Two-dimensional circularly polarized beam frequency scanning antenna and design method thereof

Abstract

The invention discloses a two-dimensional circularly polarized beam frequency scanning antenna and a design method thereof, and belongs to the technical field of microwaves and antennas. A sector-ring-shaped patch is arranged above a metal ground, one straight edge of the sector-ring-shaped patch is connected with the metal ground through a short-circuit wall, and a non-closed structure with one straight edge short-circuited and the other straight edge, an inner arc and an outer arc open-circuited is formed; a coaxial feed unit is arranged on the non-closed structure for feeding; a short circuit column connected with the metal ground is arranged on the sector-ring-shaped patch, regulation and control of two or more working modes of the antenna are achieved by changing the inner diameter, the outer diameter and the central angle of the sector-ring-shaped patch and the position of the short circuit column, and then the two-dimensional beam scanning design of the circularly polarized antenna is achieved. According to the invention, a plurality of working modes can be reasonably and flexibly regulated and controlled on a single patch structure to realize the circularly polarized beam scanning capability, and the structural complexity of a traditional antenna array for realizing the two-dimensional beam scanning performance is effectively reduced.

Description

Technical Field

[0001] The invention relates to a two-dimensional circular polarization beam frequency scanning antenna and a design method thereof, and belongs to the technical field of microwaves and antennas. Background Art

[0002] With the rapid development of communication systems such as mobile communications, satellite communications, and vehicle communications, higher requirements are placed on the beam scanning performance of antennas.

[0003] Compared with linearly polarized antennas, circularly polarized (CP) antennas are widely used in many wireless communication systems because they can effectively reduce multipath interference and polarization mismatch losses caused by misalignment. Therefore, the realization of two-dimensional circularly polarized beam frequency scanning antennas has very important application value in modern communication technology.

[0004] At present, two-dimensional beam scanning antennas are mainly realized based on mechanical scanning, phased array, reflect array, metasurface and other methods. Mechanical scanning realizes the change of antenna pointing through mechanical devices, but its response speed is slow and it is not suitable for rapidly changing communication environments. Phased array antennas realize beam scanning by controlling the phase of each array unit, and have fast response speed and flexible beam control capability, but their complex hardware structure and high cost limit their promotion in large-scale applications. Reflect array antennas use reflective surfaces to control the direction of the beam, and have high directivity and beam control capability, but their structure is complex, the manufacturing cost is high, and they are limited by size and weight, such as the invention named "A Ka-band two-dimensional beam scanning folded reflect array antenna based on liquid crystal". Metasurface antennas use artificially designed periodic structures to control beams, and have small size and weight, but they still face the challenges of manufacturing difficulty and broadband design in engineering practice, such as the invention named "A two-dimensional multi-beam metasurface antenna with wideband and large angle scanning". Although the two-dimensional beam scanning antennas implemented in the above manner have achieved certain success in providing beam control capabilities, they also have disadvantages such as complex structure, large size, high cost, and limited design methods, which restrict their application in certain fields.

[0005] In view of this, it is necessary to propose a more simplified, efficient and flexible two-dimensional circularly polarized beam frequency scanning antenna design method to promote the widespread application of two-dimensional circularly polarized beam frequency scanning antenna technology in various communication systems and provide important support for the development of future wireless communication technology. Summary of the invention

[0006] The purpose of the present invention is to solve the deficiencies in the prior art and to provide a two-dimensional circularly polarized beam frequency scanning antenna and a design method thereof. The antenna has a simple patch structure and clear mathematical principles, and can achieve a two-dimensional beam scanning capability of 40° in azimuth and 34° in elevation.

[0007] The present invention adopts the following technical solutions to solve the above technical problems: In one aspect, the present invention provides a design method for a two-dimensional circularly polarized beam frequency scanning antenna, the design method comprising: A fan-shaped patch is arranged above the metal ground; A straight edge of the fan-shaped patch is connected to the metal ground through a short-circuit wall, forming a non-enclosed structure in which one straight edge is short-circuited and the other straight edge and the inner and outer arcs are open; A coaxial feeding unit is arranged on the non-enclosed structure for feeding; A short-circuit post connected to the metal ground is arranged on the fan-shaped ring patch. By changing the inner and outer diameters and the central angle of the fan-shaped ring patch and the position of the short-circuit post, the antenna can be regulated in two or more working modes, thereby realizing the two-dimensional beam scanning design of the circularly polarized antenna.

