Split front-mounted vehicle-mounted unit and antenna module

Abstract

The application relates to a split front-mounted vehicle-mounted unit and an antenna module, wherein the antenna module comprises an antenna main plate, an antenna radiation main unit arranged on the top surface of the antenna main plate, a radio frequency connector plugged on the top surface of the antenna main plate, and a radio frequency cable with one end connected with the radio frequency connector; the antenna module further comprises an additional feeding structure arranged on the antenna main plate; the additional feeding structure can effectively suppress the distributed current coupled to the radio frequency connector shell and / or the radio frequency cable shielding layer due to the compact layout, greatly reduces the influence of the additional current radiation on the original antenna directional diagram, guarantees the radiation performance of the antenna module of the vehicle-mounted unit, effectively reduces the current coupling degree of the antenna module and the radio frequency connector shell and / or the radio frequency cable, and is beneficial to the improvement of the EMC performance of the overall system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vehicle-mounted units, in particular to a split front-mounted vehicle-mounted unit and an antenna module. BACKGROUND

[0002] Vehicles can be equipped with ETC (Electronic Toll Collection) vehicle-mounted devices, and more and more vehicle manufacturers have started the front-mounted OBU (On-Board Unit) project.

[0003] In actual projects, in order to ensure the working function of the ETC system in the limited automobile layout space, a split arrangement scheme is usually adopted, that is, the antenna part and the other circuit part of the vehicle-mounted unit are separated into two modules, and are connected through a radio frequency cable in the middle. Therefore, the vehicle-mounted unit antenna module needs to be combined with the radio frequency cable in a space obviously smaller than that of the conventional rear-mounted vehicle-mounted unit, and good and stable performance needs to be ensured.

[0004] Due to the limited thickness of the antenna module, the radio frequency cable or the radio frequency connector is usually arranged on the side of the antenna module radiation, so that the radiation main body of the antenna module is farther away from the front support and the front windshield glass after installation, so as to ensure the radiation effect of the antenna. This layout inevitably has three adverse effects on the performance of the antenna module of the vehicle-mounted unit: 1) the limited layout space causes the radio frequency cable or the radio frequency connector to be close to the antenna radiation part, so that coupling occurs to cause distortion of the antenna pattern; 2) the current radiation into the outside of the radio frequency cable shielding layer or directly into the radio frequency cable shielding layer, which causes the radiation performance of the overall antenna module to change with different lengths and layouts of the radio frequency cable; 3) the current path from the outside of the radio frequency cable shielding layer to the antenna, which causes the EMC performance of the overall system to deteriorate. SUMMARY

[0005] In view of the above defects in the prior art, the present application solves the technical problem of the harmful influence of the radio frequency cable or the radio frequency connector on the antenna radiation performance in the existing split front-mounted vehicle-mounted unit.

[0006] The technical scheme adopted by the present application to solve the technical problem is: an antenna module is constructed for a split front-mounted vehicle-mounted unit, which comprises an antenna main board, an antenna radiation main unit arranged on the top surface of the antenna main board, a radio frequency connector plugged into the top surface of the antenna main board, and a radio frequency cable connected to one end of the radio frequency connector; characterized in that,

[0007] The antenna module further comprises an additional feeding structure arranged on the antenna main board to suppress the current entering the outside of the shell of the radio frequency connector and / or the shielding layer of the radio frequency cable.

[0008] Preferably, the top surface of the antenna main board is provided with a plurality of first pads for connecting the ground pins of the RF connector;

[0009] Preferably, the additional feeding structure comprises at least one first feeding structure comprising a slot structure provided on the ground layer; the slot structure is arranged around the positions of the first pads corresponding to the antenna radiation main unit on the ground layer to isolate part of the corresponding ground pins from being directly connected to the ground layer.

[0010] Preferably, the additional feeding structure further comprises at least one third feeding structure comprising a third copper layer provided at the positions of the first pads on the antenna main board; the corresponding first pads are contained in the third copper layer.

[0011] Preferably, the additional feeding structure comprises at least one first feeding structure and at least one third feeding structure;

[0012] The first feeding structure comprises a slot structure provided on the ground layer; the slot structure is arranged around the positions of the first pads corresponding to the antenna radiation main unit on the ground layer;

[0013] The third feeding structure comprises a third copper layer provided at the positions of the first pads on the antenna main board; the corresponding first pads are contained in the third copper layer.

[0014] At least one of the third copper layers is provided on the first pads corresponding to the first feeding structure.

[0015] Preferably, the top surface of the antenna main board is provided with second pads for connecting the feeding coaxial inner cores of the RF connector;

[0016] The additional feeding structure further comprises a second feeding structure comprising short-circuit stubs for reducing the current distributed on the shell of the RF connector; the short-circuit stubs are provided on the top surface of the antenna main board, and the short-circuit stubs respectively connect the second pads and any two first pads to connect the feeding coaxial inner cores in the RF connector to part of the corresponding ground pins.

