A millimeter wave band circularly polarized fresnel lens antenna

Abstract

The application provides a millimeter wave frequency band circularly polarized Fresnel lens antenna, which is sequentially provided with a Fresnel lens, a polarizer, a folding member and a linear polarization source from top to bottom, the polarizer is integrated by a plurality of sawtooth-shaped polarization units, the integrated direction of the polarization units is 45 degrees of the polarization direction of the incident electromagnetic wave of the linear polarization source, the folding member is combined by a polarization selector and a polarization twist, and the linear polarization source is fed by a standard WR-15 waveguide. The antenna adopting the technical scheme of the application has the effects of low profile size, high gain, wide bandwidth and circular polarization. The impedance bandwidth of the antenna can reach 50%, the highest gain can reach 26.17dBic, and the axial ratio bandwidth is 29.7%. Meanwhile, the antenna also has the characteristics of high directivity, low sidelobe and narrow beam width, and has great application potential in the field of millimeter waves.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a millimeter-wave band circularly polarized Fresnel lens antenna. Background Technology

[0002] With the continuous development of electronic technology, the demand for high-speed, high-bandwidth data transmission is increasing. Since communication equipment transmits wireless signals through antennas, obtaining high-efficiency antennas directly affects the quality of communication.

[0003] Currently, there are many research directions for antennas, including using antenna arrays to improve antenna gain, using lens antennas to improve antenna gain, using single-feed networks to achieve circular polarization, and using double-feed networks to achieve circular polarization. However, among these methods, those using antenna arrays typically require a complex feeding network, leading to high costs; moreover, as the feeding network increases, the antenna will experience significant insertion loss, reducing efficiency. Lens-based solutions require higher focal lengths, increasing the antenna's design profile height. Single-feed networks result in insufficient axial ratio (AR) bandwidth for the designed CP antenna. Double-feed networks require a complex feeding network, making them prohibitively expensive. Summary of the Invention

[0004] To address the above technical problems, this invention discloses a millimeter-wave band circularly polarized Fresnel lens antenna, which features low profile size, wide bandwidth, high gain, and circular polarization.

[0005] The technical solution adopted by this invention is as follows:

[0006] A millimeter-wave band circularly polarized Fresnel lens antenna comprises, from top to bottom, a Fresnel lens, a polarizer, a folding component, and a linear polarization source. The polarizer is composed of several sawtooth polarization units integrated together, and the folding component is composed of a polarization selector and a polarization torsion device.

[0007] This technical solution uses a Fresnel lens, which can convert the spherical phase plane into a planar phase plane while meeting the requirements of miniaturization, thereby enhancing its directivity and achieving high-gain phase compensation; the polarizer realizes the transition from linear polarization to circular polarization, and uses several sawtooth polarization units as a transition to reduce reflection; the folding component is composed of a polarization selector and a polarization torsion device, realizing "double folding of the wave" and reducing the antenna's profile size.

[0008] As a further improvement of the present invention, the integration direction of the polarization unit is 45° to the polarization direction of the electromagnetic wave incident from the linear polarization source.

[0009] As a further improvement of the application, the polarization unit is a V-shaped dielectric grating, and a plurality of the dielectric gratings are arranged in a horizontal direction.

[0010] As a further improvement of the application, the height of the polarization unit is 10-12 mm, and the angle of the V-shaped polarization unit is 7.5°-8.5°.

[0011] Further preferably, the height of the polarization unit is 11 mm, and the angle of the V-shaped polarization unit is 7.8°.

[0012] As a further improvement of the application, the polarization selector comprises a DiClad880 dielectric substrate and a metal grating, the thickness of the DiClad880 dielectric substrate is 1 / 2 wavelength, the metal grating is integrated by a plurality of parallel microstrip line units, and the grating direction is the same as the polarization direction of the incident electromagnetic wave of the linear polarization source.

[0013] As a further improvement of the application, the polarization twist comprises a metal grating, a Rogers4350 dielectric substrate and a metal surface layer in sequence, the thickness of the Rogers4350 dielectric substrate is 1 / 4 wavelength (the wavelength refers to the wavelength of the 60GHz electromagnetic wave in the material), the metal grating is integrated by a plurality of parallel microstrip line units, and the integrated direction is at an angle of 45° with the polarization direction of the incident wave. By using this technical solution, the metal grating orthogonally decomposes the incident electromagnetic wave into two electromagnetic waves parallel and perpendicular to the integrated direction, reflects the parallel component and transmits the perpendicular component, and the metal surface layer fully reflects the transmitted perpendicular component.