[0008] Furthermore, the arc lengths of the outer and inner arcs of the fan-shaped patch are both odd multiples of 1 / 4 of the wavelength corresponding to the center frequency of the antenna's operating frequency band.

[0009] Furthermore, the ratio of the arc lengths of the outer and inner arcs of the fan-shaped patch is greater than 1.4.

[0010] Furthermore, the feeding point of the coaxial feeding unit is located at the edge of the open straight side of the non-enclosed structure.

[0011] Furthermore, the distance between the feeding point of the coaxial feeding unit and the center of the fan-shaped patch ranges from 1.07 times the inner diameter of the fan-shaped patch to 0.99 times the outer diameter of the fan-shaped patch.

[0012] Furthermore, the central angle of the fan-shaped patch ranges from 180° to 350°.

[0013] Furthermore, a dielectric is filled between the sector ring patch and the metal ground, and the dielectric constant of the dielectric can be any value.

[0014] Furthermore, the fan-shaped ring patch is parallel to the metal ground, and the distance between the fan-shaped ring patch and the metal ground is less than 0.06 times the wavelength.

[0015] Furthermore, the short-circuit post is arranged at the location where the surface current density of the low-order resonant mode of the fan-shaped patch is maximum, so as to excite and disturb the low-order resonant mode and couple with the high-order resonant mode to realize circularly polarized radiation. The fan-shaped patch, metal ground and short-circuit post constitute a tuning structure of the low-order resonant mode, antenna operating frequency band and circularly polarized radiation.

[0016] On the other hand, the present invention provides a two-dimensional circularly polarized beam frequency scanning antenna, which is obtained by the above-mentioned design method.

[0017] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects: (1) The antenna of the present invention is implemented by a fan-shaped patch structure, which has a simple structure and can reasonably and flexibly adjust multiple working modes on a single patch structure to achieve circular polarization beam scanning capability, effectively reducing the structural complexity of the traditional antenna array to achieve two-dimensional beam scanning performance; (2) The antenna of the present invention has circular polarization beam scanning capability in the azimuth plane and the elevation plane, that is, it can achieve a beam scanning range of 0°~40° in the azimuth plane and a beam scanning range of 3°~37° in the elevation plane; (3) The antenna of the present invention has the advantages of low profile, high gain, easy processing, and convenient mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a top view structural schematic diagram and a reference coordinate system of the two-dimensional circularly polarized beam frequency scanning antenna of the present invention.

[0019] Figure 2 It is a three-dimensional schematic diagram and reference coordinate system of the two-dimensional circular polarization beam frequency scanning antenna of the present invention.

[0020] Among them, 1 is a fan-shaped patch, 2 is a metal ground, 3 is a short-circuit wall, 4 is a short-circuit column, and 5 is a coaxial feeding unit.

[0021] Figure 3 It is the simulated reflection coefficient (S11) of Example 1 of the two-dimensional circularly polarized beam frequency scanning antenna of the present invention.

[0022] Figure 4 It is an axial ratio frequency response diagram of Example 1 of the two-dimensional circularly polarized beam frequency scanning antenna of the present invention at different azimuth angles and elevation angles.

[0023] Figure 5 is the radiation pattern of the two-dimensional circularly polarized beam frequency scanning antenna example 1 of the present invention at different azimuth angles, elevation angles, and frequencies, where (a) is the frequency f is 3.2GHz, and the azimuth plane is located at φ =0° plane, (b) is the frequency f is 3.5GHz, and the azimuth plane is located at φ =15° plane, (c) is the frequency f is 3.64GHz, located in the azimuth plane φ =30° plane, (d) is the frequency f is 3.64GHz, located in the azimuth plane φ =40° plane. DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0025] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0026] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings: The mathematical principle of the design method of the two-dimensional circularly polarized beam frequency scanning antenna proposed in the present invention can be described by equation (1):

[0027] In the formula, k is a free space beam, α is the central angle of the fan-shaped patch, a and b are the inner and outer diameters of the fan-shaped patch, ν is the circumferential eigenvalue determined by the central angle of the fan-shaped patch, and yes ν The derivatives of the first and second Bessel functions of the order. The antenna operating mode is determined by the roots of equation (1) of the ring sector patch, the central angle α , inner diameter a and outer diameter b Commonly determined, inner diameter a and outer diameter b It is composed of the inner arc length, outer arc length and central angle α It is determined that the lengths of the inner arc and the outer arc are odd multiples of 1 / 4 of the wavelength corresponding to the center frequency of the antenna working frequency band, and two or more working modes are effectively excited to realize a two-dimensional circularly polarized beam frequency scanning antenna.