[0017] Preferably, the top surface of the antenna main board is further provided with a plurality of parasitic patches arranged at the circumferential positions of the antenna radiation main unit.

[0018] Preferably, the antenna main board is provided with first copper sinking holes at the positions of each of the first pads;

[0019] The slot structure comprises a ring-shaped slot, which is arranged at the circumferential outer side of the first copper-plated hole corresponding to the grounding pin and based on the grounding pin.

[0020] Preferably, the slot structure comprises an arc-shaped slot and a U-shaped slot connected with the arc-shaped slot, the arc-shaped slot is arranged at the circumferential outer side of the grounding layer corresponding to the grounding pin as the base point.

[0021] The gap direction of the arc-shaped slot is towards the U-shaped slot, or the gap direction of the arc-shaped slot is arranged opposite to the opening direction of the U-shaped slot.

[0022] Preferably, the third copper-plated layer is connected with the grounding pin adjacent to the antenna radiation main unit, so as to lead out the corresponding grounding pin to be coplanar with the antenna radiation main unit.

[0023] The application also discloses a split front-mounted vehicle-mounted unit, which comprises a vehicle-mounted unit main module and the above-mentioned antenna module, and the other end of the radio frequency cable of the antenna module is connected with the vehicle-mounted unit main module.

[0024] The application has the following beneficial effects: by introducing the additional feeding structure in the feeding part of the antenna module, the distributed current coupled to the radio frequency connector shell and / or the radio frequency cable shielding layer due to the compact layout can be effectively suppressed, the influence of the additional current radiation on the original antenna pattern can be greatly reduced, the radiation performance of the antenna module of the vehicle-mounted unit is ensured, the current coupling degree of the antenna module and the radio frequency connector shell and / or the radio frequency cable is effectively reduced, and the EMC performance of the overall system is also improved. BRIEF DESCRIPTION OF DRAWINGS

[0025] The application will be further described below with reference to the drawings and embodiments, and the drawings show:

[0026] Figure 1 FIG. 1 is a structure schematic diagram of the connection between the antenna module and the radio frequency connector in the prior art;

[0027] Figure 2 FIG. 2 is a structure schematic diagram of the top surface of the antenna module in the prior art;

[0028] Figure 3 FIG. 3 is a structure schematic diagram of the bottom surface of the antenna module in the prior art;

[0029] Figure 4 FIG. 4 is a structure schematic diagram of the connection between the antenna module and the radio frequency connector in the application;

[0030] Figure 5 FIG. 5 is a structure schematic diagram of the top surface of the antenna module in the application;

[0031] Figure 6is a structure diagram of the first feeding structure of the antenna module in the present application in embodiment 1-2;

[0032] Figure 7 is a structure diagram of the first feeding structure of the antenna module in the present application in embodiment 1-1;

[0033] Figure 8 is a simple structure diagram of the antenna module connected with the bent cable in the conventional scheme or the present application;

[0034] Figure 9 is a function diagram reflecting the change of the antenna directional diagram of the conventional scheme with the length of the cable from 20mm to 120mm;

[0035] Figure 10 is a function diagram reflecting the change of the antenna directional diagram of the conventional scheme with the length of the cable from 120mm to 300mm;

[0036] Figure 11 is a function diagram reflecting the change of the radiation performance of the conventional scheme with the length of the bent section from 40mm to 120mm;

[0037] Figure 12 is a function diagram reflecting the change of the surface current intensity of the cable with the length of the cable in each scheme;

[0038] Figure 13 is a function diagram reflecting the change of the antenna gain with the length of the cable in each scheme;

[0039] Figure 14 is a function diagram reflecting the change of the antenna directional diagram of the design scheme in the present application with the length of the cable from 20mm to 120mm;

[0040] Figure 15 is a function diagram reflecting the change of the antenna directional diagram of the design scheme in the present application with the length of the cable from 120mm to 300mm;

[0041] Figure 16 is a function diagram reflecting the influence of the length of the radio frequency cable on the half-power beam width under the total gain and the right-hand circular polarization gain of the design scheme and the conventional scheme respectively in the present application;

[0042] Figure 17 is a function diagram reflecting the influence of the length of the radio frequency cable on the gain and the deviation angle of the two schemes of the design scheme and the conventional scheme in the present application;

[0043] Figure 18 is a function diagram reflecting the change of the radiation performance of the design scheme in the present application with the length of the bent section;

[0044] Figure 19is a function graph reflecting the influence of the length of the RF cable bending section on the half-power beam width of the total gain and the right-hand circularly polarized gain of the design scheme and the conventional scheme in the application respectively;

[0045] Figure 20 is a function graph reflecting the influence of the length of the RF cable bending section on the gain and the deviation angle of the design scheme and the conventional scheme in the application. DETAILED DESCRIPTION

[0046] In order to have a clearer understanding of the technical features, objects and effects of the application, the specific embodiments of the application will be described in detail with reference to the drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "upper", "lower", "left", "right", "vertical", "horizontal", "vertical", "horizontal", "top", "bottom", "inner", "outer", "head", "tail" and the like are based on the directions or positional relationships shown in the drawings, constructed and operated in a particular direction, and are only for the convenience of describing the technical solutions, and cannot be understood as indicating that the devices or elements indicated must have a particular direction, therefore, it cannot be understood as a limitation on the application.

