Miniaturized Multi - Antenna for Vehicle - mounted OBD Terminal and Its Application

Abstract

The present invention relates to a miniaturized multi-antenna applied to an in-vehicle OBD terminal and its application, including a grooved plastic bracket with a through groove opened at the bottom of the plastic bracket; a BDS / GPS / Galileo triple-mode antenna is attached to the plastic bracket and a first 4G antenna coupled thereto, and a WLAN antenna is attached to the plastic bracket and a second 4G antenna coupled thereto; the BDS / GPS / Galileo triple-mode antenna includes radiation patches respectively attached to the outer bottom surface, inner bottom surface, outer side surface and inner side surface of the through groove of the plastic bracket; the WLAN antenna includes radiation patches respectively attached to the outer bottom surface, inner bottom surface and inner side surface of the through groove of the plastic bracket; both the first 4G antenna and the second 4G antenna include radiation patches respectively attached to the outer surface, inner bottom surface, outer side surface and inner side surface of the plastic bracket. The miniaturized multi-antenna covers the BDS / GPS / Galileo triple-mode frequency band, the WLAN frequency band and the 4G frequency band, has good performance and small size, and is suitable for application in in-vehicle OBD mobile small terminal devices.

Description

Technical Field

[0001] The present invention relates to a miniaturized multi-antenna applied to an in-vehicle OBD terminal and its application, belonging to the field of wireless communication technology. Background Art

[0002] OBD is the English abbreviation of the vehicle automatic diagnosis system. It can detect the running state of the vehicle during operation. OBD can monitor whether there are abnormalities in the power system and control system and the working states of other components. When a vehicle breaks down, OBD can determine the specific fault situation and send a fault alarm to the vehicle occupants. With the iterative development of OBD, it mainly uses a small in-vehicle wireless transceiver system to automatically notify management departments of information such as the vehicle identification number, fault code, and vehicle location through wireless cellular communication, satellite communication, or the GPS system. As an important part of this system, the antenna plays an important role. With the booming development of the Internet of Vehicles, the requirements for the communication function of OBD are becoming increasingly rich. It has evolved from the original communication methods such as BDS / GPS / Galileo triple-mode, WLAN, and GPRS to the 4G communication method step by step. The antenna design for an OBD system integrating multiple communication methods is even more of a challenge. Calculated according to the 1 / 4 working wavelength of the antenna, the 1 / 4 wavelength corresponding to BDS / GPS / Galileo triple-mode is about 48 mm, the 1 / 4 wavelength corresponding to WLAN is about 31 mm (2.4 GHz), and the 1 / 4 wavelength corresponding to 4G is about 107 mm (700 MHz). Therefore, the research on the communication method of miniaturized multi-antennas has broad application prospects in the OBD system. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a miniaturized multi-antenna applied to an in-vehicle OBD terminal that is small in size, easy to install, and has good performance, covering the BDS / GPS / Galileo triple-mode frequency band, WLAN frequency band, and 4G frequency band.

[0004] The present invention is implemented by the following solution: A miniaturized multi-antenna applied to an in-vehicle OBD terminal, including a trough-shaped plastic bracket, and a through slot is opened at the bottom of the plastic bracket; a BDS / GPS / Galileo triple antenna, a first 4G antenna located beside and coupled with the BDS / GPS / Galileo triple antenna, a WLAN antenna, and a second 4G antenna located beside and coupled with the WLAN antenna are attached to the plastic bracket; the BDS / GPS / Galileo triple antenna includes radiation patches respectively attached to the outer bottom surface, inner bottom surface, outer side surface, and the inner side surface of the through slot of the plastic bracket; the WLAN antenna includes radiation patches respectively attached to the outer bottom surface, inner bottom surface, and the inner side surface of the through slot of the plastic bracket; the BDS / GPS / Galileo triple antenna and the WLAN antenna are located on two opposite sides of the through slot; both the first 4G antenna and the second 4G antenna include radiation patches respectively attached to the outer surface, inner bottom surface, outer side surface, and the inner side surface of the through slot of the plastic bracket.

