Double-arm spiral double-frequency circularly polarized navigation antenna

Abstract

The utility model belongs to the technical field of satellite navigation antennas, and particularly discloses a double-arm spiral double-frequency circularly polarized navigation antenna, which comprises a cylindrical dielectric substrate and an antenna feed network, four radiation grooves with the same structure are etched on the upper surface of the cylindrical dielectric substrate, a spirally rising radiator spiral arm is arranged in each radiation groove, and the antenna feed network is connected with the antenna feed network. The bottom of the dielectric substrate adopts a power division-phase shifter for feeding, the reflection ground of the dielectric substrate is manufactured by adopting a copper coating process, the bottom end of the radiator spiral arm is connected with a microstrip line with the impedance of 50 ohms, and the microstrip line extends to the outer side of the common ground and the common plane. According to the double-arm spiral double-frequency circularly polarized navigation antenna, the size of the spiral antenna and a coaxial feed mode are optimized, so that the navigation antenna has excellent circularly polarized characteristics and impedance matching characteristics, and the navigation antenna has important significance for obtaining a solution from a new angle for the research of a satellite navigation antenna.

Description

TECHNICAL FIELD

[0001] The utility model relates to satellite navigation antenna technical field especially is related to a double -arm spiral dual -frequency circular polarization navigation antenna. BACKGROUND

[0002] As one of important components in satellite navigation communication system, the antenna is mainly used for receiving radio electromagnetic signal in space, and completes navigation positioning function with the back end receiver, and directly determines the performance and communication quality of satellite communication system to a certain extent. With the development of information technology, the requirement of communication quality and speed is higher and higher, satellite navigation communication can realize long distance communication, wide coverage, is not limited by terrain condition, high reliability, and is widely applied in different fields such as military and civil. At the same time, with the miniaturization of navigation antenna application terminal such as mobile phone, automobile, aircraft and other carrier platform, the satellite of various navigation communication systems is limited in space, therefore, in the low information rate, small capacity satellite navigation communication system, the structure of antenna also determines the shape of carrier and the proportion of occupied space, so the navigation antenna needs to develop towards miniaturization, wide frequency band and light weight.

[0003] According to various portable, multifunctional requirements of satellite navigation communication system, domestic and foreign scholars continuously research the miniaturization, dual frequency / multi-band, anti-interference, circular polarization and other technologies of antenna, and have obtained a lot of research results, and the common microstrip patch antenna, cross dipole antenna, spiral antenna and the like are used in actual engineering application.

[0004] The spiral antenna has many wide frequency band characteristics, whether it is directional characteristic, impedance characteristic or polarization characteristic is wide band, and has the advantages of small volume, light weight, wide frequency band, good circular polarization characteristic and the like, and is widely used in the field of satellite navigation. Compared with microstrip antenna and monopole antenna, the spiral antenna is more easy to meet the omnidirectional, circular polarization, small size, high gain design requirements of navigation system.

[0005] At present, common structural forms include single-arm spiral, double-arm spiral and four-arm spiral. The single-arm spiral antenna has lower gain compared with the double-arm spiral antenna, the double-arm spiral antenna has two spiral arms, does not depend on the single pole feeding form through the ground, and has wider bandwidth and more abundant directional pattern characteristics than the single-arm spiral antenna through differential feeding. The four-arm spiral antenna can realize good electrical performance, but the feeding circuit is complex, and a sequential feeding power dividing circuit needs to be specially designed. This increases the loss of the antenna and reduces the gain of the antenna. The double-arm spiral antenna is between the two, and also has the advantages of high gain, wide beam, simple feeding and small size, so the double-arm spiral antenna becomes a suitable choice in the satellite navigation system.

[0006] The technical research of the dual-arm helical antenna in miniaturization wide-beam circular polarization can be widely applied to satellite navigation antennas, but the research on the multi-frequency realization of the dual-arm helical antenna is relatively less at present, and the wide-frequency and multi-frequency design methods of the four-arm helical antenna are more, and the most common one is to load a parasitic arm to the helical arm, or to realize multi-frequency operation by coupling feeding or directly connecting feeding.

