Double-frequency four-arm helical antenna with ultra-low profile and wide-angle radiation characteristics

Abstract

The invention discloses a dual-frequency four-arm helical antenna with ultra-low profile and wide-angle radiation characteristics. The dual-frequency four-arm helical antenna comprises a first circular ring dielectric substrate, sickle-shaped radiation arms, an FPC dielectric substrate, helical radiation arms, a circular ring-shaped support, a covering film, a floor and a coaxial feed. The antenna can realize wide axial ratio beam width, wide half-power beam width and relatively high gain in a working frequency band range of satellite navigation, has an ultra-low profile, can be used for realizing an unmanned aerial vehicle-mounted satellite navigation terminal with low wind resistance and high sensitivity, and effectively improves the positioning precision and speed of a high-speed motion carrier.

Description

Technical Field

[0001] The present invention relates to the field of satellite navigation antennas, and in particular to a dual-frequency four-arm helical antenna having both ultra-low profile and wide-angle radiation characteristics. Background Art

[0002] In the field of UAV applications, with the continuous advancement and innovation of technology, the positioning accuracy and speed requirements for high-speed moving carriers are increasing. In order to meet this demand, it is particularly important to design a navigation terminal with low wind resistance and high sensitivity. As an important component of the navigation terminal, the performance of the antenna is directly related to the positioning accuracy and communication stability of the UAV. During the flight, the UAV needs to rely on the satellite navigation system for precise positioning and navigation. Traditional satellite navigation antennas are often large in size and high in profile, which not only increases the wind resistance of the UAV, but also limits its application in complex environments. At the same time, the traditional antenna beam width is narrow, which makes it difficult to meet the needs of UAVs for rapid satellite search and stable tracking in a wide airspace.

[0003] In order to improve the flight efficiency and positioning accuracy of unmanned aerial vehicles, it is necessary to develop a satellite navigation antenna with low profile and wide-angle radiation characteristics. Low-profile antennas can reduce the wind resistance of unmanned aerial vehicles and improve flight efficiency; while wide-angle radiation can enable the antenna to cover more satellite signals, improve satellite search speed and positioning accuracy. Low-profile antennas are also easier to be integrated with the body of the unmanned aerial vehicle, reducing the impact of the antenna on the appearance of the unmanned aerial vehicle. At the same time, wide-angle radiation performance can also ensure that the unmanned aerial vehicle can still maintain stable positioning when the signal is weak or interfered. Since the frequency of receiving signals by single-frequency antennas is limited, dual-frequency and multi-frequency antennas are very promising for research. In recent years, many researchers have been committed to achieving low-profile performance in satellite navigation antennas on unmanned aerial vehicles, but some antennas have reduced the vertical component of radiation for low profile, and it is difficult to achieve wide beam performance; some low-profile antennas are still not low enough to meet the requirements. To this end, the present invention proposes a dual-frequency four-arm helical antenna with both ultra-low profile and wide-angle radiation characteristics, which has the advantages of ultra-low profile, wide axial ratio beam and wide half-power beam. Summary of the invention

[0004] According to the problems existing in the prior art, the present invention discloses a dual-frequency four-arm helical antenna with ultra-low profile and wide-angle radiation characteristics, comprising: a first annular dielectric substrate, a sickle-shaped radiation arm, an FPC dielectric substrate, a helical radiation arm, an annular support, a covering film, a floor, and a coaxial feed;

[0005] The inner wall of the first annular dielectric substrate is connected to the FPC dielectric substrate and is located directly above the FPC dielectric substrate;

[0006] There are four groups of sickle-shaped radiation arms, and every two groups are placed at an interval of 90 degrees on the first annular dielectric substrate, and each group of sickle-shaped radiation arms includes a long sickle-shaped radiation arm and a short sickle-shaped radiation arm;

[0007] The outer surface of the FPC dielectric substrate is closely connected to the first annular dielectric substrate, the inner wall is closely connected to the annular support, and the two ends of the FPC dielectric substrate are connected and surrounded on the outer surface of the annular support, and the upper end of the FPC dielectric substrate is flush with the upper surface of the first annular dielectric substrate, and the lower end is flush with the floor;

[0008] The spiral radiating arms are closely attached to the outer surface of the FPC dielectric substrate. There are four groups of spiral radiating arms, and every two groups are placed at an interval of 90°. Each group includes a first spiral radiating arm, a second spiral radiating arm, a metal connecting strip, a ground patch and a feeding patch. The first spiral radiating arm is connected to the long sickle-shaped radiating arm, and the second spiral radiating arm is connected to the short sickle-shaped radiating arm.

