System and method for improving the directivity pattern of a wedge-shaped radome

Abstract

The present invention discloses a system and method for improving the directional pattern of a wedge-shaped radome, and relates to the field of antenna technology. The invention is used to solve the problem of concave antenna directional pattern in a wedge-shaped radome environment. The present invention divides the internal area of ​​the radome by analyzing the scattering source, places additional dielectric blocks in various areas between the antenna array and the wedge-shaped radome, ensures that the additional dielectric blocks are loaded symmetrically and adjust the size, height and angle, and finally adjusts the dielectric constant of the dielectric blocks to achieve regulation of the zero points of the directional patterns of two columns of antennas at different angles, thereby improving the radiation performance.

Description

Technical Field

[0001] The invention belongs to the technical field of antennas, and in particular relates to a system and method for improving the directional pattern of a wedge-shaped radome. Background Art

[0002] In order to ensure the stability and reliability of the antenna from the influence of the external environment, the antenna is often placed in a radome that meets aerodynamic requirements. The radome is often located in the near field of the antenna, and the radome material is mostly made of ceramics, organic materials or sandwich composite materials, and its dielectric parameters are different from those of the background medium, so the electromagnetic waves radiated by the antenna in the radome will produce amplitude and phase distortion when passing through the radome wall. In addition, the closed antenna cabin structure formed by the radome and the antenna array will form a strong coupling environment between the cabin and the array elements, and cause the electromagnetic waves to reflect multiple times in the antenna cabin, causing multipath transmission effects.

[0003] When the antenna is placed in a wedge-shaped radome, the difference in dielectric constant between the radome material and the air will cause the electromagnetic waves to be reflected and refracted to a certain extent at the interface, and the reflection and refraction characteristics of the wedge-shaped radome are different at different positions, causing the amplitude and phase of the synthesized electromagnetic waves on the outer surface of the radome to be distorted. In addition, there will be strong coupling between the radome and the antenna, which will change the electromagnetic performance of the antenna and lead to the deterioration of the far-field radiation characteristics of the antenna system, thereby affecting the signal transmission or reception capabilities of the radar and navigation communication system, deteriorating the system's anti-interference and anti-reflection capabilities, and reducing the aiming accuracy.

[0004] In response to the beam distortion caused by the inherent characteristics of the radome, the patent application with the authorization publication number CN108091998A, entitled "A V-shaped radar radome structure and preparation method", announced a method of integrated design of antenna and radome, which ensures that there is no gap between the antenna and the radome, and reduces the influence of multi-layer interfaces on the propagation path. It reduces the influence of multi-layer reflection interference on the surface of the traditional sandwich radome, improves the wave transmittance of the "V" radome, and improves the antenna pattern and phase consistency.

[0005] The prior art designs the antenna, skin and filling core layer to be co-cured, and the antenna is loaded into the filling core layer through the adhesive layer, which limits the size, quantity, and placement of the antenna. In addition, when different types of antennas are used, the radome needs to be redesigned, which increases the complexity of the design and lacks certain universality for the antenna. Summary of the invention

[0006] In view of the above-mentioned problems, the present invention proposes a system and method for improving the radiation pattern of a wedge-shaped radome. The present invention loads dielectric blocks with different dielectric constants at specific positions and angles in the cavity of the radome, and for oblique polarization antennas, realizes the regulation of the reflection angle, reflection coefficient, transmission angle, and transmission coefficient, thereby ensuring the phase consistency of each electromagnetic wave component at the outer skin of the radome, thereby solving the problem of radiation pattern distortion.

