An inflatable axial mode helical antenna

Abstract

The present application relates to an inflatable axial mode helical antenna, comprising: a balloon, a radiator, a floor and a radio frequency connector; the balloon is a cylindrical structure, one end of the balloon is connected to the floor to form a closed inflatable cavity, and the other end is freely extended; the radiator is a strip structure, and is axially spirally wound on the side wall of the balloon; the inner conductor of the radio frequency connector passes through the floor and is connected to one end of the spiral radiator, and the outer conductor is connected to the floor. The present application can combine the characteristics of an axial mode helical antenna and an inflatable antenna, has a broadband range and stable performance, and is small in size, light in weight, and low in cost.

Description

Technical Field

[0001] The present application relates to the field of antenna technology, and in particular to an inflatable axial mode helical antenna. Background Art

[0002] The axial mode helical antenna is a helical antenna that uses the circular polarization working principle.

[0003] With the rapid increase in communication needs, the integration and complexity of electronic equipment on ships and satellites have increased exponentially, the space inside the system has become increasingly tight, and the cost has also risen sharply. There is an urgent need for an axial-mode helical antenna that is small in size, light in weight, low in cost, and has stable performance over a wide range. Summary of the invention

[0004] Based on this, it is necessary to provide an inflatable axial mode helical antenna to address the above technical problems. It has the characteristics of both an axial mode helical antenna and an inflatable antenna, has a wideband range and stable performance, and is small in size, light in weight, and low in cost.

[0005] An inflatable axial mode helical antenna, comprising: a balloon, a radiator, a floor and a radio frequency connector;

[0006] The balloon is a columnar structure, one end of which is connected to the floor and the other end of which is freely extended;

[0007] The radiator is a strip-shaped structure and is spirally wound on the side wall of the balloon along the axial direction;

[0008] The inner conductor of the radio frequency connector passes through the floor and is connected to one end of the radiator, and the outer conductor is connected to the floor.

[0009] In one embodiment, the pitch of the radiator is 1 / 4 times the wavelength of the electromagnetic wave.

[0010] In one embodiment, the rise angle of the radiator ranges from 12° to 15°.

[0011] In one embodiment, the number of turns of the radiator is greater than 3.

[0012] In one embodiment, the ratio of the diameter of the radiator to the wavelength of the electromagnetic wave is in the range of 0.25-0.42.

[0013] In one embodiment, the pitch of the radiator is 51 mm, the rise angle of the radiator is 14°, the number of turns of the radiator is 12.5, and the diameter of the radiator is 64 mm.

[0014] In one embodiment, the width of the radiator is 25 mm.

[0015] In one embodiment, the radiator is a conductive tape.

[0016] The above-mentioned inflatable axial mode helical antenna is designed with a balloon based on the axial mode helical antenna, and the balloon is connected to the floor. It has the characteristics of both the axial mode helical antenna and the inflatable antenna, has a wideband range and stable performance, and is small in size, light in weight, and low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a three-dimensional schematic diagram of an inflatable axial mode helical antenna in one embodiment;

[0018] Figure 2 It is an enlarged schematic diagram of point A of an inflatable axial mode helical antenna in one embodiment;

[0019] Figure 3 A three-dimensional schematic diagram of an inflatable axial mode helical antenna in another embodiment;

[0020] Figure 4 Schematic diagram of the structural principle of an inflatable axial mode helical antenna in one embodiment; (a) is a schematic diagram of the diameter, pitch and rise angle of the radiator, and (b) is a schematic diagram of the rise angle, circumference and pitch of the radiator;

[0021] Figure 5 A schematic diagram of an antenna S11 corresponding to different I values ​​of an inflatable axial mode helical antenna in an embodiment;

[0022] Figure 6 1. is a graph showing antenna axial ratio and gain curves corresponding to different I values ​​of an inflatable axial mode helical antenna in an embodiment;

[0023] Figure 7 The antenna radiation pattern of the inflatable axial mode helical antenna at 1.4 GHz frequency point at phi=0° in one embodiment;

[0024] Figure 8 The antenna radiation pattern of the inflatable axial mode helical antenna at 1.6 GHz frequency point at phi=0° in one embodiment;

[0025] Fig. 9 The antenna radiation pattern of the inflatable axial mode helical antenna at 1.8 GHz frequency point at phi=0° in one embodiment;

[0026] Fig.10 The antenna radiation pattern of the inflatable axial mode helical antenna at 2 GHz frequency at phi=0° in one embodiment;

[0027] Fig.11 A schematic diagram of a simulated and measured S11 curve of an inflatable axial mode helical antenna in one embodiment;

[0028] Fig.12 A schematic diagram of a simulated and measured axial ratio curve of an inflatable axial mode helical antenna in one embodiment;

