Compact constant-beam GNSS (Global Navigation Satellite System) antenna capable of resisting multipath interference

Abstract

The invention discloses an anti-multipath interference compact constant beam GNSS antenna, which comprises a turbine cavity and a support medium arranged in the turbine cavity, and is characterized in that the support medium is provided with a radiation unit and a plurality of coupling feed sheets; wherein the turbine cavity comprises a metal mounting flange and a first reflection area and a second reflection area which are arranged on the metal mounting flange, the first reflection area is located in the second reflection area, the radiation unit and the plurality of coupling feed sheets are located in the first reflection area, the first reflection area is composed of a plurality of first spacers, and the second reflection area is composed of a plurality of second spacers. The second reflection area is composed of a plurality of second spacers, gaps exist between every two adjacent first spacers and between every two adjacent second spacers, the height of the second spacers is larger than that of the first spacers, a turbine structure is further arranged on one side of the second reflection area, and the rotation direction of the turbine structure is consistent with the polarization direction of the antenna. And a broadband power division phase shift network is arranged in the metal mounting flange. According to the invention, cross polarization of the antenna can be effectively suppressed, and the anti-multipath interference capability of the antenna is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communications, and in particular relates to a compact constant-beam GNSS antenna resistant to multipath interference. Background Art

[0002] GNSS (Global Navigation Satellite System) is the abbreviation of the Global Navigation Satellite System. The GNSS antenna is a terminal antenna used to receive satellite signals. In order to be able to receive electromagnetic waves of any polarization, the polarization form of the GNSS antenna mostly adopts right-hand circular polarization.

[0003] Currently, the commonly used satellite communication frequency bands are GPS: L1: 1575MHz, L2: 1227MHz, L5: 1176MHz; BeiDou II: B1: 1561MHz; B2: 1207MHz; B3: 1268MHz; GLONASS: 1612MHz, i.e., the satellite communication frequency band. The GNSS antenna bandwidth must cover at least 1160MHz to 1615MHz.

[0004] In the current GNSS, GNSS signals encounter reflectors such as buildings, ground, and water during propagation, forming multiple propagation paths to reach the receiver antenna. As a result, the received signal is a superposition of the direct signal and multiple reflected signals, causing code phase deviation, carrier phase disturbance, and signal distortion. Multipath error is the main source of error affecting the GNSS receiving system. Therefore, anti-multipath interference is the key to improving the system positioning accuracy.

[0005] A GNSS antenna's ability to resist multipath interference primarily relies on reducing the antenna's wide-angle axial ratio and suppressing backward cross-polarization. First, the primary reflection contributes the majority of the multipath signal's energy, which can alter the electromagnetic wave's polarization to varying degrees. Second, due to the influence of the platform, the antenna excites surface waves, which scatter at the ground break, resulting in significant backward cross-polarization. Multipath signals in the same rotational direction as the cross-polarization re-enter the antenna.

[0006] Existing GNSS antennas have limited ability to resist multipath interference and cannot cover all GNSS frequency bands, making it difficult to meet the requirements for high-precision system use. Summary of the Invention

[0007] The purpose of the present invention is to overcome the defects of the prior art and provide a compact constant-beam GNSS antenna that is resistant to multipath interference. When the radiating unit operates in the low frequency band, the second reflection area is the main reflection area, and when the radiating unit operates in the high frequency band, the first reflection area is the main reflection area, which can realize the broadband constant-beam radiation of the GNSS antenna. A turbine structure installed on the metal mounting flange is also provided on the side of the second reflection area away from the first reflection area, and its rotation direction is consistent with the polarization direction of the antenna. This structure can effectively suppress the cross-polarization of the antenna and improve the antenna's ability to resist multipath interference. Compared with traditional GNSS antennas, this GNSS antenna has the advantages of wide operating frequency band, low wide-angle axis ratio, constant beam width, small size, and stable phase center.