[0047] It should also be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing", "setting" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements or the interaction relationship between two elements. When an element is referred to as "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there can be one or more intervening elements. The terms "first", "second", "third" and the like are only for the convenience of describing the technical solutions, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features, therefore, the features with "first", "second", "third" and the like can explicitly or implicitly include one or more of the features. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0048] As Figures 1 to 3As shown in the prior art, the existing split front-mounted vehicle-mounted unit is generally installed at the front windshield position of the vehicle, and the split front-mounted vehicle-mounted unit includes a vehicle-mounted unit main module and an antenna module 100; the antenna module 100 generally includes an antenna main board 1, an antenna radiation main unit 11 arranged on the top surface of the antenna main board 1, a radio frequency cable and a radio frequency connector; the plug-in radio frequency connector 200 can be connected to the antenna main board 1 in a bottom surface plug-in or top surface plug-in manner. When the radio frequency connector 200 is plugged into the antenna main board 1 from the bottom surface of the antenna main board 1, the metal shell part of the radio frequency connector 200 is spaced from the antenna radiation main unit 11 by a copper ground layer 15, and the coupling current is small, and the radiation generated by the current distributed on the metal shell of the radio frequency connector 200 basically only affects the rear lobe performance and has little effect on the main beam radiation performance of the antenna. When the radio frequency connector 200 is plugged into the antenna main board 1 from the top surface of the antenna main board 1, the metal shell part is on the same side as the antenna radiation main unit 11, and when it is close to the antenna, it will become a part of the antenna that cannot be ignored, directly affecting the radiation performance of the main beam of the antenna; at the same time, the current coupled from the antenna or the feeder and directly entering the shell of the radio frequency connector 200 from the ground layer 15 will also enter the outside of the shielding layer of the radio frequency cable 300 and produce corresponding radiation, further affecting the radiation performance of the main beam of the antenna.

[0049] In actual design, the thickness of the antenna module 100 is limited, and in order to reduce the influence of the material in front of the main beam (such as the installation support and the front windshield) on the antenna performance after installation, the distance between the antenna main board 1 and the material in front is increased as much as possible during design, so that the radio frequency connector 200 can only be plugged in from the front. Such a solution inevitably makes the antenna radiation performance more susceptible to the layout of the radio frequency connector 200, the length of the radio frequency cable 300, the layout of the radio frequency cable 300, and other parameters, and the performance will differ in different application scenarios.

[0050] Therefore, in order to solve the technical problem that the radio frequency cable 300 and / or the radio frequency connector 200 have a harmful effect on the antenna radiation performance in the existing antenna module 100, the present application designs the connection position between the radio frequency connector 200 and the antenna main board 1 of the antenna module 100 on the basis of the existing antenna module 100, introduces a specific additional feeding structure to reduce the current distributed on the shell of the radio frequency connector 200 and / or outside the shielding layer of the radio frequency cable 300, thereby effectively suppressing the harmful effect of the distributed current radiation on the radiation performance of the antenna module 100 itself.

[0051] As shown in the prior art, the existing split front-mounted vehicle-mounted unit is generally installed at the front windshield position of the vehicle, and the split front-mounted vehicle-mounted unit includes a vehicle-mounted unit main module and an antenna module 100; the antenna module 100 generally includes an antenna main board 1, an antenna radiation main unit 11 arranged on the top surface of the antenna main board 1, a radio frequency cable and a radio frequency connector; the plug-in radio frequency connector 200 can be connected to the antenna main board 1 in a bottom surface plug-in or top surface plug-in manner. When the radio frequency connector 200 is plugged into the antenna main board 1 from the bottom surface of the antenna main board 1, the metal shell part of the radio frequency connector 200 is spaced from the antenna radiation main unit 11 by a copper ground layer 15, and the coupling current is small, and the radiation generated by the current distributed on the metal shell of the radio frequency connector 200 basically only affects the rear lobe performance and has little effect on the main beam radiation performance of the antenna. When the radio frequency connector 200 is plugged into the antenna main board 1 from the top surface of the antenna main board 1, the metal shell part is on the same side as the antenna radiation main unit 11, and when it is close to the antenna, it will become a part of the antenna that cannot be ignored, directly affecting the radiation performance of the main beam of the antenna; at the same time, the current coupled from the antenna or the feeder and directly entering the shell of the radio frequency connector 200 from the ground layer 15 will also enter the outside of the shielding layer of the radio frequency cable 300 and produce corresponding radiation, further affecting the radiation performance of the main beam of the antenna. Figures 4 to 7As shown, an antenna module 100 of the present invention includes an antenna main board 1, an antenna radiating main unit 11 disposed on the top surface of the antenna main board 1, an RF connector 200 plugged into the top surface of the antenna main board 1, and an RF cable 300 connected to the RF connector 200; the other end of the RF cable 300 is connected to the RF circuit. An additional feeding structure is provided on the antenna main board 1 in the antenna module 100 to suppress the current entering the outer shell of the RF connector 200 and / or the outer side of the shielding layer of the RF cable 300.