[0029] Fig.13 The simulated and measured directional patterns of an inflatable axial mode helical antenna at 1.4 GHz in one embodiment, (a) is right-hand circular polarization, and (b) is left-hand circular polarization;

[0030] Fig.14 The simulated and measured directional patterns of an inflatable axial mode helical antenna at 1.6 GHz in one embodiment, (a) is right-hand circular polarization, and (b) is left-hand circular polarization;

[0031] Fig.15 The simulated and measured directional patterns of an inflatable axial mode helical antenna at 1.8 GHz in one embodiment, (a) is right-hand circular polarization, and (b) is left-hand circular polarization;

[0032] Fig.16 The simulated and measured directional patterns of an inflatable axial mode helical antenna at 2 GHz in one embodiment, (a) is right-hand circular polarization, and (b) is left-hand circular polarization;

[0033] Fig.17 A graph showing simulated and measured gain curves of an inflatable axial mode helical antenna in one embodiment;

[0034] Fig.18 A page star map of an inflatable axial mode helical antenna applied to a satellite positioning system in one embodiment;

[0035] Fig.19 This is a page PVT view of an embodiment of an inflatable axial mode helical antenna applied in a satellite positioning system. Description of the drawings:

[0037] Balloon 1, radiator 2, floor 3, radio frequency connector 4, inflation port 5. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0039] like Figure 1 and Figure 2 As shown, an inflatable axial mode helical antenna provided by the present application, in one embodiment, comprises: a balloon 1, a radiator 2, a floor 3 and a radio frequency connector 4;

[0040] The balloon 1 is a cylindrical structure, one end of the balloon 1 is connected to the floor 3, and the other end is freely extended;

[0041] The radiator 2 is a strip-shaped structure and is spirally wound on the side wall of the balloon 1 along the axial direction;

[0042] The inner conductor of the RF connector 4 passes through the floor 3 and is connected to one end of the radiator 2 , while the outer conductor is connected to the floor 3 .

[0043] This embodiment does not limit the material of the balloon 1, for example: PVC (relative dielectric constant εr=4). The balloon 1 is provided with an inflation port 5. The balloon 1 is a closed inflation cavity, one end of which is connected to the floor 3. The specific connection method is the existing technology and will not be repeated here.

[0044] The radiator 2 is used as the radiation source of the axial mode helical antenna. The radiator 2 is made of conductive tape or metal. The current phase of the helical antenna changes continuously along the helix (radiator) and can be regarded as a traveling wave. The maximum radiation direction is the axial direction.

[0045] The floor 3 can be made of metal. The present embodiment does not limit the shape and size of the floor 3, and can be specifically set according to actual conditions. The floor can be round, and one end of the balloon is directly connected to the floor. The floor can also be annular, and the inner ring of the floor is adapted to the outer diameter of the balloon to fit one end of the balloon, and the balloon and the floor are fixed together with tape, such as Figure 3 shown.

[0046] The RF connector 4 can be a coaxial feeding port or an SMA connector, and the outer conductor is connected to the bottom of the floor. The connection method between the RF connector 4 and the radiator 2 is a prior art and will not be described here.

[0047] In this embodiment, a flexible film is used to build an inflatable cavity, and the balloon, floor, and RF connector constitute a balloon antenna or an inflatable antenna. The traditional mechanical deployment structure rigid antenna is designed to reduce its own volume and cross-section, while the inflatable antenna is flexible, rollable, and foldable before inflation, and can expand to a pre-designed size to work when inflated. Therefore, the larger the volume of the inflatable antenna, the more it can reflect the advantages of the structure. The inflatable antenna has the advantages of small size, can be designed into / any shape / conform to any shape, high portability, high deployment reliability, easy installation, and convenient retraction and release. Therefore, it can greatly reduce the volume and weight of the system, while freeing up space for other equipment.

[0048] In this embodiment, the radiator, the floor and the RF connector constitute an axial mode helical antenna, which has a wide bandwidth, can radiate circularly polarized waves, the maximum radiation direction is along the axis, and the traveling waves are approximately broadcast along the line. The input impedance is approximately pure resistance, and the radiation pattern is independent of the number of spiral turns.

[0049] The working process of this embodiment is as follows: when the antenna is not working, the gas in the balloon is small and the pressure is low, and the antenna can be scaled and folded to reduce the space occupied. When the antenna is working, gas is filled into the inflation cavity of the balloon through the inflation port, and the gas in the balloon is large and the pressure is high; the antenna adopts coaxial feeding, and the RF connector receives the antenna signal, and the electromagnetic wave is transmitted from the outer conductor to the inner conductor, and then propagates radially along the radiator.

