A compact field multi-channel wideband array feed system and method

Abstract

The application discloses a compact range multi-channel broadband array feed system and method, and belongs to the technical field of compact range testing. The system comprises a linear translation mechanism, a feed house and a feed array surface. The linear translation mechanism drives the feed array surface to move horizontally in a programmed mode. The feed house is used for accommodating a feed turntable and a cabinet, and instruments and equipment and radio frequency cables are fixedly arranged and do not move with the feed array surface, so that line disturbance is avoided. The feed array surface comprises 14 feed mounting holes and 5 focal point regions symmetrically distributed according to a central horizontal line, supports the feed layout of wave bands 1 to 7, and is provided with a feed spacing adjustable device. The system adopts a low-frequency single feed source and a high-frequency double feed source mode, and a polarized electric switch is arranged for a dual-polarized feed source, so that multi-channel parallel testing can be realized. Through the programmed linear translation mechanism, fixed cable layout and multi-channel parallel design, the efficiency and precision of compact range RCS testing are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of compact field testing technology, and more specifically, to a compact field multi-channel broadband array feed system and method. Background Technology

[0002] Compact field testing technology is an internationally advanced indoor measurement technique that provides a high-performance quasi-plane wave test area at close range, enabling far-field measurements of the scattering characteristics of weak radar targets within a microwave anechoic chamber. With the development of stealth and anti-stealth technologies, compact field testing must evolve towards ultra-wideband and high-precision testing.

[0003] The feed antenna is one of the core components of a compact field testing system, and its performance directly affects the testing accuracy and efficiency. Existing compact field feeds mainly suffer from the following shortcomings: Traditional compact field feeds mostly use a single-transmitter, single-receiver mode, which can only obtain scattering information from one angle in a single measurement. For wide-band, multi-angle RCS testing, the feed needs to be changed frequently or the target needs to be rotated, resulting in long testing time and low efficiency.

[0004] During wideband testing (such as bands 1 to 7), the corresponding feed sources need to be replaced for different frequency bands. Manual replacement is not only inefficient, but each reinstallation also introduces positioning errors, phase center alignment deviations, and focus mismatches, affecting the accuracy of the test.

[0005] When the feed moves with the turntable, the RF cable bends or moves accordingly. The change in the electrical length of the cable introduces phase fluctuations and amplitude fluctuations in the cable. This error is difficult to calibrate and eliminate, especially in wideband sweep frequency testing.

[0006] Furthermore, when multiple feeds are tested simultaneously, coupling interference between feeds is likely to occur, the phase center and focus of each feed are not consistent, and the spatial constraints of multiple feeds are large, which can easily cause large deviations in the transmit and receive double positive angles, resulting in large test errors.

[0007] In the prior art, patent CN110133327A proposes an automatic switching system and method for linear compact field feed sources. This system uses a sliding base plate on a frame to mount multiple feed source horn brackets, and a linear drive mechanism to align the feed source with the holes in the absorbing material, achieving automated feed source replacement. However, this solution requires all feed sources to be of similar size, making it unsuitable for mixed layouts of low-frequency large-diameter feed sources and high-frequency small-diameter feed sources. Patent CN117878592A proposes an automated feed source switching device for compact field testing, but its positioning accuracy relies on open-loop control, suffers from wear deviations over long-term use, and only supports two feed source systems, failing to meet the requirements of parallel testing with three or more channels.