[0052] Understandably, the RF connector 200 includes a metal housing, several grounding pins located at the bottom of the metal housing, and a feed coaxial core. The grounding pins and the feed coaxial core extend toward the antenna mainboard 1 to be inserted into the antenna mainboard 1. The antenna mainboard 1 has a first pad and a second pad on one side, corresponding to the positions of the grounding pins and the feed coaxial core of the RF connector 200. Further, the top surface of the antenna mainboard 1 has several first pads for connecting the grounding pins and corresponding to their number, and a second pad 13 for connecting the feed coaxial core; the bottom surface of the antenna mainboard 1 is a copper-clad ground layer 15. Optionally, the antenna module 100 also includes a director 3, which can be used in conjunction with the antenna radiating main unit 11 to improve the antenna gain and overall efficiency in front of it.

[0053] The antenna radiating main unit 11 is located on the top surface of the antenna main board 1. The antenna radiating main unit 11 has a feed line 14 extending into the feed coaxial core of the RF connector 200. This feed line 14 can be understood as a branch of the antenna radiating main unit 11. Several first pads are evenly and symmetrically distributed on both sides of the axis of the feed line 14. The bottom surface of the antenna main board 1 is a copper-clad ground layer 15. Each first pad has a first copper-plated via 16 connecting to the ground layer 15 for connecting the ground pin to the ground layer 15. The second pad 13 has a second copper-plated via 17 for inserting the feed coaxial core. The RF connector 200 is inserted into one side of the top surface of the antenna main board 1. The ground pin of the RF connector 200 is inserted into the antenna main board 1 through the first copper-plated via 16, and the feed coaxial core of the RF connector 200 is inserted into the antenna main board 1 through the second copper-plated via 17.

[0054] like Figure 6 and Figure 7 As shown, the additional feeding structure further includes at least one first feeding structure 41, the first feeding structure 41 including a slotted structure disposed on the ground layer 15; the slotted structure surrounds the position of the first pad of the adjacent antenna radiating main unit 11 corresponding to the ground layer 15, so as to isolate some grounding pins from direct connection with the ground layer 15.

[0055] It is appreciated that the first feeding structure 41 needs to cooperate with the specific first pad, since most of the current will enter from the first pad adjacent to the antenna radiation main unit 11, the current entering from the first pad will cause current on the radio frequency connector 200 which has a significant impact on the radiation stability, therefore, a suitable slot structure needs to be used to suppress the current entering from the ground layer 15 or the antenna coupling into the cable shielding layer. Therefore, the present application suppresses the above-mentioned current by arranging a slot structure at the periphery of the corresponding first pad; the copper-coated ground layer 15 is recessed inward to form a slot structure, which can be a solder mask layer. As shown in Figure 7 In the embodiment 1-1 of the present application, the slot structure includes an arc-shaped slot 412 and a U-shaped slot 413 connected to the arc-shaped slot 412, the arc-shaped slot 412 is arranged around the periphery of the ground pin to correspond to the circumferential outer side of the ground pin; the gap direction of the arc-shaped slot 412 is towards the U-shaped slot 413, or the opening direction of the U-shaped slot 413 is arranged opposite to the gap direction of the arc-shaped slot 412. Specifically, the arc-shaped slot 412 is an arc shape; the U-shaped slot is arranged on the side of the arc-shaped slot 412 away from the feeder 14.

[0056] Preferably, in order to better reduce the current entering from the ground pin, as shown in Figure 6 In the embodiment 1-2, the slot structure includes a ring-shaped slot 411, the ring-shaped slot 411 is a circular ring shape, the ring-shaped slot 411 is arranged around the periphery of the first copper-filled hole 16 corresponding to the ground pin as the base point, so as to completely isolate the ground pin from the ground layer 15, thereby greatly reducing the current entering from the ground pin; in addition, the ring-shaped slot structure can also reduce the size of the first feeding structure 41. It should be noted that the ring-shaped slot can be other ring-shaped structures, such as square, angular, bullet-shaped, etc., other ring-shaped structures should be included in the protection scope of the present application, as long as the current entering from the ground pin is greatly reduced.

[0057] As shown in Figure 5As shown, the additional feeding structure also includes a second feeding structure. The second feeding structure includes a short-circuit stub 421 for reducing the current distributed on the housing of the RF connector 200. The short-circuit stub 421 is located on the top surface of the antenna mainboard 1, and connects any two first pads to the second pad 13, thereby connecting the feed coaxial core in the RF connector 200 to a portion of the corresponding ground pins. This reduces distributed current while improving gain, assisting the antenna in achieving good impedance matching within a limited space. Understandably, the second feeding structure is mainly used to assist in suppressing current while adjusting matching, and does not require specific first pads. The second feeding structure can connect any two first pads to the second pad 13. Preferably, to reduce the interaction between structures, when the first feeding structure 41 is already set on the corresponding first pad, the second feeding structure can connect additional first pads to the second pad 13. Compared to other solutions, this solution has slightly increased stability after bridging. The short-circuit stub 421 is a second copper-clad layer in the shape of a line segment, located on the top surface of the antenna mainboard 1.