[0007] The above purpose is achieved through the following technical solutions:

[0008] The present invention first provides a method for improving the directional pattern of a wedge-shaped radome, the method comprising the following steps:

[0009] Step 1, divide the internal area of ​​the wedge-shaped radome. The specific method is to use electromagnetic simulation software to simulate the initial model of the wedge-shaped radome + antenna array, determine the angle of the radiation zero point from the simulated directional diagram, draw a line from the radiation zero point to the radiation center of the antenna, and form an intersection with the radome. The electromagnetic wave at the intersection is the vector sum of the direct transmission wave and the indirect reflection wave. The indirect reflection wave is a reflection wave generated by a part of the electromagnetic wave radiated to the left side of the wedge-shaped radome failing to pass through the wedge-shaped radome, and its reflection path passes through the radiation zero point on the right side of the wedge-shaped radome. According to the source of the indirect reflection wave, the inside of the wedge-shaped radome is divided as follows:

[0010] First, a comparison diagram of the horizontal polarization radiation pattern of the elevation plane of the wedge-shaped radome + antenna array and the single antenna array under the condition of left antenna feeding is made. The introduction of the wedge-shaped radome in the comparison diagram leads to the generation of a radiation zero point HNL1 and HNR1 in the left and right half airspaces of the horizontal polarization radiation pattern respectively. The airspace inside the radome where the radiation zero point is located is recorded as area A and area B.

[0011] Then, a comparison diagram of the vertical polarization radiation pattern of the pitch plane of the wedge-shaped radome + antenna array and the single antenna array under the condition of left antenna feeding is made. In this comparison diagram, the introduction of the wedge-shaped radome results in two radiation zero points VNL1 and VNL2 in the left half of the vertical polarization radiation pattern, and the airspace inside the radome where they are located is recorded as area C and area D, and a radiation zero point VNR1 is generated in the right half of the airspace, and the airspace inside the radome where it is located is recorded as area E;

[0012] According to the principle of proximity, regions A and B where HNL1 and HNR1 are located are merged into region 1; regions C and E where VNL1 and VNR1 are located are merged into region 2; and region D is recorded as region 3;

[0013] Step 2, placing additional dielectric blocks between the antenna and the wedge-shaped antenna cover to ensure that a group of dielectric blocks are symmetrically placed. The specific process is to symmetrically place dielectric blocks D1 and D2 in area 1, symmetrically place dielectric blocks D3 and D4 in area 2, and symmetrically place dielectric blocks D5 and D6 in area 3;

[0014] Step 3, adjust the material dielectric constant of the additional dielectric block in each of the three areas in the simulation software. Changing the dielectric constant of the dielectric block may improve a certain zero point in the radiation pattern, but may deteriorate a certain zero point. The principle of adjustment is to give priority to improving the first zero point and the second zero point in the radiation pattern, and finally determine the dielectric constant of the dielectric block based on the overall effect.

[0015] Furthermore, the dielectric block is made of common high-frequency board material, and the dielectric block is fixed by using PMI foam as a support: the specific fixing method is to first fill the gap between the array antenna and the antenna cover with PMI foam, and then cut a groove on the PMI foam according to the placement position determined in step two to insert the dielectric block into it.

[0016] Furthermore, the length of the dielectric block is equal to the length of the antenna array, the width is controlled within 20 mm, the height is set at the center height of the area where the dielectric block is located, and the angle between the dielectric block and the antenna array is not greater than the angle between the wedge cover and the antenna array.

[0017] Furthermore, the dielectric constants of the dielectric blocks in step 3 are finally selected as 9.8 for dielectric blocks D1 and D2, 4.4 for dielectric blocks D3 and D4, and 2.65 for dielectric blocks D5 and D6.

[0018] The present invention also provides a system for improving the directivity pattern of a wedge-shaped radome, the system comprising a wedge-shaped radome, wherein three pairs of dielectric blocks are arranged inside the wedge-shaped radome using the above method.