[0028] like Figure 1 and Figure 2 As shown, a two-dimensional circular polarization beam frequency scanning antenna and a design method thereof of the present invention comprises a fan-shaped patch 1, a metal ground 2, a short-circuit wall 3, a short-circuit column 4 and a coaxial feeding unit 5. A straight edge of the fan-shaped patch 1 is connected to the metal ground 2 through the short-circuit wall 3, forming a non-closed structure with three open sides and one closed side.

[0029] During specific implementation, the fan-shaped ring patch 1 is located above the metal ground 2 and is parallel to the metal ground 2 , and the distance between the two is less than 0.06 times the wavelength.

[0030] In specific implementation, the feeding point of the coaxial feeding unit 5 is located at the edge of the open circuit end of the circumferential boundary of the non-closed structure. It should be noted here that the edge of the open circuit end of the circumferential boundary of the non-closed structure is the edge of the non-short-circuited straight side.

[0031] Furthermore, the distance between the feeding point and the center of the fan-shaped ring patch 1 ranges from 1.07 times the inner diameter of the fan-shaped ring patch 1 to 0.99 times the outer diameter of the fan-shaped ring patch 1 .

[0032] In specific implementation, by adjusting the inner and outer diameters and the central angle of the fan-shaped patch 1 and the position of the short-circuit post 4, the antenna can be regulated in two or more working modes, thereby realizing the two-dimensional beam scanning design of the circularly polarized antenna.

[0033] Furthermore, the short-circuit post 4 is placed at the location where the surface current density of the low-order resonant mode of the fan-shaped ring patch 1 is the largest, to excite and disturb the low-order resonant mode, and couple with the high-order resonant mode to achieve circularly polarized radiation. The fan-shaped ring patch 1, the metal ground 2 and the short-circuit post 4 constitute a tuning structure for the low-order resonant mode, the antenna operating frequency band and the circularly polarized radiation.

[0034] In specific implementation, the lengths of the inner arc and the outer arc of the fan-shaped ring patch 1 are odd multiples of 1 / 4 of the wavelength corresponding to the center frequency of the antenna working frequency band; the central angle range of the fan-shaped ring patch 1 is 180°~350°; a medium is filled between the fan-shaped ring patch 1 and the metal ground 2, and the dielectric constant of the medium can be any value; the distance between the fan-shaped ring patch 1 and the metal ground 2 is less than 0.06 times the wavelength.

[0035] Compared with the two-dimensional beam scanning array antenna, the two-dimensional circular polarization beam frequency scanning antenna designed by the present invention adopts a simple and novel fan-shaped ring structure, and realizes two-dimensional circular polarization beam scanning by exciting two or more resonant modes of the antenna and adjusting the amplitude of the radiation electric field components to be equal and the phase to be orthogonal. The structure of the antenna is simple and easy to design. The resonant frequency and working mode are adjusted by correcting the center angle and inner and outer diameters of the fan-shaped ring patch 1; the circular polarization beam scanning angle and scanning range are adjusted by correcting the position of the short-circuit column 4; and the impedance matching characteristics of the antenna can be improved to a certain extent by correcting the position of the coaxial feeding point, thereby meeting the setting requirements of the wireless system. Example

[0036] The antenna of this embodiment uses air as the dielectric medium (dielectric constant is 1), the distance between the fan-shaped patch 1 and the metal ground 2 is 5 mm, the outer diameter of the fan-shaped patch 1 is 20 mm, the inner diameter is 4 mm, the inner and outer diameter ratio is 5, the central angle of the fan-shaped patch 1 is 330°, the radius of the metal ground 2 is 60 mm, the distance between the coaxial feeding point and the center of the circle is 16 mm, and the distance between the short-circuit column 4 and the center of the circle is 14 mm.

[0037] Compare with Figure 3 , Figure 3 The reflection coefficient S of the antenna in Example 1 is given as 11 .Depend on Figure 3 It can be seen that the working frequency range of the antenna (S 11 >-10dB) is 2.56~3.73GHz, and the relative bandwidth reaches 37.2%. It can be seen that the antenna has dual-harmonic broadband radiation characteristics.

[0038] Compare with Figure 4 , Figure 4 The axial ratio frequency response diagram of the antenna of Example 1 at different azimuth angles and elevation angles is given. Figure 4 It can be seen that the antenna is yz It exhibits good circularly polarized beam scanning capability and can achieve a two-dimensional beam scanning range of 40° in azimuth and 34° in elevation.

