High-gain planar end-fire circularly polarized antenna with mixed structure

Abstract

The invention discloses a high-gain planar end-fire circularly polarized antenna with a mixed structure, which is loaded on a dielectric substrate with any dielectric constant and comprises a planar rectangular magnetic dipole, a pair of double-sided microstrip lines, a two-dimensional fan-shaped electric dipole and a planar spiral oscillator. The whole planar rectangular magnetic dipole is of a cuboid structure which is short-circuited in the back reflection direction and open-circuited in the other three sides, and the upper (lower) surface of the two-dimensional fan-shaped electric dipole is connected to the upper (lower) surface of the opening of the planar rectangular magnetic dipole through a microstrip line. By changing the radius and the central angle of the electric dipole, the characteristic that the half-power beam width of the azimuth plane and the pitching plane and the 3-dB axial ratio beam width are broadened at the same time can be realized; the spiral oscillator is arranged in the end-fire (+ x) direction of the two-dimensional fan-shaped electric dipole on the dielectric substrate, the resonant structure is used for driving the traveling wave structure to achieve the high-gain end-fire characteristic, and the radiation characteristic that the half-power beam width of a pitching plane (azimuth plane) and the 3-dB axial ratio beam width are equalized is achieved by changing the coupling transition structure between the spiral oscillator and the electric dipole.

Description

Technical Field

[0001] The invention relates to a hybrid structure high-gain planar end-fire circularly polarized antenna, belonging to the fields of wireless communication and microwave technology. Background Art

[0002] With the rapid development of wireless communication technology, high-gain antennas focus electromagnetic energy in a specific direction, thereby improving the coverage and anti-interference ability of communication systems, and have become one of the core technologies supporting remote communications, satellite communications, and radar systems. Traditional high-gain antennas are often large in size and high in profile, which makes it difficult to meet the needs of modern communications for miniaturization and lightweight.

[0003] Although the traveling-wave planar end-fire circularly polarized antenna helps to improve the end-fire gain, it can only maintain the circularly polarized radiation within a narrow angle range close to the end-fire direction, and the profile height is large. The resonant planar end-fire circularly polarized antenna has a simple structure, a low profile, and can relatively easily achieve the characteristics of beam width equalization. However, when existing designs achieve high gain and beam width equalization characteristics at the same time, they usually require a complex structure and introduce high-order mode resonance, resulting in frequency dispersion characteristics. Summary of the invention

[0004] In view of the problems described in the background technology, the present invention proposes a novel hybrid structure high-gain planar end-fire circularly polarized antenna. By driving the traveling-wave planar spiral oscillator through the resonant planar circularly polarized antenna and changing the coupling transition structure, a hybrid high-gain planar end-fire circularly polarized antenna with half-power beam width and axial ratio beam width equalization is realized. The hybrid structure antenna maintains the inherent low-profile characteristics of the resonant antenna, and its profile height is less than 0.06 wavelengths. In addition, the overall width of the antenna is about half a wavelength, and it has broad application prospects in array antenna systems.

[0005] The present invention adopts the following technical solutions to solve the above technical problems: A hybrid structure high-gain planar end-fire circularly polarized antenna, comprising a dielectric substrate; on the dielectric substrate, a planar rectangular magnetic dipole, a pair of double-sided microstrip lines, a two-dimensional sector-shaped electric dipole and a planar spiral vibrator are arranged in sequence from left to right; The planar rectangular magnetic dipole comprises two rectangular patches respectively located on the upper and lower surfaces of a dielectric substrate, and one long side of the two rectangular patches is connected by a short-circuit wall to form a non-closed rectangular parallelepiped structure with one long side short-circuited and the other three sides open-circuited; The two-dimensional fan-shaped electric dipole comprises two fan-shaped patches respectively located on the upper and lower surfaces of a dielectric substrate, wherein the two-dimensional fan-shaped electric dipole arm located on the upper surface of the dielectric substrate is symmetrical with the two-dimensional fan-shaped electric dipole arm on the lower surface about the end-fire direction, and the two fan-shaped patches are respectively connected to the other long sides of the two rectangular patches through microstrip lines; The end of the planar spiral vibrator close to the two-dimensional fan-shaped electric dipole is provided with a coupling transition structure; A feeding structure is arranged on the planar rectangular magnetic dipole.

