Series-fed four-arm spiral circularly polarized omnidirectional antenna based on carbon material

Abstract

The invention relates to a series-fed four-arm spiral circularly polarized omnidirectional antenna based on a carbon material, and belongs to the technical field of microwave antennas. According to the antenna, a four-arm helical antenna is made of a carbon material, and omnidirectional circularly polarized radiation is realized through a feed network. Compared with a traditional metal antenna, the carbon material is adopted to replace metal, the weight and cost of the antenna are effectively reduced, and meanwhile good antenna performance is kept. The feed network adopts the microstrip line design, the structure is simple, special devices and materials are not needed, and the cost is further reduced. The antenna has the advantages of being simple in structure, easy to process and manufacture, good in omnidirectional circular polarization radiation characteristic and the like, and has wide application prospects in the fields of satellite communication, mobile communication, radar systems and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave antennas and relates to a series-fed four-arm spiral circularly polarized omnidirectional antenna based on carbon materials. Background Art

[0002] In wireless communication systems, antennas are key devices for transmitting and receiving wireless signals. Traditional antennas can usually only achieve linear polarization, that is, the vibration direction of electromagnetic waves is fixed, which limits the performance and application range of antennas. Compared with traditional linear polarization antennas, omnidirectional circularly polarized antennas can transmit and receive circularly polarized electromagnetic waves in any direction, which makes the antenna insensitive to the polarization direction of electromagnetic waves, thereby improving the quality of signal reception. And because the polarization direction of circularly polarized electromagnetic waves is random, omnidirectional circularly polarized antennas can receive signals in a wider range, which helps to improve the coverage and reliability of signals. In solving the problem of anti-interference of transmission signals, omnidirectional circularly polarized antennas can simultaneously receive horizontally and vertically polarized electromagnetic waves, which helps to reduce signal interference and noise and improve signal transmission quality. In practical applications, omnidirectional circularly polarized antennas can adapt to different wireless communication environments, such as satellite communications, mobile communications, radar systems, etc., which makes the antenna have a wider application prospect.

[0003] Carbon materials, especially two-dimensional and nanomaterials such as graphene and carbon nanotubes, have attracted extensive attention in recent years in the study of electromagnetic wave absorption, reflection and transmission due to their unique physical and chemical properties. These materials may have high electrical conductivity, high thermal conductivity, high mechanical strength and good electromagnetic wave response characteristics, which makes them potential for application in wireless communications, radar, satellite communications and electromagnetic shielding. In addition, the production cost of carbon-based materials is relatively low, which may make them more attractive in cost-sensitive applications. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a carbon material-based series-fed four-arm spiral circularly polarized omnidirectional antenna. While realizing the omnidirectional circularly polarized radiation of the antenna through the feeding network, a carbon material film with high conductivity is used instead of metal, which effectively reduces the cost of the antenna and realizes the lightweight of the antenna while ensuring that the gain loss of the antenna is small.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The carbon material-based series-fed four-arm spiral circularly polarized omnidirectional antenna includes:

[0007] The antenna radiation arm 1 is made of carbon material, and the length is an odd multiple of 1 / 4 of the wavelength corresponding to the antenna operating frequency;

[0008] A dielectric column 2, wherein the dielectric column 2 is a cylindrical structure with two ends opened, and the antenna radiation arm 1 is wound around the outer side of the dielectric column 2;

[0009] A feeding structure 3, wherein the feeding structure 3 is arranged on a feeding network dielectric substrate 5, the feeding network dielectric substrate 5 is coaxially arranged with the dielectric column 2, and the four ports of the feeding structure 3 respectively correspond to the four antenna radiation arms 1 for feeding;

[0010] The feeding structure 3 includes a feeding network 4, wherein four ports of the feeding network 4 respectively feed the four antenna radiation arms 1, and the length of the transmission line between adjacent feeding ports of the feeding network 4 depends on the wavelength corresponding to the antenna operating frequency;

[0011] The lower surface of the feed network dielectric substrate 5 is a grounding plate 6 .

[0012] Furthermore, the carbon material is graphene or carbon nanotubes.

[0013] Furthermore, the material of the dielectric column 2 is polytetrafluoroethylene.

