Small frequency sweep angle ultralow sidelobe antenna housing integrated waveguide linear array

Abstract

A conventional traveling wave conductor array is large in frequency deflection angle and large in zenith scanning blind area, so that mechanical scanning efficiency is low, and the antenna is prone to being eroded by rainwater, dust and the like, and therefore effective protection measures need to be taken, and the excellent transmission radiation performance of the antenna needs to be guaranteed. Therefore, the invention provides the small-frequency sweep-angle ultralow-sidelobe antenna housing integrated waveguide linear array which is mainly composed of a waveguide coaxial converter, a waveguide slot antenna, a flange, a low-reflection-coefficient load, a radio-frequency signal interface, an inverted-trapezoidal-section antenna housing and a bracket. The linear array has the advantages of ultralow sidelobe, small frequency sweep angle, high power capacity, simple and compact structure, good consistency and the like, and is suitable for forming a large high-performance ultralow sidelobe array plane.

Description

Technical Field

[0001] The present invention belongs to the field of antenna and microwave technology, and particularly relates to a waveguide linear array integrated with a radome having a small frequency scanning angle and an ultra-low sidelobe. Background Art

[0002] Due to the complex working environment of airport weather radars, in order to effectively counter ESM interception and improve the anti-jamming ability of radars, low-sidelobe antennas have become an important part of high-performance electronic systems. In order to work effectively in an environment with severe ground clutter and electronic interference, low-sidelobe array antennas are a general requirement for modern radars.

[0003] The main advantages of waveguide slot traveling-wave antennas are that their aperture amplitude distribution is easy to accurately control, and it is easy to achieve the design requirements of low sidelobes, narrow beams, and shaped beams, meeting the requirements of radar anti-jamming. Traveling-wave antennas have frequency scanning characteristics, and the beam pointing can change with frequency to meet specific coverage requirements. Conventional traveling-wave waveguide linear arrays have a large frequency deviation angle and a large zenith scanning blind area, resulting in a low mechanical scanning efficiency.

[0004] Waveguide slot antennas are hollow metal aluminum tubes with a smooth inner wall. When used in outdoor environments, waveguide antennas are vulnerable to erosion by rain, dust, etc. Therefore, effective protection measures need to be taken, and excellent transmission and radiation performance of the antennas also need to be ensured. Summary of the Invention

[0005] For this reason, the present invention proposes a waveguide linear array integrated with a radome having a small frequency scanning angle and an ultra-low sidelobe. This linear array has the advantages of ultra-low sidelobes, small frequency scanning angles, high power capacity, simple and compact structure, good consistency, etc., and is suitable for forming a large-scale high-performance ultra-low sidelobe array surface.

[0006] A waveguide linear array integrated with a radome having a small frequency scanning angle and an ultra-low sidelobe of the present invention includes a waveguide coaxial transformation, a waveguide slot antenna, a flange, a low reflection coefficient load, a radio frequency signal interface, a radome with an inverted trapezoidal cross-section, and a bracket.

[0007] The waveguide slot antenna is interconnected with the waveguide coaxial transformation and the low reflection coefficient load through a flange, and the waveguide slot antenna is assembled to the antenna array surface skeleton through a bracket to form a large-scale waveguide slot antenna array. Radiation slots are formed by cutting different inclination angles and depths on the narrow side of the hollow metal aluminum tube with a smooth inner wall of the waveguide slot antenna.

[0008] The radome with an inverted trapezoidal cross-section is integrally formed along the axis of the waveguide slot antenna, with a waterproof film attached to the inner surface and a rainproof coating applied to the outer surface. It is bonded to the waveguide slot antenna, and the side is not closely attached to the waveguide, so as not to affect the slot radiation.

[0009] The RF signal interface adopts a coaxial feeding form and is interconnected with the backend power supply through a cable. The signal is fed into the RF signal port and coupled through a probe of a coaxial waveguide transformation, and the RF signal is conducted from the coaxial end to the square waveguide port.

[0010] The end of the waveguide slot antenna is connected to a low reflection coefficient load. In addition to absorbing the remaining energy and reducing the reflected energy, it also weakens the energy reflected towards the feeding end without destroying the ultra-low sidelobe performance.

[0011] Furthermore, the trapezoidal cross-section radome is made of glass fiber and epoxy resin.

[0012] Furthermore, the height of the bracket is greater than 0.5 times the length dimension of the waveguide cross-section and is evenly distributed on the narrow wall of the unradiated slot of the waveguide, so as not to affect the slot radiation and not to destroy the ultra-low sidelobe characteristics.

[0013] The beneficial effects of the present invention are as follows

[0014] 1. Simple structure and low cost: The waveguide-coaxial transformation, waveguide antenna, and low reflection coefficient load are all made of metal. The waveguide antenna is machined, and this process technology is mature, which can meet the consistency requirements of the antenna.

