CN216354803U - Split type front-mounted vehicle-mounted unit and antenna module - Google Patents

Abstract

The utility model relates to a split type front-mounted vehicle-mounted unit and an antenna module, wherein the antenna module comprises an antenna main board, an antenna radiation main unit arranged on the top surface of the antenna main board, a radio frequency connector inserted in the top surface of the antenna main board, and a radio frequency cable with one end connected with the radio frequency connector; the antenna module also comprises an additional feed structure arranged on the antenna main board; the distributed current coupled to the radio frequency connector shell and/or the radio frequency cable shielding layer due to compact layout can be effectively inhibited, the influence of extra current radiation on an original antenna directional diagram is greatly reduced, the radiation performance of the vehicle-mounted unit antenna module is ensured, the coupling degree of the antenna module and the radio frequency connector shell and/or the radio frequency cable is effectively reduced, and the improvement of the EMC performance of the whole system is facilitated.

Description

Split type front-mounted vehicle-mounted unit and antenna module

Technical Field

The utility model relates to the field of vehicle-mounted units, in particular to a split type front-mounted vehicle-mounted unit and an antenna module.

Background

From 7/1 of 2020, the new approved vehicle model requires the addition of ETC (electronic Toll Collection) vehicle-mounted devices in the optional equipment, and more host factories start the project of On-Board units (OBUs).

In practical projects, in order to ensure the working function of the ETC system in a limited vehicle layout space, a split arrangement scheme is generally adopted, an antenna part and other circuit parts of an on-board unit are separated into two modules, and the two modules are connected through a radio frequency cable. Therefore, the on-board unit antenna module needs to be organically integrated with the radio frequency cable and ensure good and stable performance in a space significantly smaller than that of a conventional after-loading on-board unit.

Because the thickness of the antenna module is limited, the radio frequency cable or the radio frequency connector is generally arranged on the radiation side of the antenna module, so that the radiation main body is farther away from the front support and the front windshield at equal distance after the antenna module is installed, and the radiation effect of the antenna is ensured. This layout inevitably has three undesirable effects on the performance of the antenna module of the on-board 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 is generated to cause the antenna directional diagram to be distorted; 2) the radiation performance of the whole antenna module can be changed along with the lengths and the layouts of different radio frequency cables due to current radiation coupled or directly entering the outer side of the shielding layer of the radio frequency cable; 3) the current path outside the shielding of the rf cable to the antenna degrades the EMC performance of the overall system.

SUMMERY OF THE UTILITY MODEL

Aiming at the defects in the prior art, the utility model aims to solve the technical problem that the radiation performance of an antenna is adversely affected by a radio frequency cable or a radio frequency connector in the existing split type front-mounted vehicle-mounted unit.

The technical scheme adopted by the utility model for solving the technical problems is as follows: an antenna module is constructed and used for a split type front-mounted vehicle-mounted unit, and comprises an antenna main board, an antenna radiation main unit arranged on the top surface of the antenna main board, a radio frequency connector inserted in the top surface of the antenna main board, and a radio frequency cable with one end connected with the radio frequency connector; it is characterized in that the preparation method is characterized in that,

the antenna module further comprises an additional feed structure arranged on the antenna main board to inhibit current entering the shell of the radio frequency connector and/or the outer side of the shielding layer of the radio frequency cable.

Preferably, the top surface of the antenna main board is provided with a plurality of first pads which are used for connecting the grounding pins of the radio frequency connector and correspond to the grounding pins in number; the bottom surface of the antenna mainboard is a copper-clad grounding layer.

Preferably, the additional feeding structure comprises at least one first feeding structure comprising a slotted structure provided to the ground plane; the slotted structure is arranged around the periphery of the position, corresponding to the grounding layer, of the first bonding pad adjacent to the antenna radiation main unit, so that the grounding pin corresponding to the isolation part is directly connected with the grounding layer.

Preferably, the additional feeding structure further comprises at least one third feeding structure comprising a third copper-clad layer disposed at the position of the antenna main board on the first pad; and the corresponding first bonding pad is contained in the third copper clad layer.

Preferably, the additional feed structure comprises at least one first feed structure and at least one third feed structure;

the first feed structure comprises a slotted structure arranged on the ground layer; the slotted structure is arranged around the periphery of the position, corresponding to the grounding layer, of the first bonding pad adjacent to the antenna radiation main unit;

the third feeding structure comprises a third copper-clad layer arranged at the position of the antenna main board on the first bonding pad; the corresponding first bonding pad is contained in the third copper-clad layer;

and at least one third copper-clad layer is arranged on the first bonding pad corresponding to the first feeding structure.

