Multi-band four-arm spiral composite antenna

Abstract

The invention relates to a multi-band four-arm spiral composite antenna. The antenna mainly comprises a top antenna unit and at least two four-arm helical antenna units which are located below the top antenna unit, are in a coaxial distribution state and are arranged at intervals, the top antenna unit comprises a top assembly and first floors which are located below the top assembly and are arranged at intervals, and a balun structure is arranged between each first floor and the top assembly. The four-arm helical antenna unit comprises a top ring body, a bottom assembly and a cylindrical support body which is located between the top ring body and the bottom assembly and is made of a PEEK material, a helical antenna is fixed in a helical groove of the cylindrical support body, the top end of the helical antenna is connected with the top ring body, and the bottom end of the helical antenna is connected with the bottom assembly; the bottom assembly comprises two power dividers and a metal floor located between the two power dividers. The antenna is high in overall supporting capacity, and does not deform in long-term vibration and impact environments. Meanwhile, the system has the receiving and transmitting functions of Beidou, Tiantong and star network signals.

Description

Technical Field

[0001] The present invention relates to the field of antenna manufacturing, in particular to a multi-band four-arm helical composite antenna. Background Art

[0002] A multi-band quadrifilar helical antenna typically consists of multiple quadrifilar helical antenna elements, each operating in a different frequency band. Each quadrifilar helical antenna element is supported and connected by a hollow tube located at the center of the structure. Due to the limited load-bearing capacity of the supporting hollow tube, each quadrifilar helical antenna element is fabricated by attaching the helical antenna arms to a flexible support tube.

[0003] The above-mentioned structure of the prior art has the following shortcomings: the hollow tube has limited support capacity. If this composite antenna is used on a moving object, the object will be subjected to long-term vibration and impact. These forces can easily cause the hollow tube of the antenna to deform, resulting in deformation or damage to the entire antenna. At the same time, due to the limited support force of the hollow tube, the material used to attach the helical antenna arms must be a lightweight and flexible material. This material has limited support capacity and is easily deformed in a vibrating and impact environment, which in turn causes the shape of each helical antenna arm to deform, resulting in the antenna not being able to operate normally. Moreover, the positional accuracy of each helical antenna arm of this four-arm helical antenna unit must be high. The existing support tube made of lightweight and flexible materials is relatively soft and cannot be equipped with any positioning structure. Therefore, winding the helical antenna arms on it is time-consuming and labor-intensive, and the processing accuracy is difficult to ensure. Summary of the Invention

[0004] Based on this, a multi-band four-arm helical composite antenna is provided. The composite antenna has a strong overall support capability and can maintain the antenna without deformation in long-term vibration and impact environments.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A multi-band four-arm helical composite antenna, comprising:

[0007] A top antenna unit and at least two quadrifilar helical antenna units spaced apart and coaxially distributed below the top antenna unit.

[0008] The top antenna unit includes a top component and a first floor spaced below the top component, with a balun structure disposed between the first floor and the top component.

[0009] The four-arm helical antenna unit includes a top ring body, a bottom component, and a cylindrical support body located between the top ring body and the bottom component. The side wall of the cylindrical support body is provided with a spiral groove, and the spiral antenna is fixed in the spiral groove. The top end of the spiral antenna is connected to the top ring body, and the bottom end of the spiral antenna is connected to the bottom component. The bottom component includes two power dividers and a metal floor located between the two power dividers.

[0010] A plurality of connecting posts are provided between the first floor and the top ring of a quadrifilar helical antenna unit adjacent thereto, and a plurality of connecting posts are provided between the bottom assembly of the quadrifilar helical antenna unit and the top ring of the adjacent quadrifilar helical antenna unit adjacent thereto.

[0011] The coaxial line passes through the interior of each quadrifilar helical antenna unit and passes through the first floor. The coaxial line is connected to the power divider of the corresponding quadrifilar helical antenna unit and is also connected to the top antenna unit.

[0012] In one embodiment,

[0013] The top component of the top antenna unit includes two groups of dipole antennas with unequal arm lengths and orthogonal structures, and the dipole antennas are provided with a downwardly bent structure.

[0014] In one embodiment,

[0015] The number of quadrifilar helical antenna units is 3, namely: the upper quadrifilar helical antenna unit, the middle quadrifilar helical antenna unit and the lower quadrifilar helical antenna unit.