[0005] Further, the BDS / GPS / Galileo triple antenna adopts a PIFA antenna; the feed point rectangular stub patch A6 and the ground point rectangular stub patch A7 of the radiation patch of the BDS / GPS / Galileo triple antenna attached to the inner bottom surface of the plastic bracket are bent to the inner side surface of the through slot and are coupled and connected to the radiation patch A22 on the outer bottom surface of the plastic bracket, and the radiation patch A22 extends a rectangular radiation patch A23 to the outer side surface of the plastic bracket.

[0006] Further, the WLAN antenna adopts a PIFA antenna; an L-shaped interval 24 is left between the feed point rectangular stub patch B18 and the ground point rectangular stub patch B19 of the radiation patch of the WLAN antenna, and a rectangular radiation patch B25 extends from the end of the feed point rectangular stub patch; at the short-circuit point of the feed point rectangular stub patch B18 and the ground point rectangular stub patch B19, it is coupled and connected to the radiation patch C27 on the outer bottom surface of the plastic bracket through the radiation patch B26 on the inner side surface of the through slot.

[0007] Further, the radiation patch C27 is composed of a rectangular stub patch, a trapezoidal stub patch, and an L-shaped stub patch.

[0008] Further, the first 4G antenna uses a folded loop antenna with a dual loop; in the radiation patch of the first 4G antenna, the feed point rectangular stub patch C38 attached to the inner bottom surface of the plastic bracket is bent into the inner side surface of the through slot and coupled and connected to two rectangular strip patches A8 on the outer bottom surface of the plastic bracket, and the ground point rectangular stub patch C39 attached to the inner bottom surface of the plastic bracket is bent into the inner side surface of the through slot and coupled and connected to the stepped radiation patch 31 on the outer bottom surface of the plastic bracket. The two rectangular strip patches A8 are connected by a rectangular stub patch A13, and the rectangular strip patch A on the outer side extends a rectangular radiation patch C28 and an L-shaped stub patch A9 towards the outer side surface of the plastic bracket; the stepped radiation patch 31 extends a loop patch formed by an L-shaped radiation patch A33, an L-shaped stub patch B11, a rectangular radiation patch F32 and a T-shaped stub patch 10 towards the outer side surface of the plastic bracket. The rectangular radiation patch C28 and the L-shaped stub patch A9 and the loop patch are located on two adjacent outer side surfaces of the plastic bracket, and the loop patch is connected to the rectangular radiation patch C28 through two rectangular radiation patches E30 and a rectangular radiation patch D29 at the outer corner of the plastic bracket.

[0009] Further, the second 4G antenna uses a folded loop antenna; in the radiation patch of the second 4G antenna, the feed point rectangular stub patch D40 and the ground point rectangular stub patch D41 attached to the inner bottom surface of the plastic bracket are bent into the inner side surface of the through slot and respectively coupled and connected to the rectangular stub patch D21 and the rectangular stub patch C20 on the outer bottom surface of the plastic bracket. The rectangular stub patch C20 is connected to the radiation patch F37 on the inner bottom surface of the plastic bracket. The rectangular stub patch D21 extends towards the outer side surface of the plastic bracket to form a radiation patch D34 with an L-shaped structure and a rectangular stub patch B14. The radiation patch F37 extends an L-shaped stub patch C17 towards the outer side surface of the plastic bracket. One end of the L-shaped stub patch C17 is connected to one end of an L-shaped radiation patch B36 on an adjacent outer side surface. The other end of the L-shaped radiation patch B36 is connected to the radiation patch D34 through a radiation patch E35. A rectangular strip patch B15 and a composite stub patch 16 formed by a T-shaped stub patch and an L-shaped stub patch extend from the side of the radiation patch E35.

[0010] Another technical solution of the present invention: a vehicle-mounted OBD terminal, in which the vehicle-mounted OBD terminal is provided with the miniaturized multi-antenna applied to the vehicle-mounted OBD terminal as described above.

[0011] Compared with the prior art, the present invention has the following beneficial effects: The miniaturized multi-antenna applied to the vehicle-mounted OBD terminal of the present invention forms a multi-antenna system composed of four antennas, covering the BDS / GPS / Galileo triple-band, WLAN band and 4G band. The antenna has good port impedance, can achieve a wide impedance bandwidth of the antenna, has good performance, is small in size, realizes miniaturized design, is convenient for installation, has strong practicability, and is suitable for application in vehicle-mounted OBD mobile small terminal devices.