[0050] The above-mentioned inflatable axial-mode helical antenna (i.e. IAMHA, full name is inflatable axial-mode helical antenna) is designed with a balloon on the basis of the axial-mode helical antenna, and an inflatable structure is installed for the antenna. The balloon and the floor form a closed inflatable cavity, which can have the characteristics of both the axial-mode helical antenna and the inflatable antenna, with a wide band range and stable performance. The antenna can be scaled, folded and stored when not in working state, and can be inflated to a pre-designed size to work in working state, thereby reducing the size and volume of the antenna, saving space and weight, and reducing costs at the same time. It is easy to carry, so as to replace the traditional hard antenna, and can be applied to fields such as satellite navigation and positioning systems.

[0051] In one embodiment, the pitch of the radiator 2 is 1 / 4 times the wavelength of the electromagnetic wave, the rise angle of the radiator 2 ranges from 12° to 15°, the number of turns of the radiator 2 is greater than 3, and the ratio of the diameter of the radiator 2 to the wavelength of the electromagnetic wave ranges from 0.25 to 0.42.

[0052] In this embodiment, the radiator 2 is a strip-shaped spiral line.

[0053] like Figure 4 As shown, D represents the diameter of the helix, S represents the pitch of the helix, α represents the rise angle of the helix, and C represents the circumference corresponding to the radius of the helix.

[0054] The relationship between the rise angle α of the helix, the diameter D and the pitch S is:

[0055]

[0056] The parametric equation of the helix is:

[0057]

[0058] Where N is the number of turns of the spiral line.

[0059] Assume that the pitch of the axial mode helical antenna is S≈λ / 4, the range of the rise angle is 12°<α<15°, the number of spiral turns N>3, and the axial mode radiation of the helical antenna satisfies:

[0060]

[0061] Where λ is the wavelength of the electromagnetic wave.

[0062] In this embodiment, the ratio λ of the diameter D of the helical antenna to the wavelength determines the radiation mode of the antenna (radiation modes include: normal mode radiation, axial mode radiation and conical mode radiation), and the antenna operates at 1.38-2.03 GHz.

[0063] In a specific embodiment, the pitch of the radiator 2 is S=51 mm, the rise angle of the radiator 2 is α=14°, the number of turns of the radiator 2 is N=12.5, and the diameter of the radiator 2 is D=64 mm.

[0064] In this embodiment, the rise angle α=14° satisfies the condition of axial mode radiation of the helical antenna 12°<α<15°, and the rise angle is relatively large, which can achieve better antenna axial ratio performance; the number of turns of the radiator is N=12.5, and the number of turns is relatively large, which can achieve higher antenna gain and better axial radiation performance; the diameter of 64mm can realize a broadband circularly polarized antenna covering the L band.

[0065] Preferably, the width of the radiator is 25 mm.

[0066] like Figure 5 The results of optimizing the width l are shown in Figure 1. The width l of the helix is ​​a key parameter that affects the impedance matching and impedance bandwidth of the antenna. When l = 25 mm, the impedance matching and impedance bandwidth of the helical antenna are optimal. The impedance bandwidth of the antenna can cover 1.31-2.19 GHz, and the relative bandwidth is 50.3%.

[0067] like Figure 6 The axial ratio and gain curves of the helical antenna corresponding to different l values ​​are shown. The simulation results show that within the working frequency band, the helical line width l has little effect on the axial ratio and gain performance of the antenna, and the axial ratio and gain curves corresponding to different l values ​​are basically consistent. Based on the impedance matching performance of the antenna and the needs of subsequent physical processing, the line width l of the inflatable axial mode helical antenna designed in this paper is 25mm. When l = 25mm, the 3dB axial ratio of the axial mode helical antenna can cover 1.12-2.08GHz, and the relative bandwidth is 60%. The maximum gain of the axial mode helical antenna can reach 14.4dBi at 1.7GHz.

[0068] like Figures 7 to 10 As shown in Figure 1, the RHCP and LHCP patterns of the helical antenna at different frequencies when l = 25 mm and phi = 0°. The maximum gain direction of the RHCP pattern of the inflatable axial mode helical antenna propagates along the axial direction. As the frequency increases, the side lobes of the RHCP and LHCP patterns begin to increase.

[0069] like Fig.11 The simulation and actual measurement of the inflatable axial mode helical antenna are shown in S11. The measured impedance bandwidth of the inflatable axial mode helical antenna can cover 1.38-2.03 GHz, and the relative bandwidth is 38.1%.

[0070] like Fig.12 The axial ratio curves of the inflatable antenna simulation and measurement are shown. The measured 3dB axial ratio bandwidth of the antenna can cover 1.1-2.12GHz, and the relative bandwidth is 63.4%. Compared with the simulation results, the axial ratio bandwidth of the actual antenna is wider, which can achieve full coverage of the impedance bandwidth of the antenna.

