Narrow-beam high-gain low-sidelobe antenna

Abstract

The invention discloses a narrow-beam high-gain low-sidelobe antenna which comprises a profile structural member, a waveguide slot line source and a polarization array. The length direction of the trumpet-shaped cavity is set as the X direction, the width direction of the trumpet-shaped cavity is set as the Y direction, and the height direction of the trumpet-shaped cavity is set as the Z direction; the waveguide slot line source is arranged at the necking part of the horn-shaped cavity and is arranged along the X direction; the polarization array is arranged at a flaring of the horn-shaped cavity; the polarization array comprises a plurality of metal sheets which are uniformly distributed along the X direction at intervals D; wherein the distance D is 0.2-0.5 times of the electromagnetic wave length; the long edge of each metal sheet is arranged in the Y direction, the height of each metal sheet is arranged in the Z direction, and the width of each metal sheet in the X direction does not exceed 1 mm. According to the invention, the gain in indexes after integration with the cover is greater than 37.3 dBi; the broadband is larger than 0.5 Ghz, the beam width is smaller than 0.42 degrees, the sidelobe level is smaller than-30 dB, and the broadband broadband low-noise amplifier can safely operate in various severe environments such as rainstorm, salt mist and rain and snow.

Description

Technical Field

[0001] The invention relates to the field of radar antennas, in particular to a narrow beam high gain low side lobe antenna. Background Art

[0002] Antenna is an important equipment in radar for radiating and receiving electromagnetic waves to observe and perceive target information. Radar antenna has the function of focusing electromagnetic waves into beams, and emitting and receiving electromagnetic waves in a directionally direction. Important tactical performances of radar, such as detection distance, detection range, angle measurement (azimuth, elevation) accuracy, angle resolution and anti-interference capability are all related to antenna performance. The higher the antenna gain, the longer the radar detection distance and range; the narrower the antenna beam width, the better the radar angle measurement accuracy and angle resolution; the larger the antenna sidelobe level (the ratio of the main lobe to the sidelobe in the antenna radiation pattern), the better the anti-false target interference performance. When the radar is used for target monitoring, it must have the characteristics of high gain, narrow bandwidth and low sidelobe at the same time.

[0003] In theory, horizontal or vertical polarized antennas will generate corresponding vertical or horizontal polarized electromagnetic waves at certain specific angles, which seriously interfere with the normal use of the antenna. This is caused by the radiation principle of the slot waveguide and can only be filtered out by external means (such as polarization grids). Conventional polarization grids are in the form of grids and are close to the waveguide slot line source. When filtering out vertical polarized electromagnetic waves, they also block some normal working horizontal polarized electromagnetic waves. Especially when the grid is close to the waveguide line source, it not only disturbs the radiation field of the antenna, but also reflects some electromagnetic waves back to the waveguide line source, affecting the performance of the antenna.

[0004] In addition, the antenna needs to be equipped with a radome to ensure the stability of commercial use. The electromagnetic waves emitted by the antenna will produce different phenomena such as transmission, reflection, scattering, and diffraction on the radome, which will have a great impact on performance indicators (such as bandwidth, gain, side effects, etc.) and reduce the performance of the radar. Therefore, it is particularly critical to ensure the high performance of the antenna after integration with the radome. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a narrow beam high gain low side lobe antenna in view of the deficiencies of the above-mentioned prior art. The narrow beam high gain low side lobe antenna can simultaneously meet the high performance technical indicators such as detection distance, detection range, angle measurement accuracy, angle resolution and anti-interference capability required by commercial radar, and has high stability.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A narrow beam high gain low side lobe antenna comprises a profile structure, a waveguide crack line source and a polarization array.

[0008] The profile structure has a trumpet-shaped cavity, and the length direction of the trumpet-shaped cavity is set as the X direction, the width direction is set as the Y direction, and the height direction is set as the Z direction.

[0009] The waveguide crack line source is arranged at the constriction of the horn-shaped cavity and arranged along the X direction.