[0009] The annular support includes a first annular support and a second annular support, wherein the outer surface of the first annular support is in close contact with the inner surface of the FPC dielectric substrate, and the upper surface of the first annular support is flush with the upper surface of the first annular dielectric substrate; the outer surface of the second annular support is in close contact with the inner surface of the FPC dielectric substrate, and the lower surface of the second annular support is flush with the floor;

[0010] The covering film is closely attached to the outer surface of the spiral radiating arm, which can slow down the oxidation of the metal surface, and a gap of 2 mm is retained at the top and bottom of the covering film to facilitate circuit connection.

[0011] Furthermore, by adopting the annular support and the first annular dielectric substrate, the shielding of the spiral radiating arm by the dielectric is significantly reduced, the radiation efficiency of the antenna is significantly improved, and the stability of the antenna is enhanced.

[0012] Furthermore, by providing the sickle-shaped radiating arm, the cross section of the antenna can be greatly reduced and wide-angle radiation characteristics can be achieved. Accordingly, by providing the long sickle-shaped radiating arm, the low-frequency HPBW can be widened; and by providing the short sickle-shaped radiating arm, the high-frequency HPBW can be widened.

[0013] Furthermore, under the premise of maintaining the advantage of small size, by increasing the distance between the first helical radiation arm and the second helical radiation arm, it can be ensured that the antenna has the characteristics of wide axial ratio beamwidth at dual frequency points.

[0014] Furthermore, the antenna can operate at dual frequencies by adjusting the length of a long sickle-shaped radiation arm and a short sickle-shaped radiation arm.

[0015] Furthermore, by adjusting the length ratio of the sickle-shaped radiation arm in the horizontal direction and the first spiral radiation arm and the second spiral radiation arm in the vertical direction, the height is reduced as much as possible while ensuring a wide beam to achieve an ultra-low profile.

[0016] Due to the adoption of the above technical solution, the dual-frequency four-arm helical antenna provided by the present invention has both ultra-low profile and wide-angle radiation characteristics, which has the following advantages: (1) The antenna has a relatively wide 3-dB axial ratio beam width in the two frequency bands of Beidou navigation. Specifically, the 3-dB axial ratio beam width in each direction at the 1.207 GHz frequency point reaches more than 145°; the 3-dB axial ratio beam width in each direction at the 1.561 GHz frequency point reaches more than 128°. (2) The antenna has a relatively wide half-power beam width in the two frequency bands of Beidou navigation. Specifically, the half-power beam width in each direction at the 1.207 GHz frequency point reaches more than 120°; the half-power beam width in each direction at the 1.561 GHz frequency point reaches more than 112°. (3) The antenna has an ultra-low profile, with a height of only 14.2 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 This is a 3D structural diagram of a dual-frequency four-arm helical antenna with ultra-low profile and wide-angle radiation characteristics of the present invention;

[0019] Figure 2 This is a horizontal structural exploded diagram of a dual-frequency four-arm helical antenna having both ultra-low profile and wide-angle radiation characteristics according to the present invention;

[0020] Figure 3 It is a 3D structural decomposition diagram of a dual-frequency four-arm helical antenna with ultra-low profile and wide-angle radiation characteristics of the present invention;

[0021] Figure 4 It is a structural diagram of a vertical radiation arm of a dual-frequency four-arm helical antenna having both ultra-low profile and wide-angle radiation characteristics according to the present invention;

[0022] Figure 5 It is an S parameter curve of a dual-frequency four-arm helical antenna having both ultra-low profile and wide-angle radiation characteristics of the present invention;

[0023] Figure 6The present invention is a graph showing gain variation with frequency of a dual-frequency four-arm helical antenna having both ultra-low profile and wide-angle radiation characteristics.