[0014] Furthermore, the helical angle of the antenna radiation arm 1 is between 60° and 70°.

[0015] Furthermore, the sheet resistance of the carbon material is not higher than 10Ω.

[0016] Furthermore, the excitation end 401 of the feed network 4 is arranged at the center of the feed network dielectric substrate 5 .

[0017] Furthermore, the feed network 4 comprises:

[0018] A first transmission line 404, wherein an input end of the first transmission line 404 is connected to the excitation end 401, and an output end of the first transmission line 404 is connected to a first feeding port 405 and a second transmission line 407;

[0019] A second transmission line 407, wherein an input end of the second transmission line 407 is connected to an output end of the first transmission line 404, and an output end of the second transmission line 407 is connected to a second feeding port 406, a third transmission line 410 and a first phase matching branch 411;

[0020] A third transmission line 410, wherein an input end of the third transmission line 410 is connected to an output end of the second transmission line 407, and an output end of the third transmission line 410 is connected to a third feeding port 408 and a second phase matching branch 412;

[0021] a first phase matching branch 411, wherein an input end of the first phase matching branch 411 is connected to an output end of the second transmission line 407;

[0022] a second phase matching branch 412, wherein an input end of the second phase matching branch 412 is connected to an output end of the third transmission line 410;

[0023] The widths of the first transmission line 404 , the second transmission line 407 , and the third transmission line 410 decrease in sequence. The lengths of the first phase matching branch 411 and the second phase matching branch 412 are equal and are equal to the length of the first transmission line 404 .

[0024] Furthermore, the top of the antenna radiation arm 1 is an open circuit structure.

[0025] Furthermore, the feed network dielectric substrate 5 is a PCB board.

[0026] Furthermore, the feed network dielectric substrate 5 is circular in shape and is provided with a plurality of hollow circular holes to reduce weight.

[0027] The beneficial effects of the present invention are:

[0028] (1) Taking advantage of the excellent conductivity and chemical stability of carbon materials, carbon materials are used instead of metals to effectively reduce the weight of the antenna while providing good antenna radiation.

[0029] (2) The feeding network is designed with microstrip lines. The path difference of the feeding signal transmission realizes four feeding ports with phases differing by 90°. While ensuring the antenna performance, the routing design is simpler, without special devices and materials, and the antenna cost is reduced.

[0030] (3) The traditional metal helical antenna etching process on a cylindrical dielectric substrate has high requirements, is difficult to process, has high cost, and is easily oxidized. The carbon material used in the present invention is easy to extract and has low cost. The film can obtain excellent conductivity and flexibility after simple processing and is easy to process into an antenna, which can effectively reduce costs.

[0031] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0033] Figure 1 It is a schematic diagram of the overall structure of a carbon material-based series-fed four-arm spiral circularly polarized omnidirectional antenna of the present invention;

[0034] Figure 2 It is a schematic structural diagram of the quadrifilar helical antenna of the present invention;

[0035] Figure 3 It is a schematic diagram of the three-dimensional structure of the feeding structure of the present invention;

[0036] Figure 4 is a top view of the feeding structure of the present invention;

[0037] Figure 5 A voltage standing wave ratio (VSWR) curve diagram of the antenna of the present invention;

[0038] Figure 6 The E-plane and H-plane radiation patterns of the antenna of the present invention at the center frequency;

[0039] Figure 7 Graph showing the axial ratio of the antenna of the present invention.

[0040] Figure numerals: antenna radiation arm 1, dielectric column 2, feeding structure 3, feeding network 4, feeding network dielectric substrate 5, ground plate 6, first antenna arm 101, second antenna arm 102, third antenna arm 103, fourth antenna arm 104, excitation end 401, feeding line 402, impedance matcher 403, first transmission line 404, first feeding port 405, second feeding port 406, second transmission line 407, third feeding port 408, fourth feeding port 409, third transmission line 410, first phase matching branch section 411, second phase matching branch section 412. DETAILED DESCRIPTION

[0041] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0042] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0043] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0044] Figure 1 The present invention provides a carbon material-based series-fed four-arm spiral circularly polarized omnidirectional antenna, comprising an antenna radiation arm 1, a dielectric column 2 and a feeding structure 3;

[0045] The antenna radiation arm 1 includes a first antenna arm 101 , a second antenna arm 102 , a third antenna arm 103 and a fourth antenna arm 104 .

