Reflectance testing method based on double-arch frame high-temperature reflectance testing system

Abstract

The application relates to a reflectivity testing method based on a double-arch high-temperature reflectivity testing system, and the double-arch high-temperature reflectivity testing system comprises semicircular arches, linear guides, sample supports, upper heating devices, single-pole multi-throw radio frequency switches, vector network analyzers and controllers, two semicircular arches and two linear guides are arranged in parallel, the sample supports are arranged below the linear guides and the centers of the linear guides and the centers of the top portions of the sample supports are coplanar, the upper heating devices are arranged above the sample supports, a plurality of antennas with different frequency bands are slidably arranged on the linear guides, the antennas with different frequency bands on the linear guides are electrically connected to the vector network analyzers through the single-pole multi-throw radio frequency switches, and the vector network analyzers are electrically connected to the controllers. The application has the beneficial effects that the antennas are accurately pointed and conveniently switched, the influences of the heat preservation materials and the heating devices on the testing can be eliminated, and the working efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of reflectivity testing technology for absorbing materials, and specifically to a reflectivity testing method based on a high-temperature reflectivity testing system with a double-arched frame. Background Technology

[0002] With the development of stealth technology, the overall stealth performance of aircraft has improved, and the stealth requirements for high-temperature components have also been significantly increased. Radar absorbing materials are one of the important measures in the field of stealth technology. Reflectivity is the core indicator for evaluating radar absorbing materials, and accurate measurement of high-temperature reflectivity is crucial for the development and application of high-temperature resistant radar absorbing materials.

[0003] In measuring high-temperature reflectivity, factors significantly affecting the measurement results include the stability of the vector network analyzer, the amplitude and phase stability of the RF cable, the antenna's standing wave ratio and gain, the antenna pointing accuracy, interference from the high-temperature sample holder structure, and environmental background. Frequent manual replacement of the test antenna also limits testing efficiency. While the vector network analyzer, RF cable, and environmental background can be addressed by selecting high-performance products, antenna pointing and replacement efficiency are constrained by the existing bow-shaped frame structure, and the high-temperature sample holder structure is limited by the existing heating scheme.

[0004] Currently, the main structures used in the traditional bow-shaped method for measuring reflectivity include single bow-shaped frame structures and L-shaped rocker arm structures. In the single bow-shaped frame structure, each sliding mechanism only mounts one antenna. When changing the test frequency band, the antenna needs to be moved to the bottom of the bow-shaped frame via the sliding mechanism, resulting in low efficiency. In the L-shaped rocker arm structure, the antenna is mounted at the end of the rocker arm, and the drive shaft located outside the test area drives the antenna to rotate along the semi-circular arc. Antennas capable of accurately measuring reflectivity in the 1-4 GHz frequency band are relatively large and heavy. At the end of the L-shaped rocker arm structure, gravity causes the antenna to deviate from the center of the high-temperature sample holder, thus affecting the reflectivity measurement results. Furthermore, existing high-temperature holders for placing the sample have insulation material or heating modules at the bottom, which affects the diffraction of radar waves at the edges of the high-temperature holder, further impacting the reflectivity measurement results. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a reflectivity testing method based on a double-arched frame high-temperature reflectivity testing system. The antenna pointing is accurate and switching is convenient, which can eliminate the influence of insulation materials and heating devices on the test and improve work efficiency.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A reflectivity testing method based on a dual-arched frame high-temperature reflectivity testing system is disclosed. The dual-arched frame high-temperature reflectivity testing system includes a semi-circular arched frame, a linear guide rail, a sample holder, an upper heating device, a single-pole multi-throw RF switch, a vector network analyzer, and a controller. Two semi-circular arched frames and two linear guide rails are provided, arranged in parallel. The two ends of the linear guide rails slide on the two semi-circular arched frames respectively. The sample holder is located below the linear guide rails, with the center of the linear guide rails coplanar with the top center of the sample holder. A microwave absorbing material is laid around the sample holder between the two semi-circular arched frames. The upper heating device is located above the sample holder. Multiple antennas of different frequency bands slide on the linear guide rails toward the sample holder. The antennas of different frequency bands on the linear guide rails are electrically connected to the vector network analyzer via the single-pole multi-throw RF switch. The vector network analyzer is electrically connected to the controller.