[0058] like Figure 5 As shown, the additional feeding structure further includes at least one third feeding structure 43, which includes a third copper layer 431 disposed on a first pad adjacent to the main antenna radiating unit 11 in the antenna motherboard 1; the corresponding first pad is contained within the third copper layer 431. Understandably, when the third feeding structure 43 is disposed on the antenna motherboard 1, it can be used to suppress current; secondly, the third feeding structure 43 needs to be disposed on the first pad adjacent to the main antenna radiating unit 11 to further stabilize the antenna pattern from the radiation angle while assisting in suppressing current, because it is closest to the main antenna radiating unit 11 and can help stabilize the antenna pattern through coupling. Furthermore, the third copper layer 431 has a square planar structure, similar in shape to the parasitic patch 19; the third copper layer 431 is connected to the ground pin of the main antenna radiating unit 11 in the RF connector 200 to bring out a portion of the ground pin coplanar with the main antenna radiating unit 11. It should be noted that in practice, the third copper layer 431 is not connected to the ground pin (the third copper layer is set to avoid being connected to the ground pin) and there is still a stable effect, but the effect is slightly worse than the current one, and the overall structure is less compact. Therefore, the solution of connecting them was chosen.

[0059] Furthermore, if a first feed structure 41 and a third feed structure 43 are simultaneously provided on the antenna mainboard 1, the third feed structure 43 must be provided on the first pad corresponding to the first feed structure 41. Specifically, if there is one first feed structure 41 and multiple third feed structures 43, one third feed structure 43 must be provided on the first pad corresponding to the first feed structure 41, while others can be provided on other corresponding first pads; if there are multiple first feed structures 41, at least one third feed structure 43 must be provided on the first pad corresponding to the first feed structure 41.

[0060] Understandably, for the antenna module 100 as a whole, each introduced additional feeding structure can significantly improve the stability of radiation performance when set individually. Introducing multiple additional feeding structures and a symmetrical design can further enhance stability and overall radiation performance. Understandably, a symmetrical design refers to having two first feeding structures 41, respectively positioned around the first copper vias 16 adjacent to the main antenna radiating element 11 and located on either side of the axis of the feed line 14; alternatively, it can involve having two third feeding structures 43, respectively positioned on the first pads adjacent to the main antenna radiating element 11 and located on either side of the axis of the feed line 14.

[0061] like Figure 5 As shown, furthermore, the top surface of the antenna main board 1 is also provided with several parasitic patches 19 arranged around the antenna radiating main unit 11. Understandably, the parasitic patches 19 are square copper-clad layers, respectively disposed on the top surface of the antenna main board 1 around the antenna radiating main unit 11; preferably, a distance conforming to electrical standards is maintained between the parasitic patches 19 and the antenna radiating main unit 11. By providing parasitic patches 19 around the antenna radiating main unit 11, the beam deflection phenomenon caused by the RF connector 200 being too close to the antenna can be finely adjusted within a limited space, resulting in a more symmetrical radiation pattern, while simultaneously improving the antenna's radiation performance, thus improving both the antenna's gain and efficiency.

[0062] In order to better illustrate the technical solutions, the following examples are given. The existing radio frequency connector 200 includes a feed coaxial inner core and four ground pins arranged around the feed coaxial inner core. The four ground pins are arranged in a square shape at equal intervals. Correspondingly, four first pads and first copper sinking holes 16 are provided. The four first pads are arranged on both sides of the axis of the feed line 14 in pairs, and the first pads are arranged around the second pads 13. The first copper sinking holes 16 are arranged around the second copper sinking holes 17. Among them, the four ground pins of the radio frequency connector 200 are respectively referred to as a first ground pin, a second ground pin, a third ground pin, and a fourth ground pin. Correspondingly, the first pads are respectively first pad 12a, first pad 12b, first pad 12c, and first pad 12d. The first pad 12a and the first pad 12b respectively refer to two first pads 12 close to the edge of the antenna main plate 1. The first pad 12c and the first pad 12d respectively refer to two first pads close to the antenna radiation main unit 11. The first ground pin corresponds to the first pad 12a, and so on, which will not be described in detail.

[0063] In some embodiments of the present application, as shown in Figure 6 The first feed structure 41 includes two annular grooves 411 arranged on the ground layer 15, which are arranged around the first copper sinking holes 16 corresponding to the third ground pin and the fourth ground pin.