[0046] The dielectric column 2 and the feeding structure 3 are coaxially placed, and the four ports of the feeding structure 3 are respectively connected to the four antenna radiation arms 1 via conductive silver paste for feeding, and the dielectric column 2 and the feeding network dielectric substrate 5 are bonded to stabilize the structure.

[0047] The antenna body includes four antenna radiation bands 1 and an impedance matching trapezoidal patch at the lower end of each antenna radiation band. The antenna is composed of four single-arm spiral antennas. The radiation pattern is omnidirectional like the single-arm spiral antenna. The antenna radiation band 1 is spirally wound along the dielectric column 2 in a right-handed manner, and the four antenna radiation bands are equidistantly distributed on the outer surface of the dielectric column 2.

[0048] The traditional material used for processing and manufacturing all-metal quadrifilar helical antennas is copper alloy, with an average density of 8.9g / cm 3 , the conductivity is about 5×107S / m. Based on the requirements for antenna radiation performance, the material used to make the antenna needs to have sufficiently excellent conductivity to avoid loss of antenna performance; at the same time, considering that it is difficult to find a material with a lower cost than copper alloy in metals, the present invention uses carbon material as the target antenna material. Carbon material is made of carbon atoms as raw materials and is prepared by chemical vapor deposition. The carbon material not only has good conductivity and flexibility, but also can further improve the conductivity after protonation treatment. After the carbon material used in the present invention is treated, it is tested that the square resistance of the material is 0.2Ω / □, which can effectively replace metal to meet the performance requirements of the antenna.

[0049] The dielectric column 2 is a circular cylindrical structure with a radius of 4 mm, a thickness of 1 mm, and a hollow structure in the middle, which helps to reduce the weight of the dielectric column 2 and achieve lightweight antenna; the material used for the dielectric column 2 is polytetrafluoroethylene, with a relative dielectric constant of 2.1 and a loss tangent of 0.001.

[0050] Combination Figure 2 , the specific parameters of the antenna of the present invention are described below:

[0051] The four antenna arms are evenly distributed and wound on the surface of the dielectric column. The antenna width W = 2mm, and the antenna arm length L = 34mm. The length is approximately 3 / 4 of the wavelength corresponding to the antenna operating frequency, which is an odd multiple of 1 / 4 of the antenna wavelength. According to the theoretical knowledge of the four-arm helical antenna structure, the top of the antenna is open; the antenna's helical angle a = 63°, and the helical direction is right-handed; in order to achieve impedance matching with the feeding network at the bottom of the antenna, a balun structure is designed, which is in the shape of a trapezoidal patch, and the structural parameters are: upper width Wu = 1mm, lower width Wd = 0.6mm, height D = 2mm.

[0052] The impedance matching of the antenna is mainly achieved by adjusting the upper width Wu, lower width Wd and height D of the trapezoidal patch below;

[0053] The working frequency of the antenna is achieved by adjusting the length L of the four antenna radiating arms 1;

[0054] The radiation direction of the antenna is mainly achieved by adjusting the spiral angle a of the four antenna radiation arms 1;

[0055] The lower end of the antenna is connected to the feeding structure 3 via an impedance matching trapezoidal patch.

[0056] Combination Figure 3 and Figure 4 , the specific structure and parameters of the feeding network of the present invention are described below:

[0057] The feeding structure 3 includes, from top to bottom, a feeding network 4, a feeding network dielectric substrate 5 and a grounding plate 6. The feeding network dielectric substrate 5 is made of Rogers 5880 grade material, the relative dielectric constant of the material is 2.1, and the loss tangent is 0.0009;

[0058] The feed network dielectric substrate 5 is circular in shape, with a radius of 14 mm and a thickness of 1 mm. Four hollow circular holes with a radius of 1.2 mm are designed 2 mm away from the boundary. The four circular holes are evenly distributed to reduce the weight of the feed structure 3 and achieve lightweight antenna.