[0007] Therefore, it is urgent to design a circularly polarized helical antenna for satellite navigation. Content of the utility model

[0008] The utility model discloses a dual-arm helical dual-frequency circularly polarized navigation antenna, which is a dual-frequency helical antenna working in the Beidou wave band.

[0009] To achieve the above object, the utility model provides a dual-arm helical dual-frequency circularly polarized navigation antenna, which comprises a cylindrical dielectric substrate and an antenna feed network.

[0010] Preferably, the feed phases of the radiation body helical arms are 180 degrees apart, the radiation body helical arms comprise main helical arms and coupled helical arms, the main helical arms are connected with the coupled helical arms through coupling units, and the coupling units are connected with the microstrip lines.

[0011] Preferably, the bottom of the dielectric substrate is provided with a PCB printed board, the PCB printed board comprises an upper layer PCB circuit board and a lower layer PCB circuit board.

[0012] The antenna feed network comprises two layers of single-layer feed networks, and the two layers of single-layer feed networks are arranged on the upper layer PCB circuit board and the lower layer PCB circuit board respectively.

[0013] Preferably, the dielectric substrate is made of Rogers RT / duroid 5880 high-frequency circuit board material, the relative dielectric constant thereof is 2.2, the relative permeability coefficient thereof is 1, the loss tangent angle thereof is 0.0009, the thickness thereof is 0.2 mm, the radius thereof is 20 mm, and the height thereof is 32 mm.

[0014] Preferably, the PCB printed board is made of Rogers TMM 4 material, and the single-layer feed network structure comprises a power-division phase shifter arranged on the surface of the PCB printed board, and the output port of the power-division phase shifter is a lumped port, and the feed mode is a coaxial feed with a phase difference of 180 degrees.

[0015] Preferably, the pitch of the main spiral arm is 64 mm, and the number of spiral turns is 0.7 turns, the pitch of the coupling spiral arm is 64 mm, and the number of spiral turns is 0.7 turns.

[0016] Preferably, the width of the main spiral arm is 4.79 mm, and the height from the top end to the upper PCB circuit board is 31.5 mm; the width of the coupling spiral arm is 4.89 mm, and the height from the top end to the upper PCB circuit board is 20.05 mm.

[0017] Preferably, the width of the main spiral arm and the coupling spiral arm and the length of the coupling unit are all 10 mm.

[0018] Therefore, the double-arm spiral double-frequency circularly polarized navigation antenna has the beneficial effects as follows:

[0019] (1) The double-arm spiral double-frequency circularly polarized antenna applied to a satellite navigation communication system is designed, electromagnetic simulation software is used to improve the structure of the double-arm spiral antenna, the size of the spiral antenna and the coaxial feed mode are optimized, and the antenna size and the feed network have excellent circular polarization characteristics and impedance matching characteristics.

[0020] (2) Due to the mutual coupling between the radiation arms, the length of the radiation arm in the actual double-arm model is greatly different from the theoretical value, in order to ensure good satellite searching capability, the navigation receiving antenna should ensure that the upper hemisphere of the directional diagram is covered. The design of the utility model solves the above problems, and realizes the requirements of gain≥2dBi and axial ratio≤2 in the working frequency bands of 1.575GHz (1.55-1.65) and 1.227GHz (1.207-1.227).

[0021] (3) The antenna beam width is a parameter that can directly affect the coverage range of the received signal, and the design of the circular polarization of the utility model widens the antenna beam width, and the wider the antenna beam is, the more satellite signals the terminal receives.

[0022] The technical scheme of the utility model will be further described in detail below with reference to the drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the overall structure schematic diagram of the double-arm spiral double-frequency circularly polarized navigation antenna embodiment of the utility model.