Preferably, the top surface of the antenna main board is provided with a second pad for connecting a feeding coaxial inner core of the radio frequency connector;

the additional feed structure further comprises a second feed structure which comprises short-circuit branch lines used for reducing current distributed on the shell of the radio frequency connector, the short-circuit branch lines are arranged on the top surface of the antenna main board, and the short-circuit branch lines are used for communicating the second bonding pads with any two first bonding pads respectively so as to connect the coaxial inner cores of the feed in the radio frequency connector with the partially corresponding grounding pins.

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

Preferably, the antenna main board is provided with a first copper sinking hole at the position of each first bonding pad;

the grooving structure comprises an annular groove, and the annular groove is arranged around the circumferential outer side of the first copper sinking hole corresponding to the grounding pin by taking the grounding pin as a base point.

Preferably, the slotted structure includes an arc-shaped slot and a U-shaped slot connected to the arc-shaped slot, and the arc-shaped slot is surrounded on the circumferential outer side of the ground layer using the corresponding ground pin as a base point;

the notch direction of the arc-shaped groove faces towards the U-shaped groove, or the notch direction of the arc-shaped groove and the opening direction of the U-shaped groove are arranged in a back-to-back mode.

Preferably, the third copper-clad layer is connected to a ground pin adjacent to the antenna radiation main unit, so as to lead out the corresponding ground pin to be coplanar with the antenna radiation main unit.

The utility model also constructs a split front-mounted vehicle-mounted unit, which comprises a main module of the vehicle-mounted unit and the antenna module, wherein the other end of the radio frequency cable of the antenna module is connected with the main module of the vehicle-mounted unit.

The implementation of the utility model has the following beneficial effects: by introducing the additional feed structure into the feed 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 compact layout can be effectively inhibited, the influence of extra current radiation on an original antenna directional diagram is greatly reduced, the radiation performance of the vehicle-mounted unit antenna module is ensured, the coupling degree of the current between the antenna module and the radio frequency connector shell and/or the radio frequency cable is effectively reduced, and the improvement of the EMC performance of the whole system is facilitated.

Drawings

The utility model will be further described with reference to the accompanying drawings and examples, in which:

fig. 1 is a schematic structural diagram of an antenna module connected with a radio frequency connector in a conventional scheme;

fig. 2 is a schematic structural view of the top surface of an antenna module in a conventional solution;

fig. 3 is a schematic structural view of the bottom surface of an antenna module in a conventional scheme;

FIG. 4 is a schematic diagram of the connection of the antenna module and the RF connector according to the present invention;

FIG. 5 is a schematic diagram of the top surface of the antenna module of the present invention;

fig. 6 is a schematic structural view of a first feeding structure of the antenna module in the present invention in the embodiment 1-2;

fig. 7 is a schematic structural view of a first feeding structure of the antenna module in the present invention in embodiment 1-1;

fig. 8 is a schematic view showing a simple structure of an antenna module connected to a meander cable in a conventional scheme or in the present invention;

FIG. 9 is a functional graph reflecting the antenna pattern of the conventional scheme as a function of cable length between 20-120 mm;

FIG. 10 is a functional diagram showing the antenna pattern as a function of the length of the cable at 120-300mm in the conventional scheme;

FIG. 11 is a functional graph reflecting the radiation performance of the conventional solution as a function of the length of the bend at 40-120 mm;

FIG. 12 is a functional graph reflecting the variation of the current intensity on the surface of the cable with the length of the cable according to various schemes;

FIG. 13 is a functional graph reflecting aspects of antenna gain as a function of cable length;

FIG. 14 is a functional graph reflecting the antenna pattern of the design of the present invention as a function of cable length between 20 and 120 mm;

FIG. 15 is a functional diagram showing the antenna pattern of the present invention as a function of the cable length at 120-300 mm;

FIG. 16 is a functional graph showing the effect of RF cable length on half power beamwidth for total gain and right hand circularly polarized gain for the design and conventional schemes of the present invention, respectively;

FIG. 17 is a graph of a function reflecting the effect of radio frequency cable length on gain and deflection angle for both the design of the present invention and the conventional scheme;

FIG. 18 is a functional graph reflecting the variation of the radiation performance of the design of the present invention with the bend length;

FIG. 19 is a functional diagram showing the effect of the bending section length of the RF cable on the half-power beam width under the total gain and the right-hand circularly polarized gain for the design and the conventional scheme of the present invention, respectively;

fig. 20 is a functional diagram reflecting the effect of the length of the bent section of the rf cable on the gain and the deviation angle of the design scheme of the present invention and the conventional scheme.

Detailed Description

For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the following description, it is to be understood that the orientations and positional relationships indicated by "front", "rear", "upper", "lower", "left", "right", "longitudinal", "lateral", "vertical", "horizontal", "top", "bottom", "inner", "outer", "leading", "trailing", and the like are configured and operated in specific orientations based on the orientations and positional relationships shown in the drawings, and are only for convenience of describing the present invention, and do not indicate that the device or element referred to must have a specific orientation, and thus, are not to be construed as limiting the present invention.

