0113] In one example, the parasitic antenna 2 and the second ground terminal of the mainboard 3 are connected to achieve grounding of the parasitic antenna 2. When the parasitic antenna 2 is grounded, the mainboard 3 can act as a radiation array of the parasitic antenna 2, radiating electromagnetic waves outward, thereby effectively shortening the size of the parasitic antenna 2.

[0114] As described above, the outer conductor of the feeder connected to the main antenna 1 is connected to the first ground terminal of the mainboard 3 for grounding, and the parasitic antenna 2 is connected to the second ground terminal of the mainboard 3 for grounding. The main antenna 1 and the parasitic antenna 2 can share a common ground, which means that the reference ground plane is the same.

[0115] The main antenna 1 and the parasitic antenna 2 share a common ground, that is, the first grounding terminal connected to the outer conductor of the feeder and the second grounding terminal connected to the parasitic antenna 2 share a common ground.

[0116] For example, as shown in Figure 1, the upper surface of the mainboard 3 represents the first ground plane 31, and the lower surface represents the second ground plane 32. If the first ground terminal and the second ground terminal are both located on the upper surface of the mainboard 3, that is, the outer conductor of the feeder and the parasitic antenna 2 are both connected to the upper surface of the mainboard 3, then the ground planes referenced by the main antenna 1 and the parasitic antenna 2 are the same, both being the first ground plane 31.

[0117] If the first ground terminal and the second ground terminal are both located on the lower surface of the main board 3, that is, the outer conductor of the feeder and the parasitic antenna 2 are both connected to the lower surface of the main board 3, then the ground planes referenced by the main antenna 1 and the parasitic antenna 2 are also the same, both being the second ground plane 32.

[0118] If one of the first ground terminal and the second ground terminal is located on the upper surface of the motherboard 3 and the other is located on the lower surface of the motherboard 3, and the upper surface and the lower surface are connected through a metal via of the motherboard 3, then the first ground plane 31 and the second ground plane 32 represent the same ground plane, and the ground planes referenced by the main antenna 1 and the parasitic antenna 2 are also the same.

[0119] The above is a case where the main antenna 1 and the parasitic antenna 2 share a common ground, and a method for implementing the common ground.

[0120] In another example, the main antenna 1 and the parasitic antenna 2 may not share a common ground, that is, the ground planes referenced by the two are inconsistent.

[0121] For example, let's assume that the top surface of motherboard 3 represents the first ground plane 31, and the bottom surface represents the second ground plane 32. As an example, the outer conductor of the feeder line connected to the main antenna 1 can be connected to the top surface of motherboard 3. In this case, the reference ground plane is the first ground plane 31. The parasitic antenna 2 can be connected to the bottom surface of motherboard 3. In this case, the reference ground plane is the second ground plane 32. There is no electrical connection between the first ground plane 31 and the second ground plane 32, thereby ensuring that the main antenna 1 and parasitic antenna 2 do not share a common ground. To ensure that the parasitic antenna 2 does not connect to the top surface of motherboard 3 when connected to the bottom surface of motherboard 3, a slot can be created in motherboard 3. The parasitic antenna 3 passes through the slot and connects to the bottom surface of motherboard 3.

[0122] Among them, this embodiment does not specifically limit whether the main antenna 1 and the parasitic antenna 2 are connected to the same ground, and can be flexibly selected according to the design requirements of the antenna and the expected effect to be achieved. The following description of the antenna resonant mode will introduce the effect produced when the main antenna 1 and the parasitic antenna 2 are connected to the same ground.

[0123] As described above, the antenna increases the number of antenna resonant modes through the coupling between the main antenna 1 and the parasitic antenna 2, thereby broadening the antenna's resonant frequency band. Consequently, the resonant frequency of the main antenna 1 and the resonant frequency of the parasitic antenna 2 are close. For example, the difference between the resonant frequency of the main antenna 1 and the resonant frequency of the parasitic antenna 2 is less than a target threshold.

[0124] In one example, the difference between the resonant frequency of the main antenna 1 and the resonant frequency of the parasitic antenna 2 can be the absolute value of the absolute difference, specifically the absolute value of the difference between the resonant frequency of the main antenna 1 and the resonant frequency of the parasitic antenna 2. For example, if the resonant frequency of the main antenna is f1 and the resonant frequency of the parasitic antenna is f2, then the difference between the resonant frequency of the main antenna and the resonant frequency of the parasitic antenna is |f1-f2|.

[0125] Alternatively, the difference between the resonant frequency of the main antenna 1 and the resonant frequency of the parasitic antenna 2 may be the absolute value of the relative difference, specifically the percentage between the absolute value of the difference between the resonant frequency of the main antenna 1 and the resonant frequency of the parasitic antenna 2 and the midpoint of the two resonant frequencies. For example, if the resonant frequency of the main antenna is f1 and the resonant frequency of the parasitic antenna is f2, then the difference between the resonant frequency of the main antenna and the resonant frequency of the parasitic antenna is,

[0126] Then, if the difference between the resonant frequencies of main antenna 1 and parasitic antenna 2 is the absolute value of the absolute difference, the target threshold is a frequency value. If the difference between the resonant frequencies of main antenna 1 and parasitic antenna 2 is the absolute value of the relative difference, the target threshold is a percentage.

[0127] Regardless of whether the target threshold is a frequency value or a percentage, it is related to the frequency bands of the main antenna 1 and the parasitic antenna 2. That is, if the frequency bands of the main antenna 1 and the parasitic antenna 2 are different, the target threshold will be different. The frequency bands of the main antenna 1 and the parasitic antenna 2 are related to the frequency band to be widened by the antenna.

[0128] For example, in cellular communications, the operating frequency bands of 4G antennas and 5G antennas are generally divided into low frequency bands (700MHz to 960MHz), medium and high frequency bands (1710MHz to 2690MHz), and high frequency bands (3300MHz to 5000MHz).