[0015] 2. Lightweight design: The antenna adopts a cavity waveguide, reducing the volume and weight.

[0016] 3. High radiation efficiency: The medium inside the waveguide is air, and the dielectric loss can be ignored. Except for the heat loss caused by the waveguide wall of non-ideal conductor material and the energy absorbed by the load, the remaining energy is radiated into free space.

[0017] 4. Ultra-low sidelobe: Through amplitude Taylor weighting and phase design, the tilt angle and slot depth of each slot of the waveguide slot antenna are adjusted, and the amplitude-phase distribution of the waveguide slot linear array is controlled, so as to achieve a -40dB sidelobe within a 7.5% bandwidth.

[0018] 5. Small frequency scan angle: By reasonably selecting the element spacing, the beam pointing is close to the normal direction, thereby reducing the scanning blind area and improving the scanning efficiency of the radar mechanical scan.

[0019] 6. Protection design: In addition to having process performance requirements such as moisture-proof, dust-proof, and sealing, the cross-section of the radome is trapezoidal, which does not affect the slot radiation and does not destroy the ultra-low sidelobe performance. Description of the Drawings

[0020] Figure 1 It is a three-dimensional view of the waveguide linear array.

[0021] Figure 2 It is a partial three-dimensional view of the waveguide-coaxial transformation and the front end of the waveguide.

[0022] Figure 3It is a partial three-dimensional view of the end of the waveguide array and a low-reflection coefficient load.

[0023] Figure 4 It is a partial three-dimensional view of the waveguide array.

[0024] Figure 5 It is a partial top view of the waveguide array.

[0025] Figure 6 It is a cross-sectional view of the XOZ plane of the waveguide array.

[0026] Figure 7 It is a schematic diagram of the waveguide array prototype.

[0027] Figure 8 It is the measured radiation pattern in the azimuth direction of the waveguide slot antenna within the frequency band.

[0028] The meanings of the reference numerals are as follows: 1. waveguide coaxial transformation; 2. waveguide slot antenna; 3. low-reflection coefficient load; 4. radiation slot; 5. RF signal port; 6. flange; 7. trapezoidal cross-section radome; 8. bracket. Specific embodiments

[0029] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] As Figures 1 - 6 shown, a small frequency-scanning angle and ultra-low sidelobe radome integrated waveguide array of the present invention mainly consists of a waveguide coaxial transformation (1), a waveguide slot antenna (2), a flange (6), a low-reflection coefficient load (3), a trapezoidal cross-section radome (7), etc. from left to right in the azimuth direction.

[0031] The waveguide slot antenna (2) is interconnected with the waveguide coaxial transformation (1) and the low-reflection coefficient load (3) through the flange (6). The flange (6) realizes the connection and fixation of the waveguide slot antenna (2) with the waveguide coaxial transformation (1) and the low-reflection coefficient load (3). The waveguide slot antenna (2) is assembled to the array surface skeleton through the bracket (8) to form a large waveguide slot antenna array. The height of the bracket (8) is greater than 0.5 times the length dimension of the waveguide cross-section and is equally spaced on the narrow wall of the non-radiating slot of the waveguide, ensuring the stability of the antenna center of gravity. The bracket (8) is not allowed to affect the slot radiation and does not destroy the ultra-low sidelobe characteristics.

[0032] The waveguide slot antenna (2) is a hollow metal aluminum tube with a smooth inner wall and narrow edges on which radiation slots (4) of different inclination angles and depths are cut. The inverted trapezoidal cross-section antenna cover (7) can protect the radiation slot (4) from environmental erosion such as rain and dust. The inverted trapezoidal cross-section antenna cover (7) is made of glass fiber and epoxy resin with good weather resistance, and is formed in an integrated manner along the axial direction of the waveguide slot antenna (2). Adhesion is not allowed to affect the antenna radiation and destroy the ultra-low side lobe characteristics. A waterproof film is attached to the inner surface of the antenna cover, and a rainproof coating is applied to the outer surface. Adhesion is used between the antenna cover and the waveguide slot antenna (2) to achieve dustproof and waterproof effects. The cross-section of the antenna cover is an inverted trapezoid, and the side of the antenna cover is not close to the waveguide, so as not to affect the slot radiation.

[0033] The RF signal interface (5) adopts a coaxial feeding form and is interconnected with the back-end power supply through a cable. The signal is fed from the RF signal port (5), and the RF signal is conducted from the coaxial end to the square waveguide port through the probe coupling of the coaxial waveguide conversion (1), thereby exciting the main mode TE10 wave. The end of the waveguide slot antenna (2) is connected to a low reflection coefficient load, which, in addition to absorbing the residual energy and reducing the reflected energy, is required to weaken the energy reflected to the feeding end without destroying the ultra-low sidelobe performance.

