Supporting structure for antenna, preparation method for supporting structure and use of supporting structure

Abstract

Provided in the embodiments of the present application are a supporting structure for an antenna, a preparation method for a supporting structure, and the use of a supporting structure. The supporting structure is connected between a feed tube of an antenna and a secondary reflective surface thereof, and is specifically a hollow supporting joint, wherein the supporting joint is made of a foaming material, and the size shrinkage rate of the supporting joint after the supporting joint is placed in an environment of a temperature of 70°C-100°C and a relative humidity of 50%-95% for four days is less than or equal to 1%. The secondary reflective surface is supported by using the supporting joint containing the foaming material, causing little obstruction and loss to electromagnetic wave transmission, such that a better antenna performance can be ensured, a lower humidity and heat deformation rate is achieved, and it can be ensured that the antenna performance does not deteriorate significantly during the long-lasting use of the antenna.

Description

Antenna support structure and preparation method and application thereof

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on June 30, 2023, with application number 202310801041.X and application name “Support structure for antenna, preparation method and application thereof”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of microwave antenna technology, and in particular to an antenna support structure and a preparation method and application thereof. Background Art

[0003] Microwave antennas are a crucial component of microwave communication systems. Existing microwave antennas typically utilize dual-reflector antennas, which offer advantages such as short feeder distances, long equivalent focal lengths, and flexible design. These antennas typically consist of a primary reflector, a feed source, a secondary reflector, and a supporting structure for the secondary reflector. The supporting structure is typically mounted directly on the primary reflector or on the feed source tube and is typically a metal bracket. However, metal brackets are complex and can easily block electromagnetic wave transmission, reducing antenna efficiency and affecting the antenna's radiation pattern.

[0004] Summary of the Invention

[0005] In view of this, embodiments of the present application provide a support structure for a sub-reflector, an antenna, etc. that have little impact on the performance of a microwave antenna.

[0006] Specifically, the first aspect of an embodiment of the present application provides a support structure for an antenna, which is used to connect between the feed tube and the sub-reflecting surface of the antenna. The support structure is a hollow support joint, and the support joint is made of foam material. The dimensional shrinkage rate of the support joint after being placed in an environment with a temperature of 70-100°C and a relative humidity of 50-95% for 4 days is less than or equal to 1%.

[0007] The embodiment of the present application uses a hollow support joint made of foam material to support the antenna sub-reflector surface. It has a simple structure and has minimal impact on the obstruction and loss of electromagnetic wave transmission. It also has good resistance to moisture and heat and a small dimensional shrinkage rate, ensuring that the antenna has better near-axis sidelobe performance.

[0008] In the embodiments of the present application, the foam material exhibits a constant Dk of less than or equal to 1.2 at frequencies between 6 and 86 GHz. Due to the foam material's cellular structure, its Dk can be reduced to below 1.2, lower than that of a homogeneous, unfoamed solid material. This ensures that the support joint has minimal impact on electromagnetic wave transmission losses, ensuring superior antenna performance.

[0009] In the embodiment of the present application, the dielectric loss of the foam material at a frequency of 6-86 GHz is less than or equal to 0.005. When the Dk of the foam material is less than or equal to 1.2, controlling the dielectric loss below 0.005 can further ensure that the support joint has a minimal impact on the loss / attenuation of electromagnetic wave transmission, ensuring better antenna performance.

[0010] In the embodiment of the present application, the support joint, with a wall thickness of less than 10 mm, has a transmittance of greater than or equal to 90% for vertically incident electromagnetic waves in the frequency range of 6-86 GHz. This indicates that the support joint has good microwave transparency, which reduces microwave loss in the support joint and thus promotes better antenna performance.

[0011] In the embodiment of the present application, the Shore C hardness of the support joint is greater than or equal to 50. This can reflect to a certain extent that the mechanical strength of the support joint is high and a good support effect can be achieved.

[0012] In the embodiment of the present application, any of the inner surface or outer surface of the support joint is at least 2 cm 2 In the region of , the number of exposed cells is less than or equal to 20. This indicates that the number of exposed cells on the inner and outer surfaces of the support joint is small, which helps to make the support joint more resistant to moisture and heat. In some embodiments of the present application, any of at least 2 cm on the inner or outer surface of the support joint 2 In the area, the number of exposed cells is less than or equal to 5.

[0013] In the embodiment of the present application, the closed cell ratio of the supporting joint is greater than or equal to 90%. A higher closed cell ratio is beneficial for ensuring that the supporting joint has excellent moisture and heat resistance and high structural strength.

[0014] In the embodiment of the present application, the density of the support joint is 0.5g / cm 3 The support joints made of the above foaming materials can also take into account the above-mentioned good moisture and heat resistance and high strength characteristics when the density is low, and have excellent comprehensive performance. In some embodiments, the density of the support joints is 0.08-0.15g / cm 3 .

[0015] In an embodiment of the present application, the glass transition temperature of the support joint is greater than or equal to 150°C. This reflects that the support joint has good heat resistance and is particularly suitable for use in high temperature environments. In some embodiments, the glass transition temperature of the support joint is greater than or equal to 190°C.

[0016] In the embodiment of the present application, the foaming material comprises a polymer having an aromatic structure in the main chain. Aromatic polymers have good heat resistance and a low thermal expansion coefficient, which is also conducive to reducing their dimensional shrinkage.

[0017] In the embodiment of the present application, the polymer includes one or more of polyimide, polyethersulfone, polyarylene ether, and polyarylene sulfide, the main chain of which contains an aromatic structure.

[0018] A second aspect of an embodiment of the present application provides a foam material for use in a support structure of an antenna sub-reflector, wherein the dielectric constant of the foam material at a frequency of 6-86 GHz is less than or equal to 1.2.

[0019] In an embodiment of the present application, the dielectric loss of the foam material at a frequency of 6-86 GHz is less than or equal to 0.005.

[0020] In the embodiment of the present application, the Shore hardness C of the foaming material is greater than or equal to 50.

[0021] In the embodiment of the present application, the density of the foaming material is 0.5g / cm 3 the following.

[0022] A third aspect of an embodiment of the present application provides an antenna assembly, which includes a sub-reflecting surface, a feed tube and a support structure as described in the first aspect of the embodiment of the present application, wherein the opposite ends of the support structure are respectively connected to the feed tube and the sub-reflecting surface.

[0023] A fourth aspect of the embodiments of the present application provides an antenna, which includes a main reflecting surface and the antenna assembly as described in the third aspect of the embodiments of the present application, wherein the feed tube is connected to the main reflecting surface.

[0024] The antenna using the above-mentioned support structure has excellent antenna performance, high polarization gain, good antenna directivity pattern, and little impact on the near-axis sidelobe performance of the antenna.

[0025] A fifth aspect of the embodiments of the present application provides a communication device, which includes the antenna as described in the fourth aspect of the embodiments of the present application, as well as an outdoor unit and an indoor unit.