[0008] The object of the present invention is achieved through the following technical solutions:

[0009] A compact constant-beam GNSS antenna resistant to multipath interference comprises a turbine cavity and a supporting medium arranged in the turbine cavity, wherein a radiation unit and a plurality of coupling feed plates are arranged on the supporting medium;

[0010] Wherein, the turbine cavity includes a metal mounting flange and a first reflection area and a second reflection area provided on the metal mounting flange, the first reflection area and the second reflection area both extend circumferentially along the center of the metal mounting flange, the first reflection area is located in the second reflection area, the radiation unit and the plurality of coupling feed plates are both located in the first reflection area, the first reflection area is composed of a plurality of first spacers, the second reflection area is composed of a plurality of second spacers, there is a gap between two adjacent first spacers and two adjacent second spacers, the height of the second spacer is greater than the height of the first spacer, a turbine structure mounted on the metal mounting flange is further provided on the side of the second reflection area away from the first reflection area, the rotation direction of the turbine structure is consistent with the polarization direction of the antenna, and a broadband power division and phase shifting network is provided in the metal mounting flange;

[0011] Through this embodiment, the turbine cavity is provided with two first reflection areas and a second reflection area with inconsistent heights. The radiation unit and the plurality of coupling feed plates are all located in the first reflection area. When the radiation unit operates in the low frequency band, the second reflection area is the main reflection area, and when the radiation unit operates in the high frequency band, the first reflection area is the main reflection area, which can realize the broadband constant beam radiation of the GNSS antenna. The rotation direction of the turbine structure on the second reflection area is consistent with the polarization direction of the antenna, which effectively suppresses the cross polarization of the antenna and improves the antenna's anti-multipath interference capability.

[0012] In one embodiment, the turbine structure includes a plurality of turbine spacers, and each of the second spacers is provided with a turbine spacer on a side away from the first spacer.

[0013] In one embodiment, one end of each of the turbine spacers is mounted on the centerline of the second spacer.

[0014] In one embodiment, the radiation unit is in a circular sheet-like structure, and the end of the radiation unit is bent upward by 90°.

[0015] In one embodiment, a plurality of slot structures are evenly arranged on the radiation unit.

[0016] In one embodiment, each of the coupling feed plates includes a feeding rod and a coupling plate arranged thereon, the feeding rod is connected to the power divider and phase shift port of the broadband power divider and phase shift network, and the coupling plates of the multiple coupling feed plates feed the radiating unit through capacitive coupling.

[0017] In one embodiment, the bottom end of the supporting medium is connected to the metal mounting flange, and a first supporting column for installing the radiation unit is installed on the bottom end. A plurality of second supporting columns are also arranged around the first supporting column, and the second supporting columns are connected to the coupling feed plate.

[0018] In one embodiment, the printed circuit of the broadband power splitter and phase shifter network is a stripline structure, the printed circuit is printed inside two dielectric plate substrates, and the metal mounting flange has a cavity for accommodating the dielectric plate substrates.

[0019] In one embodiment, the broadband power division phase shift network includes a feeding port directly connected to the connector and four power division phase shift ports, each power division phase shift port is connected to a coupling feeding plate. When the feeding port is fed, the four power division phase shift ports have the same amplitude and the phases differ by 90°.

[0020] In one embodiment, the turbine cavity, the supporting medium, the radiation unit and the coupling feed plate are all metal structures.

[0021] The beneficial effects of the present invention are:

[0022] (1) The present invention provides a compact constant-beam GNSS antenna that is resistant to multipath interference. When the radiation unit operates in the low frequency band, the second reflection zone is the main reflection zone, and when the radiation unit operates in the high frequency band, the first reflection zone is the main reflection zone, which can realize the broadband constant-beam radiation of the GNSS antenna. A turbine structure mounted on the metal mounting flange is further provided on the side of the second reflection zone away from the first reflection zone, and its rotation direction is consistent with the polarization direction of the antenna. This structure can effectively suppress the cross-polarization of the antenna and improve the antenna's ability to resist multipath interference. The GNSS antenna provided by the present invention has a standing wave of less than 1.32 within a relative bandwidth of 40%, a ±75° wide-angle axis ratio of less than 3 decibels, a constant beam width, a gain greater than 5.9 decibels, and a backward cross-polarization suppression greater than 21 decibels, which can effectively suppress multipath interference.