[0016] The operating frequency band of the upper four-arm helical antenna unit is: 1980-2200MHz, the operating frequency band of the middle four-arm helical antenna unit is: 1518-1675MHz, the operating frequency band of the lower four-arm helical antenna unit is: 1207-1268MHz, and the operating frequency band of the top antenna unit is: 2491.75±5MHz.

[0017] In one embodiment,

[0018] It also includes a supporting structure and an inner cover connected to the supporting structure. The top antenna unit and each quadrifilar helical antenna unit are located in the inner cover.

[0019] In one embodiment,

[0020] The bottom component of the lowest quadrifilar helical antenna unit is connected to the supporting structure below.

[0021] The coupler is located below the supporting structure, and the coaxial line is connected to the coupler.

[0022] In one embodiment,

[0023] A coupler is fixed between the bottom component of the lowest four-arm helical antenna unit and the supporting structure below, and a coaxial line is connected to the coupler, and the coupler is located in the internal cover.

[0024] In one embodiment, 0-270° phase increment feeding of the quadrifilar helical antenna unit is achieved through various power dividers and couplers.

[0025] In one embodiment, the distance between two adjacent quadrifilar helical antenna units is greater than 10 mm.

[0026] In one embodiment, the support structure is disposed on a base, the base is connected to the outer casing, and the inner casing and the support structure are both located inside the outer casing.

[0027] In one embodiment, the cylindrical support body is made of PEEK material.

[0028] The beneficial effects of this application are:

[0029] 1. In the prior art, each four-arm helical antenna unit is supported by a central tube, resulting in low overall structural strength and prone to deformation in vibration or impact environments. This application pre-machines a spiral groove on the side wall of the cylindrical support body, within which the helical antenna is located. The spiral groove positions and supports the helical antenna, making it less susceptible to deformation. Furthermore, due to the provision of the spiral groove, installation of the helical antenna requires only securing it within the groove, which is quick, convenient, and highly precise.

[0030] On the basis of the above, the present application has also optimized the structure and does not adopt the central tube support structure of the prior art. In the present application, a plurality of connecting columns are provided between the first floor and the top ring body of a four-arm helical antenna unit adjacent below, and a plurality of connecting columns are provided between the bottom assembly of the four-arm helical antenna unit and the top ring body of the adjacent four-arm helical antenna unit below. The two ends of the connecting columns are respectively connected to the corresponding structures by screws, so that the connection and support between each unit are very reliable, and easy to assemble and disassemble. Sometimes, antenna units with different working frequency bands need to be used in different occasions. When antennas with different working frequency bands need to be combined together, it is only necessary to connect the units in series through the connecting columns. When a unit needs to be replaced, it can be replaced by disassembling the unit as a whole and then replacing it with a new unit. Moreover, the present application achieves circular polarization through a simple structure.

[0031] 2. The top antenna unit of this application includes two sets of orthogonal dipole antennas with unequal arm lengths. The dipole antennas are configured with a downwardly bent structure, which facilitates antenna miniaturization. The unequal length dipole antennas achieve circular polarization by varying the current flow through their length design. The metal post below the top component of the top antenna unit not only serves as a balun structure but also provides support.

[0032] 3. The operating frequency band of the upper quadrifilar helical antenna unit of this application is: 1980-2200MHz, the operating frequency band of the middle quadrifilar helical antenna unit is: 1518-1675MHz, the operating frequency band of the lower quadrifilar helical antenna unit is: 1207-1268MHz, and the operating frequency band of the top antenna unit is: 2491.75±5MHz. This facilitates the antenna to simultaneously transmit and receive Beidou, Tiantong, and StarNet signals.

[0033] 4. Research has shown that the distance between quadrifilar helical antenna elements can affect the radiation pattern to a certain extent. The closer the distance, the greater the obstruction of the lower quadrifilar helical antenna element by the upper quadrifilar helical antenna element. Furthermore, too close a distance makes welding the feed coaxial line difficult. Therefore, the spacing between quadrifilar helical antenna elements is controlled to at least 10mm. This helps prevent mutual interference between the elements and facilitates welding the feed coaxial line.

[0034] 5. The present application adopts a cylindrical support made of PEEK material, which has both rigidity and toughness, excellent wear resistance and fatigue resistance, and is not easily deformed in vibration and impact environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of a multi-band quadrifilar helical composite antenna with an inner cover and an outer cover according to an embodiment of the present application.