[0012] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below through specific embodiments and related drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a top perspective view of one orientation of an embodiment of the present invention;

[0014] Figure 2 is a top perspective view of another orientation of an embodiment of the present invention;

[0015] Figure 3 is a bottom perspective view of one orientation of an embodiment of the present invention;

[0016] Figure 4 is a top perspective view of another orientation of an embodiment of the present invention;

[0017] Figure 5 is a front view of an embodiment of the present invention;

[0018] Figure 6 is a rear view of an embodiment of the present invention;

[0019] Figure 7 is a right view of an embodiment of the present invention;

[0020] Figure 8 is a top view of an embodiment of the present invention;

[0021] Figure 9 is a bottom view of an embodiment of the present invention;

[0022] Figure 10 is a test result diagram of the reflection coefficient of the BDS / GPS / Galileo triple-band antenna in an embodiment of the present invention;

[0023] Figure 11 is a test result diagram of the reflection coefficient of the WLAN antenna in an embodiment of the present invention;

[0024] Figure 12 is a test result diagram of the reflection coefficient of the first 4G antenna in an embodiment of the present invention;

[0025] Figure 13It is the test result diagram of the reflection coefficient of the second 4G antenna in the embodiment of the present invention;

[0026] Explanation of the reference numerals in the figure: 1 - BDS / GPS / Galileo triple antenna, 2 - First 4G antenna, 3 - Second 4G antenna, 4 - WLAN antenna, 5 - Plastic bracket, 6 - Feeding point rectangular stub patch A, 7 - Grounding point rectangular stub patch A, 8 - Rectangular strip stub patch A, 9 - L-shaped stub patch A, 10 - T-shaped stub patch, 11 - L-shaped stub patch B, 12 - Through slot, 13 - Rectangular stub patch A, 14 - Rectangular stub patch B, 15 - Rectangular strip stub patch B, 16 - Composite stub patch, 17 - L-shaped stub patch C, 18 - Feeding point rectangular stub patch B, 19 - Grounding point rectangular stub patch B, 20 - Rectangular stub patch C, 21 - Rectangular stub patch D, 22 - Radiation patch A, 23 - Rectangular radiation patch A, 24 - L-shaped spacer, 25 - Rectangular radiation patch B, 26 - Radiation patch B, 27 - Radiation patch C, 28 - Rectangular radiation patch C, 29 - Rectangular radiation patch D, 30 - Rectangular radiation patch E, 31 - Stepped radiation patch, 32 - Rectangular radiation patch F, 33 - L-shaped radiation patch A, 34 - Radiation patch D, 35 - Radiation patch E, 36 - L-shaped radiation patch B, 37 - Radiation patch F, 38 - Feeding point rectangular stub patch C, 39 - Grounding point rectangular stub patch C, 40 - Feeding point rectangular stub patch D, 41 - Grounding point rectangular stub patch D. Detailed implementation manners

[0027] Such as Figures 1 to 13As shown in the figure, a miniaturized multi-antenna applied to an in-vehicle OBD terminal includes a grooved plastic bracket. A through groove is formed at the bottom of the plastic bracket, and the through groove is rectangular. A BDS / GPS / Galileo triple antenna, a first 4G antenna located beside and coupled with the BDS / GPS / Galileo triple antenna, a WLAN antenna, and a second 4G antenna located beside and coupled with the WLAN antenna are attached to the plastic bracket. The BDS / GPS / Galileo triple antenna includes radiation patches respectively attached to the outer bottom surface, inner bottom surface, outer side surface, and inner side surface of the through groove of the plastic bracket. The WLAN antenna includes radiation patches respectively attached to the outer bottom surface, inner bottom surface, and inner side surface of the through groove of the plastic bracket. The BDS / GPS / Galileo triple antenna and the WLAN antenna are located on two opposite sides of the through groove. Both the first 4G antenna and the second 4G antenna include radiation patches respectively attached to the outer surface, inner bottom surface, outer side surface, and inner side surface of the plastic bracket. The miniaturized multi-antenna of the present invention forms a multi-antenna system composed of four antennas, covering the BDS / GPS / Galileo triple band, the WLAN band, and the 4G band. The antenna has good port impedance, can achieve a wide impedance bandwidth of the antenna, and has good performance. The four antennas are integrated on a plastic housing with a spatial size of 49*43*23.2 mm, with a small size, realizing miniaturized design, being easy to install, and suitable for application in in-vehicle OBD mobile small terminal devices.