[0019] Compared with the prior art, the present invention has the following significant advantages:

[0020] 1. The present invention uses an additional structure to compensate for the antenna array pattern without changing the design of the radome and the antenna array element itself;

[0021] 2. The additional medium block loaded by the present invention has a simple structure and does not require additional processing, which is easy to implement;

[0022] 3. In view of actual needs, the antenna array element of the present invention adopts an oblique polarization antenna, which can take into account both horizontal polarization and vertical polarization. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the structure of the wedge-shaped radome directivity pattern improvement system proposed by the present invention;

[0024] Figure 2 In the figure, (a) is a schematic diagram of the radome system and electromagnetic wave synthesis, and (b) is a diagram of the internal area division of the radome;

[0025] Figure 3 is the far-field radiation pattern;

[0026] Figure 4 To compare the radiation patterns before and after loading the radome, Figure 4 (a) is horizontal polarization and (b) is vertical polarization.

[0027] Figure 5 Schematic diagram for loading additional media blocks;

[0028] Figure 6 The comparison of the radiation pattern at 13 GHz between the original antenna and the wedge-shaped antenna cover with and without the wedge-shaped antenna cover with the proposed pattern improvement system is shown in FIG. Figure 6 (a) is horizontal polarization, Figure 6 (b) is vertical polarization. DETAILED DESCRIPTION

[0029] In the following, in conjunction with the accompanying drawings, a system for improving the directivity pattern of a wedge-shaped antenna cover proposed by the present invention is described in detail with reference to a specific embodiment.

[0030] like Figure 1 The figure shows the structure schematic diagram of the directional diagram improvement system of the wedge-shaped radome proposed in the present invention. In the figure, the wedge-shaped radome takes the form of outer skin-core layer-inner skin, in which: 1, outer skin; 2, inner skin; 3, core layer; 4, additional dielectric block; 5, oblique polarization antenna array; the radome in this embodiment has an opening angle of 20°, the oblique polarization antenna array adopts a 2×8 array, and additional dielectric blocks are added to three areas inside the radome.

[0031] The present invention also provides a method for improving the directional pattern of a wedge-shaped radome, and the specific steps are as follows:

[0032] Step 1, divide the internal area of ​​the radome. The specific process is to use electromagnetic simulation software to simulate the initial model of the radome + antenna array. The electromagnetic simulation software used in this embodiment is HFSS. Of course, other electromagnetic simulation software can also be used to determine the angle of the radiation zero point from the directional diagram obtained by simulation, such as Figure 2 As shown, a line is drawn from the zero point to the antenna radiation center (i.e., the antenna center), forming an intersection with the antenna cover. The electromagnetic wave at this point is the vector sum of the direct transmission wave and the indirect reflection wave. The reflection wave is a reflection wave generated by a part of the electromagnetic wave radiated to the left antenna cover that fails to pass through the antenna cover. Its reflection path passes through the radiation zero point on the right antenna cover. According to the source of the indirect reflection wave, the inside of the antenna cover is divided into several areas: as shown in the figure, Figure 4 (a) is a comparison diagram of the horizontal polarization radiation pattern of the elevation plane of the radome + antenna array and the single antenna array when the antenna is fed on the left. The introduction of the wedge radome results in a radiation zero point HNL1 and HNR1 in the left and right half of the radome. The airspace inside the radome where the radiation zero point is located is recorded as area A and area B. Figure 4 (b) is the vertical polarization radiation pattern of the radome + antenna array and the single antenna array in the case of antenna feeding on the left side. The introduction of the wedge radome causes two radiation zeros VNL1 and VNL2 in the left half of the vertical polarization pattern. The airspace inside the radome where they are located is recorded as region C and region D. A radiation zero VNR1 is generated in the right half of the airspace, and the airspace inside the radome where it is located is recorded as region E. Since the heights of regions A and B are very close, they are merged into region 1. Since the heights of regions C and E are very close, they are merged into region 2, and region D is recorded as region 3.