[0024] Figure 7 It is an axial ratio beam width diagram of a dual-frequency four-arm helical antenna having both ultra-low profile and wide-angle radiation characteristics at 1.207GHz of the present invention;

[0025] Figure 8 It is an axial ratio beam width diagram of a dual-frequency four-arm helical antenna having both ultra-low profile and wide-angle radiation characteristics at 1.561GHz of the present invention;

[0026] Fig. 9 It is a half-power beam width diagram of a dual-frequency four-arm helical antenna having both ultra-low profile and wide-angle radiation characteristics at 1.207GHz of the present invention;

[0027] Fig.10 It is a half-power beam width diagram of a dual-frequency four-arm helical antenna having both ultra-low profile and wide-angle radiation characteristics at 1.561GHz of the present invention;

[0028] In the figure: 1. first circular dielectric substrate, 2. sickle-shaped radiation arm, 21. long sickle-shaped radiation arm, 22. short sickle-shaped radiation arm, 3. FPC dielectric substrate, 4. spiral radiation arm, 41. first spiral radiation arm, 42. second spiral radiation arm, 43. metal connecting strip, 44. ground patch, 45. feeding patch, 5. circular support, 51. first circular support, 52. second circular support, 6. covering film, 7. floor, 8. coaxial feeding. DETAILED DESCRIPTION

[0029] In order to make the technical solutions and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention:

[0030] like Figure 1 , 2 A dual-band four-arm helical antenna with ultra-low profile and wide-angle radiation characteristics shown in , 3, and 4 includes: a first circular dielectric substrate 1, a sickle-shaped radiation arm 2, an FPC dielectric substrate 3, a helical radiation arm 4, a circular support 5, a covering film 6, a floor 7 and a coaxial feed 8.

[0031] The inner wall of the first annular dielectric substrate 1 is connected to the FPC dielectric substrate 3 and is located directly above the FPC dielectric substrate 3; there are 4 groups of sickle-shaped radiation arms 2, and every two groups are placed 90° apart, and are placed on the first annular dielectric substrate 1, and each group of sickle-shaped radiation arms 2 includes a long sickle-shaped radiation arm 21 and a short sickle-shaped radiation arm 22; the outer surface of the FPC dielectric substrate 3 is tightly connected to the first annular dielectric substrate 1, and the inner wall is tightly connected to the annular support 5, and the two ends of the FPC dielectric substrate 3 are connected and surrounded by the outer surface of the annular support 5, and the upper end of the FPC dielectric substrate 3 is flush with the upper surface of the first annular dielectric substrate 1, and the lower end is flush with the floor 7; the spiral radiation arm 4 is tightly attached to the outer surface of the FPC dielectric substrate 3, and there are 4 groups of spiral radiation arms 4, and every two groups are placed 90° apart, and each group includes the first spiral radiation Arm 41, second spiral radiation arm 42, metal connecting strip 43, ground patch 44 and feeding patch 45, the first spiral radiation arm 41 is connected to the long sickle-shaped radiation arm 21, and the second spiral radiation arm 42 is connected to the short sickle-shaped radiation arm 22; the annular support 5 includes a first annular support 51 and a second annular support 52, the outer surface of the first annular support 51 is tightly connected to the inner surface of the FPC dielectric substrate 3, and the upper surface of the first annular support 51 is flush with the upper surface of the first annular dielectric substrate 1; the outer surface of the second annular support 52 is tightly connected to the inner surface of the FPC dielectric substrate 3, and the lower surface of the second annular support 52 is flush with the floor 7; the covering film 6 is tightly attached to the outer surface of the spiral radiation arm 4, which can slow down the oxidation of the metal surface, and a 2mm gap is retained at the top and bottom of the covering film 6 to facilitate circuit connection.