[0129] If the antenna broadens the coverage bandwidth of the low-frequency band through the parasitic antenna 2, then the resonant frequencies of the main antenna 1 and the parasitic antenna 2 are both located in the low-frequency band, the absolute value of the absolute difference between the resonant frequency of the main antenna 1 and the resonant frequency of the parasitic antenna 2 is less than 350M, and the absolute value of the relative difference between the resonant frequency of the main antenna 1 and the resonant frequency of the parasitic antenna 2 is less than 42%.

[0130] If the antenna broadens the coverage bandwidth of the medium and high frequency bands through the parasitic antenna 2, then the resonant frequencies of the main antenna 1 and the parasitic antenna 2 are both located in the medium and high frequency bands, the absolute value of the absolute difference between the resonant frequency of the main antenna 1 and the resonant frequency of the parasitic antenna 2 is less than 600M, and the absolute value of the relative difference between the resonant frequency of the main antenna 1 and the resonant frequency of the parasitic antenna 2 is less than 40%.

[0131] If the antenna broadens the coverage bandwidth of the high-frequency band through the parasitic antenna 2, then the resonant frequencies of the main antenna 1 and the parasitic antenna 2 are both located in the high-frequency band, the absolute value of the absolute difference between the resonant frequency of the main antenna 1 and the resonant frequency of the parasitic antenna 2 is less than 800M, and the absolute value of the relative difference between the resonant frequency of the main antenna 1 and the resonant frequency of the parasitic antenna 2 is less than 25%.

[0132] As can be seen from the above, this antenna uses electromagnetic field coupling between the main antenna 1 and the parasitic antenna 2 to increase the number of antenna resonant modes and thus broaden the antenna's frequency band. The degree of coupling between the main antenna 1 and the parasitic antenna 2 affects the antenna's resonant frequency. Therefore, adjusting the coupling between the main antenna 1 and the parasitic antenna 2 can adjust the antenna's resonant frequency.

[0133] In one example, the degree of coupling between the main antenna 1 and the parasitic antenna 2 can be adjusted by adjusting the positional relationship between the electric field strength point of the main antenna 1 and the electric field strength point of the parasitic antenna 2, as well as the positional relationship between the magnetic field strength point of the main antenna 1 and the magnetic field strength point of the parasitic antenna 2.

[0134] Generally, points of strong current correspond to points of strong magnetic field, and points of weak current correspond to points of strong electric field.

[0135] Therefore, the key to adjusting the degree of coupling between the main antenna 1 and the parasitic antenna 2 lies in adjusting the positional relationship between the current strong point of the main antenna 1 and the current strong point of the parasitic antenna 2, as well as adjusting the positional relationship between the current weak point of the main antenna 1 and the current weak point of the parasitic antenna 2.

[0136] The locations of the current strong point and the current weak point are related to the type of antenna.

[0137] For example, for a monopole antenna, as shown in Figure 2, the current distribution when exciting a quarter-wavelength line mode is strongest at the feed point and weakest at the open end. Typically, the end of a monopole antenna connected to the mainboard 3 is designated as the starting end and the feed point, while the other end is designated as the open end and the end. Therefore, for a monopole antenna, the starting end is the location of the strongest current, and the end is the location of the weakest current.

[0138] It should be pointed out that the black filled solid dots in Figure 2 represent the locations of strong current points, and the unfilled dots represent the locations of weak current points. This representation method is also applicable to other figures. The arrows in Figure 2 represent the current at a certain moment, and the arrows in other figures also represent the current at a certain moment.

[0139] FIG2 is a schematic diagram of current distribution at a certain moment when current is loaded on the monopole antenna shown in FIG4 .

[0140] For another example, as shown in Figure 3, in the current distribution of a loop antenna that excites a half-wavelength loop mode, the current is weakest at the center (i.e., at a quarter wavelength) and strongest at the ends. Therefore, for a loop antenna, the center is the weakest current point, while the ends are the strongest.

[0141] FIG3 is a schematic diagram of current distribution at a certain moment when current is loaded on the monopole antenna shown in FIG5 .

[0142] Based on the above, in one example, the spatial distance between the current strong point position of the main antenna 1 and the current strong point position of the parasitic antenna 2, as well as the spatial distance between the current weak point position of the main antenna 1 and the current weak point position of the parasitic antenna 2 can be adjusted through simulation software to optimize the electromagnetic field coupling effect between the main antenna 1 and the parasitic antenna 2, so that the operating frequency band of the antenna is relatively wide, meets the expected bandwidth, and realizes the wide bandwidth coverage of the antenna.

[0143] Regarding the antenna types of the main antenna 1 and the parasitic antenna 2, for example, the main antenna 1 can be a monopole antenna or a loop antenna, and the parasitic antenna 2 can also be a monopole antenna or a loop antenna, then there will be the following four solutions.

[0144] In one solution, the main antenna 1 is a monopole antenna and the parasitic antenna 2 is a loop antenna. In another solution, both the main antenna 1 and the parasitic antenna 2 are loop antennas. In another solution, both the main antenna 1 and the parasitic antenna 2 are monopole antennas. In another solution, the main antenna 1 is a loop antenna and the parasitic antenna 2 is a monopole antenna.

[0145] The following describes the characteristics of the antennas, respectively, in the case where the main antenna 1 is a monopole antenna, the parasitic antenna 2 is a loop antenna, and both the main antenna 1 and the parasitic antenna 2 are monopole antennas.

[0146] Among them, the monopole antenna is an antenna that can excite a specific wavelength line mode after an excitation signal is input thereto. For example, inputting an excitation signal to the monopole antenna can excite a resonant mode of a 1 / 4 wavelength line mode.

[0147] A loop antenna, also known as a loop antenna, is a structure consisting of a metal conductor wound into a specific shape, such as a circle, square, or triangle, with the two ends of the conductor acting as output terminals. When an excitation signal is input to the loop antenna, a resonant mode at a specific wavelength, such as a half-wavelength ring mode, is excited.