[0024] Figure 2 is a single-layer feed network structure schematic diagram of a dual-arm helix dual-frequency circularly polarized navigation antenna embodiment of the present application;

[0025] Figure 3 is a structure schematic diagram of a radiating body helix arm of a dual-arm helix dual-frequency circularly polarized navigation antenna embodiment of the present application;

[0026] Figure 4 is a 1207-1227 frequency band axial ratio and right-handed circular gain curve of a dual-arm helix dual-frequency circularly polarized navigation antenna embodiment of the present application;

[0027] Figure 5 is a 1550-1650 frequency band axial ratio and right-handed circular gain curve of a dual-arm helix dual-frequency circularly polarized navigation antenna embodiment of the present application;

[0028] Figure 6 is a voltage standing wave ratio under a center frequency of 1.57542 GHz of a dual-arm helix dual-frequency circularly polarized navigation antenna embodiment of the present application;

[0029] Figure 7 is a voltage standing wave ratio under a center frequency of 1.228 GHz of a dual-arm helix dual-frequency circularly polarized navigation antenna embodiment of the present application.

[0030] Reference signs

[0031] 1, main helix arm; 2, coupled helix arm; 3, first feed point; 4, coupling unit; 5, lumped port; 6, microstrip line; 7, upper layer PCB circuit board; 8, second feed point; 9, dielectric substrate; 10, lower layer PCB circuit board; 11, power division-phase shifter. DETAILED DESCRIPTION

[0032] The technical scheme of the present application is further described below through the drawings and embodiments.

[0033] Unless otherwise defined, technical terms or scientific terms used in the present application shall have the ordinary meaning as understood by a person of ordinary skill in the art to which the present application pertains. The terms "first", "second", and similar terms used in the present application do not represent any order, number, or importance, but are only used to distinguish different components. The terms "include" or "contain" and similar terms mean that the elements or objects listed before the terms encompass the elements or objects listed after the terms and their equivalents, without excluding other elements or objects. The terms "connect" or "connected" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right", and the like are only used to represent relative positional relationships, which can change accordingly when the absolute positions of the described objects change.

[0034] The dual-arm helical dual-frequency circularly polarized navigation antenna has unique performance advantages, including wideband performance, high efficiency performance, and stable performance, and can be widely applied in satellite navigation antennas, as follows:

[0035] 1. Traffic field: In the field of aerospace, dual-arm helical antennas are also widely used in communication and navigation systems. Due to the high requirements of aerospace equipment on the weight, size, and performance of antennas, dual-arm helical antennas have become an ideal antenna type in the aerospace field due to their compact structure, high efficiency, and stable circular polarization characteristics. Modern vehicle navigation systems need to be able to receive satellite signals of multiple frequency bands to ensure the accuracy and reliability of navigation. Dual-arm helical antennas have wideband and circular polarization characteristics, and can receive satellite signals of different frequency bands and polarization directions, so they are very suitable for use in vehicle navigation systems. GNSS systems are used to collect urban traffic conditions, and by establishing digital traffic stations, real-time traffic information is updated to mobile vehicle intelligent terminals. Autonomous navigation of vehicles will be realized in the near future based on GNSS system positioning information, through electronic maps and real-time traffic conditions, and optimal navigation paths will be obtained by intelligent algorithms.

[0036] 2. Agricultural applications: Dual-arm helical navigation antennas have high-precision positioning capabilities, which can provide centimeter-level positioning accuracy for agricultural production. This feature enables automatic assisted driving technology based on satellite navigation systems to be widely used in agricultural machinery. For example, seeding machines and cotton picking machines equipped with Beidou navigation automatic assisted driving systems can achieve precise field work such as ridging, seeding, spraying, and harvesting, avoiding overlapping or missing work, and greatly improving work precision and efficiency. In addition, through satellite navigation systems, agricultural machinery can realize automatic driving, path planning, and work monitoring functions, further improving the intelligent level and efficiency of agricultural production.