[0023] (2) The GNSS antenna provided by the present invention has a simple structure and can be realized by machining or 3D printing, so that the GNSS antenna provided by the present invention has the advantages of high mechanical strength, low cost and good consistency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be described in more detail below based on embodiments and with reference to the accompanying drawings, wherein:

[0025] Figure 1 Shows a schematic structural diagram of the present invention;

[0026] Figure 2 shows a schematic structural diagram of the radiation unit of the present invention;

[0027] Figure 3 Shows a schematic structural diagram of the coupling feed sheet of the present invention;

[0028] Figure 4 A schematic diagram showing the structure of the support medium of the present invention is shown;

[0029] Figure 5 A schematic structural diagram of the turbine cavity of the present invention is shown;

[0030] Figure 6 Shows a schematic structural diagram of the broadband power division and phase shifting network of the present invention;

[0031] Figure 7 A standing wave simulation curve diagram of the GNSS antenna of the present invention is shown;

[0032] Figure 8 The f of the invented GNSS antenna is shown min Directional pattern simulation results;

[0033] Figure 9 The f0 pattern simulation results of the GNSS antenna of the present invention are shown;

[0034] Figure 10 The f of the GNSS antenna of the present invention is shown max Directional pattern simulation results;

[0035] Figure 11 The f of the GNSS antenna of the present invention is shown min Simulation results of wide angle axis ratio;

[0036] Figure 12 The simulation results of the f0 wide-angle axial ratio of the GNSS antenna of the present invention are shown;

[0037] Figure 13 The f of the GNSS antenna of the present invention is shown max Simulation results of wide angle axis ratio;

[0038] In the drawings, like reference numerals are used for like parts, but the drawings are not necessarily true to scale.

[0039] Reference numerals:

[0040] 1-radiating element, 2-coupling feeding plate, 3-support medium, 4-turbine cavity, 5-broadband power divider and phase shift network, 6-first reflection zone, 7-second reflection zone, 101-slot structure, 201-coupling plate, 202-feeding rod, 301-first supporting column, 302-second supporting column, 401-first spacer, 402-second spacer, 403-turbine spacer, 404-metal mounting flange, 501-printed circuit, 502-resistance, 503-feeding port, 504-power divider and phase shift port. DETAILED DESCRIPTION

[0041] The present invention will be further described below with reference to the accompanying drawings.

[0042] The present invention provides a compact constant beam GNSS antenna that is resistant to multipath interference, such as Figure 1 As shown, it includes a turbine cavity 4 and a supporting medium 3 arranged in the turbine cavity 4, and a radiation unit 1 and a plurality of coupling feed sheets 2 are arranged on the supporting medium 3;

[0043] In which, the turbine cavity 4 includes a metal mounting flange 404 and a first reflection zone 6 and a second reflection zone 7 arranged on the metal mounting flange 404. The first reflection zone 6 and the second reflection zone 7 both extend circumferentially along the center of the metal mounting flange 404. The first reflection zone 6 is located in the second reflection zone 7. The radiation unit 1 and multiple coupling feed plates 2 are all located in the first reflection zone 6. The first reflection zone 6 is composed of multiple first spacers 401, and the second reflection zone 7 is composed of multiple second spacers 402. There is a gap between two adjacent first spacers 401 and two adjacent second spacers 402. The height of the second spacer 402 is greater than the height of the first spacer 401. A turbine structure mounted on the metal mounting flange 404 is also provided on the side of the second reflection zone 7 away from the first reflection zone 6. The rotation direction of the turbine structure is consistent with the polarization direction of the antenna. A broadband power division and phase shifting network 5 is provided in the metal mounting flange 404;

[0044] It should be noted that in this embodiment, based on the structure of the GNSS antenna, when the radiating unit 1 operates in the low frequency band, the second reflection area 7 serves as the primary reflection area, while when the radiating unit 1 operates in the high frequency band, the first reflection area 6 serves as the primary reflection area, thereby achieving broadband constant beam radiation of the GNSS antenna. Furthermore, a turbine structure mounted on a metal mounting flange 404 is provided on the side of the second reflection area 7 away from the first reflection area 6, and its rotation direction is consistent with the polarization direction of the antenna. This structure can effectively suppress cross-polarization of the antenna and improve the antenna's ability to resist multipath interference. The GNSS antenna provided in this embodiment has a standing wave of less than 1.32 within a relative bandwidth of 40%, a ±75° wide-angle axial ratio of less than 3 dB, a constant beam width, a gain greater than 5.9 dB, and backward cross-polarization suppression greater than 21 dB, effectively suppressing multipath interference. That is, compared with traditional GNSS antennas, this GNSS antenna has the advantages of a wide operating frequency band, a low wide-angle axial ratio, a constant beam width, a small size, and a stable phase center.