[0148] (1) The main antenna 1 is a monopole antenna, and the parasitic antenna 2 is a loop antenna.

[0149] As shown in Figure 4, this is a schematic diagram of the structure of a main antenna 1. One end of the main antenna 1 is fixed to the surface of the main board 3, and the other end is open. The main antenna 1 is a monopole antenna. Then, as described above, the end fixed to the main board 3 is recorded as the starting end, and the open end is recorded as the ending end. The starting end is the feeding point, the current strong point of the main antenna 1 is the starting end, and the current weak point is the ending end.

[0150] Figure 5 shows the structure of a parasitic antenna 2. Both ends (i.e., the first and second ends) of the parasitic antenna 2 are fixed to the surface of the mainboard 3 and electrically connected to the mainboard 3 for grounding. Parasitic antenna 2 is a loop antenna. As mentioned above, the center of the parasitic antenna 2 is the weakest current point, while the ends are the strongest current points.

[0151] Therefore, when adjusting the degree of coupling between the main antenna 1 and the parasitic antenna 2, the positional relationship between the starting end of the main antenna 1 and the end of the parasitic antenna 2 can be adjusted, as well as the positional relationship between the end of the main antenna 1 and the middle position of the parasitic antenna 2 can be adjusted to satisfy the antenna after the main antenna 1 and the parasitic antenna 2 are coupled, including multiple resonant modes to broaden the coverage bandwidth of the antenna.

[0152] In one example, the positional relationship between the starting end of the main antenna 1 and the end of the parasitic antenna 2 is adjusted. For example, the distance between the starting end of the main antenna 1 and the end of the parasitic antenna 2 is less than a first value, so that the starting end of the main antenna 1 and the ends of the parasitic antenna 2 are relatively close, as shown in Figure 6 (to facilitate distinguishing between the main antenna 1 and the parasitic antenna 2, the solid line in Figure 6 represents the main antenna 1, and the dotted line represents the parasitic antenna 2).

[0153] Similarly, the positional relationship between the end of the main antenna 1 and the middle position of the parasitic antenna 2 is adjusted. For example, the distance between the end of the main antenna 1 and the middle position of the parasitic antenna 2 is less than the second value, so that the end of the main antenna 1 and the middle position of the parasitic antenna 2 are relatively close, as shown in Figure 6.

[0154] Since the first and second ends of the parasitic antenna 2 are both locations where current is strong, the distance between the starting end of the main antenna 1 and the end of the parasitic antenna 2, as shown in FIG6 , can be the distance between the starting end of the main antenna 1 and the first end of the parasitic antenna 2. Of course, it can also be the distance between the starting end of the main antenna 1 and the second end of the parasitic antenna 2, and can also include the distance between the starting end of the main antenna 1 and the first end of the parasitic antenna 2, and the distance between the starting end of the main antenna 1 and the second end of the parasitic antenna 2.

[0155] The first value and the second value can be determined through simulation results. Moreover, if the main antenna 1 and the parasitic antenna 2 are located in different resonant frequency bands, the values ​​may also be different. For example, if the resonant frequencies of the main antenna 1 and the parasitic antenna 2 are both located in the low frequency band (700 MHz to 960 MHz), the first value may be 8 mm and the second value may be 35 mm.

[0156] Among them, the distances mentioned above are all spatial distances in three-dimensional space.

[0157] It should be noted that, in order to make the parasitic antenna 2 a loop antenna, the distance between the two ends of the parasitic antenna 2 cannot be too large, and is usually less than a certain value, for example, less than 25 mm.

[0158] The antenna shown in FIG6 can have at least the current distribution shown in FIG2 and the current distribution shown in FIG3 by adjusting the positional relationship between the starting end of the main antenna 1 and the first end of the parasitic antenna 2, as well as adjusting the positional relationship between the end of the main antenna 1 and the middle position of the parasitic antenna 2, thereby exciting at least a 1 / 4 wavelength line mode resonant mode and a 1 / 2 wavelength ring mode resonant mode.

[0159] The above is about the positional relationship arrangement between the main antenna 1 and the parasitic antenna 2. The structural features of the main antenna 1, the structural features of the parasitic antenna 2 and the simulation results will be introduced below.

[0160] (1) Structural features of the main antenna 1.

[0161] As shown in Figure 4, the main antenna 1 includes a first radiating arm 11 and a second radiating arm 12, wherein one end of the first radiating arm 11 is vertically fixed to the surface of the main board 3, and the other end is vertically connected to the second radiating arm 12. That is, the first radiating arm 11 is arranged vertically relative to the main board 3, and the second radiating arm 12 is arranged horizontally relative to the main board 3. The main antenna 1 includes the vertical first radiating arm 11 and the horizontal second radiating arm 12, which can compress the vertical size of the main antenna 1 to adapt to the height of the shark fin of the car, or the height of the luggage rack of the car.

[0162] Continuing with reference to FIG4 , the second radiating arm 12 includes a first inclined branch 121 and a horizontal branch 122 , where “inclined” and “horizontal” are both relative to the mainboard 3 , with the plane where the mainboard 3 is located being the horizontal plane. The second radiating arm 12 is designed in this way, on the one hand, to shorten the lateral dimension of the main antenna 1 and make the main antenna more compact; on the other hand, to adjust the positional relationship between the end of the main antenna 1 and the middle position of the parasitic antenna 2 so that the end of the main antenna 1 and the middle position of the parasitic antenna 2 are closer.

[0163] Continuing with FIG4 , first radiating arm 11 includes a first branch 111 and a second branch 112. One end of first branch 111 is perpendicularly positioned on the surface of mainboard 3, and the other end is connected to one end of second branch 112. The other end of second branch 112 is perpendicularly connected to second radiating arm 12. As shown in FIG4 , the width of second branch 112 is greater than the width of first branch 111.