[0037] To this end, the utility model discloses a double -frequency helical antenna of working in the big dipper wave band, adopts the mode of power divider plus phase shifter and feeds, easy to integrate planar circuit, increase the length of helical array appropriately, increase the resonance of other frequency points, realize double -frequency. The working index of the antenna is as follows:

[0038] Frequency band: 1.55-1.65GHz, 1.207-1.227GHz;

[0039] Polarization mode: right-handed circular polarization (RHCP);

[0040] Impedance: 50Ω;

[0041] Gain: ≥2dBi;

[0042] Axial ratio: ≤2dB;

[0043] Voltage standing wave ratio: ≤2.0.

[0044] Based on the double -frequency helical antenna can be combined with the development requirement of microwave radio frequency circuit realizes the requirement of high performance, high integration, miniaturization, completes the requirement of electric wave conversion.

[0045] (1) Antenna efficiency: during the transmission of electric wave, the medium and conductor can cause the loss of the transmission signal of the antenna, so that the input and output power of the antenna are not proportional, and the relevant regulations are not met. Therefore, it is required to select a resistance with large radiation resistance and small loss.

[0046] (2) Directivity coefficient: in order to properly measure the radiation intensity of the antenna, the coefficient of the maximum radiation direction of the antenna needs to be selected.

[0047] (3) Gain: the directivity coefficient of the antenna is multiplied by the antenna efficiency to obtain the result of the antenna gain. It is required to pay attention to the influence of the antenna radiation efficiency on the field and the field change of directivity, so as to carry out parameter analysis.

[0048] (4) Directional diagram: using three-dimensional, two-dimensional and one-dimensional methods, the antenna radiation power in different directions is drawn to form a directional diagram, which is used to analyze the strength and weakness of the antenna directivity.

[0049] (5) Input impedance: after the input impedance and output impedance are matched, the antenna can achieve the best working effect.

[0050] (6) Working frequency band: in order to determine the standard of the antenna working frequency band width, the actual situation of the microwave radio frequency circuit system needs to be clear. The embedded 50Ω microstrip line feed is used to realize the debugging of the microwave radio frequency circuit antenna input impedance, and the half-mode antenna of the microwave radio frequency circuit is adopted.

[0051] For example Figure 1As shown, a dual-arm spiral dual-frequency circularly polarized navigation antenna adopts a dual-arm spiral basic parameter design. It includes a cylindrical dielectric substrate 9 and an antenna feed network. A power splitter-phase shifter 11 is used for power feeding at the bottom of the dielectric substrate 9. The reflective ground of the cylindrical dielectric substrate 9 is manufactured using a copper cladding process. Four identical radiation slots are etched on the top surface of the cylindrical dielectric substrate 9. The slots contain spirally ascending radiator arms. The feeding phases between the radiator arms are 180° apart, generating axial circularly polarized waves across a wide frequency band.

[0052] Each radiator spiral arm consists of a main spiral arm 1 and a coupling spiral arm 2. The main spiral arm 1 determines the change in the antenna's low-frequency resonant frequency, while the coupling spiral arm 2 determines the change in the antenna's high-frequency resonant frequency. The main spiral arm 1 is connected to the coupling spiral arm 2 via a coupling unit 4. A 50-ohm microstrip line 6 is connected to the bottom end of the radiator spiral arm, and the coupling unit 4 is connected to the microstrip line 6. The spiral antenna, consisting of four identical radiator spiral arms with a 90° phase difference, effectively achieves the miniaturization of the navigation antenna and the requirements of the right-hand original design.

[0053] A PCB printed board is provided at the bottom of the dielectric substrate 9. The PCB printed board is made of Rogers TMM 4 material. The PCB printed board includes an upper PCB circuit board 7 and a lower PCB circuit board 10. The antenna feed network includes two single-layer feed networks, which are respectively provided on the upper PCB circuit board 7 and the lower PCB circuit board 10.

[0054] like Figure 2 As shown, the single-layer feeding network structure mainly realizes bottom feeding in the form of microstrip line 6. Specifically:

[0055] The single-layer feeding network structure includes a power splitter-phase shifter 11 arranged on the surface of the PCB printed board, the output port of the power splitter-phase shifter 11 adopts a lumped port 5, and its feeding method adopts a coaxial feeding with a phase difference of 180°. The position of the feeding point is as follows: Figure 1 In order to make the antenna seamlessly connected with other planar microstrip circuits, a microstrip line 6 with an impedance of 50 ohms is connected to the bottom of the radiator spiral arm. The microstrip line 6 extends to the outside of the common ground coplanar surface, which is convenient for the actual production and measurement of the antenna.