[0036] Figure 2 This is a schematic diagram of multiple quadrifilar helical antenna units connected in sequence according to an embodiment of the present application.

[0037] Figure 3 This is a schematic diagram of the coaxial line connected to each quadrifilar helical antenna unit and the top antenna unit in an embodiment of the present application.

[0038] Figure 4 This is a circuit diagram of the arrangement of two power dividers in an embodiment of the present application.

[0039] Figure 5 This is a schematic structural diagram of the top antenna unit of an embodiment of the present application.

[0040] Figure 6 This is a circuit diagram of a power divider according to an embodiment of the present application.

[0041] Figure 7 This is a structural diagram of a Lange coupler according to an embodiment of the present application.

[0042] Figure 8 VSWR simulation curve of the top antenna unit according to an embodiment of the present application.

[0043] Figure 9 This is a simulation curve of the far-field pattern of the top antenna unit of an embodiment of the present application, where f=2492 MHz.

[0044] Figure 10 This is a simulation curve of the axial ratio of the top antenna unit of an embodiment of the present application, where f=2492 MHz.

[0045] Figure 11 VSWR simulation curve of the upper quadrifilar helical antenna unit according to an embodiment of the present application.

[0046] Figure 12 1 is a simulation curve of the far-field pattern of the upper quadrifilar helical antenna unit of the embodiment of the present application, where f=2100 MHz.

[0047] Figure 13 1 is a simulation curve of the axial ratio of the upper quadrifilar helical antenna unit according to an embodiment of the present application, wherein f=2100 MHz.

[0048] Figure 14 This is a VSWR simulation curve of the middle quadrifilar helical antenna unit of an embodiment of the present application.

[0049] Figure 15 This is a simulation curve of the far-field pattern of the middle quadrifilar helical antenna unit of an embodiment of the present application, where f=1600 MHz.

[0050] Figure 16 This is a simulation curve of the axial ratio of the middle quadrifilar helical antenna unit of an embodiment of the present application, where f=1600 MHz.

[0051] Figure 17 This is a VSWR simulation curve of the lower quadrifilar helical antenna unit of an embodiment of the present application.

[0052] Figure 18 This is a simulation curve of the far-field pattern of the lower quadrifilar helical antenna unit of an embodiment of the present application, where f=1240 MHz.

[0053] Figure 19 1 is a simulation curve of the axial ratio of the lower quadrifilar helical antenna unit of the embodiment of the present application, where f=1240 MHz.

[0054] in:

[0055] 101. Top antenna unit; 102. Upper quadrifilar helical antenna unit; 103. Middle quadrifilar helical antenna unit; 104. Lower quadrifilar helical antenna unit; 105. Support structure; 106. Base; 107. Coaxial line; 108. Inner cover; 109. Outer cover; 110. Top ring; 111. Cylindrical support; 112. Bottom assembly; 113. Connecting post.

[0056] 1011. Top assembly; 1012. Balun structure; 1013. First floor;

[0057] 10111. Board; 10112. Dipole antenna. DETAILED DESCRIPTION

[0058] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0059] like Figures 1 to 3 As shown, an embodiment of the present application provides a multi-band quadrifilar helical composite antenna, comprising: a top antenna unit 101 and at least two quadrifilar helical antenna units spaced apart and coaxially distributed below the top antenna unit 101. For example, the number of quadrifilar helical antenna units can be two, three, etc.

[0060] The top antenna unit 101 includes a top component 1011 and a first floor 1013 spaced apart below the top component 1011. A balun structure 1012 is provided between the first floor 1013 and the top component 1011. The four-arm helical antenna unit includes a top ring body 110, a bottom component 112, and a cylindrical support body 111 made of PEEK material located between the top ring body 110 and the bottom component 112. Corresponding connecting structures can be provided at both ends of the cylindrical support body 111 and connected to the bottom component 112 and the top ring body 110 by screws, or it can be fixed between the bottom component 112 and the top ring body 110 by other means. The sidewall of the cylindrical support body 111 is provided with a spiral groove, within which a helical antenna is secured. The top end of the helical antenna is connected to the top metal ring, and the bottom end of the helical antenna is connected to the bottom assembly 112. The bottom assembly 112 includes two power dividers and a metal floor between the two power dividers. Multiple connecting posts 113 are provided between the first floor 1013 and the top ring 110 of the adjacent quadrifilar helical antenna unit below. For example, four, six, or another number of connecting posts 113 may be provided along the circumference. The length of the connecting posts 113 can also be used to control the distance between adjacent quadrifilar helical antenna units. Multiple connecting posts 113 are provided between the bottom assembly 112 of a quadrifilar helical antenna unit and the top ring 110 of the adjacent quadrifilar helical antenna unit below. A coaxial line 107 passes through the interior of each quadrifilar helical antenna unit and through the first floor 1013. The coaxial line 107 is connected to the power divider of the corresponding quadrifilar helical antenna unit and is also connected to the top antenna unit 101.