[0164] As shown in FIG7 , the second branch 112 is relatively wide, so there are multiple current paths distributed on the second branch 112. Although the electrical lengths corresponding to these current paths are similar, they are slightly different. Different electrical lengths stimulate different resonant frequencies. Therefore, multiple different electrical lengths stimulate multiple close but different resonant frequencies, which is beneficial to broadening the bandwidth of the antenna.

[0165] Since the second branch 112 is relatively wide, the second branch 112 can be hollowed out to form a ring shape as shown in FIG. 8 , including a hollow area 1120 and first and second branches 1121 and 1122 on the left and right sides of the hollow area 1120 .

[0166] As shown in Figure 8, the second branch 112 includes a first branch 1121 and a second branch 1122 that are independent of each other. Then, the current distributed in the first branch 1121 can excite an electromagnetic wave of one resonant frequency, and the current distributed in the second branch 1122 can excite an electromagnetic wave of another resonant frequency, thereby increasing the number of resonant frequencies of the antenna and broadening the bandwidth of the antenna by increasing the number of resonant frequencies.

[0167] As shown in Figure 9, the main antenna 1 can also include a first matching branch 14. As shown in Figure 9, since the second branch 112 is wider than the first branch 111, there is a certain distance between the second branch 112 and the main board 3, and the first matching branch 14 can be located in this distance. For example, the first matching branch 14 is fixed to the main board 3 and is located on one side of the first branch 111, between the second branch 112 and the main board 3.

[0168] In this way, capacitance can be formed between the mutually adjacent edges of the first matching branch 14 and the first branch 111, and / or between the mutually adjacent edges of the first matching branch 14 and the second branch 112. The capacitance formed can be used to adjust the impedance matching between the antenna and the feeder to reduce the return loss and improve the radiation efficiency of the antenna.

[0169] For example, the antenna can be a full-band antenna that can transmit and receive electromagnetic waves in low frequency bands, medium and high frequency bands, and high frequency bands. The first matching branch 14 mentioned above can be used to adjust the impedance matching characteristics of the medium and high frequencies and reduce the return loss of the medium and high frequencies.

[0170] Continuing with FIG9 , main antenna 1 may further include a second matching branch 15. Second matching branch 15 is fixed to the surface of mainboard 3 and is located on the side of first matching branch 111 opposite first matching branch 14. That is, first matching branch 111 is located between first matching branch 14 and second matching branch 15. As shown in FIG9 , the edges of second matching branch 15 and first matching branch 111 that are close to each other can also form a capacitor. Therefore, second matching branch 15 can also be used to adjust the impedance matching characteristics between main antenna 1 and the feeder.

[0171] In one example, the first matching branch 14 and the second matching branch 15 can be integrally formed. For example, the metal plate where the first matching branch 14 and the second matching branch 15 are located has an opening, which divides the metal plate into the first matching branch 14 and the second matching branch 15. The first branch 111 passes through the opening and is fixed to the surface of the main board 3.

[0172] In another example, the first matching branch 14 and the second matching branch 15 may also be two independent metal plates.

[0173] In one example, the main antenna 1 can adjust the impedance matching characteristics with the feeder through the first matching branch 14, can also adjust the impedance matching characteristics with the feeder through the second matching branch 15, and can also adjust the impedance matching characteristics with the feeder through the first matching branch 14 and the second matching branch 15. This embodiment is not limited to this.

[0174] As described above, one end of the first radiating arm 11 is vertically located on the surface of the main board 3, and the other end is vertically connected to one end of the second radiating arm 12. As shown in Figure 10, the main antenna 1 can also include a third radiating arm 13, one end of the third radiating arm 13 is vertically connected to the other end of the second radiating arm 12, and the other end of the third radiating arm 13 is the open end (that is, the end) of the main antenna 1.

[0175] As shown in FIG10 , the third radiating arm 13 is arranged vertically relative to the main board 3 , so as to further shorten the lateral dimension of the main antenna 1 and make the main antenna 1 more compact.

[0176] Continuing with FIG10 , second radiating arm 12 includes not only first inclined branch 121 and horizontal branch 122, but also second inclined branch 123. First inclined branch 121, horizontal branch 122, and second inclined branch 123 are sequentially connected. The structural feature of second radiating arm 12 including first inclined branch 121, horizontal branch 122, and second inclined branch 123 connected sequentially further reduces the lateral dimensions of main antenna 1, making the structure of main antenna 1 more compact.

[0177] (2) Structural features of the parasitic antenna 2.

[0178] As shown in Figures 5 and 11, parasitic antenna 2 is a polygonal ring formed by connecting multiple edges. The ring-shaped arrangement of parasitic antenna 2 is primarily designed to coordinate with main antenna 1. For example, as shown in Figures 6 and 12, this ensures that the width of parasitic antenna 2 is equal to or nearly equal to the width of main antenna 1, and the height of parasitic antenna 2 is equal to or nearly equal to the height of main antenna 1. Furthermore, this ensures that the end of main antenna 1 is close to the middle of parasitic antenna 2. Furthermore, this ensures that the beginning of main antenna 1 is close to the first end of parasitic antenna 2.

[0179] To facilitate the distinction between the main antenna 1 and the parasitic antenna 2 , the solid line in FIG12 represents the main antenna 1 , and the dotted line represents the parasitic antenna 2 .

[0180] In one example, as shown in FIG11 , the width of the second end of the parasitic antenna 2 is widened. The widened design means that the width of the second end is greater than the width at other positions. Such a widened design is similar to a loaded inductor and can be used to adjust the impedance matching characteristics between the antenna and the feeder and reduce the return loss.

[0181] (3) Simulation results of the antenna shown in FIG12.

[0182] In one example, the antenna shown in FIG. 12 is simulated to obtain characteristic diagrams shown in FIG. 13 to FIG. 15 .

[0183] Figure 13 shows a return loss characteristic graph. The ordinate represents the magnitude of the return loss. 0 dB indicates maximum return loss and the worst impedance matching between the antenna and feeder. Negative infinity represents minimum return loss and the best impedance matching between the antenna and feeder. The abscissa represents frequency.