[0026] A sixth aspect of the present application provides a communication system, comprising at least two communication devices according to the fifth aspect of the present application, wherein the communication devices can communicate with each other. The communication system can operate stably and efficiently.

[0027] The present application also provides a method for preparing the antenna support structure, including:

[0028] The reaction raw materials for forming the support structure are placed in a mold whose cavity shape corresponds to the shape of the support structure to be prepared and sealed. After heat treatment, the reaction raw materials react with each other and generate gas to obtain a hollow support joint containing a foaming material; wherein the support joint has a dimensional shrinkage rate of less than or equal to 1% after being placed in an environment with a temperature of 70-100°C and a relative humidity of 50-95% for 4 days.

[0029] The above preparation method is particularly suitable for in-situ preparation of a support joint with high heat resistance, and giving it a cellular structure, and making the support joint have good moisture and heat resistance and low dielectric properties.

[0030] The present application also provides another method for preparing the antenna support structure, including the following steps:

[0031] The expanded particles are placed in a mold having a cavity shape corresponding to the shape of the support structure to be prepared and sealed. The expanded particles are then treated with hot steam to fuse to form a foamed material, thereby obtaining a hollow support joint. The support joint has a dimensional shrinkage rate of less than or equal to 1% after being placed in an environment with a temperature of 70-100°C and a relative humidity of 50-95% for 4 days.

[0032] The above preparation method is also suitable for making support joints containing foamed materials, and imparting them with low dielectric properties and good moisture and heat resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a schematic diagram showing an exemplary structure of an existing microwave antenna and its supporting structure.

[0034] FIG2 shows a schematic structural diagram of an antenna assembly including a support connector according to an embodiment of the present application, wherein the right figure is a cross-sectional view of the left figure.

[0035] FIG. 3 shows a schematic structural diagram of an antenna with the antenna assembly shown in FIG. 2 .

[0036] FIG4 is a schematic structural diagram of a communication device provided in an embodiment of the present application.

[0037] FIG5 is a schematic structural diagram of a metal bracket for an antenna in Comparative Example 1, wherein the right figure is a cross-sectional view of the left figure.

[0038] FIG6 summarizes the antenna radiation patterns of the antenna of comparative example 1 (a), the antenna of comparative example 2 (b), and the antenna of embodiment 1 (c) in the horizontal polarization direction measured at a frequency of 78.5 GHz.

[0039] FIG7 shows the antenna radiation pattern of the antenna of Example 1 in the horizontal polarization direction measured at a frequency of 78.5 GHz after the damp heat test.

[0040] Explanation of the main figure marks: 200-antenna assembly; 20-support structure or support joint of an embodiment of the present application; 201-first main body; 202-second main body; 21-feed tube; 22-secondary reflector; 23-primary reflector; 300-antenna provided in an embodiment of the present application; 24-radome. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0042] Figure 1 is a schematic diagram of an exemplary structure of an existing microwave antenna and its supporting structure. As shown in Figure 1, microwave antenna 100 includes a main reflector 101, a feed tube 102 connected to the main reflector 101, a sub-reflector 103, and a support bracket 104. The support bracket 104 is used to support the sub-reflector 103 above the feed tube 102 and is connected to the main reflector 101. The support bracket 104 is mostly made of metal and is usually a complex structure composed of multiple parts. Its processing / assembly is difficult and can cause significant obstruction and loss to electromagnetic wave transmission, thereby reducing the antenna's aperture efficiency and gain and affecting its antenna radiation pattern (which can be reflected in degraded antenna near-axis sidelobe performance). Some microwave antennas also have a support structure consisting of multiple dielectric support rods connected between the sub-reflector and the feed tube (such as CN 105161827 A). The dielectric support rods are usually solid structures with a dielectric constant greater than 2, which can also cause obstruction and loss to electromagnetic wave transmission, resulting in deteriorated antenna performance. Therefore, to address the problem that the sub-reflector support structure used in existing microwave antennas easily leads to deterioration of antenna performance, the embodiments of the present application provide a sub-reflector support structure that does not deteriorate the performance of the microwave antenna.

[0043] Please refer to Figure 2, which shows an antenna assembly including a support structure according to an embodiment of the present application. The right figure in Figure 2 is a cross-sectional view of the left figure. The antenna assembly 200 includes a feed tube 21, a sub-reflector 22, and a support structure 20, wherein the opposite ends of the support structure 20 are respectively connected to the feed tube 21 and the sub-reflector 22. The support structure 20 is connected between the feed tube 21 and the sub-reflector 22 of the antenna. The support structure 20 is specifically a hollow support joint 20, which is made of a foam material. The dimensional shrinkage rate of the support joint 20 after being placed in an environment with a temperature of 70-100°C and a relative humidity of 50-95% for 4 days is less than or equal to 1%.

[0044] In this application, the support structure for the antenna sub-reflector is changed from a common complex support bracket to a hollow support joint. The support joint causes little obstruction and loss to the transmission of electromagnetic waves, and it is a single part and does not need to be assembled itself. This can simplify the design, processing, and assembly of the support structure. While ensuring the basic support function, there is no need to design a separate sealing structure for the feed tube to protect the feed set on the feed tube as when using a support bracket. After the support joint 20 is connected to the feed tube 21 and the sub-reflector 22, the feed can be sealed and dustproof. More importantly, the support joint uses a foam material with a pore structure. With the help of a suitable pore structure, when the Dk of the foam material is low, its moisture and heat resistance will not be significantly reduced. Therefore, the support joint has little shrinkage and deformation under high temperature and high humidity conditions, which will not affect the connection reliability between it and the feed tube 21 and the sub-reflector 22, and will not excessively affect the polarization gain and antenna radiation pattern of the antenna.

[0045] Therefore, the support joint made of the foam material provided in the embodiment of the present application is used to support the secondary reflector. It has a simple structure and a low dielectric constant, and has minimal impact on the obstruction and loss of electromagnetic wave transmission, thereby ensuring better antenna performance. At the same time, it can also take into account good moisture and heat resistance, which is conducive to ensuring that it can play a stable supporting / connecting role on the antenna for a long time.

[0046] In the embodiment of the present application, the dimensional shrinkage rate of the support joint 20 after being placed in an environment with a temperature of 70-100°C and a relative humidity of 50-95% for one week (i.e., 7 days) is less than or equal to 1%, for example, less than or equal to 0.8%, less than or equal to 0.5%, less than or equal to 0.3%, etc. In some embodiments, the dimensional shrinkage rate of the support joint 20 after being placed in an environment with a temperature of 85°C and a relative humidity of 95% for 4 days is less than or equal to 1%, and the dimensional shrinkage rate after being placed for one week is still less than or equal to 1%.