[0028] In this embodiment, the BDS / GPS / Galileo triple antenna adopts a PIFA antenna. The feed point rectangular stub patch A6 and the ground point rectangular stub patch A7 of the radiation patch of the BDS / GPS / Galileo triple antenna attached to the inner bottom surface of the plastic bracket are bent to the inner side surface of the through groove and coupled and connected to the radiation patch A22 on the outer bottom surface of the plastic bracket. The radiation patch A22 extends a rectangular radiation patch A23 to the outer side surface of the plastic bracket, and the rectangular radiation patch A23 is coupled with the adjacent first 4G antenna to cover the BDS+GPS+Galileo triple antenna band.

[0029] In this embodiment, the WLAN antenna adopts a PIFA antenna. An L-shaped gap 24 is left between the feed point rectangular stub patch B18 and the ground point rectangular stub patch B19 of the radiation patch of the WLAN antenna attached to the inner bottom surface of the plastic bracket to form a coupling resonance. The end of the feed point rectangular stub patch extends a rectangular radiation patch B25. At the short-circuit point of the feed point rectangular stub patch B18 and the ground point rectangular stub patch B19, it is coupled and connected to the radiation patch C27 on the outer bottom surface of the plastic bracket through the radiation patch B26 on the inner side surface of the through groove.

[0030] In this embodiment, the radiation patch C27 is composed of a rectangular stub patch, a trapezoidal stub patch, and an L-shaped stub patch, and is coupled with the adjacent second 4G antenna, so as to cover the WLAN antenna frequency band.

[0031] In this embodiment, the first 4G antenna adopts a folded loop antenna with a double loop; the feed point rectangular stub patch C38 attached to the inner bottom surface of the plastic bracket in the radiation patch of the first 4G antenna is bent into the inner side surface of the through groove and is coupled and connected with two rectangular strip patches A8 on the outer bottom surface of the plastic bracket, and the ground point rectangular stub patch C39 attached to the inner bottom surface of the plastic bracket is bent into the inner side surface of the through groove and is coupled and connected with the stepped radiation patch 31 on the outer bottom surface of the plastic bracket. The stepped radiation patch 31 and the radiation patch A22 of the BDS / GPS / Galileo triple-mode antenna are located on one long side of the through groove. The two rectangular strip patches A8 are connected by a rectangular stub patch A13, and the rectangular strip patch A on the outer side extends a rectangular radiation patch C28 and an L-shaped stub patch A9 to the outer side surface of the plastic bracket, forming high-frequency resonance and expanding the bandwidth. The two rectangular strip patches A8 and the rectangular stub patch A13 are located on one short side of the through groove. The stepped radiation patch 31 extends a loop patch composed of an L-shaped radiation patch A33, an L-shaped stub patch B11, a rectangular radiation patch F32, and a T-shaped stub patch 10 to the outer side surface of the plastic bracket, which can realize a wide impedance bandwidth of the high-frequency antenna. The rectangular radiation patch C28 and the L-shaped stub patch A9 are located on two adjacent outer side surfaces of the plastic bracket. The loop patch is connected to the rectangular radiation patch C28 through two rectangular radiation patches E30 and the rectangular radiation patch D29 at the outer corner of the plastic bracket. And the L-shaped stub patch B11 is coupled with the radiation patch A of the BDS / GPS / Galileo triple-mode antenna and the rectangular radiation patch A to realize low-frequency resonance and bandwidth. The above-mentioned rectangular radiation patch D29, the rectangular radiation patch E30, the stepped radiation patch 31, and the ground point rectangular stub patch C39 form a first loop. The above-mentioned rectangular radiation patch D29, the rectangular radiation patch F32, the L-shaped stub patch B11, the L-shaped radiation patch A33, the stepped radiation patch 31, and the ground point rectangular stub patch C39 form a second loop. The L-shaped stub patch B11 on the side of the first 4G antenna close to the BDS / GPS / Galileo triple-mode antenna is coupled with the BDS+GPS+Galileo triple-mode antenna, and the L-shaped stub patch B11 and the rectangular radiation patch A23 are located on the same side surface of the plastic bracket.