[0056] like Figure 3 The specific dimensions of the antenna designed in this utility model are as follows:

[0057] The radius of the dielectric substrate 9 is set to 20mm and the height is set to 32mm to achieve the miniaturization requirement, and the dielectric substrate 9 is made of Rogers RT / duroid 5880 high-frequency circuit board material, the relative dielectric constant of which is 2.2, the relative permeability is 1, the loss tangent angle is 0.0009, the thickness is 0.2mm, the radius is 20mm, and the height is 32mm.

[0058] The pitch of the main spiral arm 1 is 64mm, the number of spiral turns is 0.7 turns, the width of the main spiral arm 1 is 4.79mm, and the height from the top end to the upper layer PCB circuit board 7 is 31.5mm.

[0059] The pitch of the coupling spiral arm 2 is 64mm, the number of spiral turns is 0.7 turns, the width of the coupling spiral arm 2 is 4.89mm, and the height from the top end to the upper layer PCB circuit board 7 is 20.05mm. The width of the main spiral arm 1 and the coupling spiral arm 2 and the length of the coupling unit 4 are all 10mm.

[0060] The performance can be optimized by adjusting the physical parameters of the spiral, such as the spiral wire diameter D, the feed point distance d, the growth rate a, the spiral arm width W, etc., and the shaped beam of the main lobe pointing to the satellite can be obtained, which meets the specific communication requirements. The dual-arm spiral antenna has a wide directional diagram, the axial ratio is less than 3dB within the beam width, the azimuth plane is omnidirectional radiation, and the gain can reach a high level.

[0061] As shown in Figures 4-7 , the utility model improves the structure of the dual-arm spiral antenna by using electromagnetic simulation software, so as to optimize the size of the spiral antenna and the coaxial feeding mode, and researches the antenna size and the feeding network with excellent circular polarization characteristics and impedance matching characteristics.

[0062] Since in the circularly polarized antenna, the smaller the axial ratio is, the higher the polarization purity is. As shown in Figure 4 , in the 1207-1227 frequency band, the axial ratio is less than 2dB, and the right-handed circular gain curve is greater than 3dB, which indicates that the designed antenna has good right-handed circular polarization characteristics.

[0063] As shown in Figure 5 , in the 1550-1650 frequency band, the axial ratio is less than 2dB, and the right-handed circular gain curve is greater than 2dB, which indicates that the designed antenna has good right-handed circular polarization characteristics in the 1550-1650 frequency band.

[0064] Voltage standing wave ratio (VSWR) refers to the ratio of the amplitude of the voltage of the standing wave crest to the amplitude of the voltage of the node. In a radio frequency system, the voltage standing wave ratio is an important index parameter. It directly reflects the matching degree of the transmission line, that is, the matching condition of the characteristic impedance of the transmission line and the load impedance. When the standing wave ratio is equal to 1, it indicates that the impedance of the feeder and the antenna is completely matched, but in a mobile communication system, the voltage standing wave ratio is required to be less than 1.5. In the navigation antenna, the GPS satellite signals are divided into L1 and L2, and the frequencies are 1.57542GHz and 1.228GHz, respectively, and Figure 6 And Figure 7 It can be seen that the standing wave ratio of the design at the center frequencies of 1.575.42GHz and 1.228GHz is less than 1.5, which meets the requirements of the GPS communication satellite.

[0065] The simulation results show that the improved dual-arm helical antenna has good radiation performance and can cover the main frequency band of the GNSS antenna. At the same time, in order to realize the miniaturization of the dual-arm helical antenna main body and the simplification of the feeding, the structure size of the antenna is: 20*20*32mm, which well controls the size of the antenna, and the antenna size and the feeding network have excellent circular polarization characteristics and impedance matching characteristics, so that the antenna can be widely used in the field of satellite navigation.