[0045] At the same time, the antenna provided by this embodiment has a simple structure and the overall size of the antenna is only Φ0.625λ max ×0.21λ max (λ max The minimum operating frequency f min corresponding wavelength), which can be realized by machining or 3D printing, and has the advantages of high mechanical strength, low cost and good consistency;

[0046] In one embodiment, the turbine structure includes a plurality of turbine spacers 403. Each second spacer 402 is provided with a turbine spacer 403 on a side away from the first spacer 401. One end of each turbine spacer 403 is mounted on the center line of the second spacer 402. The radiation unit 1 has a circular sheet structure, and the end of the radiation unit 1 is bent upward by 90°.

[0047] It should be noted that if Figure 1 、 Figure 2 as well as Figure 5 As shown, the radiation unit 1 is a circular sheet metal structure, the end of which is bent upward at 90 degrees, and the diameter of the radiation unit 1 is 0.21λ max , with a height of 0.02λ max , the thickness of the metal sheet is 0.0055λ max , 4 slot structures 101 are evenly opened on the radiation unit 1, and their lengths are all 0.08λ max To increase the antenna working bandwidth, multiple turbine spacers 403 form a turbine structure, which is consistent with the polarization direction of the antenna, effectively suppressing the cross polarization of the antenna and improving the antenna's anti-multipath interference capability;

[0048] In one embodiment, as 1 and Figure 3 As shown, the GNSS antenna provided in this embodiment includes four coupling feed plates 2, each of which includes a feeding rod 202 and a coupling plate 201 provided thereon. The feeding rod 202 is connected to the power division phase shift port 504 of the broadband power division phase shift network 5. The coupling plates 201 of the multiple coupling feed plates 2 feed the radiating element 1 through capacitive coupling.

[0049] Specifically, the coupling feed plate 2 is a metal structure, and the size of the coupling plate 201 is Φ0.059λ max ×0.0055λ max , the size of the feed rod 202 is Φ0.0048λ max ×0.148λ max The bottom ends of the four coupled feeding plates 2 are respectively connected to the four ports of the broadband power division and phase shifting network 5, and the top ends thereof are used to feed the radiation unit 1 through capacitive coupling;

[0050] In one embodiment, the bottom end of the supporting medium 3 is connected to the metal mounting flange 404, and a first supporting column 301 for mounting the radiation unit 1 is installed on the bottom end. A plurality of second supporting columns 302 are further arranged around the first supporting column 301, and the second supporting columns 302 are connected to the coupling feed sheet 2;

[0051] Specifically, if Figure 1 and Figure 4 As shown, the supporting medium 3 is located inside the turbine cavity 4, with its bottom end connected to the turbine cavity 4 and a top end having a first supporting column 301 and four second supporting columns 302. The first supporting column 301 is fixed to the radiation unit 1 through a dielectric screw, and the four second supporting columns 302 are respectively connected to the four coupling feed plates 2 through dielectric screws.

[0052] In one embodiment, Figure 6As shown, the printed circuit 501 of the broadband power splitter and phase shifter network 5 adopts a stripline structure. The printed circuit 501 is printed inside two dielectric substrates. The broadband power splitter and phase shifter network 5 includes three 100Ω resistors 502. The feed port 503 is the external input and output port of the antenna and is directly connected to the connector. The four power splitter and phase shifter ports 504 are respectively connected to the four coupled feed plates 2. When the feed port 503 is feeding, the four power splitter and phase shifter ports 504 have the same amplitude and a phase difference of 90°.