[0047] In the embodiments of the present application, the dielectric constant Dk of the foamed material at frequencies between 6 and 86 GHz is less than or equal to 1.2. Due to the appropriate cell structure of the foamed material, the dielectric constant Dk at frequencies between 6 and 86 GHz can be reduced to below 1.2, lower than that of a homogeneous, solid, unfoamed material. As a result, the support structure of the embodiments of the present application has minimal impact on electromagnetic wave transmission losses and, consequently, minimal degradation of antenna performance.

[0048] In the embodiment of the present application, the dielectric loss Df of the foam material at a frequency of 6-86 GHz is less than or equal to 0.005. The lower end of the support joint 20 (i.e., the end close to the feed tube 21) is generally close to the secondary reflector 22. The above-mentioned low Dk performance of the foam material has helped to reduce the blocking / loss of the support joint 20 on the electromagnetic wave transmission. On this basis, controlling Df below 0.005 can further ensure that the support joint 20 has little effect on the loss / attenuation of electromagnetic wave transmission, thereby ensuring better antenna performance. Specifically, the Df can be less than or equal to 0.004, further less than or equal to 0.003, less than or equal to 0.002, or less than or equal to 0.001, etc.

[0049] Among them, the above D k and D f The sample of the foam material can be measured according to the resonant cavity method. Specifically, a grid analyzer can be used for testing, and a fixture with a resonant cavity can be used. Among them, the frequency of 6-86GHz is the common frequency range corresponding to microwaves. Common microwave frequency bands include 6-42GHz, 57-64GHz and 71-86GHz. In this application, the dielectric constant Dk of the above-mentioned foam material at a frequency of 6-42GHz is less than or equal to 1.2; the dielectric constant Dk of the foam material at a frequency of 57-64GHz is less than or equal to 1.2; the dielectric constant Dk of the foam material at a frequency of 71-86GHz is less than or equal to 1.2. The Dk values ​​under each frequency band can be found in the description in the previous paragraph. Similarly, the dielectric loss Df of the foam material at a frequency of 6-42 GHz is less than or equal to 0.005; the dielectric loss Df of the foam material at a frequency of 57-64 GHz is less than or equal to 0.005; and the dielectric loss Df of the foam material at a frequency of 71-86 GHz is less than or equal to 0.005. For the Df values ​​in each frequency band, please refer to the description in the previous paragraph.

[0050] In an embodiment of the present application, the support joint 20, having a wall thickness of less than 10 mm, has a transmittance of 90% or more (i.e., greater than or equal to 90%) for vertically incident electromagnetic waves in the frequency range of 6-86 GHz. This transmittance can be measured according to the method described in the following document: Sichuan Ordnance Journal, Volume 32, Issue 4, "Dielectric Properties and Test Methods of Transparent Dielectric Materials." A transmittance of 90% or more indicates that the foam material used in the support joint 20 has good microwave transparency, resulting in less loss when microwaves pass through the support joint 20, thereby ensuring good performance of antennas using this support structure. In some embodiments, the transmittance is above 92%, and can further be above 95%, for example, 95.5%, 96%, 96.5%, 97%, 98%, or 99%. Electromagnetic waves in the 6-86 GHz range are generally microwaves. As mentioned above, common microwave frequency bands include the 6-42 GHz band, the 57-64 GHz band, and the 71-86 GHz band. The support joint 20 with a wall thickness of less than 10 mm has a wave transmittance of more than 90% for vertically incident microwaves with a frequency range of 6-42 GHz, 57-64 GHz, or 71-86 GHz. For the wave transmittance values ​​within each frequency range, please refer to the description in this paragraph.

[0051] In the embodiments of the present application, the support joint 20 has a Shore C hardness greater than or equal to 50. This, to a certain extent, reflects the high mechanical strength of the support joint 20, which can achieve a good supporting effect. It does not significantly deform when bearing weight and is unlikely to collapse when impacted, thus preventing significant displacement of the secondary reflector 22 and other components supported by it. In some embodiments, the support joint 20 has a Shore C hardness greater than or equal to 70.

[0052] In the embodiment of the present application, any one of the inner surface or outer surface of the support joint 20 is at least 2 cm 2 In the region of the support joint 20, the number of exposed cells is less than or equal to 20. This indicates that the number of exposed cells on the inner and outer surfaces of the support joint 20 is relatively small, which helps to ensure that the support joint 20 has excellent water absorption resistance and high structural / shape stability, such as ensuring that the dimensional shrinkage rate after being placed in high humidity and high heat conditions for 4 days is less than 1%. Specifically, the number of exposed cells is less than or equal to 15, less than or equal to 10, less than or equal to 8, etc. In some embodiments of the present application, any area of ​​at least 2 cm on the inner or outer surface of the support joint 20 2 In the region, the number of exposed cells is less than or equal to 5, and further, there are no exposed cells on the inner and outer surfaces of the support joint 20. In this case, the support joint 20 has better resistance to moisture and heat.

[0053] In embodiments of the present application, the closed-cell ratio of the cells in the support joint 20 is greater than or equal to 90%, for example, greater than 92%, greater than 95%, greater than 96%, greater than 97%, greater than 98%, or greater than 99%. A higher closed-cell ratio indicates that the majority of cells in the support joint 20 are closed cells, which helps ensure the foam material's excellent moisture and heat resistance and high structural strength. The closed-cell ratio of the foam material can be measured according to GB / T 10799-2008. In some embodiments, the cells in the support joint 20 are closed cells, meaning that its closed-cell ratio is 100%.

[0054] In this application, the support joint 20 is a foam material with few surface skin cells, many internal cells, and a high cell closed cell rate. These structural characteristics enable the Dk of the foam material to be below 1.2, and its dimensional shrinkage rate is still below 1% after being placed under high temperature and high humidity conditions for one week.

[0055] In the embodiment of the present application, the density of the support joint 20 is 0.5 g / cm 3 The following. The apparent density of the support joint can be tested according to GB / T6343-2009 standard. The support joint using the above foam material has a low density, which is conducive to ensuring that the device shown in Figure 2 using it is lightweight and takes into account the above-mentioned good moisture and heat resistance, high strength and other characteristics. In some embodiments of the present application, the density of the support joint 20 is 0.4g / cm 3 Below, or at 0.3g / cm 3 Below, or at 0.2g / cm 3 In some embodiments, the density of the support joint 20 is 0.08 g / cm 3 -0.15g / cm 3 , for example, 0.09, 0.10, 0.12, 0.13, 0.14, 0.145 g / cm 3 In this case, the support joint 20 can achieve a better support effect and better balance low dielectric properties, good moisture and heat resistance, etc.