[0039] Compare with Figure 5 , Figure 5 The radiation patterns of the antenna in Example 1 at different azimuth angles, elevation angles, and frequencies are given. Figure 5 It can be seen that when the frequency f is 3.2GHz, located in the azimuth plane φ =0° plane, the best pointing direction of circularly polarized beam is ( φ , θ ) = (0°, 10°); when the frequency f is 3.5GHz, located in the azimuth plane φ =15° plane, the best pointing direction of circular polarization beam is ( φ , θ ) = (15°, 20°); when the frequency f is 3.64GHz, located in the azimuth plane φ =30° plane, the best pointing direction of circular polarization beam is ( φ , θ ) = (30°, 30°); when the frequency f is 3.64GHz, located in the azimuth plane φ =40° plane, the best pointing direction of circular polarization beam is ( φ , θ ) = (40°, 35°), realizing two-dimensional circular polarization beam scanning that varies with frequency.

[0040] In summary, the two-dimensional circularly polarized beam frequency scanning antenna designed in the present invention can obtain good two-dimensional circularly polarized beam scanning capability for different operating frequency bands of wireless communication systems by simply adjusting the central angle and inner and outer diameters of the fan-shaped patch and the position of the short-circuit post, thereby achieving flexible universality and good compatibility in antenna design and application.

[0041] The above description is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technology can understand and think of any changes or substitutions within the technical scope disclosed by the present invention, which should be included in the scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A design method for a two-dimensional circularly polarized beam frequency scanning antenna, characterized in that: The design method comprises: A fan-shaped ring patch (1) is arranged above the metal ground (2); A straight edge of the fan-shaped ring patch (2) is connected to the metal ground (2) via a short-circuit wall (3), forming a non-enclosed structure in which one straight edge is short-circuited and the other straight edge and the inner and outer arcs are open; A coaxial feeding unit (5) is arranged on the non-enclosed structure for feeding; A short-circuit post (4) connected to the metal ground (2) is arranged on the fan-shaped ring patch (1), and by changing the inner and outer diameters and the center angle of the fan-shaped ring patch (2) and the position of the short-circuit post (4), the antenna can be regulated in two or more working modes, thereby realizing a two-dimensional beam scanning design of a circularly polarized antenna.

2. The design method of the two-dimensional circularly polarized beam frequency scanning antenna according to claim 1, characterized in that: The arc lengths of the outer and inner arcs of the fan-shaped ring patch (2) are both odd multiples of 1 / 4 of the wavelength corresponding to the center frequency of the antenna's operating frequency band.

3. The design method of the two-dimensional circularly polarized beam frequency scanning antenna according to claim 1, characterized in that: The ratio of the arc lengths of the outer and inner arcs of the sector ring patch (2) is greater than 1.

4.

4. The design method of the two-dimensional circularly polarized beam frequency scanning antenna according to claim 1, characterized in that: The feeding point of the coaxial feeding unit (5) is located at the edge of the open straight side of the non-enclosed structure.

5. The design method of the two-dimensional circularly polarized beam frequency scanning antenna according to claim 1, characterized in that: The distance between the feeding point of the coaxial feeding unit (5) and the center of the fan-shaped patch (1) ranges from 1.07 times the inner diameter of the fan-shaped patch (1) to 0.99 times the outer diameter of the fan-shaped patch (1).

6. The design method of the two-dimensional circularly polarized beam frequency scanning antenna according to claim 1, characterized in that: The central angle of the fan-shaped patch (2) ranges from 180° to 350°.

7. The design method of a two-dimensional circularly polarized beam frequency scanning antenna according to claim 1, characterized in that: A medium is filled between the fan-shaped ring patch (2) and the metal ground (2).

8. The design method of a two-dimensional circularly polarized beam frequency scanning antenna according to claim 1, characterized in that: The fan-shaped ring patch (1) is parallel to the metal ground (2), and the distance between the fan-shaped ring patch (2) and the metal ground (2) is less than 0.06 times the wavelength.

9. The design method of the two-dimensional circularly polarized beam frequency scanning antenna according to claim 1, characterized in that: The short-circuit column (4) is arranged at a location where the surface current density of the low-order resonance mode of the fan-shaped ring patch (2) is maximum.

10. A two-dimensional circularly polarized beam frequency scanning antenna, characterized in that: The antenna is obtained by any design method described in claims 1 to 9.

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