[0006] Furthermore: the connection point between the fan-shaped patch and the microstrip line is located on a radius parallel to the end-fire direction.

[0007] Furthermore: the coupling transition structure is a single-turn spiral arm or any other structure, including but not limited to an arc structure concentric with the lower surface of the two-dimensional fan-shaped electric dipole, a straight structure, a fan-shaped structure, etc.

[0008] Further: At the center frequency f 0 fixed condition, the width of the plane rectangular magnetic dipole W 0.5 wavelength, length L It is 0.25 wavelength and the height is less than 0.1 wavelength.

[0009] Furthermore: the length of the microstrip line l Greater than or equal to 0.25 wavelength and less than 0.4 wavelength, width w Greater than 0.01 wavelength and less than 0.2 wavelength.

[0010] Furthermore: the central angle of the sector-shaped patch α Greater than or equal to 180° and less than 360°, radius R The wavelength is greater than 0.1 and less than or equal to 0.3; the spacing between the two sector patches is greater than 0.01 and less than 0.1.

[0011] Furthermore: the distance between the two-dimensional fan-shaped electric dipole and the planar rectangular magnetic dipole is less than 0.2 wavelength.

[0012] Furthermore: the single turn length of the planar helical vibrator D h Greater than or equal to 0.75 wavelength and less than or equal to 1 wavelength, single turn width W h Greater than or equal to 0.04 wavelength and less than or equal to 0.2 wavelength, pitch angle β Greater than or equal to 5° and less than or equal to 15°, number of turns N When the number of turns is greater than 3, the end-fire gain of the antenna increases with the increase of the number of turns of the spiral, while the half-power beamwidth and 3-dB axial ratio beamwidth of the antenna decrease with the increase of the number of turns of the spiral.

[0013] Furthermore: the distance between the coupling transition structure and the two-dimensional fan-shaped electric dipole does not exceed 0.25 wavelengths.

[0014] Furthermore: the dielectric constant of the dielectric substrate is 1-100.

[0015] The present invention adopts the above technical solution and has the following technical effects: the present invention uses a resonant planar circularly polarized antenna to drive a planar spiral structure to achieve high-gain end-fire characteristics, and by changing the coupling transition structure between the planar spiral oscillator and the fan-shaped electric dipole, the radiation characteristics of equalization of the half-power beam width and the 3-dB axial ratio beam width in the elevation plane (azimuth plane) are achieved. The planar end-fire circularly polarized antenna realized by the present invention has a simple structure, high gain, wide beam, and low profile. In addition, the overall width of the antenna is about half a wavelength, and it has a wide range of application backgrounds in array system design. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic diagram of the front structure and reference coordinates of an antenna in one embodiment of the present invention; Figure 2 is a three-dimensional schematic diagram of an antenna and a schematic diagram of reference coordinates in one embodiment of the present invention; Figure 3 In one embodiment of the present invention, the antenna reflection coefficient and axial ratio frequency response characteristics are calculated by HFSS software; Figure 4 In one embodiment of the present invention, the antenna gain frequency response characteristic is calculated by using HFSS software; Figure 5 In one embodiment of the present invention, the antenna is calculated using HFSS software at a pitch plane of 2.40 GHz ( zox ) Radiation pattern; Figure 6 In one embodiment of the present invention, the antenna is calculated using HFSS software at 2.40 GHz in the azimuth plane ( xoy ) Radiation pattern; Among them, 1 is a dielectric substrate, 2 is a planar rectangular magnetic dipole, 3 and 3' are microstrip lines, 4 and 4' are fan-shaped patches, 5 is a planar spiral oscillator, 6 is a coupled transition structure, and 7 is a coaxial feed. DETAILED DESCRIPTION

[0017] 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.