It is also noted that, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," "disposed," and the like are intended to be inclusive and mean, for example, that they may be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. When an element is referred to as being "on" or "under" another element, it can be "directly" or "indirectly" on the other element or intervening elements may also be present. The terms "first", "second", "third", etc. are only for convenience in describing the present technical solution, and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated, whereby the features defined as "first", "second", "third", etc. may explicitly or implicitly include one or more of such features. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

As shown in fig. 1 to 3, in the prior art, a conventional split front-mount on-board unit is generally installed at a front windshield position of a vehicle, and the split front-mount on-board unit includes an on-board 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 disposed on a top surface of the antenna main board 1, a radio frequency cable, and a radio frequency connector; the board-type rf connector 200 may be connected to the antenna main board 1 by bottom surface plugging or top surface plugging. When the rf connector 200 is plugged into the antenna motherboard 1 from the bottom surface of the antenna motherboard 1, the metal housing of the rf connector 200 is on the non-radiation surface, and the copper-clad ground layer 15 is separated from the antenna radiation main unit 11, so that the coupling current is small, and meanwhile, the radiation generated by the current distribution on the metal housing of the rf connector 200 basically only affects the back lobe performance, and also has a small effect on the main beam radiation performance of the antenna. When the rf connector 200 is plugged into the antenna main board 1 from the top surface of the antenna main board 1, the metal casing portion is on the same side as the antenna radiation main unit 11, and when the metal casing portion is close to the radiation antenna, the metal casing portion will become a non-negligible portion of the antenna, which directly affects the radiation performance of the antenna main beam; at the same time, the current from the antenna or feed coupling and from the ground plane 15 directly into the housing of the rf connector 200 will enter the outside of the shielding layer of the rf cable 300 and generate corresponding radiation, which further affects the radiation performance of the main beam of the antenna.

In practical design, the thickness of the antenna module 100 is limited, and in order to reduce the influence of the main beam front material (such as a mounting bracket and a front windshield) on the antenna performance after mounting, the distance between the antenna main board 1 and the front material is increased as much as possible during design, so that the rf connector 200 can only be plugged from the front. Such a scheme inevitably makes the antenna radiation performance more easily affected by the layout of the rf connector 200, the length of the rf cable 300, the routing layout of the rf cable 300, and other parameters, and the performance may be different in different applications.

Therefore, in order to solve the technical problem that the radiation performance of the antenna is adversely affected by the rf cable 300 and/or the rf connector 200 in the conventional antenna module 100, the present invention designs the connection position of the antenna module 100 between the rf connector 200 and the antenna main board 1 on the basis of the conventional antenna module 100, and introduces a specific additional feeding structure to reduce the current distributed on the housing of the rf connector 200 and/or the outer side of the shielding layer of the rf cable 300, thereby effectively suppressing the harmful effect of the distributed current radiation on the radiation performance of the antenna module 100 itself.

As shown in fig. 4 to 7, an antenna module 100 of the present invention includes an antenna main board 1, an antenna radiation main unit 11 disposed on a top surface of the antenna main board 1, a radio frequency connector 200 plugged into the top surface of the antenna main board 1, and a radio frequency cable 300 connected to the radio frequency connector 200; the other end of the radio frequency cable 300 is connected to the radio frequency circuit. An additional feeding structure is provided on the antenna main board 1 in the antenna module 100 to suppress a current entering the housing of the radio frequency connector 200 and/or the outside of the shielding layer of the radio frequency cable 300.

It is understood that the rf connector 200 includes a metal shell, a plurality of ground pins disposed at a lower portion of the metal shell, and a feeding coaxial inner core; the grounding pin and the feeding coaxial inner core extend towards the direction of the antenna main board 1 to be inserted into the antenna main board 1. The antenna main board 1 has a first pad and a second pad on one side thereof, wherein the first pad and the second pad correspond to the ground pin of the rf connector 200 and the coaxial core of the feeding coaxial core respectively. Furthermore, the top surface of the antenna main board 1 is provided with a plurality of first bonding pads which are used for connecting the grounding pins and correspond to the grounding pins in number and second bonding pads 13 which are used for connecting the feeding coaxial inner core; the bottom surface of the antenna main board 1 is a copper-clad grounding layer 15. Optionally, the antenna module 100 is further provided with a director 3, which can be used with the antenna radiation main unit 11, and can be used to improve the gain and overall efficiency of the antenna right in front.