[0061] Specifically, such as Figure 4 As shown, the circuit portion of the bottom component 112 of the four-arm helical antenna unit is formed by laminating and rotating two identical power dividers, and the laminating surfaces of the two power dividers are printed with metal as a metal floor. Each power divider is composed of a microstrip line printed on a dielectric plate with a dielectric constant of 6.15. The microstrip line is formed into an equal power divider with a phase of 0° / 180° by calculating its width and length. The input ports of the two power dividers are connected to the Lange coupler to change their phase to 0° / 90°. Finally, the phase of the port connected to the four helices can be made into 0° / 90° / 180° / 270°, thereby achieving circular polarization.

[0062] like Figure 4 and Figure 5 As shown, the four spiral arms of each quadrifilar helical antenna unit are respectively connected to the four output terminals of the power divider, namely the output terminals numbered ③-⑥, and the input terminals of the power divider are terminals ① and ②.

[0063] like Figure 6 and Figure 7As shown, the power divider of the present application is used to divide the signal into two equal paths, and the phase difference between the two paths is 180°. Figure 6 Port 1 is the input port. The microstrip line width gives it a characteristic impedance of 50 ohms. Connecting it to two microstrip lines with a characteristic impedance of 70.7 ohms creates a 1-to-2 splitting effect, with equal energy and phase alignment at points A and B. A further 50 ohm microstrip line is connected to create a 180° phase shift. The 50 ohm transmission line in the first section 201 is of the same length, while the 50 ohm transmission line in the second section 202 creates a 180° phase shift, resulting in equal power splitting at output ports 2 and 3 with a 180° phase shift. The dielectric constant and thickness of the board determine the length and width of the transmission lines. The front of the board features printed metal transmission lines, while the back is entirely metal ground plane, with space in the center for the lines used by the other power dividers. The same shape is rotated 90° and mirrored along the -z axis, so that the two power dividers share the central metal ground plane. Output ports 2, 3, 4, and 5 (ports 4 and 5 are not shown; they are actually located where ports 2 and 3 are rotated 90°) connect to the four arms of the four-arm spiral. The two input ports are connected through a Lange coupler, so that the phase difference between the two input ports is 90 degrees. In this way, by superimposing the phase differences, the phase differences of ports 2, 3, 4, and 5 can be made 0, 90, 180, and 270 degrees. The coupler uses a Lange coupler. The through end and the coupling end of the Lange coupler are connected to the two input ends of the power divider mentioned above. The input end of the Lange coupler is connected to the input feeder. Figure 7 The phase difference between ② and ③ is 90°, and the power is equal.

[0064] Furthermore, when there are three quadrifilar helical antenna units, namely, upper quadrifilar helical antenna unit 102, middle quadrifilar helical antenna unit 103, and lower quadrifilar helical antenna unit 104, the coaxial lines 107 are arranged as follows: seven coaxial lines 107 are provided, with five coaxial lines 107 passing through the middle of the lower quadrifilar helical antenna unit 104 to feed the upper antennas. Two coaxial lines 107 are connected to the two inputs of the power divider of the lower quadrifilar helical antenna unit 104, and each coaxial line 107 is connected to a Lange coupler at the bottom suitable for the corresponding frequency band. Three coaxial lines 107 pass through the middle of the middle quadrifilar helical antenna unit 103 to feed the upper quadrifilar helical antenna unit 102 and the top antenna unit 101. The power divider of the middle quadrifilar helical antenna unit 103 is also fed by two coaxial lines 107. One coaxial line 107 passes through the middle of the upper quadrifilar helical antenna unit 102 to feed the top antenna. The power divider of the upper quadrifilar helical antenna unit 102 is fed by two coaxial cables 107 .