[0064] In some embodiments of the present application, as shown in Figure 5 The second feed structure includes a short-circuit stub 421 extending from the second pad 13 to the first pad 12a and the first pad 12b. The overall structure of the short-circuit stub 421 is T-shaped, including a first line segment unit 4211 connecting the first pad 12a and the first pad 12b, and a second line segment unit 4212 connecting the first line segment unit 4211 and the second pad 13. It should be noted that the overall structure of the short-circuit stub 421 is T-shaped, which is only one embodiment in the present application, and is not a specific limitation on the specific shape of the short-circuit stub. In the short-circuit stub 421, the length and width of the line segment between the second pad 13 and the first pad 12a / b affect the optimization of matching and radiation pattern stability. In other words, the line width and length of the first line segment unit 4211 and the second line segment unit 4212 can be adjusted according to the matching and radiation pattern stability.

[0065] In some embodiments of the present application, as shown in Figure 5 The third feed structure 43 includes two third copper layers 431 arranged at the positions of the first pad 12c and the first pad 12d on the antenna main plate 1. The two third copper layers 431 are symmetrical to each other with the feed line 14 as the axis of symmetry, and the first pad 12c and the first pad 12d are respectively contained in the corresponding third copper layer 431.

[0066] As Figure 2 shown, the top surface of the antenna module 100 in the prior art is also provided with a matching branch 18, which has a certain improvement effect on the gain; while in the present application, the short-circuit branch line 421 replaces the matching function of the matching branch 18, and has the effects of improving the gain and stabilizing the radiation pattern.

[0067] Based on the same inventive concept, the present application also constructs a split front-loaded vehicle-mounted unit, which comprises a vehicle-mounted unit main module and an antenna module connected with the vehicle-mounted unit main module, and the antenna module is the above-mentioned antenna module.

[0068] As Figures 8 to 20 shown, a series of test experiments are conducted to compare and analyze the above-mentioned scheme of introducing an additional feeding structure and the traditional scheme. It should be noted that the design scheme described in the following text and the accompanying drawings refers to the technical scheme of the antenna module 100 which is provided with the first feeding structure 41, the second feeding structure and the third feeding structure 43 at the same time.

[0069] The difference between the technical scheme of the present application and the traditional scheme lies in that a feeding structure for suppressing the current entering the outside of the shell of the radio frequency connector 200 and / or the shielding layer of the radio frequency cable 300 is designed, and the area of the antenna main plate 1 is effectively utilized, and the layout of the parasitic patch 19 can further improve the radiation performance of the antenna. Since the current radiation on the radio frequency connector 200 and the radio frequency cable 300 has a more obvious effect on the antenna radiation performance along the plane in the out-line direction, the radiation performance of the antenna using the antenna in the plane is compared and analyzed. For the case that the vehicle-mounted unit antenna is usually designed as right-hand circular polarization in ETC application, in order to make the data more objective and comparable, the antennas of the technical scheme of the present application and the traditional scheme are respectively optimized to make them all show good right-hand circular polarization performance in the front direction, i.e. the axial ratio is less than 3dB.

[0070] As Figure 8 shown, Figure 8 is a schematic view of the antenna module 100 with a bent cable, and ΔX represents the length of the bending section of the radio frequency cable 300. As Figure 9 and Figure 10 shown, the change of the antenna radiation performance in the plane along the radio frequency out-line direction is described when the total length of the cable changes from 20mm to 300mm without bending the radio frequency cable 300. Using the traditional scheme, the performance of the main beam of the antenna near Theta<±35 degrees will fluctuate obviously with the change of the length of the radio frequency cable 300, including the deformation of the radiation pattern, the fluctuation of the maximum gain value, the deflection of the maximum gain position, the change of the half-power beam width, etc., and the degree of change of the curve only begins to slow down when the length of the radio frequency cable 300 reaches 200mm or more.

[0071] In order to be closer to the actual layout, the RF cable 300 with the total length of 250 mm is selected, and the change of the antenna radiation performance in the traditional scheme when the length of the bending section changes is further investigated. Figure 11 From the Figure 11 It can be seen from the

[0072] Through analysis, the reason for the change of the antenna radiation performance in the traditional scheme is mainly that there is a large distribution current on the shell of the RF connector 200, which is further transmitted to the outer surface of the shielding layer of the RF cable 300, thereby generating radiation other than design. The additional radiation field strength is superimposed on the radiation field strength of the antenna itself, resulting in fluctuations in the radiation performance of the overall antenna module 100 under different states of the RF cable 300.

[0073] It can be predicted that the overall antenna module 100 with unstable radiation performance will also change in radiation performance due to the change of the length of the RF cable 300, the layout of the RF cable 300, and metal devices near the RF cable 300 when finally installed, thereby affecting the consistency of the system communication performance, and even possibly deviating greatly from the estimated system communication performance.

[0074] In view of this problem, the present application proposes a feeding structure for effectively suppressing the current entering the shell of the RF connector 200 and the outside of the shielding layer of the RF cable 300, which can significantly improve the fluctuations in the radiation performance of the overall antenna module 100 caused by the length and layout of the RF cable 300, and ensure the stability of the radiation performance of the overall module.