[0059] The feeding network 4 is etched on the upper surface of the feeding network dielectric substrate 5. The center of the feeding network dielectric substrate 5 is a 0.7 mm circular hole design, which is set as the excitation end 401 for implementing coaxial feeding for the feeding network. The length L1 of the feeding line 402 is 4.9 mm, and the width W1 is 1.71 mm. The impedance matcher 403 is connected to the first transmission line 404 after a single bend. The impedance matching between the feeding line 402 and the first transmission line 404 can be achieved by adjusting the width and length of the impedance matcher 403.

[0060] The impedance matcher 403 comprises two sections, wherein the width W2 = 3 mm and the length 5 mm of the first end, and the distance from the center of the second section to the circle is r1 = 8 mm and the width is W3 = 3 mm, and the angle corresponding to the arc length is 30°;

[0061] The input end and the output end of the first transmission line 404 are connected to the first feeding port 405 and the second transmission line 407 and the second feeding port 406 respectively. The phase and amplitude difference of the output signal between the first feeding port 405 and the second feeding port 406 can be achieved by adjusting the length and width of the first transmission line 404;

[0062] The first transmission line 404 has a width W4=4mm, a distance from the center of the circle r0=7mm, and a corresponding arc length angle of 90°. The first feeding port 405 has a distance L3=2.5mm from the first transmission line 404, and a corresponding width of 0.2mm.

[0063] The input end and the output end of the second transmission line 407 are respectively connected to the second feeding port 406, the third transmission line 410, the third feeding port 408 and the first phase matching branch 411. The phase and amplitude difference of the output signal between the second feeding port 406 and the third feeding port 408 can be achieved by adjusting the length and width of the second transmission line 407 and the first phase matching branch 411;

[0064] The width of the second transmission line 407 is W5=2.8mm, the distance from the center of the circle is r0=7mm, and the corresponding arc length angle is 90°. The distance from the second feeding port 406 to the second transmission line 407 is L3=2.5mm, and the corresponding width is 0.2mm. The distance from the third feeding port 408 to the second transmission line 407 is L3=2.5mm, and the corresponding width is 0.2mm. The length of the first phase matching branch 411 is L4=4.5mm, and the width is 0.4mm.

[0065] The input end and the output end of the third transmission line 410 are respectively connected to the third feeding port 408 and the second phase matching branch 412 and the fourth feeding port 409. The phase and amplitude difference of the output signal between the third feeding port 408 and the fourth feeding port 409 can be achieved by adjusting the length and width of the third transmission line 410 and the second phase matching branch 412.

[0066] The width of the third transmission line 410 is W6=1.2mm, the distance from the center of the circle is r0=7mm, and the corresponding arc length angle is 90°. The distance between the fourth feeding port 409 and the third transmission line 410 is L3=2.5mm, and the corresponding width is 0.2mm. The length of the second phase matching branch 412 is L4=4.5mm, and the width is 0.4mm.

[0067] By adjusting the value of r0, the length of the transmission line can be adjusted so that the signal transmission path difference of the four feeding ports is approximately 1 / 4 of the wavelength corresponding to the antenna operating frequency of 5 GHz, and the phase difference of the output signal is 90°.

[0068] By adjusting the width of the three-section transmission line, the power distribution of the feeding network to the four feeding ports can be realized, and the signal output of equal amplitude can be achieved.

[0069] Figure 5 It shows that the voltage standing wave ratio of the port of the antenna is less than 2 in the frequency range of 4.9-5.5GHz, and the impedance matching of the port can be achieved;

[0070] Figure 6 : is the radiation pattern of the antenna of the present invention at the E plane and H plane at the center frequency of 5 GHz. It can be seen from the figure that the radiation direction of the antenna is omnidirectional, and the maximum radiation gain is about 2 dB;

[0071] Figure 7 : is an axial ratio curve diagram of the antenna of the present invention. In the diagram, the axial ratio of the antenna is less than 3dB in the frequency range of 4.9-5.2GHz, indicating that the antenna has good circular polarization radiation characteristics in the frequency range near the center frequency of 5GHz.