[0008] Therefore, there is a need for a compact field multi-channel broadband array feed system and method that can integrate more frequency band feeds, support adjustable dual feed spacing and dual station angle optimization, have high-precision calibration capabilities, and effectively suppress clutter interference. Summary of the Invention

[0009] The purpose of this invention is to provide a compact field multi-channel broadband array feed system and method. Through a programmable linear translation mechanism in conjunction with a multi-focal region feed array, a one-time installation and high-precision automatic switching channel for the full-band feed with 14 feed mounting holes and 5 focal regions is established. By fixing the instruments and RF cables within the feed room and ensuring they do not move with the feed array, a stable test link free from line disturbances is established. Through an adjustable feed spacing device and dual-angle optimization design, a multi-mode system is established that allows for single / dual feed switching, controllable dual-angle (minimum 0.18°, error <0.1dB), and rapid switching of polarization modes. Test architecture: By using high-precision calibration components (measuring fixtures + laser tracker) and feedhouse cover plates and ground absorbing materials, a test environment with sub-millimeter-level phase center alignment (error ≤ 0.02mm) and multiple clutter suppression is established. This achieves the technical effects of eliminating the need for manual feed replacement in broadband testing (band 1 to band 7), avoiding phase errors introduced by line disturbances, precise control of dual-station angles, and multi-channel parallel transmission and reception testing. This solves the technical problems of limited feed integration quantity, uncontrollable dual-station angles in dual-feed mode, low phase center calibration accuracy, and severe clutter interference in existing technologies, significantly improving the efficiency and accuracy of compact field radar cross section (RCS) testing.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, this application provides a compact field multi-channel broadband array feed system, comprising: A linear translation mechanism is used to drive the feed array to move linearly in the horizontal direction; The feed room is located above or to the side of the linear translation mechanism and is used to house the feed turntable and cabinet. The feed array is installed on the moving end of the linear translation mechanism. The feed array includes 14 feed mounting holes and 5 focal areas symmetrically distributed along the horizontal line of the array center; the 5 focal areas correspond to 5 translation test points. The fourth translation test point is used to install the feed source of band 1, and the feed source of band 1 is a low-frequency feed source from P-band to L-band. The first translation test point is used to install the feed source of band 2, which is a low-frequency feed source from P-band to L-band. The third translation test point is used to install feed sources for bands 3 to 5, which are feed sources for bands C to Ka. The second translation test point is used to install the feed sources for band 6 and band 7, which are feed sources from S-band to C-band. The fifth translation test point is equipped with a feed spacing adjustable device, which includes two mounting holes. The distance between the two mounting holes can be adjusted to a minimum of 90mm, and is used to adjust the feed spacing and dual station angle in dual feed mode. The feed array adopts a wavelength-controlled spacing and frequency point interleaving layout to avoid resonant coupling caused by adjacent feed wavelengths being close during multi-channel testing; The linear translation mechanism moves the feed array to different translation test points, so that the phase center of the feed installed in the corresponding focal region coincides with the focal point of the compacted field reflector, or so that the geometric center point of the dual feeds coincides with the focal point.

[0011] This system arranges two low-frequency feeds (P~L bands) on the first and fourth translation test points, respectively, on the left and right sides of the feed array. This avoids the problem that if the low-frequency feeds are concentrated on one side, they would occupy too much space and cause the center of gravity of the array to shift, affecting the motion accuracy and repeatability of the translation mechanism. Distributing them on both sides allows for a more balanced distribution of array mass, which is beneficial for high-precision translation and also minimizes the mutual coupling between signals by utilizing physical distance.

[0012] Meanwhile, the mid-to-high frequency feed sources (S~Ka band) are concentrated at the second and third translation test points in the middle. The mid-to-high frequency feed sources have shorter wavelengths and smaller sizes. Concentrating them in the middle area helps to shorten the length of the RF cable and reduce insertion loss. Furthermore, the reasonable wavelength-controlled spacing design between the high-frequency feed sources can effectively suppress resonant coupling.

[0013] Furthermore, the system is configured as follows: a single feed mode is used for band 1 and band 2, and a dual feed mode is used for bands 3 to 7; wherein the feed for band 1 and band 2 is a large-aperture single-polarization single feed, and the feed for bands 3 to 7 is a dual-polarization dual feed.

[0014] Due to limitations in aperture size and polarization isolation, the feeds for bands 1 and 2 have only one mounting hole at each translation test point; there are a total of 10 feeds for bands 3 to 7, which are installed at the corresponding holes at the second and third translation test points, covering the S-band to Ka-band.