[0033] Step 2, place the additional dielectric block between the antenna and the wedge-shaped radome to ensure that a group of dielectric blocks are placed symmetrically. The specific process is to place dielectric blocks D1 and D2 in area 1, dielectric blocks D3 and D4 in area 2, and dielectric blocks D5 and D6 in area 3. Common high-frequency board materials such as PTFE, glass fiber composite materials, ceramic substrates, etc. are selected for the dielectric blocks. The dielectric blocks are fixed by using PMI foam as a support: since the dielectric constant and loss of PMI foam are close to those of air, the gap between the array antenna and the radome is filled with PMI foam, and then some slots are opened on the foam to insert the dielectric blocks. According to the Huygens principle, the characteristics of electromagnetic waves are regulated inside the radome to achieve the regulation of the synthesized electromagnetic waves on the outer skin surface of the radome. Through simulation, the size, height and angle of different dielectric blocks are continuously adjusted, and the improvement trend of several radiation zero points is observed at the same time. According to the use needs, the improvement effect of the first and second zero points is prioritized. When this requirement is met, the size, height and angle of the dielectric block can be preliminarily determined. The length of the dielectric block is equal to the length of the antenna array, the width is controlled within 20mm, the height is as close as possible to the center height of the area, and the angle between the dielectric block and the antenna array is not greater than the angle between the wedge cover and the antenna array;

[0034] Step 3, adjust the material dielectric constant of the additional dielectric block in each area in the simulation software. This embodiment uses HFSS simulation software. Changing the dielectric constant of the dielectric block may improve a certain zero point of the directional diagram, but deteriorate a certain zero point. According to the principle of giving priority to improving the first and second zero points, the dielectric constant of the dielectric block is determined by comprehensively considering the overall effect: the dielectric constants of D1 and D2 are 9.8, the dielectric constants of D3 and D4 are 4.4, and the dielectric constants of D5 and D6 are 2.65.

[0035] Figure 2This is a schematic diagram of the distortion of the radiation pattern when the antenna is placed in a wedge-shaped radome environment. The field on the outer surface of the radome includes direct transmission waves and indirect reflection waves. The electromagnetic wave at a certain point on the radome is the vector sum of the direct transmission wave and the indirect reflection wave. When the direct transmission wave and the indirect reflection wave at a point on the radome surface are superimposed in anti-phase, a zero point will appear in the radiation pattern.

[0036] Figure 3 This is an antenna-wedge-shaped radome system without additional structure. When the left antenna is fed, the horizontal polarization radiation pattern of the elevation plane at the 13GHz frequency point has a radiation zero point in both the left and right half-spaces.

[0037] Figure 4 (a) is a comparison of the horizontal polarization radiation patterns of the elevation plane at 13 GHz when the antenna cover + antenna array and the single antenna array are fed by the antenna on the left. The introduction of the wedge antenna cover results in a radiation zero point in both the left and right halves of the pattern. Figure 4 (b) is the vertical polarization radiation pattern of the elevation plane of the radome + antenna array and the single antenna array when the antenna is fed on the left. The introduction of the wedge radome causes a radiation zero point in the right half of the vertical polarization pattern and two radiation zero points in the left half.

[0038] Figure 5 Schematic diagram for loading additional media blocks;

[0039] Figure 6 The comparison of the radiation pattern at 13 GHz between the original antenna and the wedge-shaped antenna cover with and without the wedge-shaped antenna cover with the proposed pattern improvement system is shown in FIG. Figure 6 (a) is a comparison diagram of the horizontal polarization radiation pattern of the elevation plane of the antenna-wedge-shaped radome system after loading the dielectric block. When the left antenna is fed, the radiation zero points in the left and right half of the airspace have been greatly improved. Figure 6 (b) is the vertical polarization radiation pattern in the elevation plane, and the radiation zero point in the right half of the airspace has also been improved to a certain extent. The above are only the best embodiments of the present invention, but the present invention is not limited to the above embodiments. The above specific implementations are only illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, which are all within the protection of the present invention.