The antenna radiation main unit 11 is arranged on the top surface of the antenna main board 1, the antenna radiation main unit 11 is provided with a feeder 14 extending to the feeding coaxial core in the radio frequency connector 200, and the feeder 14 can be understood as a branch part of the antenna radiation main unit 11; the first pads are equally and symmetrically distributed on two sides of the axis of the feed line 14. The bottom surface of the antenna mainboard 1 is a copper-clad grounding layer 15; each first pad is provided with a first copper sinking hole 16 communicated to the grounding layer 15 for connecting a grounding pin with the grounding layer 15; the second bonding pad 13 is provided with a second copper sinking hole 17 for inserting the power feeding coaxial inner core. The radio frequency connector 200 is inserted into one side of the top surface of the antenna main board 1, the grounding pin of the radio frequency connector 200 is inserted into the antenna main board 1 through the first copper sinking hole 16, and the feeding coaxial inner core of the radio frequency connector 200 is inserted into the antenna main board 1 through the second copper sinking hole 17.

As shown in fig. 6 and 7, further, the additional feeding structure includes at least one first feeding structure 41, and the first feeding structure 41 includes a slot structure disposed on the ground layer 15; the slot structure is arranged around the first pad of the adjacent antenna radiation main unit 11 corresponding to the position periphery of the ground layer 15 to isolate part of the ground pin from being directly connected with the ground layer 15.

It will be appreciated that the first feed structure 41 needs to cooperate with a specific first pad, and since most of the current will enter from the first pad adjacent to the antenna radiating main unit 11, where the entering current will cause a current on the rf connector 200 that significantly affects the radiation stability, a suitable slot structure needs to be used to suppress the current coupling from the ground plane 15 or the antenna into the cable shield. Therefore, the utility model restrains the current by arranging the groove structure at the periphery of the corresponding first bonding pad; the copper-clad ground layer 15 is recessed to form a slotted structure, which may be a solder resist layer. As shown in fig. 7, in embodiment 1-1 of the present invention, the slotted 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 enclosed in the ground layer 15 and is located outside the circumference of the ground layer 15 with the corresponding ground pin as a base point; the gap direction of the arc-shaped groove (412) faces the U-shaped groove (413), or the opening direction of the U-shaped groove 413 is opposite to the gap direction of the arc-shaped groove 412. Specifically, the arc-shaped slot 412 is a major arc; the U-shaped slot is disposed on a side of the arcuate slot 412 away from the feed line 14.

Preferably, in order to better reduce the current entering from the ground pin, as shown in fig. 6, in embodiment 1-2, the slotted structure includes an annular slot 411, where the annular slot 411 is annular, and the annular slot 411 uses the ground pin as a base point and is arranged around the circumferential outer side of the first copper-sinking hole 16 corresponding to the ground pin, so as to completely isolate the ground pin from being connected to the ground layer 15, thereby greatly reducing the current entering from the ground pin; in addition, the annular slotted structure can also reduce the size of the first feeding structure 41. It should be noted that the annular groove may have an annular structure with other shapes, such as a square shape, an angular shape, a bullet shape, etc., and other annular structures are within the scope of the present invention as long as the current entering from the ground pin is greatly reduced.

As shown in fig. 5, the additional feeding structure further includes a second feeding structure, the second feeding structure includes a short-circuit branch line 421 for reducing the current distributed on the housing of the rf connector 200, the short-circuit branch line 421 is disposed on the top surface of the antenna main board 1, and the short-circuit branch line 421 connects any two first pads with the second pads 13 respectively, so as to connect the feeding coaxial core in the rf connector 200 with a part of the corresponding ground pins, thereby improving the gain while reducing the distributed current, and assisting the antenna to achieve good impedance matching in a limited space. It will be appreciated that the second feed structure is primarily intended to assist in simultaneous adjustment matching of the current suppression, and need not be matched to a particular first pad, and that the second feed structure may select any two first pads to communicate with the second pad 13. Preferably, in order to reduce the interaction between the structures, in the case that the first feeding structure 41 is already disposed at the corresponding first pad, the second feeding structure may select an additional first pad to be connected with the second pad 13, which slightly increases the stability after the cross-over compared to other solutions. The short-circuit branch line 421 is a second copper-clad layer in a line segment shape, and is disposed on the top surface of the antenna main board 1.

As shown in fig. 5, further, the additional feeding structure further includes at least one third feeding structure 43, which includes a third copper-clad layer 431 disposed on the first pad of the antenna main board 1 adjacent to the antenna radiation main unit 11; the corresponding first pad is contained within the third copper-clad layer 431. It is understood that the third feeding structure 43 may be used to suppress current when disposed on the antenna main board 1; secondly, the third feeding structure 43 needs to be disposed on the first pad adjacent to the antenna radiation main unit 11 to further stabilize the antenna pattern from the radiation angle while cooperating with suppressing the current, since it is closest to the antenna radiation main unit 11 and can assist in stabilizing the antenna pattern by coupling. Further, the third copper-clad layer 431 has a square planar structure, and the structural shape is similar to that of the parasitic patch 19; the third copper-clad layer 431 is connected to the ground pin of the rf connector 200 adjacent to the antenna radiation main unit 11, so as to lead out the corresponding partial ground pin to be coplanar with the antenna radiation main unit 11. It should be noted that, in practice, the third copper-clad layer 431 has a stable effect without being connected to the ground pin (the third copper-clad layer is not connected to the ground pin), but the effect is slightly worse than that of the conventional method, and the overall structure compactness is reduced, so that the connection scheme is adopted.