[0032] The dual-frequency four-arm helical antenna with ultra-low profile and wide-angle radiation characteristics adopts a three-dimensional helical structure to achieve low profile and good radiation characteristics. By adopting an annular support 5 and a first annular dielectric substrate 1, the shielding of the spiral radiating arm 4 by the medium is significantly reduced, the radiation efficiency of the antenna is significantly improved, and the stability of the antenna is enhanced. By setting the sickle-shaped radiating arm 2, the cross-section of the antenna can be greatly reduced and the wide-angle radiation characteristics can be achieved. Correspondingly, by setting the long sickle-shaped radiating arm 21, the low-frequency HPBW can be widened; by setting the short sickle-shaped radiating arm 22, the high-frequency HPBW can be widened. Under the premise of maintaining the advantage of small size, by increasing the spacing between the first helical radiating arm 41 and the second helical radiating arm 42, it can be ensured that the antenna has the characteristics of wide axial ratio beam width at the dual frequency points. The antenna is made to work at dual frequencies by adjusting the length of the long sickle-shaped radiating arm 21 and a short sickle-shaped radiating arm 22. By adjusting the length ratio of the sickle-shaped radiation arm 2 in the horizontal direction and the first spiral radiation arm 41 and the second spiral radiation arm 42 in the vertical direction, the height is reduced as much as possible while ensuring a wide beam to achieve an ultra-low profile.

[0033] The technical indicators adopted by the present invention are as follows:

[0034] Center frequency: 1.08GHz-1.42GHz and 1.48GHz-1.89GHz

[0035] Polarization: RHCP

[0036] Axial ratio bandwidth (AR<3): (1.11-1.26GHz) 12.7% and (1.43-1.71GHz) 17.8%

[0037] Gain:>3.8dBic

[0038] Axial ratio beamwidth: >145°(1.207GHz) and >128°(1.561GHz)

[0039] Half-power beamwidth: >120°(1.207GHz) and >112°(1.561GHz)

[0040] Figure 5 The S parameter curve of the dual-frequency quadrifilar helical antenna with ultra-low profile and wide-angle radiation characteristics of the present invention shows that the frequency range in which the return loss of the antenna is greater than 10dB is 1.08-1.42GHz (27.2%) and 1.48-1.89GHz (24.3%).

[0041] Figure 6 This is a graph showing the gain versus frequency of a dual-frequency quadrifilar helical antenna with ultra-low profile and wide-angle radiation characteristics. The results show that the gain of the antenna is greater than 3.8dB at 1.15GHz-1.3GHz and greater than 5.1dB at 1.55GHz-1.59GHz.

[0042] Figure 7 The following is the axial ratio beamwidth curve of the antenna at 1.207GHz when phi is 0°, 45°, 90° and 135°. The 3-dB axial ratio beamwidth measured at 0° is 154°, the measured value at 45° is 160°, the measured value at 90° is 146°, and the measured value at 135° is 145°. This shows that the antenna has a wide 3-dB axial ratio beamwidth.

[0043] Figure 8 The following is the axial ratio beamwidth curve of the antenna at 1.561GHz when phi is 0°, 45°, 90° and 135°. The 3-dB axial ratio beamwidth measured at 0° is 128°, the measured value at 45° is 129°, the measured value at 90° is 129°, and the measured value at 135° is 128°. This shows that the antenna has a wide 3-dB axial ratio beamwidth.

[0044] Fig. 9 The half-power beamwidth curve of the antenna at 1.207GHz when phi is 0°, 45°, 90° and 135°. The half-power beamwidth measured at 0° is 120°, the measured value at 45° is 124°, the measured value at 90° is 120°, and the measured value at 135° is 121°. And at 1.207GHz, the gain of the antenna is 4.1dB. This shows that the antenna has a wide half-power beamwidth and achieves good gain at different elevation angles.

[0045] Fig.10 The half-power beamwidth curve of the antenna at 1.561GHz when phi is 0°, 45°, 90° and 135°. The half-power beamwidth measured at 0° is 113°, the measured value at 45° is 112°, the measured value at 90° is 113°, and the measured value at 135° is 112°. And at 1.561GHz, the gain of the antenna is 5.1dB. This shows that the antenna has a wide half-power beamwidth and achieves good gain at different elevation angles.