[0034] In order to meet the small frequency sweep angle and ultra-low sidelobe performance of the antenna, the electromagnetic field numerical algorithm is combined with simulation technology to achieve ultra-low sidelobe antenna through optimization design and performance comparison. In the design optimization stage, the antenna unit spacing is first determined according to the array aperture to achieve small frequency sweep angle. In the linear array design stage, Taylor weighting is used in the azimuth direction to achieve ultra-low sidelobe, fully considering the mutual coupling effect between adjacent units of the waveguide slot antenna, the approximate design error in the array design, and the error caused by actual processing. The inclination angle and slot depth of each slot, the distance between the radome and the waveguide slot, the absorption rate and reflection coefficient of the waveguide load, the cross-sectional shape of the radome, and the radome forming method are adjusted and optimized. Through the optimization of these parameters, a waveguide line array with low sidelobe, narrow beam, small frequency sweep angle and protection function is finally realized.

[0035] Specific embodiments according to the above-mentioned design, assembly and fixing methods and dimensional requirements are given below.

[0036] 1) The length of the waveguide slot antenna is 80λ0 (λ0 is the free space wavelength of the center frequency), the cross-section is rectangular, and the inner size is 0.74λ0×0.19λ0; the spacing between two adjacent slots of the waveguide slot antenna is 0.61λ0, which realizes small frequency deviation angle scanning, reduces the scanning blind area, and improves the mechanical scanning efficiency; the radome is 0.221λ0 away from the antenna surface, and the thickness of the radome is 0.02λ0, which does not affect the amplitude distribution of the linear array and destroys the ultra-low sidelobe characteristics.

[0037] 2) The main performance indicators achieved by the antenna are:

[0038] Operating frequency: FL~FH (relative bandwidth 7.5% F0);

[0039] Azimuth sidelobe level (lobe level other than the main lobe): < -40 dB;

[0040] Figure 7 This is a schematic diagram of the prototype of the embodiment of the present invention. Figure 8 This is the azimuth normalized radiation pattern tested in the near-field environment for the embodiment of the present invention. In the figure, the abscissa represents the theta angle, the ordinate represents the normalized level (dB), and the three curves represent the radiation patterns of the antenna at high, medium, and low frequency points. It can be seen that the antenna of the present invention can achieve an azimuth sidelobe level better than -40 dB within the operating frequency band, and the high-frequency beam direction is close to the normal direction. Therefore, this antenna has the advantages of ultra-low sidelobe characteristics and a small scanning blind area.

[0041] The present invention is not limited to the above specific embodiments, and the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the technical essence of the present invention shall be included in the protection scope of the present invention.

Claims

1. A small frequency-sweeping angle and ultra-low sidelobe radome integrated waveguide array, characterized in that: It includes a waveguide coaxial transformer, a waveguide slot antenna, a flange, a low reflection coefficient load, a radio frequency signal interface, an inverted trapezoidal cross-section radome, and a bracket; The waveguide slot antenna is interconnected with the waveguide coaxial transformer and the low reflection coefficient load through the flange, and the waveguide slot antenna is assembled to the antenna array frame through the bracket to form a large waveguide slot antenna array; The inverted trapezoidal cross-section radome is integrally formed along the axial direction of the waveguide slot antenna. A waterproof film is pasted on the inner surface, and a rainproof coating is applied on the outer surface. It is adhesively bonded to the waveguide slot antenna, and the side is not closely attached to the waveguide, so as not to affect the slot radiation; The radio frequency signal interface adopts a coaxial feeding form and is interconnected with the rear-end power supply through a cable. The signal is fed into from the radio frequency signal port and is coupled by the probe of the coaxial waveguide transformation to conduct the radio frequency signal from the coaxial end to the square waveguide port; The end of the waveguide slot antenna is connected to a low reflection coefficient load. In addition to absorbing the remaining energy and reducing the reflected energy, it also weakens the energy reflected towards the feeding end and does not damage the ultra-low sidelobe performance.

2. The integrated waveguide array of a small frequency-scanning angle and ultra-low sidelobe radome according to claim 1, wherein: The waveguide slot antenna cuts radiation slots with different angles and depths on the narrow side of a hollow metal aluminum tube with a smooth inner wall.

3. The integrated waveguide array of a small frequency-scanning angle and ultra-low sidelobe radome according to claim 1, characterized in that: The inverted trapezoidal cross-section radome is made of glass fiber and epoxy resin.

4. The integrated waveguide array of a small frequency-scanning angle and ultra-low sidelobe radome according to claim 1, characterized in that: The height of the bracket is greater than 0.5 times the length dimension of the waveguide cross-section and is equally spaced on the narrow wall of the unradiated slot of the waveguide, so as not to affect the slot radiation and not to damage the ultra-low sidelobe characteristics.

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