[0065] In one embodiment, Figure 5As shown, the top component 1011 of the top antenna unit 101 includes a plate body 10111, on which are disposed two groups of dipole antennas 10112 with unequal arm lengths and orthogonal structures, and the dipole antennas 10112 are provided with a structure that bends downward. Figure 5 In the figure, next to the coaxial line 107 is a balun structure 1012, which is one-quarter wavelength long. The first floor 1013 is printed on FR4 material with a dielectric constant of 4.4. At the top are two sets of dipole antennas 10112, each about one-quarter wavelength long. The varying lengths create circular polarization. To achieve miniaturization, the dipole antennas 10112 are bent downward. The metal post below the top antenna unit 101 not only acts as a balun, but also serves as a feeder and support. The top antenna unit 101 can operate in the BeiDou 2491.75±5MHz frequency band.

[0066] In one embodiment, the number of quadrifilar helical antenna units is three, namely: an upper quadrifilar helical antenna unit 102, a middle quadrifilar helical antenna unit 103 and a lower quadrifilar helical antenna unit 104. The operating frequency band of the upper quadrifilar helical antenna unit 102 is 1980-2200 MHz, the operating frequency band of the middle quadrifilar helical antenna unit 103 is 1518-1675 MHz, the operating frequency band of the lower quadrifilar helical antenna unit 104 is 1207-1268 MHz, and the operating frequency band of the top antenna unit 101 is 2491.75±5 MHz.

[0067] Specifically, in the design of the helical antenna, the rotation direction of the helical antenna arm (clockwise or counterclockwise) and the feeding phase jointly determine the rotation direction of the circular polarization of the antenna. Among them, the lower four-arm helical antenna unit 104 is right-handed circularly polarized, and the spiral antenna arms of the middle four-arm helical antenna unit 103 and the upper four-arm helical antenna unit 102 are left-handed circularly polarized. In order to realize the formation of circularly polarized waves by the feeding phase, a combination of a power divider and a Lango coupler is adopted in the design. Two 0° / 180° one-to-two power dividers are designed in the bottom component 112 of each four-arm helical antenna unit, and then lead to the Lango coupler at the bottom connected to the corresponding frequency band through the coaxial line 107, thereby realizing 0-270° phase incremental feeding of the four-arm helical antenna. Parameters such as the size, radius and number of rotations of the spiral antenna arm of the four-arm helical antenna unit jointly determine its operating frequency band. The upper quadrilateral helical antenna unit 102 operates in the Tiantong operating frequency band: 1980-2200MHz, the middle quadrilateral helical antenna unit 103 operates in the Xingwang frequency band and covers part of the Beidou operating frequency band: 1518-1675MHz, and the lower quadrilateral helical antenna unit 104 operates in part of the Beidou operating frequency band: 1207-1268MHz.

[0068] From the above description, it can be seen that the above-mentioned multi-band four-arm spiral composite antenna of the present application can form a Beidou, Tiantong, and Starnet narrowband multi-frequency composite antenna. It is a multi-functional integrated antenna that has the functions of transmitting and receiving Beidou, Tiantong, and Starnet signals. Its operating frequency includes the Beidou antenna (B2b, B3, Lf1~Lf4, S) frequency band: 1207.14MHz±10.23MHz (right-hand circular polarization), 1268.52MHz±10.23MHz (right-hand circular polarization), 2491.75MHz±8.16MHz (right-hand circular polarization), 1614.26MHz±4. 08MHz (left-hand circular polarization), 1615.68MHz±4.08MHz (left-hand circular polarization), 1622.42MHz±4.08MHz (left-hand circular polarization), 1624.524MHz±1.6376MHz (left-hand circular polarization); Tiantong antenna frequency band: 1980MHz~2010MHz (left-hand circular polarization), 2170MHz~2200MHz (left-hand circular polarization); Starnet antenna frequency band: 1518MHz~1525MHz (left-hand circular polarization), 1668MHz~1675MHz (left-hand circular polarization) multiple frequency bands.

[0069] In one embodiment, the antenna further comprises a support structure 105 and an internal housing 108 connected to the support structure 105. The top antenna unit 101 and each quadrifilar helical antenna unit are located within the internal housing 108. This structure is conducive to resisting the impact of external media and protecting the internal antenna structure from damage.