[0056] In the embodiment of the present application, the glass transition temperature Tg of the support joint 20 is greater than or equal to 150°C. A higher Tg reflects that the support joint has good heat resistance, and its thermal decomposition temperature and cell collapse temperature must also be above 150°C, which makes the support joint particularly suitable for use in high temperature environments. In addition, a high Tg can also, to a certain extent, have high rigidity and good mechanical properties. Generally, due to the limitations of the foaming process (such as supercritical foaming method), the Tg of conventional organic foaming materials rarely exceeds 150°C; and organic medium materials with high Tg (such as thermosetting polyimide) are difficult to convert into foaming materials with a cellular structure. The foaming material used in the support joint 20 of the present application is prepared by the preparation method described below in the embodiment of the present application, which can well balance these two contradictions. Specifically, the Tg of the support joint 20 can be 150°C, 160°C, 180°C, 190°C, 195°C, 200°C, or above 220°C. In some embodiments, the glass transition temperature of the support joint 20 is greater than or equal to 190° C., further greater than or equal to 200° C., for example, 200-450° C. In this case, the support joint has better heat resistance.

[0057] In an embodiment of the present application, the foaming material includes a polymer having an aromatic structure in its main chain. The rigid aromatic structure in the main chain of the polymer helps to improve the heat resistance of the polymer, reduce the coefficient of thermal expansion (CTE) of the polymer, and also helps to reduce its dimensional shrinkage under high temperature and high humidity conditions. The polymer includes one or more of polyimide having an aromatic structure in its main chain, polyethersulfone having an aromatic structure in its main chain, polyarylene ether (such as polyphenylene ether PPO), polyarylene sulfide (such as polyphenylene sulfide PPS), etc., but is not limited thereto.

[0058] In some embodiments of the present application, the above-mentioned polymer is a polymer that can generate reaction gas during the preparation process of the polymer, such as a polyimide with an aromatic structure in the main chain. In this way, a support joint that meets the above-mentioned low dielectric, heat and humidity resistance and other requirements can be obtained by the following preparation method provided in the embodiment of the present application, and its thermal stability is relatively high. Among them, the foaming material containing polyimide can be prepared by the in-situ reaction of dianhydride or polyacid and polyisocyanate. The dianhydride or polyacid contains an aromatic ring, or the polyisocyanate contains an aromatic ring, or the dianhydride or polyacid contains an aromatic ring and the polyisocyanate contains an aromatic ring.

[0059] In this application, the support joint 20 is made of the aforementioned foam material, so the descriptions of the properties of the support joint 20 and the foam material (such as Tg, hardness, density, etc.) in the previous text of this application can be equivalently replaced. For example, the Tg of the support joint 20 is also the glass transition temperature of the foam material.

[0060] In the present application and in the embodiments of the present application, the support joint 20 is a hollow structure to facilitate connection with the feed tube. The opening size of the support joint 20 increases gradually from one end to the other. Specifically, the opening size of the support joint 20 increases gradually from the feed tube 21 toward the sub-reflector 22. It is understandable that the opening size of the support joint 20 near the feed tube 21 is larger than the opening size near the sub-reflector 22. This facilitates connection between the feed tube with a small diameter and the sub-reflector 22 with a large transverse dimension.

[0061] The specific increasing method of "gradient increase" can be: gradually increasing, or first remaining unchanged and then gradually increasing, or first remaining unchanged - then increasing - then remaining unchanged - then increasing, etc. In some embodiments, the "gradient increase" specifically means first remaining unchanged and then gradually increasing. As shown in Figure 2, the support joint 20 includes a first main body 201 and a second main body 202, wherein the first main body 201 is close to the feed tube 21, and the second main body 202 is close to the sub-reflector 22; wherein the opening size of the first main body 201 remains unchanged, and the opening size of the second main body 202 gradually increases in the direction toward the sub-reflector 22. In this way, a stable connection between the support joint 20 and the feed tube 21 and the sub-reflector 22 can be achieved. In order to improve the stability of the connection, the end face of the support joint 20 connected to the sub-reflector 22 can have an end face that matches the shape of the sub-reflector 22, and the end face of the support joint 20 connected to the feed tube 21 can have an end face that matches the shape of the feed tube 21.

[0062] In the embodiment of the present application, the side surface of the support joint 20 is a smooth curved surface. The "side surface" specifically refers to the shaping surface of the support joint, that is, the portion of its outer surface excluding the portion perpendicular to the length direction of the feed tube 21. In the present application, the side surface of the support joint 20 is smooth and not stepped, so that when the opening size of the support joint 20 changes, the overall support joint will not have too many sharp edges that interfere with the transmission of electromagnetic waves. In some embodiments, the support joint 20 is a hollow frustum structure, and its side surface is a frustum-shaped side surface.

[0063] In some embodiments of the present application, the side surfaces of the support joint 20 are symmetrical about the central axis of the feed tube 21. In this way, only one side of the support joint needs to be parameterized, and the other side can use the same parameters, which can reduce the difficulty of process design and production.

[0064] In the embodiment of the present application, the wall thickness of the support joint 20 can be within the range of 7-15 mm, for example, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm, 10 mm, 11 mm, 12 mm, 13 mm, or 14 mm. Controlling the thickness of the support joint within an appropriate range can ensure that it has sufficient strength to provide physical support while not being too thick to cause electromagnetic wave loss and affect antenna gain.

[0065] The embodiments of the present application also provide a method for preparing the above-mentioned support structure.

[0066] Specifically, in some embodiments, the preparation method may include the following steps:

[0067] The reaction raw materials for forming the support structure are placed in a mold having a mold cavity shape corresponding to the shape of the support structure to be prepared and sealed. After heat treatment, the reaction raw materials react with each other and generate gas, thereby obtaining a hollow support joint containing a foaming material, that is, obtaining a support structure; wherein the dimensional shrinkage rate of the support joint after being placed in an environment with a temperature of 70-100°C and a relative humidity of 50-95% for 4 days is less than or equal to 1%.

[0068] In the embodiment of the present application, the reaction raw materials are also the raw materials required to form the foaming material; the reaction raw materials are generally greater than or equal to two types. The temperature of the heat treatment should be above the starting temperature of the reaction between the reaction raw materials. The gas generated by the reaction between the reaction raw materials has the effect of a porogen, and the in-situ preparation of the foaming material can be achieved with the help of a sealed mold, and there are basically no exposed bubbles in the place in contact with the mold cavity wall of the mold, and the foaming material is simultaneously given the required shape, that is, a hollow support joint is obtained. In this way, the additional CNC (computer numerical control) processing can be greatly reduced, and the surface of the support joint can be avoided to be covered with exposed bubbles, thereby ensuring that the dimensional shrinkage rate of the support joint after being placed under the above-mentioned high temperature and high humidity conditions for 4 days is less than 1%.

[0069] It should be noted that for raw materials with high heat resistance (such as aromatic polymers with a Tg above 150°C or even above 190°C), due to the limitations of conventional foaming processes, it is difficult to convert them into foam materials with a cellular structure through conventional foaming methods such as supercritical foaming or physical foaming with foaming microspheres. When the raw materials are thermosetting raw materials, it is even more difficult to convert them into foam materials. The above-mentioned preparation method provided in the embodiments of the present application is particularly suitable for making foam materials with high heat resistance (for example, particularly suitable for foam materials with a Tg above 190°C), and imparts them with good moisture and heat resistance and low dielectric properties.