In addition, if the first feeding structure 41 and the third feeding structure 43 are disposed on the antenna main board 1 at the same time, the third feeding structure 43 must be disposed on the first pad corresponding to the first feeding structure 41. If there is one first feeding structure 41 and there are multiple third feeding structures 43, one of the third feeding structures 43 must be disposed on the first pad corresponding to the first feeding structure 41, and the others may be disposed on the other corresponding first pads; and, when a plurality of first feeding structures 41 are provided, at least one third feeding structure 43 is provided on the first pad corresponding to the first feeding structure 41.

It can be understood that, for the antenna module 100 as a whole, each of the introduced additional feeding structures is separately provided, which can significantly improve the stability of the radiation performance. And simultaneously, a plurality of additional feed structures and a symmetrical design form are introduced, so that the stability and the overall radiation performance can be further improved. It is understood that the symmetrical design means that two first feeding structures 41 are provided, and are respectively disposed at the peripheral positions of the first copper vias 16 adjacent to the antenna radiation main unit 11 and located at two sides of the axial line of the feeding line 14; two third feeding structures 43 may be provided, respectively, on the first pads adjacent to the antenna radiation main unit 11 and located on both sides of the axis line of the feed line 14.

As shown in fig. 5, further, the top surface of the antenna main board 1 is also provided with a plurality of parasitic patches 19 arranged at circumferential positions of the antenna radiation main unit 11. As can be understood, the parasitic patches 19 are copper-clad layers in a square shape, and are respectively disposed on the top surface of the antenna main board 1 at positions in the circumferential direction of the antenna radiation main unit 11; preferably, the parasitic patch 19 is kept at a distance from the antenna radiating main unit 11 that meets electrical standards. By arranging the parasitic patches 19 around the antenna radiation main unit 11, the beam deflection phenomenon caused by the fact that the radio frequency connector 200 is too close to the antenna can be finely adjusted in a limited space, a more symmetrical radiation pattern is obtained, meanwhile, the radiation performance of the antenna is improved, and the gain and the efficiency of the antenna are improved.

For better illustration of the present technical solution, the conventional rf connector 200 includes a feeding coaxial inner core and four grounding pins disposed around the feeding coaxial inner core, and the four grounding pins are arranged in a square shape at equal intervals; correspondingly, four first bonding pads and four first copper depositing holes 16 are arranged, wherein every two of the four first bonding pads are arranged on two sides of the axial lead of the feeder line 14, the first bonding pads are arranged around the periphery of the second bonding pad 13, and the first copper depositing holes 16 are arranged around the periphery of the second copper depositing hole 17. Wherein, the four grounding pins of the rf connector 200 are respectively designated as a first grounding pin, a second grounding pin, a third grounding pin and a fourth grounding pin; correspondingly, the first pads are the first pad 12a, the first pad 12b, the first pad 12c and the first pad 12d, respectively. The first pads 12a and 12b respectively denote two first pads 12 near the edge of the antenna main board 1, and the first pads 12c and 12d respectively denote two first pads near 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.

In some embodiments of the present invention, as shown in fig. 6, the first feeding structure 41 includes two annular grooves 411 disposed on the ground layer 15, and the annular grooves are respectively defined by the third ground pin and the fourth ground pin as base points and are disposed around the circumferential outer side of the first copper sinking hole 16 corresponding to the ground pin.

In some embodiments of the present invention, as shown in fig. 5, the second feeding structure includes a short-circuit branch line 421 extending from the second pad 13 to the first pad 12a and the first pad 12b, respectively; the short branch line 421 has a T-shaped overall structure, and includes a first segment unit 4211 connecting the first pad 12a and the first pad 12b, and a second segment unit 4212 connecting the first segment unit 4211 and the second pad 13. It should be noted that the overall structure of the short-circuit branch line 421 is T-shaped, which is only one embodiment of the present invention, and the specific shape of the short-circuit branch line is not particularly limited. In the short-circuit branch line 421, the length and width of the line from the second pad 13 to the first pad 12a/b affect the optimization of the matching and the stability of the radiation pattern, in other words, the line width and the line length of the first line unit 4211 and the second line unit 4212 can be adjusted according to the matching and the stability of the radiation pattern.