[0014] As a further improvement of the application, the dielectric constant of the Fresnel lens and the polarization device is 2.77, and the loss tangent angle is 0.02. Further, the radius of the Fresnel lens is 35.5 mm.

[0015] As a further improvement of the application, the Fresnel lens and the polarization device are made by a 3D printer.

[0016] As a further improvement of the application, the linear polarization source is provided by a WR-15 waveguide.

[0017] Compared with the prior art, the application has the following beneficial effects:

[0018] The antenna adopting the technical scheme of the application has the effects of low profile size, high gain, wide bandwidth and circular polarization. Further, the antenna is fed by a standard WR-15 waveguide, the impedance bandwidth of the antenna can reach 50%, the gain can be up to 26.17dBic, and the axial ratio bandwidth is 29.7%. Meanwhile, the antenna has the characteristics of high directivity, low sidelobe and narrow beam width, and has great application potential in the field of millimeter wave. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a structural schematic diagram of a millimeter wave frequency band circularly polarized Fresnel lens antenna according to an embodiment of the application.

[0020] Figure 2 is a structural schematic diagram of a Fresnel lens according to an embodiment of the application.

[0021] Figure 3 is a structural schematic diagram of a polarizer according to an embodiment of the application.

[0022] Figure 4 is a front view of a polarizer according to an embodiment of the application.

[0023] Figure 5 is a structural schematic diagram of a polarization selector according to an embodiment of the application.

[0024] Figure 6 is a structural schematic diagram of a polarization rotator according to an embodiment of the application.

[0025] Figure 7 is a reflection coefficient detection result of an antenna according to an embodiment of the application.

[0026] Figure 8 is a relationship curve between the gain of an antenna and the frequency according to an embodiment of the application.

[0027] Figure 9 is an antenna pattern diagram under different frequencies according to an embodiment of the application.

[0028] 1-Fresnel lens, 2-polarizer, 3-folding member, 4-linear polarization source. DETAILED DESCRIPTION

[0029] The following is a further detailed description of a preferred embodiment of the application.

[0030] A millimeter wave frequency band circularly polarized Fresnel lens antenna, as shown in Figure 1 , is composed of four parts: from top to bottom, a Fresnel lens 1, a polarizer 2, a folding structure 3 and a linear polarization source 4. The Fresnel lens 1 and the polarizer 2 can be made by a 3d printer; the relevant parameters are a dielectric constant of 2.77 and a loss tangent angle of 0.02; and the linear polarization source 4 is provided by a standard WR-15 waveguide.

[0031] As shown in Figure 2 , the Fresnel lens works to convert the spherical phase surface into a planar phase surface to enhance its directivity. In simple terms, the lens can achieve high gain through phase compensation. With the Fresnel lens, the profile size can be reduced to meet the design requirements of antenna miniaturization.

[0032] As shown in Figure 3 and Figure 4 , the polarizer is integrated by many sawtooth-shaped polarization units, which can serve as a transition to reduce reflection. The integrated direction of the polarization units is 45° to the polarization direction of the incident electromagnetic wave from the linear polarization source, which is a key condition to achieve circularly polarized waves. When the wave propagates to the polarizer, it can be orthogonally decomposed into two equal-amplitude components, and the directions of the components are perpendicular and parallel to the integrated direction of the polarizer, respectively. When the two components propagate in the polarizer, a phase difference of 90° will be generated due to the difference in permittivity. This can achieve the transition from linear polarization to circular polarization. The present invention verifies that the width and height will affect the performance of CP. When the width is equal to 1.5 mm and the height is 11 mm, the bandwidth of the antenna is the widest and the polarization performance is the best.

[0033] The folding member is composed of both the polarization selector and the polarization twist. As shown in Figure 5 , the polarization selector is composed of a DiClad880 dielectric substrate with a thickness of 1 / 2 wavelength (the wavelength of the substrate at the center frequency (60 GHz)) and a metal grid integrated by multiple parallel microstrip line units, and the grid direction is the same as the polarization direction of the incident electromagnetic wave. When the wave first propagates to the polarization selector, it will be completely reflected due to the direction of the metal grid being parallel to the polarization direction of the wave. The polarization twist reverses the polarization direction by 90°, and when the wave reaches the polarization selector for the second time, the polarization direction is perpendicular to the metal grid, so it is completely transmitted. This is the process of the polarization selector completely reflecting the first incident wave and completely transmitting the second incident wave.