[0018] 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.

[0019] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings: like Figure 1 and 2 As shown, the hybrid structure high-gain planar end-fire circularly polarized antenna in this example is made in a dielectric substrate 1 with a dielectric constant of 1.3, and the overall radiating unit includes a planar rectangular magnetic dipole 2, a pair of double-sided microstrip lines 3, 3', a two-dimensional fan-shaped electric dipole, a planar spiral oscillator 5 surrounding the dielectric substrate 1, a coupling transition structure 6 and a coaxial feeding structure 7. The planar rectangular magnetic dipole 2 is generally in the form of a rectangular parallelepiped structure with a short circuit in the back-firing direction and open circuits on the other three sides; two fan-shaped electric dipole arms 4, 4' of the two-dimensional fan-shaped electric dipole are respectively connected to the upper (lower) surface of the opening of the planar rectangular magnetic dipole by a microstrip line 3, 3', and the characteristics of simultaneously widening the half-power beamwidth and the 3-dB axial ratio beamwidth in the azimuth plane and the elevation plane can be achieved by changing the radius and the central angle of the fan-shaped electric dipole; the planar spiral vibrator 5 is arranged in the end-fire (+x) direction of the two-dimensional fan-shaped electric dipole on the dielectric substrate, and a high-gain end-fire characteristic is achieved by driving a traveling wave structure with a resonant structure, and a radiation characteristic of equalizing the half-power beamwidth and the 3-dB axial ratio beamwidth in the elevation plane (azimuth plane) is achieved by changing a coupling transition structure 6 between the planar spiral vibrator and the fan-shaped electric dipole.

[0020] In one embodiment, the cross-sectional height of the antenna is 7 mm; the width of the planar rectangular magnetic dipole is W 27 mm in length L is 54 mm; the central angle of the two-dimensional sector electric dipole α is 135°, radius R 23.2 mm; the length of the double-sided microstrip line l 38.3 mm, width w 4 mm; the number of turns of the planar spiral structure N , pitch angle β , Single turn length D h ,width W h They are 12 turns, 9°, 55.6 mm, and 7 mm respectively; the bending radius of the coupled transition structure is about 79.345°.

[0021] Figure 3The antenna reflection coefficient and axial ratio frequency response characteristics calculated by HFSS software simulation are given. The black line represents the reflection coefficient of the antenna. The antenna's |S11|<-10 dB impedance bandwidth covers 0.3 GHz, and the relative bandwidth is 12.5%. The blue line represents the axial ratio in the positive X-axis direction. The antenna's 3 dB axial ratio bandwidth covers 0.45 GHz, and the relative axial ratio bandwidth is about 18.8%. It can be seen that the antenna has the wide impedance bandwidth and wide axial ratio bandwidth characteristics unique to traveling wave antennas.

[0022] Figure 4 The frequency response characteristics of the antenna end-fire gain calculated by HFSS software simulation are given. At 2.43 GHz, the antenna end-fire gain is as high as 10.3 dBic. In the frequency range of 2.40 ~ 2.46 GHz, the antenna end-fire gain exceeds 10.0 dBic, showing a good high-gain end-fire characteristic.

[0023] Figure 5 and Figure 6 The antenna elevation and azimuth radiation patterns calculated by HFSS software are given. It can be seen that in the elevation plane, the half-power beamwidth and 3-dB axial ratio beamwidth of the antenna are 52° and 64° respectively; in the azimuth plane, the half-power beamwidth and 3-dB axial ratio beamwidth of the antenna are 40° and 55° respectively. The results show that under the combined action of standing waves and traveling waves, the proposed hybrid structure antenna can produce nearly equal half-power beamwidth and 3-dB axial ratio beamwidth.