In some embodiments of the present invention, as shown in fig. 5, the third feeding structure 43 includes two third copper-clad layers 431 respectively disposed at the first pad 12c and the first pad 12d of the antenna main board 1; the two third copper-clad layers 431 are symmetrical to each other with the feed line 14 as a symmetry axis, and the first pad 12c and the first pad 12d are contained in the corresponding third copper-clad layers 431, respectively.

As shown in fig. 2, the top surface of the antenna module 100 in the prior art is further provided with a matching branch 18, which has a certain gain improvement effect; in the present invention, 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 directional diagram.

Based on the same utility model concept, the utility model also constructs a split type front-mounted vehicle-mounted unit, which comprises a main module of the vehicle-mounted unit and an antenna module connected with the main module of the vehicle-mounted unit, wherein the antenna module is the antenna module.

As shown in fig. 8 to 20, the scheme of the above-described introduced additional feeding structure is compared with the conventional scheme through a series of test experiments. It should be noted that the design schemes described below and in the drawings refer to the technical scheme of the antenna module 100 provided with the first feeding structure 41, the second feeding structure and the third feeding structure 43 at the same time.

The difference between the technical solution of the present invention and the conventional solution is that a feeding structure for suppressing the current entering the outer side of the housing of the rf connector 200 and/or the shielding layer of the rf cable 300 is designed, and the area of the antenna main board 1 is effectively utilized, and the parasitic patch 19 capable of further improving the radiation performance of the antenna is laid out. Since the current radiation on the rf connector 200 and the rf cable 300 has a more significant effect on the antenna radiation performance of the plane along the outgoing direction, a comparative analysis will be performed by using the radiation performance of the antenna on the plane. Aiming at the condition that the vehicle-mounted unit antenna in ETC application is generally designed to be right-hand circularly polarized, in order to enable data to have objective comparability, the antenna of the technical scheme and the antenna of the traditional scheme are respectively optimally designed, so that the right-hand circularly polarized performance with good performance is shown in the front of the antenna, namely the axial ratio is smaller than 3 dB.

As shown in fig. 8, fig. 8 is a schematic view of the antenna module 100 with a bent cable, and Δ X represents the length of the bent section of the rf cable 300. As shown in fig. 9 and 10, the change of the antenna radiation performance of the conventional solution on the plane along the radio frequency outgoing line direction when the total length of the cable changes from 20mm to 300mm without bending the radio frequency cable 300 is described. With the conventional scheme, the performance of the antenna near Theta < + > -35 degrees fluctuates obviously with the change of the length of the radio frequency cable 300, including the deformation of a radiation pattern, the fluctuation of a maximum gain value, the deflection of a maximum gain position, the change of a half-power beam width and the like, and the change degree of a curve is not slowed down until the length of the radio frequency cable 300 reaches more than 200 mm.

To get closer to the actual layout, the rf cable 300 with a total length of 250mm can be selected, and the variation of the antenna radiation performance in the conventional scheme when the length of the bending section is varied is continuously examined. Fig. 11 shows the corresponding radiation performance when the length of the bending section is changed. As can be seen from fig. 11, even if the length of the rf cable 300 is constant, when the length of the bent section varies, the main beam performance of the antenna still fluctuates significantly, and the main beam performance deviates from the characteristics of the rf cable 300 without bending.

By analysis, the reason for the variation of the radiation performance of the antenna in the conventional solution is mainly due to the large distributed current on the outer shell of the rf connector 200 and further transmitted to the outer surface of the shielding layer of the rf cable 300, thereby generating radiation outside the design. The additional radiation field strength is superimposed with the radiation field strength of the antenna itself, resulting in fluctuations in the radiation performance of the overall antenna module 100 in different states of the radio frequency cable 300.

It is expected that, when the whole antenna module 100 with unstable radiation performance is finally installed, the radiation performance may also change due to the length change of the rf cable 300, the routing layout of the rf cable 300, and metal devices near the rf cable 300, which finally affects the consistency of the system communication performance, and may even have a large deviation from the estimated system communication performance.

In order to solve the above problem, the present invention provides a feeding structure for effectively suppressing the current entering the outer shell of the rf connector 200 and the current outside the shielding layer of the rf cable 300, so as to significantly improve the fluctuation of the radiation performance of the whole antenna module 100 due to the length and the routing layout of the rf cable 300, and ensure the stability of the radiation performance of the whole module.

Fig. 12-13 comparatively analyze the current intensity outside the shielding layer of the rf cable 300 varying with the length of the cable when a partial feeding structure and a coplanar parasitic patch 19 are introduced, respectively, and the antenna gain value under the corresponding conditions.