[0070] In one embodiment, the bottom component 112 of the lowest quadrifilar helical antenna unit is connected to the lower support structure 105, the coupler is located below the support structure 105, and the coaxial line 107 is connected to the coupler.

[0071] In one embodiment, a coupler is fixed between the bottom component 112 of the lowest quadrifilar helical antenna unit and the supporting structure 105 below, and the coaxial line 107 is connected to the coupler, and the coupler is located in the internal cover 108.

[0072] In one embodiment, 0-270° phase increment feeding of the quadrifilar helical antenna unit is achieved through various power dividers and couplers.

[0073] In one embodiment, the distance between two adjacent quadrifilar helical antenna units is greater than 10 mm. For example, the distance between the upper quadrifilar helical antenna unit 102 and the middle quadrifilar helical antenna unit 103 is 10 mm, and the distance between the middle quadrifilar helical antenna unit 103 and the lower quadrifilar helical antenna unit 104 is 10 mm.

[0074] In one embodiment, the support structure 105 is disposed on a base 106, the base 106 is connected to an outer housing 109, and the inner housing 108 and the support structure 105 are both located inside the outer housing 109. This structure is convenient for installation and use.

[0075] This application also conducted simulation experiments, and the results are as follows.

[0076] 1. Top antenna unit 101, operating frequency: 2491.75±5MHz.

[0077] The top antenna element 101 is directly fed by the coaxial line 107 . Figure 8 The simulated VSWR curve of the top antenna unit 101 is given. It can be seen that the VSWR of the top antenna unit 101 is always less than 2 within the frequency range of 2491.75±5MHz in the Beidou frequency band.

[0078] Figure 9 A simulation curve of the far-field radiation pattern of the top antenna unit 101 at a center frequency of 2492 MHz is given. It can be seen that the top antenna unit 101 basically meets the design index requirement of a gain of not less than -2 dB at an elevation angle of 20°-90°.

[0079] Figure 10 The axial ratio simulation curve of the top antenna unit 101 at the center frequency is given. It can be seen that the axial ratio of the top antenna unit 101 is less than 3 dB at 0°, indicating that the circular polarization of the antenna is well achieved.

[0080] 2. The upper quadrifilar helical antenna unit 102 has an operating frequency of 1980-2200 MHz.

[0081] Figure 11 The voltage standing wave ratio (VSWR) curve of the upper quadrifilar helical antenna unit 102 is given. It can be seen that in the Tiantong uplink and downlink (1980-2010MHz, 2170-2200MHz) frequency bands, the standing wave ratio of the upper quadrifilar helical antenna unit 102 is less than 2.

[0082] Figure 12 The simulation curve of the directional pattern of the upper quadrifilar helical antenna unit 102 is given when the center frequency is 2100MHz. Figure 10 It can be seen that it basically meets the design index requirement of a gain of not less than -2dB at an elevation angle of 20°-90°.

[0083] Figure 13 The axial ratio simulation curve of the upper quadrifilar helical antenna unit 102 at the center frequency of 2100MHz is given. Figure 11 It can be seen that the axial ratio of the antenna is less than 3dB at 0°, indicating that the circular polarization of the antenna is well achieved.

[0084] 3. The middle quadrifilar helical antenna unit 103 has an operating frequency of 1518 MHz to 1675 MHz.

[0085] Figure 14 The voltage standing wave ratio simulation curve of the central four-arm helical antenna unit 103 is given, which meets the design requirement of a standing wave ratio of no more than 2 in the 1518MHz-1675MHz frequency band covering part of the Beidou frequency points in the star network frequency band.

[0086] Figure 15 The simulation curve of the directivity pattern of the middle quadrifilar helical antenna unit 103 is given when the center frequency is 1600 MHz, which basically meets the design index requirement of a gain of not less than -2 dB at an elevation angle of 20°-90°.

[0087] Figure 16 The axial ratio simulation curve of the middle quadrifilar helical antenna unit 103 at the center frequency of 1600 MHz is given. It can be seen that at 0°, the axial ratio of the antenna is less than 3 dB, indicating that the circular polarization of the antenna is well achieved.

[0088] 4. The lower quadrifilar helical antenna unit 104 operates in the frequency band of 1207-1268 MHz.