[0075] Figures 12-13 The change of the current intensity on the outside of the shielding layer of the RF cable 300 with the change of the length of the cable when the partial feeding structure and the coplanar parasitic patch 19 are introduced respectively is analyzed, and the antenna gain value under the corresponding condition is analyzed.

[0076] From the Figure 12 It can be seen from the Figure 12Further, the suppression of the cable surface current intensity by each feeding structure part and the parasitic patch 19 is compared, each part of the design has different degree of contribution to the suppression, wherein the first feeding structure 41 plays the most important role, and finally all parts are combined together to achieve good suppression effect on the cable surface current. It can be expected that good suppression of the cable surface current can not only improve the stability of the radiation performance of the vehicle-mounted unit antenna, but also has certain benefits for the EMC performance of the overall system.

[0077] Analysis Figure 13 Data, in addition to the first feeding structure 41, other feeding structure parts and parasitic patches 19 are beneficial to the improvement of the gain of the vehicle-mounted unit antenna, wherein the second feeding structure has the largest gain improvement degree. The final overall design scheme can significantly improve the gain performance of the vehicle-mounted unit antenna.

[0078] The performance of the vehicle-mounted unit antenna module 100 pattern between the design scheme of the present application and the conventional scheme is compared below.

[0079] Figures 14 to 15 For the case of no bending of the radio frequency cable 300, when the total length of the cable changes from 20 mm to 300 mm, the change of the antenna radiation performance in the plane along the radio frequency outlet direction of the present application design scheme. Figures 16 to 17 The change of the antenna radiation performance of the conventional scheme and the present design scheme is compared under the same no-bending radio frequency cable 300 layout. Figure 16 The change of the total gain and the half-power beam width of the right-hand circular polarization gain is mainly described, Figure 17 Then the maximum gain of the antenna radiation and the deflection angle of the maximum gain and the antenna axis in the plane along the radio frequency outlet direction of the conventional scheme and the present design scheme under different conditions are compared.

[0080] Figure 18 For the selected total length of 250 mm radio frequency cable 300, the change of the antenna radiation performance of the present design scheme when the length of the bending section changes is investigated. Figures 19 to 20 The change of the antenna radiation performance of the conventional scheme and the present design scheme under the condition of the bending section is compared.

[0081] Compared with the traditional scheme, the radiation performance of the antenna module 100 using the design scheme is greatly reduced in sensitivity to the length and layout of the radio frequency cable 300, the module radiation pattern shape is stable, the half-power beam width and the maximum gain direction deviation angle change little, and the gain is basically related only to the loss caused by the cable length. At the same time, under the condition that the right-hand circularly polarized performance is good in the front of the two schemes, the half-power beam width of the right-hand circularly polarized component and the total gain of the traditional scheme deviates from a certain value, while the beam width of the two in the design scheme is basically the same, which represents that the energy of the main beam in the design scheme is basically in the form of right-hand circularly polarized component and effectively participates in the actual work. In addition, under the condition that the half-power beam width is equivalent, the overall gain of the antenna module 100 using the design scheme is improved by nearly 2dB than the traditional scheme.

[0082] In this case, the possibility of changes in antenna radiation performance due to cable layout and installation in actual application will be greatly reduced, and the performance of the antenna in actual installation can be better guaranteed to be basically consistent with the design value, which is beneficial to ensure the consistency of system performance in different installation environments and facilitate reliable analysis and prediction of system performance. At the same time, the higher gain and the better effective right-hand circularly polarized characteristics in the main beam of the radiation performance also mean that the use of the design scheme will have not small improvement in the working performance of the system.

[0083] In summary, the application provides a split front-mounted vehicle-mounted unit and an antenna module 100, which is provided with an additional feeding structure on the antenna main board 1 of the antenna module 100. The additional feeding structure can effectively suppress the distributed current coupled to the shell of the radio frequency connector 200 and / or the shielding layer of the radio frequency cable 300 due to the compact layout, greatly reduce the influence of harmful radiation on the original antenna pattern caused by the additional current radiation, so that the radiation performance of the vehicle-mounted unit antenna no longer changes significantly due to harmful radiation caused by different lengths and layouts of the radio frequency cable 300, and the performance of the vehicle-mounted unit antenna is guaranteed to be consistent with the design value.

[0084] At the same time, the use of the parasitic patch 19 design shared with the antenna radiation main unit 11 effectively utilizes the limited space, which can not only fully improve the radiation performance of the vehicle-mounted unit antenna, but also to a certain extent, control the degree of deflection of the antenna pattern caused by the close layout of the radio frequency connector 200, so that the designed split front-mounted vehicle-mounted unit antenna module 100 can obtain a more symmetrical pattern in a more compact space.

[0085] The technical scheme in the application is directly designed on the main plate of the existing antenna module 100, without increasing cost and process complexity, while ensuring the radiation performance of the antenna module 100, effectively reducing the coupling degree of the antenna module 100 and the radio frequency cable 300 current, and being beneficial to the improvement of the EMC performance of the overall system.