[0184] As shown in Figure 13, the antenna's return loss in the low-frequency bands N28, B5, and B8 is less than -5dB. The return loss in the medium- and high-frequency bands B3, B34, B39, B40, and B41 is also less than -5dB. The return loss in the high-frequency band N79 is also less than -5dB. Therefore, the antenna can achieve 4G and 5G wide-band coverage.

[0185] Among them, the uplink frequency band of N28 is 703-748MHz, and the downlink frequency band is 758-803MHz. The uplink frequency band of B5 is 824-849MHz, and the downlink frequency band is 869-894MHz. The uplink frequency band of B8 is 880-915MHz, and the downlink frequency band is 925-960MHz. The uplink frequency band of B3 is 1710-1785MHz, and the downlink frequency band is 1805-1880MHz. The uplink and downlink frequency bands of B34 are both 2010-2025MHz. The uplink and downlink frequency bands of B39 are both 1880-1920MHz. The uplink and downlink frequency bands of B41 are both 2496-2690MHz. The uplink and downlink frequency bands of N79 are both 4800-5000MHz.

[0186] Figure 14 shows the antenna radiation efficiency characteristic. The vertical axis in Figure 14 represents the radiation efficiency loss. 0dB represents no loss, corresponding to a radiation efficiency of 1, while -3dB corresponds to a radiation efficiency of 50%. Negative infinity indicates maximum radiation loss and minimum radiation efficiency. The horizontal axis in Figure 14 represents frequency.

[0187] Figure 15 shows the system efficiency characteristic graph. Figure 15 and Figure 14 illustrate similar concepts, except that Figure 15 shows the overall system efficiency, including efficiency due to return loss and radiation efficiency. The vertical axis in Figure 15 represents the system efficiency loss. 0dB represents no loss, corresponding to a system efficiency of 1, while -3dB corresponds to a radiation efficiency of 50%. Negative infinity indicates maximum radiation loss and lowest system efficiency. The horizontal axis in Figure 15 represents frequency.

[0188] As shown in Figures 14 and 15, the in-band radiation efficiency of the antenna in the 5G frequency band is greater than -2dB.

[0189] According to Figures 14 and 15, the more negative the number on the vertical axis, the greater the loss and the lower the efficiency. Then, in the efficiency characteristic diagram, the minimum point corresponds to the radiation zero point. Therefore, as shown in Figures 14 and 15, the antenna provided in this embodiment has a radiation zero point located out of band compared with the traditional antenna that does not include a parasitic antenna, and thus has good anti-frequency interference characteristics.

[0190] The position of the radiation zero point can be adjusted by adjusting the degree of coupling between the main antenna 1 and the parasitic antenna 2. For example, the radiation zero point can be adjusted to the frequency band of the global navigation satellite system (GNSS) antenna to reduce the interference of the GNSS antenna to the B8 band and the B3 band in the 5G frequency band.

[0191] In this way, even if the communication antenna and the GNSS antenna shown in this embodiment are arranged together, the interference of the GNSS antenna on the communication antenna can be reduced.

[0192] Therefore, the antenna shown in Figure 12 can effectively broaden the antenna frequency band, achieving full 4G and 5G frequency band coverage. Furthermore, it can also improve out-of-band suppression and enhance cross-frequency interference resistance.

[0193] The above are the structural features and simulation results of the case where the main antenna 1 is a monopole antenna and the parasitic antenna 2 is a loop antenna. The following describes the structural features and simulation results of the case where the main antenna 1 is a monopole antenna and the parasitic antenna 2 is also a monopole antenna.

[0194] (2) The main antenna 1 is a monopole antenna, and the parasitic antenna 2 is also a monopole antenna.

[0195] As shown in FIG16 , it is a schematic structural diagram of a main antenna 1 . Referring to the above description, the current strong point of the main antenna 1 is the starting end, and the current weak point is the end end.

[0196] As shown in Figure 17, this is a schematic diagram of the structure of a parasitic antenna 2. One end of the parasitic antenna 2 is fixed to the surface of the mainboard 3 and is electrically connected to the mainboard 3 to be grounded. The other end of the parasitic antenna 2 is open. The parasitic antenna 2 is a monopole antenna. Therefore, as described above, the end fixed to the mainboard 3 is recorded as the starting end, and the open end is recorded as the ending end. The position of the strong current point of the parasitic antenna 2 is the starting end, and the position of the weak current point is the ending end.

[0197] Among them, the arrows in Figures 16 and 17 indicate the distribution of current on the main antenna 1 at a certain moment. Figure 16 is the current distribution when the main antenna 1 excites a 1 / 4 wavelength line mode, and Figure 17 is the current distribution when the parasitic antenna 2 excites a 1 / 4 wavelength line mode.

[0198] Therefore, when adjusting the degree of coupling between the main antenna 1 and the parasitic antenna 2, the positional relationship between the starting end of the main antenna 1 and the starting end of the parasitic antenna 2 can be adjusted, as well as the positional relationship between the end of the main antenna 1 and the end of the parasitic antenna 2 can be adjusted to satisfy the antenna after the main antenna 1 and the parasitic antenna 2 are coupled, including multiple resonant modes to broaden the coverage bandwidth of the antenna.

[0199] In one example, the positional relationship between the starting end of the main antenna 1 and the starting end of the parasitic antenna 2 is adjusted, for example, the distance between the starting end of the main antenna 1 and the starting end of the parasitic antenna 2 is less than a third value, so as to achieve a relatively close position between the starting end of the main antenna 1 and the starting end of the parasitic antenna 2, as shown in Figure 18.

[0200] Similarly, the positional relationship between the end of the main antenna 1 and the end of the parasitic antenna 2 is adjusted. For example, the distance between the end of the main antenna 1 and the end of the parasitic antenna 2 is less than the fourth value, so that the end of the main antenna 1 and the end of the parasitic antenna 2 are relatively close, as shown in Figure 18.