As can be seen from fig. 12, compared with the conventional scheme, the current intensity entering the cable outer shielding layer in the design scheme is greatly reduced, and is smoother along with the change of the cable length, so that the radiation of the current is distributed at the outer layer of the cable correspondingly, and the radiation basically does not change along with the cable length, so that the integral vehicle-mounted unit antenna has basically consistent radiation performance under different cable lengths or layouts. Comparing further the suppression of the surface current intensity of the cable by each feeding structure part and the parasitic patch 19 in fig. 12, each designed part contributes to the suppression to different extent, wherein the first feeding structure 41 plays the most important role, and finally all the parts are combined together, so as to achieve a good suppression effect on the surface current of the cable. It is expected that the good suppression of the cable surface current not only improves the stability of the radiation performance of the on-board unit antenna, but also has certain benefits to the EMC performance of the whole system.

Analyzing the data of fig. 13, in addition to the first feeding structure 41, the other feeding structure parts and the parasitic patch 19 are beneficial to the gain improvement of the on-board unit antenna, wherein the second feeding structure has the greatest degree of gain improvement. The final overall design scheme can obviously improve the gain performance of the vehicle-mounted unit antenna.

The following compares the performance of the directivity pattern of the on-board unit antenna module 100 between the design of the present invention and the conventional scheme.

Fig. 14 to 15 show the variation of the antenna radiation performance of the design scheme of the present invention on the plane along the radio frequency outgoing line direction when the total length of the radio frequency cable 300 is changed from 20mm to 300mm without bending. Fig. 16 to 17 compare the changes of the antenna radiation performance of the conventional scheme and the design scheme, also in the case of the layout of the unbent rf cable 300. Fig. 16 mainly illustrates the variation of the half-power beam width of the total gain and the right-hand circularly polarized gain, and fig. 17 compares the maximum gain of the antenna radiation along the radio frequency outgoing line direction plane and the deflection angle of the maximum gain and the antenna axis in different situations between the conventional scheme and the design scheme.

Fig. 18 is a radio frequency cable 300 with a total length of 250mm, and the change of the antenna radiation performance of the design scheme is examined when the length of the bent section is changed. Fig. 19 to 20 compare the radiation performance of the antenna in the conventional and the present design schemes with the bent section.

Compared with the traditional scheme, the radiation performance of the antenna module 100 adopting the design scheme has greatly reduced sensitivity to the length and layout of the radio frequency cable 300, the shape of a module radiation directional diagram is stable, the change range of the half-power beam width and the included angle of the maximum gain direction deviating from the axis is small, and the gain is basically only related to the loss caused by the length of the cable. Meanwhile, under the condition that the right-hand circular polarization performance in the front of the two schemes is good, the width of the right-hand circular polarization component and the half-power wave beam of the total gain in the traditional scheme are deviated by a certain amount, and the width of the wave beam in the design scheme is basically consistent with that of the wave beam in the traditional scheme, which means that the energy of the main wave beam in the design scheme is basically and effectively participated in the actual work in the form of the right-hand circular polarization component. Furthermore, with comparable half-power beamwidths, the overall gain of the antenna module 100 using the design is improved by nearly 2dB over the conventional scheme.

Under the condition, the possibility of antenna radiation performance change caused by cable layout and installation conditions in practical application is greatly reduced, the performance of the antenna in practical installation can be better ensured to be basically consistent with a design value, the consistency of system performance in different installation environments is favorably ensured, and the reliable analysis and prediction of the system performance are facilitated. Meanwhile, the radiation performance that the gain is higher and the effective right-hand circular polarization characteristic in the main beam is better also means that the working performance of the system is improved slightly by using the design scheme.

In summary, the present invention provides a split type front-mounted on-board unit and an antenna module 100, wherein an additional feeding structure is disposed on an antenna main board 1 of the antenna module 100, and the additional feeding structure is designed for a coplanar layout of a radio frequency connector 200 and an antenna radiation main unit 11, so as to effectively suppress a distributed current coupled to a housing of the radio frequency connector 200 and/or a shielding layer of a radio frequency cable 300 due to a compact layout, and greatly reduce an influence of an extra current radiation on an original antenna pattern, so that a radiation performance of an on-board unit antenna does not significantly change due to a harmful radiation generated by a difference in length and wiring of the radio frequency cable 300, and ensure that the performance of the on-board unit antenna has good consistency with a design value.

Meanwhile, the design of the parasitic patch 19 coplanar with the antenna radiation main unit 11 is used, so that the limited space is effectively utilized, the radiation performance of the vehicle-mounted unit antenna can be fully improved, and the deflection degree of an antenna directional pattern caused by the closer layout of the radio frequency connector 200 can be controlled to a certain extent, so that the designed antenna module 100 of the split type front-mounted vehicle-mounted unit can obtain a symmetrical directional pattern in a more compact space.