[0086] It can be understood that the above embodiments only express the preferred embodiments of the present application, the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope of the present application; it should be pointed out that for ordinary skilled in the art, the above technical features can be freely combined without departing from the concept of the present application, and several modifications and improvements can be made, which belong to the protection scope of the present application; therefore, any equivalent transformation and modification within the scope of the claims of the present application shall belong to the scope of the claims of the present application.

Claims

1. An antenna module for split front-mounted vehicle-mounted unit, comprising an antenna main board (1), an antenna radiation main unit (11) arranged on the top surface of the antenna main board (1), a radio frequency connector (200) plugged on the top surface of the antenna main board (1), and a radio frequency cable (300) with one end connected to the radio frequency connector (200); characterized in that, the antenna module further comprises an additional feeding structure arranged on the antenna main board (1) to suppress the current outside the shell of the radio frequency connector (200) and / or the shielding layer of the radio frequency cable (300); the top surface of the antenna main board (1) is provided with a plurality of first pads corresponding to the number of ground pins for connecting the radio frequency connector (200); and the bottom surface of the antenna main board (1) is a copper-coated ground layer (15); the additional feeding structure comprises at least one first feeding structure (41) comprising a slotted structure arranged on the ground layer (15); the slotted structure is arranged around the position corresponding to the first pad adjacent to the antenna radiation main unit (11) on the ground layer (15) to isolate the direct connection between the ground layer (15) and the ground pin corresponding to the first pad adjacent to the antenna radiation main unit (11).

2. The antenna module of claim 1, wherein, the additional feeding structure further comprises at least one third feeding structure (43) comprising a third copper layer (431) arranged on the antenna main board (1); the third copper layer (431) is arranged at the position adjacent to the first pad, and the corresponding first pad is contained therein; among all the third copper layers (431), at least one third copper layer (431) is arranged on the first pad corresponding to the first feeding structure (41).

3. The antenna module of claim 2, wherein, the third copper layer (431) arranged on the antenna main board (1) is connected to the ground pin adjacent to the antenna radiation main unit (11) to lead out the ground pin adjacent to the antenna radiation main unit (11) to be coplanar with the antenna radiation main unit (11).

4. The antenna module according to claim 1 or 2, characterized in that, the top surface of the antenna main board (1) is provided with second pads (13) for connecting the feeding coaxial inner core of the radio frequency connector (200); the additional feeding structure further comprises a second feeding structure comprising a short-circuit stub line (421) for reducing the current distributed on the shell of the radio frequency connector (200); the short-circuit stub line (421) is arranged on the top surface of the antenna main board (1), and the short-circuit stub line (421) respectively connects any two of all the first pads with the second pads (13) to connect the feeding coaxial inner core in the radio frequency connector (200) with part of the ground pins.

5. The antenna module according to claim 1 or 2, characterized in that, the top surface of the antenna main board (1) is further provided with a plurality of parasitic patches (19) arranged at the circumferential position of the antenna radiation main unit (11).

6. The antenna module according to claim 1 or 2, characterized in that, the antenna main board (1) is respectively provided with a first copper sinking hole (16) at the position of each first pad; The slot structure comprises a ring-shaped slot (411) which is arranged on the circumferential outer side of the first copper-filled hole (16) with the ground pin as the base point.

7. An antenna module for a split front-mounted vehicle-mounted unit, comprising an antenna main board (1), an antenna radiation main unit (11) arranged on the top surface of the antenna main board (1), a radio frequency connector (200) plugged on the top surface of the antenna main board (1), and a radio frequency cable (300) with one end connected to the radio frequency connector (200); characterized in that, The antenna module further comprises an additional feeding structure arranged on the antenna main board (1) to suppress the current outside the shell of the radio frequency connector (200) and / or the shielding layer of the radio frequency cable (300); The top surface of the antenna main board (1) is provided with a plurality of first pads corresponding in number to the ground pins for connecting the radio frequency connector (200); and the bottom surface of the antenna main board (1) is a copper-coated ground layer (15); The additional feeding structure comprises at least one first feeding structure (41) comprising a slot structure arranged on the ground layer (15); the slot structure is arranged around the position on the ground layer (15) corresponding to the first pad adjacent to the antenna radiation main unit (11) to partially isolate the direct connection between the ground layer (15) and the ground pin corresponding to the first pad adjacent to the antenna radiation main unit (11); The slot structure comprises an arc-shaped slot (412) and a U-shaped slot (413) connected to the arc-shaped slot (412), and the arc-shaped slot (412) is arranged around the circumferential outer side of the ground layer (15) with the ground pin as the base point. The gap direction of the arc-shaped slot (412) is towards the U-shaped slot (413), or the gap direction of the arc-shaped slot (412) is arranged opposite to the opening direction of the U-shaped slot (413).

8. A split front mount vehicle mounted unit comprising a vehicle mounted unit main module, characterized by, The antenna module (100) of any one of claims 1-7 is further included, and the other end of the radio frequency cable (300) of the antenna module (100) is connected to the vehicle-mounted unit main module.

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