[0053] In one embodiment, Figure 7 As shown in the figure, within 40% of the relative bandwidth (covering the entire GNSS frequency band), the port standing wave is less than 1.32;

[0054] like Figures 8 to 10 As shown, within the relative bandwidth of 40%, at the sections of 0°, 30°, 60°, 90°, 120° and 150°, the lowest frequency f min , center frequency f0 and highest frequency f max The pattern has a constant beamwidth, a gain greater than 5.9 dB, and backward cross-polarization suppression greater than 21 dB, indicating that the antenna can effectively suppress multipath interference;

[0055] like Figures 11 to 13 As shown in the figure, within the relative bandwidth of 40%, within the ±75° space of 0°, 30°, 60°, 90°, 120° and 150° sections, the lowest frequency f min , center frequency f0 and highest frequency f max The wide-angle axial ratio is less than 3 dB, indicating that the antenna has the ability to suppress multipath interference;

[0056] In the description of the present invention, it should be understood that the terms "upper", "lower", "bottom", "top", "front", "back", "inside", "outside", "left", "right", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention.

[0057] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be employed in conjunction with other described embodiments.

Claims

1. A compact constant beam GNSS antenna with multipath interference resistance, characterized in that: It comprises a turbine cavity and a supporting medium arranged in the turbine cavity, wherein a radiation unit and a plurality of coupling feed sheets are arranged on the supporting medium; In which, the turbine cavity includes a metal mounting flange and a first reflection zone and a second reflection zone arranged on the metal mounting flange, the first reflection zone and the second reflection zone both extend circumferentially along the center of the metal mounting flange, the first reflection zone is located in the second reflection zone, the radiation unit and the multiple coupling feed plates are all located in the first reflection zone, the first reflection zone is composed of multiple first spacers, the second reflection zone is composed of multiple second spacers, there is a gap between two adjacent first spacers and two adjacent second spacers, the height of the second spacer is greater than the height of the first spacer, and a turbine structure installed on the metal mounting flange is also provided on the side of the second reflection zone away from the first reflection zone, the rotation direction of the turbine structure is consistent with the polarization direction of the antenna, and a broadband power division and phase shifting network is provided in the metal mounting flange.

2. The compact constant beam GNSS antenna with multipath interference resistance according to claim 1, characterized in that: The turbine structure includes a plurality of turbine spacers, and each of the second spacers is provided with a turbine spacer on a side away from the first spacer.

3. The compact constant beam GNSS antenna with multipath interference resistance according to claim 2, characterized in that: One end of each of the turbine spacers is mounted on the center line of the second spacer.

4. The compact constant beam GNSS antenna with multipath interference resistance according to claim 1, characterized in that: The radiation unit is in a circular sheet structure, and the end of the radiation unit is bent upward by 90 degrees.

5. The compact constant beam GNSS antenna with multipath interference resistance according to claim 4, characterized in that: The radiation unit is also evenly provided with a plurality of slot structures.

6. The compact constant beam GNSS antenna with multipath interference resistance according to claim 1, characterized in that: Each of the coupling feed plates includes a feeding rod and a coupling plate arranged thereon, the feeding rod is connected to the power division phase shift port of the broadband power division phase shift network, and the coupling plates of the multiple coupling feed plates feed the radiation unit through capacitive coupling.

7. The compact constant beam GNSS antenna with multipath interference resistance according to claim 6, characterized in that: The bottom end of the supporting medium is connected to the metal mounting flange, and a first supporting column for mounting the radiation unit is installed on the bottom end. A plurality of second supporting columns are also arranged around the first supporting column, and the second supporting columns are connected to the coupling feed plate.

8. The compact constant beam GNSS antenna with multipath interference resistance according to claim 1, characterized in that: The printed circuit of the broadband power division and phase shifting network is a stripline structure. The printed circuit is printed inside two dielectric plate substrates. The metal mounting flange has a cavity for accommodating the dielectric plate substrates.

9. The compact constant beam GNSS antenna with multipath interference resistance according to claim 1, characterized in that: The broadband power division phase shift network includes a feeding port directly connected to the connector and four power division phase shift ports. Each power division phase shift port is connected to a coupling feeding plate. When the feeding port is fed, the four power division phase shift ports have the same amplitude and the phases differ by 90°.

10. The compact constant beam GNSS antenna with multipath interference resistance according to claim 1, characterized in that: The turbine cavity, supporting medium, radiation unit and coupling feed plate are all metal structures.

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