[0046] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A dual-frequency quadrifilar helical antenna with ultra-low profile and wide-angle radiation characteristics, characterized in that include: A first annular dielectric substrate (1), a sickle-shaped radiating arm (2), an FPC dielectric substrate (3), a spiral radiating arm (4), an annular support (5), a covering film (6), a floor (7), and a coaxial feed (8); The inner wall of the first annular dielectric substrate (1) is connected to the FPC dielectric substrate (3) and is located directly above the FPC dielectric substrate (3); The sickle-shaped radiation arms (2) include four groups, and each two groups are arranged at a 90° interval, and are placed on the first annular dielectric substrate (1), wherein each group of sickle-shaped radiation arms (2) includes a long sickle-shaped radiation arm (21) and a short sickle-shaped radiation arm (22); The outer surface of the FPC dielectric substrate (3) is tightly connected to the first annular dielectric substrate (1), and the inner wall is tightly connected to the annular support (5), and the two ends of the FPC dielectric substrate (3) are connected and surround the outer surface of the annular support (5), and the upper end of the FPC dielectric substrate (3) is flush with the upper surface of the first annular dielectric substrate (1), and the lower end is flush with the floor (7); The spiral radiating arms (4) are closely attached to the outer surface of the FPC dielectric substrate (3); the spiral radiating arms (4) include four groups, and each two groups are arranged at a 90° interval, wherein each group of spiral radiating arms (4) includes a first spiral radiating arm (41), a second spiral radiating arm (42), a metal connecting strip (43), a ground patch (44) and a feeding patch (45); the first spiral radiating arm (41) is connected to the long sickle-shaped radiating arm (21), and the second spiral radiating arm (42) is connected to the short sickle-shaped radiating arm (22); The annular support (5) comprises a first annular support (51) and a second annular support (52); the outer surface of the first annular support (51) is in close contact with the inner surface of the FPC dielectric substrate (3), and the upper surface of the first annular support (51) is flush with the upper surface of the first annular dielectric substrate (1); the outer surface of the second annular support (52) is in close contact with the inner surface of the FPC dielectric substrate (3), and the lower surface of the second annular support (52) is flush with the floor (7); The covering film (6) is closely attached to the outer surface of the spiral radiation arm (4), thereby slowing down the oxidation of the metal surface, and a certain gap is retained at the top and bottom of the covering film (6).

2. The dual-frequency quadrifilar helical antenna with ultra-low profile and wide-angle radiation characteristics according to claim 1, characterized in that: By adopting the annular support (5) and the first annular dielectric substrate (1), shielding of the spiral radiation arm (4) by the dielectric is reduced, the radiation efficiency of the antenna is improved, and the stability of the antenna is enhanced.

3. The dual-frequency quadrifilar helical antenna with ultra-low profile and wide-angle radiation characteristics according to claim 1, characterized in that: By arranging the sickle-shaped radiation arm (2), the cross section of the antenna is reduced and wide-angle radiation characteristics are achieved; by arranging the long sickle-shaped radiation arm (21), the low-frequency HPBW is widened; and by arranging the short sickle-shaped radiation arm (22), the high-frequency HPBW is widened.

4. The dual-frequency quadrifilar helical antenna with ultra-low profile and wide-angle radiation characteristics according to claim 1, characterized in that: By increasing the distance between the first helical radiation arm (41) and the second helical radiation arm (42), it is ensured that the antenna has the characteristics of wide axial ratio beam width at dual frequency points.

5. The dual-frequency quadrifilar helical antenna with ultra-low profile and wide-angle radiation characteristics according to claim 1, characterized in that: The antenna is made to work in dual frequency bands by adjusting the lengths of the long sickle-shaped radiation arm (21) and the short sickle-shaped radiation arm (22).

6. The dual-frequency quadrifilar helical antenna with ultra-low profile and wide-angle radiation characteristics according to claim 1, characterized in that: By adjusting the length ratio of the sickle-shaped radiation arm (2) in the horizontal direction and the first spiral radiation arm (41) and the second spiral radiation arm (42) in the vertical direction, the height of the antenna is reduced while ensuring a wide beam, thereby achieving an ultra-low profile.

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