[0010] The polarization array is arranged at the expansion of the horn cavity; the polarization array includes a plurality of metal sheets uniformly arranged at a spacing D along the X direction; wherein the spacing D is 0.2 to 0.5λ; wherein λ is the wavelength of the electromagnetic wave received or radiated by the narrow beam high gain low side lobe antenna in the air.

[0011] The long side of each metal sheet is arranged along the Y direction, the height of each metal sheet is arranged along the Z direction, and the width of each metal sheet in the X direction does not exceed 1 mm.

[0012] The top surface of each metal sheet is flush with the expanded top surface of the trumpet cavity.

[0013] Each metal sheet is rectangular or inverted trapezoidal.

[0014] It also includes an antenna cover, which is arranged on the outer periphery of the profile structure; the material of the antenna cover is a composite material that transmits electromagnetic waves.

[0015] The dielectric constant of the radome is between 1.2 and 3.8.

[0016] The loss tangent of the radome is less than 0.02.

[0017] The thickness of the radome is 0.5λ 罩 , where λ 罩 The wavelength of electromagnetic waves received or radiated by a narrow beam high gain low sidelobe antenna in the antenna cover material.

[0018] The profile structure is an integrally formed aluminum part.

[0019] The electromagnetic waves received or radiated by the narrow-beam high-gain low-sidelobe antenna are horizontally polarized electromagnetic waves.

[0020] The gain is greater than 37.3dBi, the bandwidth is greater than 0.5Ghz, the sidelobe level is less than -30dB, and the beamwidth is less than 0.42°.

[0021] The present invention has the following beneficial effects:

[0022] 1. The polarization array in the present invention is arranged far away from the radiation port of the slot waveguide, so as not to disturb the radiation of the slot waveguide, and at the same time does not block the normal electromagnetic wave port surface, thereby reducing the reflection of the electromagnetic wave and improving the antenna gain.

[0023] 2. The present invention experimentally verifies the material properties of the radome at the beginning of the simulation design, combines the obtained material dielectric constant and loss tangent with the material model of the radome, and fully considers the influence of the radome in the overall design of the antenna, formula derivation, and simulation parameter adjustment, ensuring the high performance of the integrated antenna with radome. It is suitable for safe operation in various harsh environments such as wind and waves, salt spray, rain and snow.

[0024] 3. The antenna performance indicators of the present invention include gain greater than 37.3dBi, bandwidth greater than 0.5Ghz, sidelobe level less than -30dB, and beam width less than 0.42°. The radar angular resolution, power, and false target interference capability are improved. The present invention can realize an integrated narrow beam high-gain low-sidelobe antenna with a cover. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic structural diagram of a narrow beam high gain low side lobe antenna of the present invention is shown.

[0026] Figure 2 An internal cross-sectional view of a narrow beam, high gain, and low side lobe antenna according to the present invention is shown.

[0027] Figure 3 A partially enlarged schematic diagram of the polarization array in the present invention is shown.

[0028] Figure 4 The azimuth direction gain diagram of the antenna of the present invention at the center operating frequency of 9 GHz-9.5 GHz is shown.

[0029] Figure 5 The elevation direction gain diagram of the antenna of the present invention at the center operating frequency of 9.5 GHz is shown.

[0030] Figure 6 The elevation direction gain diagram of the antenna of the present invention at the center operating frequency of 9 GHz is shown.

[0031] Among them are:

[0032] 10. Profile structural parts; 11. Mounting holes;

[0033] 20. Waveguide crack line source; 21. Waveguide buckle; 22. Adapter waveguide; 23. Waveguide connection port;

[0034] 30. Polarization array; 31. Metal sheet;

[0035] 40. Radome. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific preferred embodiments.

[0037] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0038] like Figure 1 and Figure 2 As shown, a narrow beam high gain low side lobe antenna includes a profile structure 10, a waveguide crack line source 20, a polarization array 30 and a radome 40.

[0039] The above-mentioned profile structural member is preferably an integrally formed aluminum member having a horn-shaped cavity. The arrangement of the aluminum member not only serves as a structural support for the entire antenna, but also forms a horn antenna inside, thereby reducing the beam width and improving the antenna gain.