[0008] The reflectivity test includes the following steps:

[0009] According to the test requirements, slide the antenna corresponding to the test frequency band to the center of the linear guide rail, slide the linear guide rail to the corresponding test angle, and align the antenna at the center of the linear guide rail with the center of the top of the sample holder.

[0010] The sample to be tested is placed on the sample holder, and the sample holder is covered from top to bottom by the upper heating device and the sample to be tested is heated.

[0011] Connect the antenna corresponding to the test frequency band to the vector network analyzer using a single-pole multi-throw RF switch, and then adjust the vector network analyzer to the test frequency band using the controller.

[0012] After the sample is heated to the test temperature, the upper heating device is moved out of the test area. The vector network analyzer then collects the reflection signal of the calibration plate or the sample. The high-temperature reflectivity can be obtained by calculating the reflection signal of the sample and the reflection signal of the calibration plate.

[0013] Furthermore, the semi-circular bow-shaped frame has bases at both ends, and the semi-circular bow-shaped frame is placed on the ground through the bases.

[0014] Furthermore, the linear guide rail is provided with sliding mechanisms at both ends. The sliding mechanisms at both ends of the linear guide rail are respectively slidably sleeved on the semi-circular bow-shaped frame, and the sliding mechanisms are electrically connected to the controller.

[0015] Furthermore, a slider corresponding to each antenna is slidably mounted on the linear guide rail, and the antenna is mounted on the corresponding slider.

[0016] Furthermore, the sample holder includes a base plate, a column, and a metal plate. The base plate is placed on the ground, the column is placed on the base plate, the metal plate is placed flat on top of the column, and the sample to be tested is placed on the metal plate.

[0017] Furthermore, the upper heating device includes a robotic arm, a heating furnace, and insulation plates. The top of the heating furnace is connected to the robotic arm via a connecting shaft. The bottom of the heating furnace has a furnace opening. Linear modules are located on both sides of the furnace opening on the heating furnace. There are two insulation plates, which are arranged opposite each other. The two sides of the insulation plates are respectively located on the two linear modules. The opposite ends of the two insulation plates have semi-circular cuts. The two semi-circular cuts together form a circular through hole that matches the shape of the support column.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention, through the setting of double bow-shaped frame and double linear guide rail, ensures that the antenna is not in a cantilevered state in any area of ​​the linear guide rail and can achieve a balanced posture in the horizontal direction; and the two ends of the double linear guide rail are fixed to the sliding mechanism on the bow-shaped frame with three-point support, so even if the elevation angle changes slightly after long-term use, the antenna can be accurately pointed by simple adjustment.

[0020] 2. This invention improves work efficiency and avoids errors introduced by manually switching antennas by installing multiple frequency bands on a linear guide rail and connecting the antennas of different frequency bands to a vector network analyzer through a single-pole multi-throw RF switch and switching them with a controller.

[0021] 3. This invention heats the sample using an upper heating device and an upper heating method. No insulation material is installed under the sample holder, which completely eliminates the influence of insulation material and heating device on the test. The upper heating device can be quickly removed by a robotic arm, reducing the cooling time and preventing the sample temperature from exceeding the allowable range of the test. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 This is a schematic diagram of the antenna installation on the linear guide rail in this invention;

[0024] Figure 3 This is a schematic diagram of the upper heating device in this invention;

[0025] Figure 4 This is a schematic diagram of the sample holder structure in this invention.