[0201] Among them, the third value and the fourth value can be determined through simulation results. Moreover, if the main antenna 1 and the parasitic antenna 2 are located in different resonant frequency bands, then the values ​​of the third value and the fourth value will also be different. For example, if the resonant frequency bands of the main antenna 1 and the parasitic antenna 2 are both in the low frequency band (700 MHz to 960 MHz), then the third value can be 8 mm and the fourth value can be 25 mm.

[0202] Among them, the distances mentioned above are all spatial distances in three-dimensional space.

[0203] The above is about the positional relationship arrangement between the main antenna 1 and the parasitic antenna 2. Regarding the structural features of the main antenna 1, since the main antenna 1 described in (2) and the main antenna 1 described in (1) above are both monopole antennas, the structural features of the main antenna 1 described in (2) can refer to those described in (1) above and will not be repeated here.

[0204] Regarding the structural features of parasitic antenna 2, as shown in Figure 17, parasitic antenna 2 also includes vertical and horizontal branches to match the main antenna 1. The main antenna 1 and parasitic antenna 2 are matched. For example, as shown in Figure 18, the width of the main antenna 1 is comparable to the width of the parasitic antenna, the height of the main antenna 1 is comparable to the height of the parasitic antenna 2, the starting point of the main antenna 1 is close to the starting point of the parasitic antenna 2, and the end of the main antenna 1 is close to the end of the parasitic antenna 2.

[0205] As shown in Figure 18, the main antenna 1 and the parasitic antenna 2 are coupled to each other, generating current distributions as shown in Figures 19 to 21. Figure 19 (a) is a front view, and (b) is a top view. As shown in Figure 19 (b), the current directions on the main antenna 1 and the parasitic antenna 2 are in the same direction, and the two are superimposed. As shown in Figure 19 (a), the currents distributed on the first ground plane 31 and the second ground plane 32 of the mainboard 3 are also in the same direction. Therefore, the resonant mode excited by the current distribution shown in Figure 19 is an effective resonant mode generated by electromagnetic coupling. This resonant mode can be recorded as the antenna's resonant mode 1, and the corresponding resonant point is recorded as resonant point 1.

[0206] Among them, (a) in Figure 20 is a front view, and (b) is a top view. As shown in (b) in Figure 20, the current direction on the main antenna 1 and the current direction on the parasitic antenna 2 are in the same direction, and the two are in a superimposed relationship. As shown in (a) in Figure 20, the currents distributed on the first ground plane 31 and the second ground plane 32 of the main board 3 are also in the same direction. Therefore, the current distribution shown in Figure 20 and the resonant mode excited are effective resonant modes generated by electromagnetic coupling. This resonant mode can be recorded as the resonant mode 2 of the antenna, and the corresponding resonant point is recorded as the resonant point 2.

[0207] Among them, (a) in Figure 21 is a front view, and (b) is a top view. As shown in (b) in Figure 21, the current direction on the main antenna 1 and the current direction on the parasitic antenna 2 are opposite, and the two are in a canceling relationship. As shown in (a) in Figure 21, the currents distributed on the first ground plane 31 and the second ground plane 32 of the main board 3 are also in opposite directions. Therefore, the current distribution shown in Figure 21 excites the resonant mode, which has low radiation efficiency and belongs to the invalid resonant mode generated by electromagnetic coupling. This resonant mode can be recorded as the resonant mode 3 of the antenna, and the corresponding resonant point is recorded as the resonant point 3.

[0208] In one example, the resonant mode 3 can be eliminated by sharing a common ground with the main antenna 1 and the parasitic antenna 2. The main antenna 1 and the parasitic antenna 2 share a common ground, that is, the outer conductor of the feeder connected to the main antenna 1 shares a common ground with the parasitic antenna 2. The common ground solution is described above and will not be repeated here.

[0209] In one example, if the resonance point 3 corresponding to resonance mode 3 is relatively close to the resonance point 2 corresponding to resonance mode 2, then after eliminating the invalid resonance mode 3, the rate of decrease of the radiation loss of resonance mode 2 can also be reduced. This is because resonance mode 3 is an invalid resonance, and the radiation loss at resonance point 3 is relatively large. In the radiation efficiency characteristic diagram, resonance point 3 corresponds to the minimum point. If resonance mode 3 is not eliminated, then in the radiation efficiency characteristic diagram, the radiation loss is in a rapid decrease from resonance point 2 to resonance point 3, and then the radiation efficiency of the antenna is in a rapid decrease from resonance point 2 to resonance point 3. If resonance mode 3 is eliminated, then since resonance point 3 is not at the corresponding minimum point in the radiation efficiency characteristic diagram, the radiation loss will not decrease rapidly from resonance point 2 to resonance point 3. Therefore, eliminating the invalid resonance mode 3 can reduce the rate of decrease of the radiation loss of resonance mode 2.

[0210] It should be pointed out that, as shown in FIG12 , the current distribution on the main antenna 1 and the parasitic antenna 2 can also excite multiple resonant modes. Among these multiple resonant modes, invalid resonant modes may also exist. Therefore, the invalid resonant modes can also be eliminated by sharing a common ground between the main antenna 1 and the parasitic antenna 2.

[0211] The simulation results of the antenna shown in FIG18 are described below.

[0212] In one example, the antenna shown in FIG. 18 is simulated to obtain characteristic diagrams shown in FIG. 22 and FIG. 23 .

[0213] Figure 22 shows a return loss characteristic graph. The ordinate in Figure 22 represents the magnitude of the return loss. 0 dB indicates maximum return loss and the worst impedance matching between the antenna and feeder. -Infinity indicates minimum return loss and the best impedance matching between the antenna and feeder. The abscissa in Figure 22 represents frequency.

[0214] According to Figure 22, the more negative the number on the vertical axis, the smaller the return loss. Then, in the echo characteristic diagram, the minimum point corresponds to a resonance point. Therefore, as shown in Figure 22, the antenna provided in this embodiment includes two resonance points compared to the traditional antenna that does not include a parasitic antenna. Therefore, it is possible to broaden the bandwidth of the antenna. The positions of the two resonance points can be adjusted by adjusting the coupling strength between the main antenna 1 and the parasitic antenna 2.