[0040] Furthermore, the side wall of the profile structure preferably has a mounting hole 11, which serves as a mechanical fixing port for the antenna and other radar components.

[0041] In this embodiment, the length direction of the horn cavity is set as the X direction, the width direction is set as the Y direction, and the height direction is set as the Z direction.

[0042] The waveguide crack line source is preferably fixed at the constriction of the horn cavity by waveguide buckle 21 and screws and arranged along the X direction. One end of the waveguide crack line source is connected to the waveguide connection port 23 through the transfer waveguide 22 .

[0043] The waveguide connection port 23 is an electrical connection port between the antenna and the radar transceiver, and is preferably arranged on a profile structure and passes through the antenna cover to transmit / receive electromagnetic waves to the radar transceiver.

[0044] The waveguide crack line source cuts a gap on the waveguide wall, so that the electromagnetic wave propagates inside the waveguide from one end to the other end. Each time the electromagnetic wave passes through a crack on the crack waveguide, it radiates an electromagnetic wave outward. The cutting depth and inclination angle of a single crack jointly determine the waveform of the electromagnetic wave radiated by a single crack. The electromagnetic waves radiated several times are arrayed to eventually form the radiation waveform of the entire antenna.

[0045] like Figure 2 and Figure 3 As shown, the polarization array is set at the expansion of the horn-shaped cavity; the polarization array includes a number of metal sheets 31 uniformly arranged at a spacing D along the X direction; wherein the spacing D is 0.2 to 0.5λ; wherein λ is the electromagnetic wavelength received or radiated by the narrow beam high gain low side lobe antenna. The setting of the spacing D allows horizontally polarized electromagnetic waves to pass through and filters out vertically polarized electromagnetic waves. Therefore, the electromagnetic waves received or radiated by the narrow beam high gain low side lobe antenna of the present invention are horizontally polarized electromagnetic waves.

[0046] The long side of each metal sheet is arranged along the Y direction, the height of each metal sheet is arranged along the Z direction, and the width of each metal sheet in the X direction does not exceed 1 mm.

[0047] The above-mentioned polarization array is arranged far away from the radiation port of the slot waveguide, so as not to disturb the radiation of the slot waveguide, and at the same time does not block the normal electromagnetic wave port surface, thus reducing the reflection of the electromagnetic wave.

[0048] Furthermore, the top surface of each metal sheet is flush with the expanded top surface of the trumpet cavity. Each metal sheet is preferably rectangular or inverted trapezoidal.

[0049] The above-mentioned antenna cover is arranged on the outer periphery of the profile structure; the material of the antenna cover adopts electromagnetic wave transparent composite material, and the material is relatively light.

[0050] Theoretically, when electromagnetic waves pass through the cover material, a part of the electromagnetic waves will be lost by the antenna cover material, and the electromagnetic energy will be converted into heat energy. The antenna cover in the present invention is designed by combining the dielectric constant of the antenna cover with the antenna radiation waveform, and has excellent performance such as loss tangent angle. The loss caused by the cover material is extremely small, and the impact of the antenna cover is reduced to a minimum. At the same time, it can protect the antenna from operating safely in various harsh environments such as heavy rain, salt fog, rain and snow.

[0051] The present application has been verified by preliminary experimental tests that the dielectric constant of the radome material is in the range of 1.2 to 3.8, the loss tangent is less than 0.02, the performance is excellent and the material is light; using the finite element method, in the three-dimensional full-wave electromagnetic simulation software, radomes of different dielectric constants and shapes are placed on the antenna radiation port surface, and simulation optimization is performed to finally select the dielectric constant and radome shape when the overall radiation performance of the antenna is optimal. In the present invention, the radome located above the flared surface of the horn cavity is arched.