[0072] The present invention proposes a carbon-based series-fed four-arm spiral circularly polarized omnidirectional antenna. According to the radiation requirements of the antenna, the materials used in the antenna and the feeding structure design are innovated. Carbon materials with high conductivity and excellent chemical and mechanical stability are used as the material for making the antenna, which overcomes the shortcomings of traditional metal antennas such as heavy weight, difficulty in bending, and high cost. The feeding network does not require special devices and materials to meet the feeding requirements of the antenna, effectively reducing the cost of the antenna. Test data show that the antenna described in the present invention has good omnidirectional circularly polarized radiation characteristics, broadens the application range of carbon-based antennas, and has the advantages of simple structure and easy processing and manufacturing, and has practical value.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A carbon-based series-fed four-arm spiral circularly polarized omnidirectional antenna, characterized by: include: An antenna radiation arm (1), the antenna radiation arm (1) being made of carbon material and having a length that is an odd multiple of 1 / 4 of a wavelength corresponding to an antenna operating frequency; A dielectric column (2), the dielectric column (2) being a cylindrical structure with openings at both ends, and the antenna radiation arm (1) being wound around the outer side surface of the dielectric column (2); A feeding structure (3), wherein the feeding structure (3) is arranged on a feeding network dielectric substrate (5), the feeding network dielectric substrate (5) is coaxially arranged with the dielectric column (2), and the four ports of the feeding structure (3) respectively correspond to the four antenna radiation arms (1) for feeding; The feeding structure (3) comprises a feeding network (4), wherein four ports of the feeding network (4) respectively correspond to four antenna radiation arms (1) for feeding, and the length of the transmission line between adjacent feeding ports of the feeding network (4) depends on the wavelength corresponding to the antenna operating frequency; The lower surface of the feed network dielectric substrate (5) is a grounding plate (6).

2. The carbon material-based series-fed four-arm spiral circularly polarized omnidirectional antenna according to claim 1, characterized in that: The carbon material is graphene or carbon nanotube.

3. The carbon material-based series-fed four-arm spiral circularly polarized omnidirectional antenna according to claim 1, characterized in that: The material of the medium column (2) is polytetrafluoroethylene.

4. The carbon material-based series-fed four-arm spiral circularly polarized omnidirectional antenna according to claim 1, characterized in that: The helical angle of the antenna radiation arm (1) is between 60° and 70°.

5. The carbon material-based series-fed four-arm spiral circularly polarized omnidirectional antenna according to claim 1, characterized in that: The sheet resistance of the carbon material is not higher than 10Ω.

6. The carbon material-based series-fed four-arm spiral circularly polarized omnidirectional antenna according to claim 1, characterized in that: The excitation end (401) of the feed network (4) is arranged at the center of the feed network dielectric substrate (5).

7. The carbon material-based series-fed four-arm spiral circularly polarized omnidirectional antenna according to claim 1, characterized in that: The feed network (4) comprises: A first transmission line (404), wherein an input end of the first transmission line (404) is connected to the excitation end (401), and an output end of the first transmission line (404) is connected to a first feeding port (405) and a second transmission line (407); A second transmission line (407), wherein an input end of the second transmission line (407) is connected to an output end of the first transmission line (404), and an output end of the second transmission line (407) is connected to a second feeding port (406), a third transmission line (410) and a first phase matching branch (411); A third transmission line (410), wherein an input end of the third transmission line (410) is connected to an output end of the second transmission line (407), and an output end of the third transmission line (410) is connected to a third feeding port (408) and a second phase matching branch (412); A first phase matching branch (411), wherein an input end of the first phase matching branch (411) is connected to an output end of the second transmission line (407); A second phase matching branch (412), wherein an input end of the second phase matching branch (412) is connected to an output end of the third transmission line (410); The widths of the first transmission line (404), the second transmission line (407), and the third transmission line (410) decrease in sequence, and the lengths of the first phase matching branch node (411) and the second phase matching branch node (412) are equal and are equal to the length of the first transmission line (404).

8. The carbon material-based series-fed four-arm spiral circularly polarized omnidirectional antenna according to claim 1, characterized in that: The top end of the antenna radiation arm (1) is an open circuit structure.

9. The carbon material-based series-fed four-arm spiral circularly polarized omnidirectional antenna according to claim 1, characterized in that: The feed network dielectric substrate (5) is a PCB board.

10. The carbon material-based series-fed four-arm spiral circularly polarized omnidirectional antenna according to claim 1, characterized in that: The feed network dielectric substrate (5) is circular in shape and is provided with a plurality of hollow circular holes to reduce weight.

Images