[0215] Figure 23 shows an efficiency characteristic graph. The vertical axis represents efficiency loss. 0dB represents zero loss, corresponding to an efficiency of 1, while -3dB corresponds to 50% efficiency. Negative infinity indicates maximum loss and lowest efficiency. The horizontal axis represents frequency. The dashed line in Figure 23 shows how radiation efficiency varies with frequency, while the solid line shows how system efficiency varies with frequency.

[0216] According to Figure 23, the more negative the number on the vertical axis, the greater the loss and the lower the efficiency. Then, in the efficiency characteristic diagram, the minimum point corresponds to the radiation zero point. Therefore, as shown in Figure 23, the antenna provided by this embodiment has a radiation zero point located outside the band (the minimum point in Figure 23 is the radiation zero point) compared with the traditional antenna that does not include a parasitic antenna, and thus has good anti-frequency interference characteristics.

[0217] The antenna including the parasitic antenna is, that is, the antenna provided by this embodiment. The antenna not including the parasitic antenna may be a traditional antenna having only a main antenna but no parasitic antenna.

[0218] The position of the radiation zero point can be adjusted by adjusting the degree of coupling between the main antenna 1 and the parasitic antenna 2. For example, the radiation zero point can be adjusted to the frequency band of the global navigation satellite system (GNSS) antenna to reduce the interference of the GNSS antenna to the B8 band and the B3 band in the 5G frequency band.

[0219] In this way, even if the communication antenna and the GNSS antenna shown in this embodiment are arranged together, the interference of the GNSS antenna on the communication antenna can be reduced.

[0220] Therefore, the antenna shown in Figure 18 can effectively broaden the antenna frequency band, achieving full 4G and 5G frequency band coverage. Furthermore, it can also improve out-of-band suppression and enhance cross-frequency interference resistance.

[0221] In the embodiment of the present disclosure, the antenna includes a main antenna and a parasitic antenna, which are arranged relative to each other. The excitation signal of the main antenna is introduced by the feeder, and the excitation signal of the parasitic antenna is introduced by coupling with the electromagnetic field of the main antenna. The main antenna and the parasitic antenna are coupled with each other, which can broaden the bandwidth of the antenna. Then, the antenna is used in a car as a communication antenna for the car, such as a 4G communication antenna, or a 5G communication antenna, and can achieve 4G or 5G wide bandwidth coverage, or even full bandwidth coverage.

[0222] In addition, the antenna can also improve the out-of-band suppression and the anti-frequency interference characteristics. For example, the antenna can improve the out-of-band suppression of the GNSS antenna, so that even if the GNSS antenna and the antenna described in this embodiment are arranged together, such as both arranged in the shark fin or both arranged in the luggage rack, the interference of the GNSS antenna on the antenna described in this embodiment can be reduced.

[0223] An embodiment of the present disclosure further provides an antenna system, which includes a radio frequency circuit and the antenna described above, wherein the radio frequency circuit is used to enable the antenna to transmit and receive wireless signals.

[0224] An embodiment of the present disclosure further provides a car, which includes the antenna system described above.

[0225] Regarding the antennas in the antenna system, their placement in the car.

[0226] In one example, the antenna of the antenna system can be placed in a luggage rack of a vehicle. For example, if a vehicle includes a left luggage rack on the left side of the vehicle body and a right luggage rack on the right side of the vehicle body, the antenna can be placed in the left luggage rack, the right luggage rack, or both the left and right luggage racks.

[0227] For example, as shown in Figure 24, the antenna architecture deployed in the luggage rack is a 4×4 multiple-in, multiple-out (MIMO) system, consisting of two 5G full-band antennas and two 5G medium- and high-frequency antennas. These four antennas are designated as full-band antenna A, full-band antenna B, medium- and high-frequency antenna C, and medium- and high-frequency antenna D. Due to the large size of the full-band antennas, full-band antennas A and B are located at the higher part of the luggage rack's cross-section, while high-frequency antenna C and medium- and high-frequency antenna D are located at the lower part of the luggage rack's cross-section.

[0228] The full-band antenna A and the full-band antenna B may be the antennas provided in this embodiment, for example, the antennas shown in FIG. 12 .

[0229] As shown in FIG25 , mainboard a of full-band antenna A, mainboard b of full-band antenna B, mainboard c of medium-high frequency antenna C, and mainboard d of medium-high frequency antenna D are all fixed to the surface of the metal base of the luggage rack.

[0230] In one example, components such as a fed coplanar waveguide transmission line, a series matching device, a parallel matching device, and a series detection resistor are printed on the above-mentioned main board. The excitation signal of the above-mentioned antenna is fed by a mini-fakra four-in-one connector, and then transmitted to the above-mentioned four main boards through the vehicle body wiring harness. Finally, the coplanar waveguide transmission line on each main board transmits the excitation signal to the above-mentioned four antennas, and then these four antennas radiate electromagnetic waves into free space.

[0231] Of course, in another example, the antenna may also be arranged in the shark fin of the car. For example, the four antennas mentioned above are all arranged in the shark fin.

[0232] Regarding the RF circuit in the antenna system and its layout in the car.

[0233] In one example, the radio frequency circuit of the antenna system may be disposed in a telematics box (T-BOX) of a car.

[0234] To reduce path loss of RF signals along the transmission path, the T-BOX where the RF circuit is located and the antenna are positioned as close as possible. For example, the T-BOX is located in the back seat of a car, close to the rear of the tire, and the antenna is located in the luggage rack. Therefore, the luggage rack where the antenna is located and the T-BOX are located on the same side of the car body.

[0235] As an example, the antenna is located in the right luggage rack on the right side of the vehicle body, and the T-BOX where the radio frequency circuit is located is located in the rear seat on the right side of the vehicle body and close to the tail of the tire.