[0066] Therefore, the dual-arm helical dual-frequency circularly polarized navigation antenna is used, the theoretical basis knowledge of the helical antenna is used, the structure form of the dual-arm helical antenna is improved, the size of the helical antenna and the coaxial feeding mode are optimized, and an electromagnetic simulation software is used to design a dual-arm helical antenna with excellent circular polarization characteristics and impedance matching characteristics, which can cover two frequency bands of GPS and Beidou, so as to provide a realistic basis and reference for solving the satellite navigation of the dual-arm helical antenna, and it has important significance to obtain a solution from a new angle for the research of the satellite navigation antenna.

[0067] Finally, it should be pointed out that: the above examples are only used to illustrate the technical scheme of the utility model and not to limit it, although the utility model has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical scheme of the utility model can still be modified or replaced, and these modifications or replacements cannot make the modified technical scheme deviate from the spirit and scope of the utility model technical scheme.

Claims

1. A dual-arm helical dual-band circularly polarized navigation antenna, characterized in that: The application relates to a cylindrical dielectric substrate and an antenna feed network, the upper surface of the cylindrical dielectric substrate is etched with four radiation slots with the same structure, a helical radiation body spiral arm is arranged in the radiation slot, the bottom of the dielectric substrate is fed by a power division-phase shifter, the reflection ground of the dielectric substrate is made by a copper coating process, the bottom end of the helical radiation body spiral arm is connected with a microstrip line with an impedance of 50 ohms, and the microstrip line extends to the outside of the common ground and coplanar surface.

2. The dual-arm helical dual-band circularly polarized navigation antenna according to claim 1, characterized in that: The feeding phase difference between the helical radiation body spiral arms is 180 degrees, the helical radiation body spiral arms comprise a main spiral arm and a coupling spiral arm, the main spiral arm is connected with the coupling spiral arm through a coupling unit, and the coupling unit is connected with the microstrip line.

3. The dual-arm helical dual-band circularly polarized navigation antenna according to claim 2, wherein: The bottom of the dielectric substrate is provided with a PCB printed board, the PCB printed board comprises an upper layer PCB circuit board and a lower layer PCB circuit board. The antenna feed network comprises two single-layer feed networks, and the two single-layer feed networks are arranged on the upper layer PCB circuit board and the lower layer PCB circuit board respectively.

4. The dual-arm helical dual-band circularly polarized navigation antenna according to claim 3, wherein: The dielectric substrate is made of Rogers RT / duroid 5880 high-frequency circuit board material, the relative dielectric constant is 2.2, the relative permeability is 1, the loss tangent angle is 0.0009, the thickness is 0.2 mm, the radius is 20 mm, and the height is 32 mm.

5. A dual-arm helical dual-band circularly polarized navigation antenna according to claim 4, characterized in that: The PCB printed board is made of Rogers TMM 4 material, the single-layer feed network comprises a power division-phase shifter arranged on the surface of the PCB printed board, the output port of the power division-phase shifter adopts a lumped port, and the feeding mode adopts coaxial feeding with a phase difference of 180 degrees.

6. A dual-arm helical dual-band circularly polarized navigation antenna according to claim 5, characterized in that: The pitch of the main spiral arm is 64 mm, and the number of spiral turns is 0.7 turns; the pitch of the coupling spiral arm is 64 mm, and the number of spiral turns is 0.7 turns.

7. A dual-arm helical dual-band circularly polarized navigation antenna according to claim 6, characterized in that: The width of the main spiral arm is 4.79 mm, and the height from the top end to the upper layer PCB circuit board is 31.5 mm; the width of the coupling spiral arm is 4.89 mm, and the height from the top end to the upper layer PCB circuit board is 20.05 mm.

8. The dual-arm helical dual-band circularly polarized navigation antenna according to claim 7, characterized in that: The width of the main spiral arm and the coupling spiral arm and the length of the coupling unit are all 10 mm.

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