Because the technical scheme of the utility model is directly designed on the main board of the existing antenna module 100, the radiation performance of the antenna module 100 is ensured without increasing the cost and the process complexity, and meanwhile, the current coupling degree of the antenna module 100 and the radio frequency cable 300 is effectively reduced, which is also beneficial to the improvement of the EMC performance of the whole system.

It is to be understood that the foregoing examples, while indicating the preferred embodiments of the utility model, are given by way of illustration and description, and are not to be construed as limiting the scope of the utility model; it should be noted that, for those skilled in the art, the above technical features can be freely combined, and several changes and modifications can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention; therefore, all equivalent changes and modifications made within the scope of the claims of the present invention should be covered by the claims of the present invention.

Claims (11)

1. An antenna module is used for a split type front-mounted vehicle-mounted unit and comprises 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) inserted into the top surface of the antenna main board (1), and a radio frequency cable (300) with one end connected with the radio frequency connector (200); it is characterized in that the preparation method is characterized in that,

the antenna module further comprises an additional feed structure arranged on the antenna main board (1) to suppress current entering the housing of the radio frequency connector (200) and/or the outside of the shielding layer of the radio frequency cable (300).

2. The antenna module according to claim 1, characterized in that the top surface of the antenna main board (1) is provided with a number of first pads corresponding to the number of ground pins for connecting the radio frequency connector (200); the bottom surface of the antenna main board (1) is a copper-clad grounding layer (15).

3. An antenna module according to claim 2, characterized in that the additional feed structure comprises at least one first feed structure (41) comprising a slotted structure provided to the ground plane (15); the slotted structure is arranged around the periphery of the position, corresponding to the grounding layer (15), of the first pad adjacent to the antenna radiation main unit (11) so as to isolate a part of the corresponding grounding pin from being directly connected with the grounding layer (15).

4. An antenna module according to claim 2, characterized in that the additional feed structure further comprises at least one third feed structure (43) comprising a third copper-clad layer (431) arranged at the location of the antenna main board (1) at the first pad; the corresponding first pad is contained within the third copper-clad layer (431).

5. An antenna module according to claim 2, characterized in that the additional feed structure comprises at least one first feed structure (41) and at least one third feed structure (43);

the first feed structure (41) comprises a slotted structure arranged on the ground layer (15); the slotted structure is arranged around the periphery of the position, corresponding to the grounding layer (15), of the first pad adjacent to the antenna radiation main unit (11);

the third feeding structure (43) comprises a third copper-clad layer (431) arranged at the position of the antenna main board (1) on the first pad; the corresponding first pad is contained within the third copper-clad layer (431);

at least one third copper-clad layer (431) is provided on the first pad corresponding to the first feeding structure (41).

6. The antenna module of any of claims 2-5,

the top surface of the antenna main board (1) is provided with a second bonding pad (13) used for connecting a feeding coaxial inner core of the radio frequency connector (200);

the additional feed structure further comprises a second feed structure which comprises a short-circuit branch line (421) used for reducing current distributed on the shell of the radio frequency connector (200), the short-circuit branch line (421) is arranged on the top surface of the antenna main board (1), and the short-circuit branch line (421) is used for communicating the second bonding pad (13) with any two first bonding pads respectively so as to connect the coaxial inner core of the feed in the radio frequency connector (200) with a part of corresponding grounding pins.

7. The antenna module according to any of claims 1-5, characterized in that the top surface of the antenna main board (1) is further provided with several parasitic patches (19) arranged at circumferential positions of the antenna radiating main unit (11).

8. The antenna module according to claim 3 or 5, characterized in that the antenna main board (1) is provided with a first copper countersink (16) at the location of each first land, respectively;

the slotted structure comprises an annular slot (411), and the annular slot (411) is arranged around the circumferential outer side of the first copper sinking hole (16) corresponding to the grounding pin by taking the grounding pin as a base point.

9. The antenna module according to claim 3 or 5, wherein the slotted structure comprises an arc-shaped slot (412) and a U-shaped slot (413) connected to the arc-shaped slot (412), the arc-shaped slot (412) is enclosed in the ground layer (15) at a circumferential outer side based on the corresponding ground pin;

the notch direction of the arc-shaped groove (412) faces the U-shaped groove (413), or the notch direction of the arc-shaped groove (412) is opposite to the opening direction of the U-shaped groove (413).

10. The antenna module according to any of claims 4 or 5, wherein the third copper-clad layer (431) is connected to a ground pin adjacent to the antenna radiating main unit (11) to bring out the corresponding ground pin coplanar with the antenna radiating main unit (11).

11. A split front-loading on-board unit comprising an on-board unit main module, characterized by further comprising an antenna module (100) according to any of claims 1-10, the other end of the radio frequency cable (300) of the antenna module (100) being connected to the on-board unit main module.

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