[0032] In this embodiment, the second 4G antenna adopts a folded loop antenna; in the radiation patch of the second 4G antenna, the feeding point rectangular stub patch D40 and the grounding point rectangular stub patch D41 attached to the inner bottom surface of the plastic bracket are bent into the inner side surface of the through slot and are respectively coupled and connected to the rectangular stub patch D21 and the rectangular stub patch C20 on the outer bottom surface of the plastic bracket. The rectangular stub patch D21, the rectangular stub patch C20 and the radiation patch C27 of the WLAN antenna are located on the other long side of the through slot. The rectangular stub patch C20 is connected to the radiation patch F37 on the inner bottom surface of the plastic bracket. The rectangular stub patch D21 extends outwards to the outer side surface of the plastic bracket to form a radiation patch D34 and a rectangular stub patch B14 with an L-shaped structure, forming a high-frequency band resonance; the radiation patch F37 extends outwards to the outer side surface of the plastic bracket to form an L-shaped stub patch C17. One end of the L-shaped stub patch C17 is connected to one end of the L-shaped radiation patch B36 on the adjacent outer side surface. The other end of the L-shaped radiation patch B36 is connected to the radiation patch D34 through the radiation patch E35. The rectangular stub patch B14 and the radiation patch E35 are located on both sides of the upper end of the radiation patch D34. The side of the radiation patch E35 extends out a rectangular strip stub patch B15 and a composite stub patch 16 composed of a T-shaped stub patch and an L-shaped stub patch. The radiation patch E35 is located at the lower part of the side surface of the plastic bracket. The rectangular strip stub patch B15 and the composite stub patch 16 extend upwards. The L-shaped stub patch C17 is located above the radiation patch E35. Both of them cross two adjacent side surfaces of the plastic bracket. The rectangular strip stub patch B15 and the composite stub patch 16 are coupled to each other to realize the high-frequency band bandwidth; and the L-shaped stub patch in the composite stub patch 16 is coupled to the radiation patch D34, and the rectangular strip stub patch B15 is coupled to the L-shaped radiation patch B36; the L-shaped radiation patch B36 is coupled to the radiation patch (i.e., the L-shaped stub patch A9) on the first 4G antenna close to it to realize the wide impedance bandwidth of the low-frequency band antenna. The L-shaped radiation patch B36 and the L-shaped stub patch A9 are located on the same side surface of the plastic bracket; the radiation patch D34, the radiation patch E35, the L-shaped radiation patch B36 on the outer side surface of the plastic bracket and the radiation patch F37 on the lower surface of the plastic bracket form a loop circuit with the rectangular stub patch C20 to realize the low-frequency resonance.

[0033] The miniaturized multi-antenna applied to the vehicle-mounted OBD terminal of the present invention forms a multi-antenna system through four antennas. The overall spatial size of the multi-antenna is about 49*43*23.2mm, realizing miniaturized design and multiple communication modes, which is much smaller than the existing antennas. The miniaturized antenna has a BDS / GPS / Galileo three-in-one antenna S11 <-10dB, a WLAN antenna S11 <-7.0dB, a first 4G antenna in the low frequency band (703-824MHz) S11 <-6dB, a high frequency band (1710-2170MHz) S11 <-6dB, and a second 4G antenna in the low frequency band S11 <-6dB. The bandwidth covered is 720-960MHz, and the high frequency band (1710-2170MHz) S11 <-5dB.

[0034] Analysis of the test results of the miniaturized multi-antenna used in the vehicle OBD terminal:

[0035] Figure 10 The S11 corresponding to 1.559 GHz is -14.73 dB, and the S11 corresponding to 1.606 GHz is -21.60 dB, which is consistent with the above-mentioned BDS / GPS / Galileo three-in-one antenna S11<-10 dB.

[0036] Figure 11 The S11 corresponding to 2.4 GHz is -8.38 dB, the S11 corresponding to 2.5 GHz is -7.53 dB, the S11 corresponding to 5.15 GHz is -7.10 dB, and the S11 corresponding to 5.85 GHz is -7.71 dB, which is consistent with the above-mentioned WLAN antenna S11<-7.0 dB.