[0070] In the present application, by controlling parameters including the types of the reaction raw materials and the molar ratio therebetween, the dimensional shrinkage of the support joint after being placed in an environment of a temperature of 70-100°C and a relative humidity of 50-95% for 4 days can be made less than or equal to 1%, and the dielectric constant of the foaming material at a frequency of 6-86GHz can be made less than or equal to 1.2. Wherein, when the cavity volume and the types of the reaction raw materials are fixed, regulating the molar ratio between the reaction raw materials can regulate the amount of gas produced by the reaction, so as to regulate the air pressure environment in the sealed mold, and control the foaming ratio and pore structure of the foaming material to be appropriate, so as to regulate its dielectric constant Dk to be as low as below 1.2. In addition, the types of the reaction raw materials affect the material of the obtained foaming material, and also correspondingly affect the dielectric properties of the foaming material and the dimensional shrinkage under hot and humid conditions.

[0071] In some embodiments, the reaction raw materials react to form a polymer, and the resulting foaming material is an organic foaming material containing the polymer. In some specific embodiments, the polymer is a polyimide with an aromatic structure in the main chain. Accordingly, the above-mentioned reaction raw materials include dianhydrides or polyacids, polyisocyanates, and catalysts. Among them, if the polymer is prepared by the reaction between dianhydrides and polyisocyanates, at least one of the dianhydrides and polyisocyanates contains an aromatic ring, for example, the reaction raw materials are specifically aromatic dianhydrides and aromatic polyisocyanates; or aromatic dianhydrides and aliphatic polyisocyanates, etc.

[0072] In some embodiments of the present application, the reaction raw materials may further include one or more of a cell stabilizer and an auxiliary foaming agent. The cell stabilizer can be used to stabilize the gases generated during polymer formation, ensuring the formation of a cellular structure. The cell stabilizer is typically a surfactant. The auxiliary foaming agent can be a low-boiling-point solvent, such as furan methanol or formic acid, which also aids in cell formation during its volatilization.

[0073] In some other embodiments, the method for preparing the support structure may include the following steps:

[0074] The expanded particles are placed in a mold having a cavity shape corresponding to the shape of the support structure to be prepared and sealed. The expanded particles are then treated with hot steam to fuse to form a foamed material, thereby obtaining a hollow support joint. The support joint has a dimensional shrinkage rate of less than or equal to 1% after being placed in an environment with a temperature of 70-100°C and a relative humidity of 50-98% for 4 days.

[0075] In an embodiment of the present application, foamed particles having a cellular structure are injected into the mold cavity of a sealed mold and subjected to hot steam treatment. The surfaces of the foamed particles can be welded together by the thermal effect of the hot steam to obtain a "welded body" with a certain configuration - a foamed material, that is, a hollow support joint. The hot steam treatment can not only weld the foamed particles together, but also facilitate the expansion of the welded foamed particles to a certain extent, thereby obtaining a foamed material with a suitable cellular structure and foaming ratio, thereby making the dielectric constant of the foamed material lower; at the same time, the hot steam treatment is also conducive to the release of internal stress of each foamed particle, the improvement of defects, etc., and is conducive to reducing the later dimensional shrinkage of the foamed material. In addition, the configuration of the foamed material is the shape of the support structure. The use of a sealed mold can also ensure that there are fewer exposed pores on the inner and outer surfaces of the support joint. As in the above method, additional CNC processing of the prepared support joint can be reduced to avoid the surface of the support joint being covered with exposed pores, thereby ensuring that the dimensional shrinkage rate of the support joint after being placed under the above-mentioned high humidity and high heat conditions for 4 days is less than 1%.

[0076] Therefore, the above-mentioned preparation method provided in the embodiments of this application is also suitable for making support structures containing foam materials, and imparting them with low dielectric properties and good moisture and heat resistance. In particular, this preparation method is more suitable for making foam materials with a glass transition temperature above 150°C. In the embodiments of this application, the dielectric constant Dk of the foam material at frequencies of 6-86 GHz can be as low as below 1.2.

[0077] The hot steam may be water vapor, flue gas, or the like, but is not limited thereto. The expanded particles contain a material corresponding to the support structure. For example, when the resulting foamed material contains a polymer, the expanded particles also contain the polymer. The material of the expanded particles also affects the dielectric constant of the foamed material. Therefore, by controlling parameters including the material of the expanded particles, the dielectric constant of the resulting foamed material can also be regulated. In order to facilitate the fusion of the expanded particles and reduce the temperature of the hot steam, the surface of the expanded particles may be subjected to a certain surface treatment, such as coating with a flux (e.g., polystyrene) that can reduce its softening temperature.

[0078] In addition, the particle size of the expanded particles can also affect the void ratio of the particle welding and the dielectric loss of the resulting foamed material. To reduce dielectric loss, in the embodiment of the present application, the particle size of the expanded particles used is controlled to be less than 1 mm.

[0079] The present application also provides a foam material for use in a support structure for an antenna sub-reflector, wherein the dielectric constant of the foam material at a frequency of 6-86 GHz is less than or equal to 1.2. In other words, the present application provides the use of a foam material in a support structure for an antenna sub-reflector.

[0080] The foam material with a pore structure is used for the support structure of the antenna sub-reflector. With its suitable pore structure, the dielectric constant Dk of the foam material at a frequency of 6-86GHz can be reduced to below 1.2, which is lower than that of the homogeneous solid material without foaming. In this way, the support structure has less impact on the degradation of the antenna's electrical performance and has little impact on the loss of electromagnetic wave (specifically microwave) transmission.

[0081] The foam material with a pore structure provided in this application has a relatively low Dk, and its mechanical hardness and density will not be significantly reduced, which can meet the support requirements; at the same time, it has good resistance to moisture and heat, etc. As mentioned above in this application, since the support joint 20 is made of the above-mentioned foam material, the description of the characteristics of the support joint 20 in this application is also applicable to the foam material. Specifically, in the embodiment of this application, the Shore hardness C of the foam material is greater than or equal to 50. The density of the foam material is 0.5g / cm 3 Below, further 0.08-0.15g / cm 3 The dielectric loss Df of the foaming material at a frequency of 6-86 GHz is less than or equal to 0.005. The glass transition temperature of the foaming material is greater than or equal to 150°C, and further greater than or equal to 190°C. 2 In the region of the foam, the number of exposed cells is less than or equal to 20, and further less than or equal to 5. The closed cell ratio of the foamed material is greater than or equal to 90%. This helps ensure that the foamed material has good resistance to moisture and heat. For specific values ​​of each parameter and further narrowed ranges, please refer to the previous description of this application.