[0089] Figure 17 The voltage standing wave ratio simulation curve of the quadrifilar helical antenna unit 104 is given, which meets the design requirement of a standing wave ratio of no more than 2 in the Beidou B2b and B3 frequency bands, i.e., 1207.14MHz±10.23MHz and 1268.52MHz±10.23MHz.

[0090] Figure 18 A simulation curve of the directivity pattern of the lower quadrifilar helical antenna unit 104 is given when the center frequency is 1240 MHz, which basically meets the design index requirement of a gain of not less than -2 dB at an elevation angle of 20°-90°.

[0091] Figure 19 The axial ratio simulation curve of the quadrifilar helical antenna at the center frequency of 1240MHz is given below. It can be seen that at 0°, the axial ratio of the antenna is less than 3dB, indicating that the circular polarization of the antenna is well achieved.

[0092] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A multi-band four-arm helical composite antenna, characterized in that: include: A top antenna unit and at least two quadrifilar helical antenna units spaced apart and coaxially distributed below the top antenna unit. The top antenna unit includes a top component and a first floor spaced below the top component. A balun structure is provided between the first floor and the top component. The four-arm helical antenna unit includes a top ring body, a bottom component, and a cylindrical support body located between the top ring body and the bottom component. The side wall of the cylindrical support body is provided with a spiral groove, and the spiral antenna is fixed in the spiral groove. The top end of the spiral antenna is connected to the top ring body, and the bottom end of the spiral antenna is connected to the bottom component. The bottom component includes two power dividers and a metal floor located between the two power dividers. A plurality of connecting posts are provided between the first floor and the top ring of a quadrifilar helical antenna unit adjacent thereto, and a plurality of connecting posts are provided between the bottom assembly of the quadrifilar helical antenna unit and the top ring of the adjacent quadrifilar helical antenna unit adjacent thereto. The coaxial line passes through the interior of each quadrifilar helical antenna unit and passes through the first floor. The coaxial line is connected to the power divider of the corresponding quadrifilar helical antenna unit and is also connected to the top antenna unit.

2. The multi-band quadrifilar helical composite antenna according to claim 1, wherein: The top component of the top antenna unit includes two sets of dipole antennas with unequal arm lengths and orthogonal structures, and the dipole antennas are provided with a downwardly bent structure.

3. The multi-band quadrifilar helical composite antenna according to claim 1, wherein: The number of quadrifilar helical antenna units is 3, namely: the upper quadrifilar helical antenna unit, the middle quadrifilar helical antenna unit and the lower quadrifilar helical antenna unit. The operating frequency band of the upper four-arm helical antenna unit is: 1980-2200MHz, the operating frequency band of the middle four-arm helical antenna unit is: 1518-1675MHz, the operating frequency band of the lower four-arm helical antenna unit is: 1207-1268MHz, and the operating frequency band of the top antenna unit is: 2491.75±5MHz.

4. The multi-band quadrifilar helical composite antenna according to claim 1, wherein: It also includes a supporting structure and an inner cover connected to the supporting structure. The top antenna unit and each quadrifilar helical antenna unit are located in the inner cover.

5. The multi-band quadrifilar helical composite antenna according to claim 4, characterized in that: The bottom component of the lowest quadrifilar helical antenna unit is connected to the supporting structure below. The coupler is located below the supporting structure, and the coaxial line is connected to the coupler.

6. The multi-band quadrifilar helical composite antenna according to claim 4, characterized in that: A coupler is fixed between the bottom component of the lowest four-arm helical antenna unit and the supporting structure below, and a coaxial line is connected to the coupler, and the coupler is located in the internal cover.

7. The multi-band quadrifilar helical composite antenna according to claim 5 or 6, characterized in that: The 0-270° phase increment feeding of the quadrifilar helical antenna unit is achieved through various power dividers and couplers.

8. The multi-band quadrifilar helical composite antenna according to claim 4, characterized in that: The supporting structure is arranged on a base, the base is connected to an external cover, and the internal cover and the supporting structure are both located inside the external cover.

9. The multi-band quadrifilar helical composite antenna according to claim 1, wherein: The cylindrical support body is made of PEEK material.

10. The multi-band quadrifilar helical composite antenna according to claim 1, wherein: The distance between two adjacent quadrifilar helical antenna units is greater than 10 mm.

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