[0037] Figure 12 The S11 corresponding to 703MHz is -6.45dB, the S11 corresponding to 824MHz is -6.22dB, the S11 corresponding to 1.71GHz is -8.56dB, and the S11 corresponding to 2.17GHz is -6.38. In line with the above, the S11 of the first 4G antenna is less than -6dB in the low frequency band (703-824MHz) and less than -6dB in the high frequency band (1710-2170MHz).

[0038] Figure 13 The S11 corresponding to 720MHz is -6.68dB, the S11 corresponding to 960MHz is -6.80dB, the S11 corresponding to 1.71GHz is -8.74dB, the S11 corresponding to 2.17GHz is -7.94, and the S11 corresponding to 1.90GHz is -5.32dB. The second 4G antenna that meets the above requirements has S11 <-6dB in the low frequency band, and can cover a bandwidth of 720-960MHz, and S11 <-5dB in the high frequency band (1710-2170MHz).

[0039] Another technical solution of the present invention: An in-vehicle OBD terminal, in which the miniaturized multi-antenna applied to the in-vehicle OBD terminal as described above is provided; four antennas are integrated on a plastic bracket, covering three communication methods of BDS / GPS / Galileo triple-mode, WLAN, and 4G. The antenna has good port impedance, can achieve wide impedance bandwidth of the antenna, is small in size and has good performance.

[0040] For any of the technical solutions disclosed by the present invention as described above, unless otherwise stated, if it discloses a numerical range, then the disclosed numerical range is a preferred numerical range. Any person skilled in the art should understand that the preferred numerical range is only the numerical values with obvious technical effects or representativeness among many implementable numerical values. Since there are too many numerical values to list exhaustively, the present invention only discloses some numerical values to illustrate the technical solutions of the present invention. Moreover, the above-listed numerical values should not constitute a limitation on the protection scope of the present invention.

[0041] If the present invention discloses or involves components or structural parts that are fixedly connected to each other, then, unless otherwise stated, the fixed connection can be understood as: a detachable fixed connection (for example, connected by bolts or screws), or can also be understood as: a non-detachable fixed connection (for example, riveting, welding). Of course, the mutual fixed connection can also be replaced by an integral structure (for example, manufactured by integral casting process) (except when it is obviously impossible to adopt the integral forming process).

[0042] In addition, for the terms used to represent the positional relationship or shape in any of the technical solutions disclosed by the present invention as described above, unless otherwise stated, their meanings include states or shapes that are approximate, similar or close to them.

[0043] Any component provided by the present invention can either be assembled from multiple separate components or be a single component manufactured by an integral forming process.