[0026] In the diagram: 1. Semi-circular bow-shaped frame; 2. Linear guide rail; 3. Sample holder; 31. Base plate; 32. Column; 33. Metal plate; 4. Antenna; 5. Base; 6. Sliding mechanism; 7. Slider; 8. Robot arm; 9. Heating furnace; 10. Connecting shaft; 11. Insulation plate; 12. Linear module; 13. Circular through hole. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0028] like Figures 1-4 A high-temperature reflectivity testing system with a double-arched frame is shown, comprising a semi-circular arched frame 1, a linear guide rail 2, a sample holder 3, an upper heating device, a single-pole multi-throw RF switch, a vector network analyzer, and a controller. The linear guide rail 2 is slidably mounted on the semi-circular arched frame 1. The sample holder 3 is positioned below the linear guide rail 2, with the center of the linear guide rail 2 and the center of the sample holder 3 coplanar. A microwave-absorbing material is laid around the sample holder 3 between the two semi-circular arched frames 1. The upper heating device is positioned above the sample holder 3, and the sample is placed on top of the sample holder 3. The upper heating device is used to heat the sample after covering the sample holder 3 from top to bottom. Multiple antennas 4 with different frequency bands are slidably mounted on the linear guide rail 2 toward the sample holder 3. The antennas 4 with different frequency bands on the linear guide rail 2 are electrically connected to the vector network analyzer via the single-pole multi-throw RF switch, and the vector network analyzer is electrically connected to the controller.

[0029] When conducting reflectivity testing using the aforementioned double-arched high-temperature reflectivity testing system, the specific testing steps include the following:

[0030] (1) According to the test requirements, slide the antenna 4 corresponding to the test frequency band to the center of the linear guide rail 2, slide the linear guide rail 2 to the corresponding test angle, so that the antenna 4 at the center of the linear guide rail 2 is aligned with the top center of the sample holder 3.

[0031] (2) Place the sample to be tested on the sample holder 3, and cover the sample holder 3 from top to bottom with the upper heating device and heat the sample to be tested.

[0032] (3) Connect the antenna 4 corresponding to the test frequency band to the vector network analyzer through a single-pole multi-throw RF switch, and adjust the vector network analyzer to the test frequency band through the controller.

[0033] (4) After the sample is heated to the test temperature, the upper heating device is moved out of the test area. The vector network analyzer then collects the reflection signal of the calibration plate or the sample. The high temperature reflectivity can be obtained by calculating the reflection signal of the sample and the reflection signal of the calibration plate.

[0034] like Figure 1As shown, there are two semi-circular bow-shaped frames 1, with bases 5 fixed at both ends. The two semi-circular bow-shaped frames 1 are supported parallel to each other on the ground via the bases 5. There are two linear guide rails 2, which are parallel to each other and span the two semi-circular bow-shaped frames 1. A sliding mechanism 6 is slidably mounted on the semi-circular bow-shaped frames 1, and the two ends of the linear guide rails 2 are slidably mounted on the two semi-circular bow-shaped frames 1 via the sliding mechanism 6. A flange for mounting the linear guide rail 2 is fixed on the sliding mechanism 6. When installing the linear guide rail 2, a three-point support method is used to fix the ends of the linear guide rail 2 to the flange. The sliding mechanism 6 is electrically connected to the controller. According to the test angle, the controller can drive the sliding mechanism 6 at both ends of the linear guide rail 2 to run synchronously, adjusting the pitch and roll angles of the linear guide rail 2, so that the antenna 4 at the center of the linear guide rail 2 accurately points to the top center of the sample holder 3. The sliding mechanism 6 is existing technology, that is, it is the same as the sliding mechanism for mounting the antenna on the existing single bow-shaped frame structure, and will not be described in detail here.

[0035] During the adjustment of the position of the linear guide rail 2, since both ends of the linear guide rail 2 have stable supports, the antenna 4 on the linear guide rail 2 can be balanced in the sliding direction, and the roll angle of the antenna 4 reaches the horizontal. The linear guide rail 2 is installed in a three-point support manner, so that the linear guide rail 2 can achieve stable support in the pitch angle and can accurately adjust the antenna 4 to point to the top center of the sample holder 3. Even if the pitch angle changes slightly after long-term use, the antenna 4 can be accurately pointed by simple adjustment. Moreover, the antenna 4 is not in a cantilevered state in any area of ​​the linear guide rail 2 and can achieve a balanced posture in the horizontal direction. The linear guide rail 2 can also support the antenna 4 with large size and weight and can always maintain balance.