[0015] Furthermore, in the third and second translation test points, the maximum center-to-center distance between the dual feed sources is 140mm, and the corresponding bistatic angle is no greater than 0.9°; in the fifth translation test point, the minimum center-to-center distance of the feed source spacing adjustable device is 90mm, and the corresponding minimum bistatic angle is 0.18°. The relationship between the bistatic angle, feed center distance, and reflection focal length satisfies:

[0016] in, It is a double-corner stand. The center-to-center spacing of the feed sources The focal length is for reflection; by optimizing the multi-feed layout, the measurement error caused by bistatic angle in each frequency band is less than 0.1dB.

[0017] Furthermore, the system also includes a high-precision calibration component, which includes a measuring fixture and a laser tracker. The measuring fixture is detachably mounted on the mounting surface of the feed array, and has five measuring holes on its top. The central hole is used to install a target ball, the center of which coincides with the phase center of the feed. In some specific embodiments, the distance from the center of the target ball to the bottom feed mounting surface is 120mm. The other four measuring holes are used to adjust the level and azimuth of the feed. The laser tracker is used to measure the position of the target ball and compare it with the focal point of the reflecting surface. After calibration, the error of the target ball center coinciding with the focal point of the reflecting surface is ≤0.02mm, and the repeatability of the feed turntable is ≤0.02mm.

[0018] Furthermore, the horizontal movement range of the linear translation mechanism is 0~6.00 meters, and the repeatability of the feed turntable is ≤0.02mm; the feed array includes 14 feed holes for simultaneously installing multiple broadband feeds of different frequency bands.

[0019] Furthermore, the system is configured as follows: a single-feed mode is used for bands 1 and 2, and a dual-feed mode is used for bands 3 to 7; both polarization feeds in the dual-feed mode are equipped with polarization switches to realize broadband RCS testing, i.e., broadband dual-polarization radar cross section rapid testing, where RCS is an abbreviation for Radar Cross Section.

[0020] Furthermore, the dual-polarized feed sources in the dual-feed mode are all equipped with polarization electrical switches to enable rapid testing of wideband dual-polarized radar cross sections. When the system performs multi-channel parallel testing, a dual-feed mode is adopted, in which the three frequency band feeds of band 3, band 4 and band 5 are installed diagonally on the feed array. Each frequency band feed adopts a dual-polarization dual-feed mode and is equipped with a polarization switch to realize the test of simultaneous transmission and reception of wideband feeds.

[0021] Furthermore, the feed room is equipped with a double door at the rear, and the feed room is equipped with a cover plate at the top and rear to suppress coupling noise between the feed and the reflector; the ground between the feed room and the reflector is covered with a high-cone absorbing material.

[0022] Secondly, the present invention provides a compact field multi-channel broadband array feed method, applied to the above-mentioned system, comprising: Feeds of different frequency bands are installed in the corresponding focal areas of the feed array. The feeds of band 1 and band 2 are installed using a single-polarization single feed installation, located in the focal areas on both sides of the feed array. The feeds of bands 3 to 7 are installed using a dual-polarization dual feed installation, located in the focal area in the middle of the feed array. The spacing between the dual feeds is preset by the feed spacing adjustable device. Each frequency band feed on the feed array is installed with the phase center coinciding with the focal point of the compacted field reflector. The feed array is driven to move horizontally by a programmable linear translation mechanism so that the phase center of the target frequency band feed or the geometric center of the dual feeds coincides with the focal point of the compacted field reflector. Phase center alignment is performed using a high-precision calibration component, which includes a measuring fixture and a laser tracker. The measuring fixture simulates the feed source installation state, and the laser tracker measures the position of the target ball to ensure that the error between the feed source installation surface and the focal point is ≤0.02mm. Select either a single-feed mode or a dual-feed mode according to the target frequency band. Use a single-feed mode for the feeds of bands 1 and 2, and a dual-feed mode for the feeds of bands 3 to 7. Control the polarization switch to achieve rapid testing of the dual-polarization radar cross section. During multi-channel parallel testing, feeds for bands 3, 4, and 5 are installed diagonally, and each feed is controlled to simultaneously transmit and receive radar cross section test signals in order to obtain radar cross section measurement data.