[0052] At the same time, at the critical surface between the upper surface of the radome and the external air, part of the electromagnetic waves will be reflected due to the different dielectric constants of the cover material and the air (similar to the projection, reflection, and refraction of light when passing through different materials, and light is also an electromagnetic wave), and the electromagnetic waves will be reflected back, and the remaining electromagnetic waves will be emitted into the external space. The above-mentioned electromagnetic waves reflected back will be reflected twice at the critical surface between the lower surface of the radome and the air inside the cover. We control the thickness of the radome to be 0.5λ 罩 , where λ 罩 The wavelength of electromagnetic waves received or radiated by the narrow beam high gain low sidelobe antenna in the radome material. When it returns to the critical surface between the upper surface of the radome and the external air, it can overlap with the electromagnetic waves of the next wave cycle. Even if the critical surface between the radome and the external air reflects several times, it will overlap with the electromagnetic waves of the following several wave cycles when it returns to the critical surface between the upper surface of the radome and the external air. That is, the electromagnetic wave energy can be perfectly superimposed without affecting the radar performance, which will significantly reduce the impact of the radome material.

[0053] When the present invention is provided with a cover, the following Figure 4 The antenna horizontal radiation pattern shows a gain of more than 37.3dBi and a sidelobe level below -30dB, such as Figure 5 The horizontal wave width shown is less than 0.42°, as Figure 6 The vertical beam width shown is less than 13.2°, which can be used in practical engineering applications of commercial radars. It also has the characteristics of compact structure, easy processing and low cost, and is suitable for safe operation in various harsh environments such as heavy rain, salt fog, rain and snow.

[0054] The preferred embodiments of the present invention are described in detail above; however, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.

Claims

1. A narrow beam high gain low side lobe antenna, characterized in that: It includes a profile structure, a waveguide crack line source and a polarization array; the profile structure has a horn cavity, the length direction of the horn cavity is set to the X direction, the width direction is set to the Y direction, and the height direction is set to the Z direction; The waveguide crack line source is arranged at the constriction of the horn cavity and arranged along the X direction; The polarization array is arranged at the expansion of the horn cavity; the polarization array includes a plurality of metal sheets uniformly arranged at a spacing D along the X direction; wherein the spacing D is 0.2 to 0.5λ; wherein λ is the electromagnetic wavelength received or radiated by the narrow beam high gain low side lobe antenna; The long side of each metal sheet is arranged along the Y direction, the height of each metal sheet is arranged along the Z direction, and the width of each metal sheet in the X direction does not exceed 1 mm.

2. The narrow beam high gain low side lobe antenna according to claim 1, characterized in that: The top surface of each metal sheet is flush with the expanded top surface of the trumpet cavity.

3. The narrow beam high gain low side lobe antenna according to claim 1, characterized in that: Each metal sheet is rectangular or inverted trapezoidal.

4. The narrow beam high gain low side lobe antenna according to claim 1, characterized in that: It also includes an antenna cover, which is arranged on the outer periphery of the profile structure; the material of the antenna cover is a composite material that transmits electromagnetic waves.

5. The narrow beam high gain low side lobe antenna according to claim 4, characterized in that: The dielectric constant of the radome is between 1.2 and 3.

8.

6. The narrow beam high gain low side lobe antenna according to claim 4 or 5, characterized in that: The loss tangent of the radome is less than 0.

02.

7. The narrow beam high gain low side lobe antenna according to claim 4, characterized in that: The thickness of the radome is 0.5λ 罩 ; Among them, λ 罩 The wavelength of electromagnetic waves received or radiated by a narrow beam high gain low sidelobe antenna in the antenna cover material.

8. The narrow beam high gain low side lobe antenna according to claim 1, characterized in that: The profile structure is an integrally formed aluminum part.

9. The narrow beam high gain low side lobe antenna according to claim 1 or 4, characterized in that: The electromagnetic waves received or radiated by the narrow-beam high-gain low-sidelobe antenna are horizontally polarized electromagnetic waves.

10. The narrow beam high gain low side lobe antenna according to claim 1 or 4, characterized in that: The gain is greater than 37.3dBi, the bandwidth is greater than 0.5Ghz, the sidelobe level is less than -30dB, and the beamwidth is less than 0.42°.

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