[0036] like Figure 1 , Figure 2 As shown, sliders 7, each corresponding to an antenna 4, slide on the linear guide rail 2. Each slider 7 can slide independently, and the antenna 4 is fixed on its corresponding slider 7. The slider 7 is driven to slide by a controller, thereby adjusting the position of the antenna 4 on the linear guide rail 2. The sliding of the slider 7 can be achieved using an existing linear rack and pinion guide structure. That is, a linear rack is installed along the length of the linear guide rail 2, and a drive motor is installed on each slider 7. A drive gear that meshes with the linear rack is installed on the output shaft of the drive motor. Under the meshing transmission of the drive gear and the linear rack, the drive motor drives the slider 7 to move. At the same time, the drive motor can be connected to a controller, and the control program of the controller can be used to move each antenna in combination. In specific testing, the controller drives the slider 7 to move the antenna 4 corresponding to the test frequency band to the center of the linear guide rail 2, while the antennas 4 of non-test frequency bands are moved to both ends of the linear guide rail 2 to avoid interference from the antenna 4 at the center.

[0037] Antennas 4 of different frequency bands on linear guide rail 2 are connected to multiple output ports of a single-pole multi-throw (SPMWTO) RF switch via RF cables. The input port of the SPMWTO RF switch is connected to the port of a vector network analyzer via RF cables. During testing, to perform tests on different frequency bands, the corresponding frequency band antenna 4 can be connected to the vector network analyzer via the SPMWTO RF switch. The vector network analyzer is then tuned to the test frequency band via the controller, and the connection port of the antenna 4 corresponding to the test frequency band is selected. This ensures that both the transmitting antenna 4 and the receiving antenna 4 are connected to the vector network analyzer. In this way, switching antennas 4 via the SPMWTO RF switch and controller during testing eliminates the need to connect the RF cables to the test antennas 4, improving testing efficiency and reducing testing errors caused by manual disassembly and switching of antennas 4 in traditional testing.

[0038] like Figure 1 , Figure 3 , Figure 4 As shown, the sample holder 3 includes a base plate 31, a column 32, and a metal plate 33. The base plate 31 is fixed to the ground by a three-point support method. The column 32 is fixed on the base plate 31. The metal plate 33 is laid flat and fixed on the top of the column 32. The sample to be tested is placed on the metal plate 33. The upper heating device includes a robot arm 8, a heating furnace 9, and a heat insulation plate 11. The top of the heating furnace 9 is connected to the robot arm 8 through a connecting shaft 10. The bottom of the heating furnace 9 has a furnace opening. Linear modules 12 are installed on both sides of the furnace opening on the heating furnace 9. There are two heat insulation plates 11, which are arranged opposite each other. The two sides of the heat insulation plate 11 are fixed to the slides of the two linear modules 12. The opposite ends of the two heat insulation plates 11 have semi-circular cuts. The two semi-circular cuts together form a circular through hole 13 that matches the shape of the column.

[0039] When heating the sample, the linear module drives the two insulation plates 11 to move in opposite directions to open the furnace opening. The robot arm 8 moves the heating furnace 9 above the sample support 3, and then the heating furnace 9 covers the sample support 3 from top to bottom. The linear module then drives the two insulation plates 11 to move relative to each other to close the furnace opening, ensuring that the heating furnace 9 has a good heat preservation effect. After the furnace opening is closed, the sample is heated. After heating is completed, the furnace opening is opened again, and the robot arm 8 quickly moves the heating furnace 9 out of the test area to reduce the cooling time and prevent the sample temperature from exceeding the test allowable range.

[0040] When performing reflectivity testing using the testing system of this invention, for samples requiring a base plate, such as absorbing coatings, the absorbing material needs to be sprayed onto an additional metal plate (e.g., a 300*300*10mm high-temperature alloy plate) to prevent the absorbing coating from failing to form independently or deforming. Simultaneously, before testing, an uncoated metal plate of the same size needs to be placed on the metal plate 33 at the top of the sample holder 3 as a calibration plate. Before testing reflectivity, the calibration plate signal must be measured to complete calibration, and then the calibration plate is removed before placing the sample on top for heating and testing. For samples that do not require a base plate, such as absorbing films and absorbing foams, the metal plate 33 at the top of the sample holder 3 can be directly used as a calibration plate for signal calibration, eliminating the need for an additional metal plate. The sample can be placed directly on the metal plate 33 for heating and testing. Regardless of the type of sample being tested, this invention eliminates the influence of insulation materials and heating modules on the reflectivity measurement results in traditional testing by combining the heating furnace 9 and above heating methods.