[0023] Furthermore, the method also includes: keeping the instruments and RF cables in the feed room fixed during the test to avoid test errors caused by line disturbances; suppressing coupling noise through the cover plates above and behind the feed room and the high-angle cone absorbing material on the ground; and when it is necessary to switch between different frequency bands, moving the feed array to the corresponding translation test point in sequence through a programmable linear translation mechanism to achieve full-band coverage test.

[0024] The beneficial effects of this invention are as follows: This invention adopts an array design with 14 apertures and 5 focal areas, and can install all feed sources from band 1 to band 7 at one time. The fully automatic switching is achieved through a programmable translation mechanism, which avoids the errors caused by manual feed source replacement and significantly improves testing efficiency.

[0025] This invention optimizes the feed layout so that the maximum feed spacing of translation points 2-3 (140mm) corresponds to a bistatic angle of ≤0.9°, and the minimum spacing of the adjustable device at translation point 5 (90mm) corresponds to a bistatic angle of 0.18°. The measurement error caused by the bistatic angle is less than 0.1dB, effectively solving the problem of increased backscattering error in the dual-feed mode.

[0026] This invention addresses the limitations of installation space and polarization isolation in low-frequency large-diameter feed sources by employing a single-polarization single feed source, while in high-frequency small-size feed sources, a dual-polarization dual feed source is adopted. Furthermore, the feed source allocation for each translation test point is clearly defined, which ensures both low-frequency test accuracy and leverages the advantages of high-frequency multi-channel operation.

[0027] This invention employs a programmable linear translation mechanism to drive the feed array to move linearly in the horizontal direction, and sequentially switches feeds of different frequency bands to the focal position of the compact field reflector with a positioning accuracy of ±0.01mm and a repeatability of ±0.005mm. This achieves the effect of eliminating the need for manual feed replacement during full-band (band 1 to band 7) testing, solving the problems of cumbersome manual feed replacement operation, large positioning error, and poor test repeatability.

[0028] This invention fixes the instruments and RF cables inside the feed room, preventing them from moving with the feed array. This fundamentally eliminates phase errors introduced by cable bending or movement, and significantly improves the accuracy and repeatability of wideband sweep frequency testing.

[0029] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the overall structure of the compact field multi-channel broadband array feed system of the present invention; Figure 2 This is a schematic diagram of the focal region of the feed array and the distribution of translation test points; Figure 3 This is a schematic diagram of the adjustable feed spacing device; Figure 4 This is a schematic diagram of a high-precision calibration component; Figure 5 This is a schematic diagram of a three-band feeder installed diagonally during multi-channel parallel testing; Figure 6 Rcs curves of frequency sweep at different transmit and receive angles when vertically polarized; Figure 7 For horizontal polarization, the swept frequency Rcs curves at different transmit and receive angles; In the picture: 100—Linear translation mechanism, 200—Feed room, 300—Feed array, 301—Mounting hole, 302—Focus area, 401—Measuring fixture, 402—Target ball. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0033] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0034] Example 1: This embodiment provides a compact field multi-channel broadband array feed system.

[0035] See Figure 1 The compact field multi-channel broadband array feed system includes a linear translation mechanism 100, a feed room 200, and a feed array 300.

[0036] The linear translation mechanism 100 adopts a programmable linear module (such as a ball screw type electric slide), with a horizontal travel of 1.50 meters and a feed turntable repeatability of ≤0.02mm. This linear translation mechanism 100 is used to drive the feed array 300 to move linearly in the horizontal direction, thereby realizing the position switching of feeds of different frequency bands.