[0082] An embodiment of the present application further provides an antenna, which includes an antenna assembly 200 of the above-mentioned support structure of the embodiment of the present application.

[0083] Please refer to Figures 2 and 3 above. Figure 3 shows a structural schematic diagram of an antenna provided in an embodiment of the present application. The antenna in Figure 3 includes the antenna assembly shown in Figure 2. The antenna 300 includes a main reflector 23, a sub-reflector 22, a feed tube 21 and a support structure 20 (i.e., the above-mentioned support joint 20), wherein the feed tube 21 is connected to the main reflector 23, and the opposite ends of the support structure 20 are respectively connected to the feed tube 21 and the sub-reflector 22. In this way, the support joint 20 is arranged between the feed tube 21 and the sub-reflector 22, connecting the two and fixing them on the same central axis. In some embodiments, the structure shown in Figure 2 includes a sub-reflector 22, a support joint 20 and a feed tube 21 connected in sequence from top to bottom and having the same central axis. The antenna shown in Figure 3 is generally used to receive / transmit electromagnetic waves in the microwave frequency band, so the antenna can be called a "microwave antenna", and can further be called a "double-reflector microwave antenna" or a Cassegrain antenna.

[0084] In some embodiments of the present application, one end of the support joint 20 is sleeved on the outside of the feed tube 21, and the other end is connected to the secondary reflector 22. In this way, one end of the feed tube 21 is located within the space enclosed by the support joint 20, thereby sealing and dustproofing the feed on the feed tube 21. The support joint 20 can be sleeved on the outside of the feed tube 21 by threaded connection or adhesive bonding, for example.

[0085] In some embodiments of the present application, the opposite ends of the support joint 20 are bonded to the feed tube 21 and the secondary reflector 22, respectively. Compared to threaded connections, bonding eliminates the need to machine threads on the inner surface of the support joint 20, reducing the manufacturing difficulty of the support joint 20 and helping to minimize the number of exposed cells on its surface.

[0086] In the present application, the antenna 300 may further include a feed source (not shown in Figures 2 and 3), which is disposed at one end of the feed tube 21 near the sub-reflector 22. The feed source is the primary radiator of the reflector microwave antenna, and its function includes converting the radio frequency signal in the feed line into a spatial electromagnetic wave and radiating it onto the sub-reflector 22. The feed source can specifically be a horn feed, a dipole feed, or a double-slot feed. Cassegrain antennas typically use a horn feed.

[0087] When the antenna transmits a signal, the feed source can be used to generate electromagnetic waves, and the secondary reflector 22 can be used to reflect the electromagnetic waves generated by the feed source to the primary reflector 23. The primary reflector 23 can further reflect the electromagnetic waves reflected by the secondary reflector 22, completing the signal radiation function of the antenna 300. When the antenna receives a signal, the signal is reflected from the primary reflector 23 to the secondary reflector 22, and finally enters the feed source, and is transmitted through the feed tube into the antenna's back-end receiving system.

[0088] In this application, the primary reflector 23 and the secondary reflector 22 are generally made of metal, such as aluminum. The primary reflector 23 is generally a parabola of revolution. In this embodiment, the tail end of the feed tube 21 (i.e., the end away from the secondary reflector 22) may also be provided with a base (not shown in FIG3 ) to facilitate mounting the feed tube 21 on the primary reflector 23.

[0089] In addition, the antenna 300 may further include a radome (not shown in FIG3 ), which is generally disposed on the primary reflector 23 to enclose the feed tube 21, the support structure 20, and the secondary reflector 22 within the space enclosed by the radome and the primary reflector 23. The radome is used to protect the feed tube 21, the support structure 20, and the secondary reflector 22 from interference from inclement outdoor weather.

[0090] An embodiment of the present application further provides a communication device, which includes the above-mentioned antenna of the embodiment of the present application.

[0091] Figure 4 illustrates an exemplary structure of a communication device provided in an embodiment of the present application. As shown in Figure 4 , communication device 400 includes the aforementioned antenna 300 (Figure 4 shows an antenna with a radome), an outdoor unit (ODU) 401, and an indoor unit (IDU) 402. The outdoor unit 401 is connected to the antenna 300, and the indoor unit 402 can be connected to the outdoor unit 401 via an intermediate frequency cable 403.

[0092] The outdoor unit 401 can be connected directly to the antenna 300 or via a flexible waveguide. This helps reduce feeder losses. The antenna 300 can be mounted on a mast 404 or tower by adjusting the bracket to facilitate antenna signal reception or transmission.

[0093] The antenna 300 shown in Figure 4 also includes a radome 24, which is positioned on the antenna's primary reflector 23 to enclose the feed tube 21, support structure 20, and secondary reflector 22 within the space enclosed by the radome 24 and the primary reflector 23. Thus, the feed tube 21, support structure 20, and secondary reflector 22 are all located inside the primary reflector 23. The radome 24 has excellent electrical electromagnetic wave penetration characteristics and mechanical properties that can withstand harsh external environments, thereby protecting the core components of the antenna from external environmental influences.

[0094] Specifically, the indoor unit 402 processes the baseband signal and converts it into an intermediate frequency (IF) signal, which it then transmits to the outdoor unit 401. The outdoor unit 401 then converts and amplifies the IF and RF signals and transmits the processed RF signal to the antenna 300, which converts the RF signal into electromagnetic waves and radiates them. The antenna receives RF signals in the opposite manner: the outdoor unit 401 selects, amplifies, and converts the received RF signal, converting it into an IF signal and transmitting it to the indoor unit 402. The indoor unit 402 then processes the IF signal and converts it into a baseband signal.

[0095] In embodiments of the present application, the aforementioned communication device may be a device for microwave frequency band communication, i.e., a microwave device. The communication frequency band of the microwave device is within the range of 6-86 GHz. In some embodiments, the communication frequency band of the microwave device includes the 6-42 GHz band, the 57-64 GHz band, and the 71-86 GHz band.

[0096] The embodiment of the present application further provides a communication system, which includes at least two of the above-mentioned communication devices, which can communicate with each other. As mentioned above, the communication device can be a microwave device with a communication frequency band within the range of 6-86 GHz.

[0097] The following further describes the embodiments of the present application in a number of specific embodiments, which are not limited to the following specific embodiments.

[0098] Example 1

[0099] A support structure for the secondary reflector of a microwave antenna is used to connect between the antenna's feed tube and the secondary reflector. The support structure is a hollow support joint (as shown by label 20 in Figure 2), one end of which is sleeved on the outside of the feed tube and bonded to the feed tube, and the other end is bonded to the secondary reflector; the wall thickness of the support joint is about 8mm.

[0100] Among them, the support joint uses a foam material, which contains polyimide (PI) with an aromatic structure in the main chain. The dielectric constant Dk of the foam material at a frequency of 6-86GHz is approximately 1.17-1.18. The dimensional shrinkage rate of the support joint after being placed in an environment with a temperature of 85°C and a relative humidity of 85% for one week is 0.2%.