[0071] like Figures 13 to 16 The figure shows a comparison of the measured and simulated radiation patterns of IAMHA, with the horizontal axis being the angle. The square legend lines and the triangle legend lines represent the simulated and measured radiation patterns of IAMHA, respectively. The RHCP measured by IAMHA has good radiation characteristics in the medium and low frequency bands, and the maximum radiation direction propagates along the axial direction. The RHCP radiation pattern has shifted by 10°-20° in the working frequency band. In addition, the measured LHCP radiation pattern gain of IAMHA is higher than that of the simulated LHCP, indicating that the cross-polarization performance of IAMHA needs to be improved. This is because the antenna will be tilted when folded and stored. In addition, wrinkles will appear on the film and conductive tape surface of the inflatable antenna, which will affect the current distribution on the tape surface. In addition, the shape of the PVC balloon carrier when inflated is not a standard cylinder, but close to an ellipsoid. These factors will have a direct impact on the radiation characteristics of the antenna.

[0072] like Fig.17 The simulated and measured gain curves of the inflatable axial mode helical antenna are shown in the figure. The measured gain curve has a similar change trend to the simulated gain curve within the working frequency band of the antenna. The maximum gain measured reaches 11.78dBi at 1.2GHz. In the mid- and high-frequency bands, the measured gain is 2-4dBi lower than the simulated gain overall. The reason for this phenomenon is that the material particles of the conductive tape affect the radiation characteristics of the antenna.

[0073] In order to test IAMHA's ability to receive satellite positioning signals, this application uses a set of four-system OEM motherboards based on ASIC chips and the K708 GNSS high-precision positioning board with Beidou satellite high-dynamic settlement engine. The test results are as follows Fig.18 and Fig.19As shown, IAMHA can receive 11 satellites including GPS satellites in G14 and G19 bands, Beidou satellites in C01, C03, C04, C07, C40 and C46, ​​and Glonass satellites in R12, R14 and R24 bands. IAMHA can receive accurate satellite positioning information. The test results of longitude and latitude are 112.947deg and 28.169deg respectively, which are 0.012° (1200m) and 0.002° (200m) different from GPS positioning respectively. The positioning accuracy of latitude, longitude and altitude are 2.94m, 0.589m and 10.029m respectively.

[0074] The inflatable axial mode spiral antenna proposed in this application has an inflatable film made of PVC film (dielectric constant of 4), the size of the antenna is 64mm in diameter * 800mm in height, the rising angle of the radiator is 14°, and the number of turns is 12.5. Compared with the traditional rigid spiral antenna, the present application has the advantages of being scalable, foldable and retractable, small in size, light in weight and low in cost. Since plastic film and conductive film are used to replace the traditional rigid materials, the manufacturing cost of the antenna is greatly reduced. The manufacturing cost of the inflatable axial mode spiral antenna is less than 2% of the price of the mechanically unfolded spiral antenna sold on the market. By inflating and deflation of the inflation port at the top of the inflatable balloon film cavity, the inflatable spiral antenna can be expanded to a pre-designed size for operation, or folded and retracted, that is, its own volume is reduced when not in use, and it can replace the traditional rigid antenna when in use. The height and weight of the folded inflatable antenna are only 4.7% and 1.6% of the rigid antenna of the same size.

[0075] The test results show that the impedance bandwidth of the antenna can cover 1.38-2.03GHz (38.1%), the 3dB axial ratio bandwidth can cover 1.1-2.12GHz, the maximum gain can reach 11.78dBi at 1.2GHz, and it has good right-hand circular polarization characteristics and axial radiation performance in a wide frequency band. After actual testing, the signal radiated by the inflatable axial mode helical antenna can be received by 11 satellites, and the positioning board can obtain high-precision position information.

[0076] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0077] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. An inflatable axial mode helical antenna, characterized in that: include: balloons, radiators, floorboards, and RF connectors; The balloon is a columnar structure, one end of which is connected to the floor and the other end of which is freely extended; The radiator is a strip-shaped structure and is spirally wound on the side wall of the balloon along the axial direction; The inner conductor of the RF connector passes through the floor and is connected to one end of the radiator, and the outer conductor is connected to the floor; The radiator is a strip-shaped spiral line; the pitch of the radiator is 1 / 4 times the wavelength of the electromagnetic wave; The range of the rising angle of the radiator is 12°-15°; The number of turns of the radiator is greater than 3; The ratio of the diameter of the radiator to the wavelength of the electromagnetic wave is in the range of 0.25-0.

42.

2. The inflatable axial mode helical antenna according to claim 1, characterized in that: The pitch of the radiator is 51 mm, the rise angle of the radiator is 14°, the number of turns of the radiator is 12.5, and the diameter of the radiator is 64 mm.

3. The inflatable axial mode helical antenna according to claim 2, characterized in that: The width of the radiator is 25 mm.

4. The inflatable axial mode helical antenna according to claim 1, characterized in that: The radiator is a conductive tape.

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