[0236] When the vehicle supplies power to the T-BOX, the RF signal generated by the RF circuit in the T-BOX is transmitted via the signal cable to the mainboard on the roof, thereby exciting the antenna and radiating the modulated signal into free space. The reverse is also true for the receiving link.

[0237] The T-BOX is located in the back seat of the car, close to the rear of the tire. Furthermore, the roof rack where the antenna is located is on the same side of the car body as the T-BOX, making the antenna and T-BOX close in distance. This shortens the signal cable harness, effectively reducing link loss caused by the cable and improving the system efficiency of the vehicle antenna.

[0238] In addition, the antenna is hidden in the luggage rack structure. The outer shell of the luggage rack adopts a melt-casting process, and a waterproof rubber pad is set between the metal seat on the top of the vehicle body, thus ensuring the concealment and reliability of the vehicle antenna.

[0239] The above description is only one embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. An antenna, characterized in that: The antenna comprises a main antenna (1), a parasitic antenna (2) and a main board (3); The main antenna (1) and the parasitic antenna (2) are both located on the surface of the main board (3), and the plane where the main antenna (1) is located is parallel to the plane where the parasitic antenna (2) is located, and their positions are opposite; The feeding point of the main antenna (1) is connected to the feeding transmission line of the main board (3), and the parasitic antenna (2) is connected to the second grounding terminal of the main board (3); Wherein, the difference between the resonant frequency point of the main antenna (1) and the resonant frequency point of the parasitic antenna (2) is less than a target threshold.

2. The antenna according to claim 1, characterized in that The feeding point of the main antenna (1) is connected to the inner conductor of the feeding transmission line of the main board (3), the outer conductor of the feeding transmission line is connected to the first grounding end of the main board (3), and the first grounding end and the second grounding end are connected to a common ground.

3. The antenna according to claim 1 or 2, characterized in that: The main antenna (1) is a monopole antenna, and the parasitic antenna (2) is a loop antenna.

4. The antenna according to claim 3, characterized in that The starting end of the main antenna (1) is a feeding point, and both ends of the parasitic antenna (2) are connected to the second grounding end of the mainboard (3); The distance between the starting end of the main antenna (1) and the end of the parasitic antenna (2) is less than a first value, and the distance between the end of the main antenna (1) and the middle position of the parasitic antenna (2) is less than a second value.

5. The antenna according to claim 1 or 2, characterized in that: The main antenna (1) is a monopole antenna, and the parasitic antenna (2) is a monopole antenna.

6. The antenna according to claim 5, characterized in that The starting end of the main antenna (1) is a feeding point, and the starting end of the parasitic antenna is connected to the second grounding end of the mainboard (3); The distance between the starting end of the main antenna (1) and the starting end of the parasitic antenna (2) is less than a third value, and the distance between the end of the main antenna (1) and the end of the parasitic antenna (2) is less than a fourth value.

7. The antenna according to claim 1 or 2, characterized in that: The main antenna (1) is a loop antenna, and the parasitic antenna (2) is a loop antenna or a monopole antenna.

8. The antenna according to any one of claims 1 to 7, characterized in that: The main antenna (1) comprises a first branch (111) and a second branch (112); One end of the first branch node (111) is vertically located on the surface of the main board (3), and the other end is connected to the second branch node (112); the width of the second branch node (112) is greater than the width of the first branch node (111).

9. The antenna according to claim 8, characterized in that The main antenna (1) also includes a first matching branch (14); There is a distance between the second branch node (112) and the main board (3); the first matching branch node (14) is fixed to the main board (3) and is located on one side of the first branch node (111) and between the second branch node (112) and the main board (3); The edges of the first matching branch (14) and the first branch (111) that are close to each other, and / or the edges of the first matching branch (14) and the second branch (112) that are close to each other are used to form a capacitor.

10. The antenna according to claim 8 or 9, characterized in that: The second branch (112) comprises a first branch (1121) and a second branch (1122), wherein the first branch (1121) and the second branch (1122) are arranged side by side along a width direction of the second branch (112); One end of the first branch (1121) is connected to one end of the second branch (1122), and the other end of the first branch (1121) and the other end of the second branch (1122) are both connected to the first branch node (111).

11. The antenna according to any one of claims 1 to 10, characterized in that: The main antenna (1) comprises a first radiation arm (11), a second radiation arm (12) and a third radiation arm (13); One end of the first radiation arm (11) is vertically located on the surface of the mainboard (3), and the other end is vertically connected to one end of the second radiation arm (12), and the other end of the second radiation arm (12) is vertically connected to one end of the third radiation arm (13).

12. The antenna according to any one of claims 1 to 11, characterized in that: The total height of the main antenna (1) is equal to the total height of the parasitic antenna (2), and the total width of the main antenna (1) is equal to the total width of the parasitic antenna (2).

13. The antenna according to any one of claims 1 to 12, characterized in that: The antenna also includes a dielectric plate, which is vertically located on the surface of the main board (3), the main antenna (1) is located on the first surface of the dielectric plate, and the parasitic antenna (2) is located on the second surface of the dielectric plate. The first surface and the second surface of the dielectric plate are opposite to each other.

14. An antenna system, characterized in that: The antenna system comprises a radio frequency circuit and the antenna according to any one of claims 1 to 13, wherein the radio frequency circuit is used to enable the antenna to send and receive wireless signals.

15. A car, characterized in that: The automobile comprises the antenna system of claim 14.

16. The automobile according to claim 15, characterized in that The antenna is located in a luggage rack of the vehicle.

17. The automobile according to claim 16, characterized in that The radio frequency circuit is arranged in the telematics processor T-BOX of the car, the T-BOX is located at the rear seat of the car and close to the rear of the tire, and the luggage rack where the antenna is located and the T-BOX are located on the same side of the car body.

18. The automobile according to claim 15, characterized in that The antenna is located in the shark fin of the car.

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