[0024] In summary, the present invention utilizes a resonant circularly polarized antenna to excite a traveling wave helical oscillator, and designs and implements a high-gain planar end-fire circularly polarized antenna with equalized beam width. By utilizing a simpler structural model of a wide-beam planar end-fire circularly polarized antenna and a planar spiral with a small pitch angle and a smaller single spiral circumference, a higher end-fire gain performance is achieved by changing the coupling transition structure. The hybrid structure high-gain planar end-fire antenna designed by the present invention not only achieves end-fire high gain characteristics, circular polarization characteristics with equalized width of half-power beam angle in elevation / azimuth plane and 3-dB axial ratio beam angle, but also maintains the original low-profile characteristics of the resonant antenna. In addition, the overall width of the antenna is approximately half a wavelength, and it has a wide range of application backgrounds in array system design.

[0025] 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 hybrid structure high-gain planar end-fire circularly polarized antenna, characterized in that: It comprises a dielectric substrate (1); on the dielectric substrate (1), a planar rectangular magnetic dipole (2), a pair of double-sided microstrip lines (3, 3'), a two-dimensional fan-shaped electric dipole and a planar spiral vibrator (5) are arranged in sequence from left to right; The planar rectangular magnetic dipole (2) comprises two rectangular patches respectively located on the upper and lower surfaces of a dielectric substrate, and one long side of the two rectangular patches is connected by a short-circuit wall to form a non-closed rectangular parallelepiped structure with one long side short-circuited and the other three sides open-circuited; The two-dimensional fan-shaped electric dipole comprises two fan-shaped patches (4, 4') respectively located on the upper and lower surfaces of a dielectric substrate, wherein the fan-shaped patch (4) located on the upper surface of the dielectric substrate (1) and the fan-shaped patch (4') located on the lower surface are symmetrical about the end-fire direction, and the two fan-shaped patches are respectively connected to the other long sides of the two rectangular patches through microstrip lines (3, 3'); The end of the planar spiral oscillator (5) close to the two-dimensional fan-shaped electric dipole is provided with a coupling transition structure (6); A coaxial feeding structure (7) is provided on the planar rectangular magnetic dipole (2).

2. The antenna according to claim 1, characterized in that: The connection point between the fan-shaped patch (4, 4') and the microstrip line (3, 3') is located on a radius parallel to the end-fire direction.

3. The antenna according to claim 1, characterized in that: The coupling transition structure (6) is a single-turn spiral arm.

4. The antenna according to claim 1, characterized in that: At the center frequency f 0 fixed condition, the width of the plane rectangular magnetic dipole (2) W 0.5 wavelength, length L It is 0.25 wavelength and the height is less than 0.1 wavelength.

5. The antenna according to claim 1, characterized in that: The length of the microstrip line (3, 3') l Greater than or equal to 0.25 wavelength and less than 0.4 wavelength, width w Greater than 0.01 wavelength and less than 0.2 wavelength.

6. The antenna according to claim 1, characterized in that: The central angle of the sector-shaped patch (4, 4') α Greater than or equal to 180° and less than 360°, radius R The wavelength is greater than 0.1 and less than or equal to 0.3 wavelengths, and the spacing between the two sector-shaped patches (4, 4') is greater than 0.01 and less than 0.1 wavelengths.

7. The antenna according to claim 1, characterized in that: The distance between the two-dimensional fan-shaped electric dipole and the planar rectangular magnetic dipole (2) is less than 0.2 wavelengths.

8. The antenna according to claim 1, characterized in that: The single turn length of the planar helical vibrator (5) D h Greater than or equal to 0.75 wavelength and less than or equal to 1 wavelength, single turn width W h Greater than or equal to 0.04 wavelength and less than or equal to 0.2 wavelength, pitch angle β Greater than or equal to 5° and less than or equal to 15°, number of turns N More than 3 turns.

9. The antenna according to claim 1, characterized in that: The distance between the coupling transition structure (6) and the two-dimensional fan-shaped electric dipole does not exceed 0.25 wavelengths.

10. The antenna according to claim 1, characterized in that: The dielectric constant of the dielectric substrate (1) is 1-100.

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