Claims

1. A method for improving the directivity pattern of a wedge-shaped radome, characterized in that: The method comprises the following steps: Step 1, divide the internal area of ​​the wedge-shaped radome. The specific method is to use electromagnetic simulation software to simulate the initial model of the wedge-shaped radome + antenna array, determine the angle of the radiation zero point from the simulated directional diagram, draw a line from the radiation zero point to the radiation center of the antenna, and form an intersection with the radome. The electromagnetic wave at the intersection is the vector sum of the direct transmission wave and the indirect reflection wave. The indirect reflection wave is a reflection wave generated by a part of the electromagnetic wave radiated to the left side of the wedge-shaped radome failing to pass through the wedge-shaped radome, and its reflection path passes through the radiation zero point on the right side of the wedge-shaped radome. According to the source of the indirect reflection wave, the inside of the wedge-shaped radome is divided as follows: First, a comparison diagram of the horizontal polarization radiation pattern of the elevation plane of the wedge-shaped radome + antenna array and the single antenna array under the condition of left antenna feeding is made. The introduction of the wedge-shaped radome in the comparison diagram leads to the generation of a radiation zero point HNL1 and HNR1 in the left and right half airspaces of the horizontal polarization radiation pattern respectively. The airspace inside the radome where the radiation zero point is located is recorded as area A and area B. Then, a comparison diagram of the vertical polarization radiation pattern of the pitch plane of the wedge-shaped radome + antenna array and the single antenna array under the condition of left antenna feeding is made. In this comparison diagram, the introduction of the wedge-shaped radome results in two radiation zero points VNL1 and VNL2 in the left half of the vertical polarization radiation pattern, and the airspace inside the radome where they are located is recorded as area C and area D, and a radiation zero point VNR1 is generated in the right half of the airspace, and the airspace inside the radome where it is located is recorded as area E; According to the principle of proximity, regions A and B where HNL1 and HNR1 are located are merged into region 1; regions C and E where VNL1 and VNR1 are located are merged into region 2; and region D is recorded as region 3; Step 2, placing additional dielectric blocks between the antenna and the wedge-shaped antenna cover to ensure that a group of dielectric blocks are symmetrically placed. The specific process is to symmetrically place dielectric blocks D1 and D2 in area 1, symmetrically place dielectric blocks D3 and D4 in area 2, and symmetrically place dielectric blocks D5 and D6 in area 3; Step 3, adjust the material dielectric constant of the additional dielectric block in each of the three areas in the simulation software. Changing the dielectric constant of the dielectric block may improve a certain zero point in the radiation pattern, but may deteriorate a certain zero point. The principle of adjustment is to give priority to improving the first zero point and the second zero point in the radiation pattern, and finally determine the dielectric constant of the dielectric block based on the overall effect.

2. A method for improving the directivity pattern of a wedge-shaped radome according to claim 1, characterized in that: The dielectric block is made of common high-frequency board material and is fixed by using PMI foam as a support: the specific fixing method is to first fill the gap between the array antenna and the antenna cover with PMI foam, and then cut a slot on the PMI foam according to the placement position determined in step 2 to insert the dielectric block.

3. A method for improving the directivity pattern of a wedge-shaped radome according to claim 1 or 2, characterized in that: The length of the dielectric block is equal to the length of the antenna array, the width is controlled within 20 mm, the height is set at the center height of the area where the dielectric block is located, and the angle between the dielectric block and the antenna array is not greater than the angle between the wedge cover and the antenna array.

4. A method for improving the directivity pattern of a wedge-shaped radome according to claim 1 or 2, characterized in that: The dielectric constants of the dielectric blocks in step 3 are finally selected as 9.8 for dielectric blocks D1 and D2, 4.4 for dielectric blocks D3 and D4, and 2.65 for dielectric blocks D5 and D6.

5. A system for improving the directivity pattern of a wedge-shaped radome, characterized in that: The system comprises a wedge-shaped radome, in which three pairs of dielectric blocks are arranged using the method described in any one of claims 1-4.

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