[0044] Finally, it should be noted that: The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the specific implementation manners of the present invention or perform equivalent replacements on some technical features; Without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A miniaturized multi-antenna applied to a vehicle-mounted OBD terminal, Characterized in that: A multi - antenna system is formed by four antennas, covering the BDS / GPS / Galileo triple - band, WLAN band, and 4G band; it includes a trough - shaped plastic bracket with a through - slot opened at the bottom of the plastic bracket; on the plastic bracket, a BDS / GPS / Galileo triple - antenna, a first 4G antenna, a WLAN antenna, and a second 4G antenna are attached. The first 4G antenna is located beside the BDS / GPS / Galileo triple - antenna and is coupled with it, and the second 4G antenna is located beside the WLAN antenna and is coupled with it; the BDS / GPS / Galileo triple - antenna includes radiation patches respectively attached to the outer bottom surface, inner bottom surface, outer side surface, and the inner side surface of the through - slot of the plastic bracket; the WLAN antenna includes radiation patches respectively attached to the outer bottom surface, inner bottom surface, and the inner side surface of the through - slot of the plastic bracket; the BDS / GPS / Galileo triple - antenna and the WLAN antenna are located on two opposite sides of the through - slot; both the first 4G antenna and the second 4G antenna include radiation patches respectively attached to the outer surface, inner bottom surface, outer side surface, and the inner side surface of the through - slot of the plastic bracket; the BDS / GPS / Galileo triple - antenna adopts a PIFA antenna; in the radiation patches of the BDS / GPS / Galileo triple - antenna, the feeding - point rectangular stub patch A(6) and the grounding - point rectangular stub patch A(7) attached to the inner bottom surface of the plastic bracket are bent to the inner side surface of the through - slot and are coupled and connected to the radiation patch A(22) on the outer bottom surface of the plastic bracket, and the radiation patch A(22) extends a rectangular radiation patch A(23) towards the outer side surface of the plastic bracket; the WLAN antenna adopts a PIFA antenna; there is an L - shaped gap(24) between the feeding - point rectangular stub patch B(18) and the grounding - point rectangular stub patch B(19) attached to the inner bottom surface of the plastic bracket in the radiation patches of the WLAN antenna, and the end of the feeding - point rectangular stub patch extends a rectangular radiation patch B(25); at the short - circuit point of the feeding - point rectangular stub patch B(18) and the grounding - point rectangular stub patch B(19), it is coupled and connected to the radiation patch C(27) on the outer bottom surface of the plastic bracket through the radiation patch B(26) on the inner side surface of the through - slot; the first 4G antenna adopts a folded loop antenna with a double - loop; in the radiation patches of the first 4G antenna, the feeding - point rectangular stub patch C(38) attached to the inner bottom surface of the plastic bracket is bent to the inner side surface of the through - slot and is coupled and connected to two rectangular strip patches A(8) on the outer bottom surface of the plastic bracket, and the grounding - point rectangular stub patch C(39) attached to the inner bottom surface of the plastic bracket is bent to the inner side surface of the through - slot and is coupled and connected to the stepped radiation patch(31) on the outer bottom surface of the plastic bracket, and the two rectangular strip patches A(8) are connected by a rectangular stub patch A(13) and the rectangular strip patch A on the outer - facing side extends a rectangular radiation patch C(28) and an L - shaped stub patch A(9) towards the outer side surface of the plastic bracket;The stepped radiation patch (31) extends outwards from the outer side surface of the plastic bracket to form an annular patch composed of an L-shaped radiation patch A (33), an L-shaped stub patch B (11), a rectangular radiation patch F (32) and a T-shaped stub patch (10). The rectangular radiation patch C (28) and the L-shaped stub patch A (9) are located on two adjacent outer side surfaces of the plastic bracket with the annular patch. The annular patch is connected to the rectangular radiation patch C (28) through two rectangular radiation patches E (30) and the rectangular radiation patch D (29) at the outer corner of the plastic bracket. The second 4G antenna adopts a folded loop antenna. The feeding point rectangular stub patch D (40) and the grounding point rectangular stub patch D (41) of the radiation patch of the second 4G antenna, which are attached to the inner bottom surface of the plastic bracket, are bent to the inner side surface of the through groove and are respectively coupled and connected to the rectangular stub patch D (21) and the rectangular stub patch C (20) on the outer bottom surface of the plastic bracket. The rectangular stub patch C (20) is connected to the radiation patch F (37) on the inner bottom surface of the plastic bracket. The rectangular stub patch D (21) extends outwards from the outer side surface of the plastic bracket to form a radiation patch D (34) and a rectangular stub patch B (14) in an L-shaped structure. The radiation patch F (37) extends outwards from the outer side surface of the plastic bracket to form an L-shaped stub patch C (17). One end of the L-shaped stub patch C (17) is connected to one end of the L-shaped radiation patch B (36) on the adjacent outer side surface. The other end of the L-shaped radiation patch B (36) is connected to the radiation patch D (34) through the radiation patch E (35). The side of the radiation patch E (35) extends out a rectangular strip stub patch B (15) and a composite stub patch (16) composed of a T-shaped stub patch and an L-shaped stub patch.; 2. The miniaturized multi-antenna applied to a vehicle-mounted OBD terminal according to claim 1, Characterized in that: The radiation patch C (27) is composed of a rectangular branch patch, a trapezoidal branch patch and an L-shaped branch patch.

3. A vehicle-mounted OBD terminal, Characterized in that: The vehicle-mounted OBD terminal is provided with a miniaturized multi-antenna applied to a vehicle-mounted OBD terminal as described in claim 1 or 2.

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