[0034] As shown in Figure 6As shown, the polarization rotator is composed of a metal grid, a Rogers 4350 dielectric substrate and a metal surface layer. The Rogers 4350 dielectric substrate has a thickness of 1 / 4 wavelength (the wavelength of the substrate at the center frequency (60 GHz)), and the metal grid is still integrated by a plurality of parallel microstrip line units, and the integrated direction is at an angle of 45° with the polarization direction of the incident field wave of the linear polarization source. The metal grid orthogonally decomposes the incident electromagnetic wave into two electromagnetic waves parallel and perpendicular to the grid direction, while reflecting the parallel component and transmitting the vertical component. Under the action of the 1 / 4 wavelength substrate and the metal surface, the vertical component of the electromagnetic wave produces a phase shift of 180°. The reflected wave of the polarization rotator is composed of the new vertical component of the electromagnetic wave and the reflected horizontal component. The polarization direction of the synthesized reflected wave is 90° with the incident direction, which is the process of the folding component to realize polarization rotation.

[0035] In general, when the electromagnetic wave is incident on the polarization selector for the first time, it is totally reflected, transmitted to the polarization rotator, and realizes polarization rotation in the polarization rotator, and then transmitted to the polarization selector. When the wave is incident on the polarization selector for the second time, it is totally transmitted and completely transmitted. Through the above process, the "two-fold of the wave" is realized, and the profile size of the antenna is reduced.

[0036] The antenna of the embodiment is tested, Figure 7 The reflection coefficient of the antenna shows that the impedance matching of the antenna is good, and the impedance bandwidth is 50%. The relationship between the antenna gain and the frequency is shown in Fig. 8. Figure 8 As shown in Fig. 9, the highest gain of the antenna is 26.17 dBic, and the ARBW is 29.7%. This proves that the antenna not only can realize high gain, but also can realize wideband circular polarization performance, which meets the design requirements.

[0037] Figure 9 The antenna patterns at different frequencies are shown in Fig. 10. As can be seen from the figure, the antenna is a left-handed circularly polarized antenna with high directivity and low sidelobe.

[0038] The above is a further detailed description of the present application in combination with a specific preferred embodiment, and the specific implementation of the present application cannot be limited to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, which should be regarded as falling within the protection scope of the present application.

Claims

1. A millimeter-wave band circularly polarized Fresnel lens antenna, characterized by: From top to bottom, there are a Fresnel lens, a polarizer, a folding member and a linear polarization source, the polarizer is composed of several sawtooth-shaped polarization units, the integration direction of the polarization units is 45° to the polarization direction of the incident electromagnetic wave of the linear polarization source; the folding member is composed of a polarization selector and a polarization twist; The polarization selector is composed of a DiClad880 dielectric substrate and a metal grid, the thickness of the DiClad880 dielectric substrate is 1 / 2 wavelength, the wavelength is the wavelength of 60GHz electromagnetic wave in the DiClad880 dielectric substrate material; the metal grid is composed of a plurality of parallel microstrip line units, the direction of the metal grid is the same as the polarization direction of the incident electromagnetic wave of the linear polarization source; The polarization twist is composed of a Rogers4350 dielectric substrate, a metal grid and a metal surface layer in turn, the thickness of the Rogers4350 dielectric substrate is 1 / 4 wavelength, the wavelength is the wavelength of 60GHz electromagnetic wave in the Rogers4350 dielectric substrate material; the metal grid is composed of a plurality of parallel microstrip line units, the integration direction is 45° to the polarization direction of the incident wave; The linear polarization source is provided by a WR-15 waveguide.

2. The millimeter-wave band circularly polarized Fresnel lens antenna according to claim 1, characterized in that: The polarization unit is a V-shaped dielectric grid, the height of the polarization unit is 10-12mm, and the angle of the V-shaped polarization unit is 7.5°-8.5°.

3. The millimeter-wave band circularly polarized Fresnel lens antenna according to claim 2, characterized in that: The height of the polarization unit is 11mm, and the angle of the V-shaped polarization unit is 7.8°.

4. The millimeter-wave band circularly polarized Fresnel lens antenna of claim 3, wherein: The dielectric constant of the Fresnel lens and the polarizer is 2.77, and the loss tangent angle is 0.

02.

5. The millimeter-wave band circularly polarized Fresnel lens antenna of claim 1, wherein: The Fresnel lens and the polarizer are made by a 3D printer.

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