[0101] The inner and outer surfaces of the support joint have no exposed cells, and the closed cell rate of the cells in the support joint is above 97%. The density of the support joint is 0.128 g / cm 3 , Shore hardness C is about 70; the glass transition temperature Tg of the support joint is 315°C, and the thermal expansion coefficient CTE of the above-mentioned PI is 48ppm / °C; the dielectric loss Df of the foam material at a frequency of 6-86GHz is about 0.004; the support joint with a wall thickness of 8mm has a wave transmittance of 90% for vertically incident electromagnetic waves with a frequency in the range of 6-86GHz.

[0102] The foaming material is formed by reacting an aromatic dianhydride (specifically phthalic anhydride) and an aromatic isocyanate (specifically polymethylene polyphenyl isocyanate) in a molar ratio of 0.9:1, along with a catalyst (specifically a composite catalyst composed of triethanolamine and dibutyltin dilaurate), anhydrous methanol as a foaming aid, and a foam stabilizer in a sealed mold under heating conditions. Specifically, the aromatic dianhydride and aromatic isocyanate react in situ to form the PI, and the CO2 generated by the reaction imparts a cellular structure. A small amount of water can be added to adjust the reaction rate and the amount of bubbles produced. The foaming material has an expansion ratio of 7 (the expansion ratio is the volume ratio of the foaming material to the reaction raw materials used to form the PI).

[0103] Example 2

[0104] A support structure for the secondary reflector of a microwave antenna is used to connect between the antenna's feed tube and the secondary reflector. The support structure is a hollow support joint (as shown by label 20 in Figure 2), one end of which is sleeved on the outside of the feed tube and bonded to the feed tube, and the other end is bonded to the secondary reflector; the wall thickness of the support joint is about 8mm.

[0105] Among them, the support joint uses a foam material, which contains polyphenylene ether (PPO) with an aromatic structure in the main chain. The dielectric constant Dk of the foam material at a frequency of 6-86GHz is approximately 1.15-1.16. The dimensional shrinkage rate of the support joint after being placed in an environment with a temperature of 85°C and a relative humidity of 85% for one week is 0.3%.

[0106] The inner and outer surfaces of the support joint have no exposed cells, and the closed cell rate of the cells in the support joint is 100%; the density of the support joint is 0.135 g / cm 3 , Shore hardness C is about 78; the glass transition temperature Tg of the support joint is 211°C, and the thermal expansion coefficient CTE of the above-mentioned PPO is 60ppm / °C; the dielectric loss Df of the foam material at a frequency of 6-86GHz is about 0.001-0.003; the support joint with a wall thickness of 8mm has a wave transmittance of 90% for vertically incident electromagnetic waves with a frequency in the range of 6-86GHz.

[0107] The preparation process of the above-mentioned support joint may include: supercritically foaming surface-modified polyphenylene ether (PPO) plastic particles (surface coated with a low-melting-point polymer (such as polystyrene)) in an extruder using nitrogen or carbon dioxide above its glass transition temperature to obtain foamed particles with a predetermined foaming ratio; then injecting the foamed particles into the mold cavity, and passing high-temperature water vapor into the mold cavity to weld the foamed particles to form a foamed material to obtain a hollow support joint.

[0108] In order to highlight the effects of the embodiments of the present application, the following comparative examples 1 and 2 are provided.

[0109] Comparative Example 1

[0110] A support structure for a microwave antenna is used to be connected to the main reflecting surface of the antenna to support the secondary reflecting surface; the support structure is a metal bracket (the structure diagram is shown in Figure 5).

[0111] Comparative Example 2

[0112] A support structure for the secondary reflector of a microwave antenna is a hollow support joint. Its structure is similar to that of Example 1, except that it is machined from a foamed sheet material containing a blend of polyphenylene ether (PPO) and polystyrene (PS). The foam material has a dielectric constant (Dk) of approximately 1.15-1.16 at frequencies of 6-86 GHz. However, the support joint exhibits a dimensional shrinkage of 3% after one week in an environment with a temperature of 85°C and a relative humidity of 85%, failing to meet the requirements for moisture-heat aging resistance.

[0113] In order to further demonstrate the beneficial effects of the present application, the support structures of Example 1 and Comparative Examples 1-2 were assembled into dual-reflection-surface microwave antennas, and the polarization gain and radiation pattern of each antenna were tested.

[0114] Table 1 below summarizes the vertical polarization gain and horizontal polarization gain of the antennas in Example 1 and Comparative Examples 1-2 at different frequencies. VV and HH represent the vertical and horizontal amplitudes of the electric field radiated by the antenna, respectively. The antenna gain test uses a comparative method. Under the same conditions, the received power of a standard antenna (with a known gain) and the received power of the antenna under test are measured. The difference between the two values ​​and the gain of the standard antenna is then added to obtain the gain of the antenna under test.

[0115] Table 1

[0116] Table 1 shows that the antenna in Comparative Example 1, which uses a metal bracket as the secondary reflector support structure, has lower vertical and horizontal polarization gains than those in Example 1 and Comparative Example 2. However, the antennas in Example 1 and Comparative Example 2, which use a support joint containing a foam material as the secondary reflector support structure, have essentially the same gain, with the vertical and horizontal polarization gains increased by approximately 0.5 dB compared to Comparative Example 1.

[0117] Figure 6 summarizes the antenna patterns of the horizontal polarization direction of the antenna of Comparative Example 1 (a), the antenna of Comparative Example 2 (b), and the antenna of Example 1 (c) measured at a frequency of 78.5 GHz. Among them, the broken line in the figure is the ETSI Class 3 standard template, and the antenna pattern needs to be below the broken line to meet the standard requirements. It can be seen from Figure 6 that, as shown in Figure 6 (a), the radiation pattern of the antenna of Comparative Example 1 performs poorly within the range of ±15°, which indicates that the metal bracket has a greater impact on the near-side lobes of the antenna radiation pattern, and there is almost no margin compared with the standard requirements, and even some positions slightly exceed the standard. The radiation patterns of the antennas of Example 1 and Comparative Example 2 have improved a lot within the range of ±15°, both with a margin of about 5dB, which meets the margin of ETSI C3.

[0118] Next, the antenna performance of Example 1 was compared before and after a damp heat test. The polarization gain of the antenna before and after the damp heat test is summarized in Table 2 below. Figure 7 illustrates the horizontal polarization pattern of the antenna of Example 1 measured at a frequency of 78.5 GHz after the damp heat test. The damp heat test was conducted in an environment of 85°C and 85% relative humidity for one week.

[0119] Table 2

[0120] Note: In Table 2, after one week of exposure to damp heat, the support joint 20 of the present embodiment undergoes a slight dimensional shrinkage. "Pulling upward by 1-2 mm" refers to the fact that, after the damp heat test, the sub-reflector 22 in Figure 2 is moved 1-2 mm away from the feed tube 21 to re-enter the upper opening of the support joint.