[0041] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A reflectance testing method based on a double-arched frame high-temperature reflectance testing system, characterized in that: The double-arched frame high-temperature reflectivity testing system includes a semi-circular arched frame (1), a linear guide rail (2), a sample holder (3), an upper heating device, a single-pole multi-throw RF switch, a vector network analyzer, and a controller. Two semi-circular arched frames (1) and two linear guide rails (2) are provided, arranged in parallel. Sliding mechanisms (6) are provided at both ends of the linear guide rails (2). The sliding mechanisms (6) at both ends of the linear guide rails (2) are slidably mounted on the two semi-circular arched frames (1). The sliding mechanisms (6) are electrically connected to the controller, and flanges are fixed on the sliding mechanisms (6). The end of the linear guide (2) is fixedly connected to the flange by a three-point support method. The sample holder (3) is located below the linear guide (2) and the center of the linear guide (2) is coplanar with the top center of the sample holder (3). A wave-absorbing material is laid around the sample holder (3) between the two semi-circular arched frames (1). The upper heating device is located above the sample holder (3). Multiple antennas (4) with different frequency bands are slidably arranged on the linear guide (2) towards the sample holder (3). The antennas (4) with different frequency bands on the linear guide (2) are electrically connected to the vector network analyzer through a single-pole multi-throw RF switch. The vector network analyzer is electrically connected to the controller. The reflectivity test includes the following steps: According to the test requirements, slide the antenna (4) corresponding to the test frequency band to the center of the linear guide (2), slide the linear guide (2) to the corresponding test angle, so that the antenna (4) at the center of the linear guide (2) is aligned with the top center of the sample holder (3); The sample to be tested is placed on the sample holder (3), and the sample holder (3) is covered from top to bottom by the upper heating device and the sample to be tested is heated. Connect the antenna (4) corresponding to the test frequency band to the vector network analyzer through a single-pole multi-throw RF switch, and adjust the vector network analyzer to the test frequency band through the controller; After the sample is heated to the test temperature, the upper heating device is moved out of the test area. The vector network analyzer then collects the reflection signal of the calibration plate or the sample. The high-temperature reflectivity can be obtained by calculating the reflection signal of the sample and the reflection signal of the calibration plate.

2. The reflectance testing method based on the double-arched frame high-temperature reflectance testing system according to claim 1, characterized in that: The semi-circular bow-shaped frame (1) has bases (5) at both ends, and the semi-circular bow-shaped frame (1) is placed on the ground through the bases (5).

3. The reflectance testing method based on the high-temperature reflectance testing system with a double-arched frame according to claim 1, characterized in that: A slider (7) corresponding to the antenna (4) is slidably mounted on the linear guide rail (2), and the antenna (4) is mounted on the corresponding slider (7).

4. The reflectance testing method based on the high-temperature reflectance testing system with a double-arched frame according to claim 1, characterized in that: The sample holder (3) includes a base plate (31), a column (32) and a metal plate (33). The base plate (31) is placed on the ground, the column (32) is placed on the base plate (31), and the metal plate (33) is placed flat on top of the column (32). The sample to be tested is placed on the metal plate (33).

5. The reflectance testing method based on the high-temperature reflectance testing system with a double-arched frame according to claim 4, characterized in that: The upper heating device includes a robotic arm (8), a heating furnace (9), and a heat insulation plate (11). The top of the heating furnace (9) is connected to the robotic arm (8) via a connecting shaft (10). The bottom of the heating furnace (9) is provided with a furnace opening. Linear modules (12) are provided on both sides of the furnace opening on the heating furnace (9). There are two heat insulation plates (11) and the two heat insulation plates (11) are arranged opposite each other. The two sides of the heat insulation plates (11) are respectively provided on the two linear modules (12). The opposite ends of the two heat insulation plates (11) are provided with semi-circular cuts. The two semi-circular cuts are enclosed to form a circular through hole (13) that matches the shape of the support column.

Images