[0121] As can be seen from Table 2, after one week of damp heat testing, the vertical polarization gain of the antenna in Example 1 at high frequencies deteriorated by only about 0.1-0.2 dB, which is a minor impact. Moreover, after focusing, the gain at each frequency can basically reach the same level as before the damp heat test, or even better.

[0122] From the comparison between Figure 7 and (c) in Figure 6 above, it can be seen that the antenna radiation pattern in the horizontal polarization direction of the antenna of Example 1 measured before and after the damp heat test has a high degree of consistency, and there is no obvious difference before and after the test, indicating that the sub-reflector support material used in the antenna has good weather resistance and will not be affected by the use environment and cause performance deterioration.

[0123] The above merely represents several exemplary embodiments of the present application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art would be able to make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

[0124] It should be understood that the terms "first," "second," and the like in this application are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features indicated. Furthermore, directional terms such as "upper" and "lower" are defined herein relative to the orientation of the structures schematically shown in the accompanying drawings. It should be understood that these directional terms are relative concepts and are used for relative description and clarification, and may vary accordingly depending on the orientation of the structures.

[0125] In the description of this application, unless otherwise specified, the meaning of "multiple" is greater than or equal to two. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0126] In this application, "and / or" describes the relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the related objects are in an "or" relationship.

Claims

1. A support structure for an antenna, used to connect between a feed tube and a sub-reflecting surface of the antenna, characterized in that: The support structure is a hollow support joint, and the support joint is made of foam material. The size shrinkage rate of the support joint after being placed in an environment with a temperature of 70-100° C. and a relative humidity of 50-95% for 4 days is less than or equal to 1%.

2. The support structure according to claim 1, characterized in that The dielectric constant of the foaming material at a frequency of 6-86 GHz is less than or equal to 1.

2.

3. The support structure according to claim 1 or 2, characterized in that: The dielectric loss of the foaming material at a frequency of 6-86 GHz is less than or equal to 0.

005.

4. The support structure according to any one of claims 1 to 3, characterized in that: The support joint has a Shore C hardness greater than or equal to 50.

5. The support structure according to any one of claims 1 to 4, characterized in that: At least 2 cm on either the inner or outer surface of the support joint 2 In the area, the number of exposed cells is less than or equal to 20.

6. The support structure according to claim 5, characterized in that At least 2 cm on either the inner or outer surface of the support joint 2 In the area, the number of exposed cells is less than or equal to 5.

7. The support structure according to any one of claims 1 to 6, characterized in that: The closed cell ratio of the cells in the supporting joint is greater than or equal to 90%.

8. The support structure according to any one of claims 1 to 7, wherein the density of the support joint is 0.5 g / cm 3 the following.

9. The support structure according to claim 8, characterized in that The density of the support joint is 0.08-0.15 g / cm 3 .

10. The support structure according to any one of claims 1 to 9, characterized in that: The support joint with a wall thickness of less than 10 mm has a wave transmittance greater than or equal to 90% for vertically incident microwaves with a frequency in the range of 6-86 GHz.

11. The support structure according to any one of claims 1 to 10, characterized in that: The glass transition temperature of the supporting joint is greater than or equal to 150°C.

12. The support structure according to any one of claims 1 to 11, characterized in that: The glass transition temperature of the supporting joint is greater than or equal to 190°C.

13. The support structure according to any one of claims 1 to 12, characterized in that: The foaming material comprises a polymer having an aromatic structure in the main chain.

14. The support structure according to claim 13, characterized in that The polymer includes one or more of polyimide, polyethersulfone, polyarylether, and polyarylether sulfide, the main chain of which contains an aromatic structure.

15. The support structure according to any one of claims 1 to 14, characterized in that: The opening size of the support joint increases gradually from one end to the opposite end, and the side surface of the support joint is a smooth curved surface.

16. The support structure according to any one of claims 1 to 15, characterized in that: The wall thickness of the support joint is in the range of 8-15 mm.

17. A foaming material used for the supporting structure of the antenna sub-reflection surface, characterized in that: The dielectric constant of the foaming material at a frequency of 6-86 GHz is less than or equal to 1.

2.

18. The foam material according to claim 17, characterized in that The dielectric loss of the foaming material at a frequency of 6-86 GHz is less than or equal to 0.

005.

19. The foam material according to claim 17 or 18, characterized in that: The Shore hardness C of the foaming material is greater than or equal to 50.

20. The foaming material according to any one of claims 17 to 19, characterized in that: The density of the foaming material is 0.5 g / cm 3 the following.

21. An antenna assembly, characterized in that: The antenna assembly includes a sub-reflecting surface, a feed tube, and a supporting structure as described in any one of claims 1 to 16, wherein opposite ends of the supporting structure are respectively connected to the feed tube and the sub-reflecting surface.

22. The antenna assembly according to claim 21, wherein: One end of the support structure is sleeved on the outside of the feed tube, and the other end is connected to the secondary reflector.

23. The antenna assembly according to claim 21 or 22, characterized in that: The opposite ends of the support structure are bonded to the feed tube and the secondary reflector respectively.

24. The antenna assembly according to any one of claims 21 to 23, characterized in that: The support structure includes a first main body and a second main body, wherein the first main body is close to the feed tube; wherein the opening size of the first main body remains unchanged, and the opening size of the second main body gradually increases toward the secondary reflector.

25. An antenna, characterized in that: The antenna comprises a main reflecting surface and an antenna assembly as described in any one of claims 21 to 24, wherein the feed tube is connected to the main reflecting surface.

26. A communication device, characterized in that: The communication device includes the antenna as claimed in claim 25, and an outdoor unit and an indoor unit.

27. A communication system, characterized in that: The communication system comprises at least two communication devices according to claim 26, and the communication devices can communicate with each other.

28. A method for preparing a supporting structure for an antenna, characterized in that: The following steps are involved: The reaction raw materials for forming the support structure are placed in a mold whose cavity shape corresponds to the shape of the support structure to be prepared and sealed. After heating treatment, the reaction raw materials react with each other and generate gas to obtain a hollow support joint containing a foaming material; wherein the support joint has a dimensional shrinkage rate of less than or equal to 1% after being placed in an environment with a temperature of 70-100°C and a relative humidity of 50-95% for 4 days.

29. A method for preparing a supporting structure for an antenna, characterized in that: The following steps are involved: The foamed particles are placed in a mold whose cavity shape corresponds to the shape of the support structure to be prepared and sealed, and the foamed particles are melted to form a foamed material through hot steam treatment to obtain a hollow support joint; wherein the support joint has a dimensional shrinkage rate of less than or equal to 1% after being placed in an environment with a temperature of 70-100°C and a relative humidity of 50-95% for 4 days.

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