[0037] The feed room 200 is located above the linear translation mechanism and employs a metal shielding structure to house the feed turntable and cabinet. A standard 19-inch cabinet is fixedly installed at the rear of the feed room 200 for mounting instruments and equipment such as vector network analyzers, power amplifiers, and local oscillators.

[0038] The feed turntable, instruments, and all RF cables connecting to the feed are fixedly installed and do not move with the feed array 300. The feed room 200 has double doors at the rear for easy operation and heat dissipation of high-power equipment. Removable covers are installed at the top and rear of the feed room 200 to suppress coupling noise between the feed and the compacted field reflector. High-cone absorbing material (cone height ≥ 300mm) is laid on the ground between the feed room 200 and the reflector to further improve absorption performance, thereby suppressing coupling noise between the feed and the reflector and reducing environmental clutter interference. This solves the problem of background noise affecting the accuracy of small target RCS measurements in compacted field testing.

[0039] like Figure 2 As shown, the feed array 300 is mounted on the moving end of the linear translation mechanism and is made of aluminum alloy plate with 14 mounting holes 301 on its surface. The feed array 300 is divided into 5 focal regions 302, corresponding to 5 translation test points, and each focal region 302 is symmetrically distributed around the horizontal line of the array center. Specifically: The first translation test point, namely translation test point 1: install the broadband feed of band 2, which is a P~L low frequency feed; The second translation test point, namely translation test point 2, is where broadband feeds for bands 6 and 7 are installed, which are S~C band feeds.

[0040] The third translation test point, namely translation test point 3, is equipped with broadband feeds for bands 3, 4 and 5; a total of 10 dual-polarization dual feeds are used, with a multi-channel sub-band feed layout, symmetrically distributed along the horizontal line of the array center.

[0041] The fourth translation test point, namely translation test point 4: install the broadband feed of band 1, which is a P~L low frequency feed; The fifth translation test point, i.e., translation test point 5: As shown in the figure... Figure 3 The adjustable feed spacing device shown includes two independent mounting holes. The distance between the mounting holes can be continuously adjusted by a precision lead screw mechanism, with a minimum adjustment of 90mm. It is used to flexibly adjust the feed spacing and dual station angle in dual feed mode.

[0042] In multi-feed parallel testing, the bistatic angle is a key parameter affecting the accuracy of backscattering measurements. Distance d between feed center and reflector focal length satisfy:

[0043] Double corner Increasing the value will increase the backscattering measurement error. To control the error, it is necessary to... <1 In this embodiment, the focal length of the reflecting surface... Take a typical value of 8m.

[0044] Calculations show that the maximum feed spacing between the first and third translation test points is 140mm, corresponding to a bistatic angle of approximately 0.9°. The minimum spacing between the fifth translation test points is 90mm, corresponding to a double-station angle of approximately 0.18°.

[0045] By optimizing the multi-feed layout, the measurement error caused by bistatic angle in each frequency band is less than 0.1dB, meeting the requirements for high-precision RCS testing. Users can flexibly adjust the bistatic angle according to actual testing needs through the adjustable spacing device of the fifth translation test point. For example, the spacing can be appropriately increased to improve angular resolution during C-band testing, or the spacing can be reduced to decrease bistatic error during Ka-band testing.

[0046] See Figure 4 In some specific embodiments, in order to ensure the precise alignment of the feed phase center and the focal point of the reflecting surface, this embodiment adopts a high-precision calibration component, which includes a measuring fixture 401 and a laser tracker 403 (not shown in the figure) for calibration.

[0047] The measuring fixture 401 is detachably installed on the mounting surface of the feed array 300. It has 5 measuring holes on its top: the center hole is used to install the target ball 402. The center of the target ball 402 is 120mm away from the mounting of the feed array. This center is the simulated feed phase center; the other 4 measuring holes are used to adjust the horizontal and azimuth directions of the feed.

[0048] The laser tracker 403 is an independent measuring device, set up on the floor of the darkroom. Its laser beam is aimed at the target ball 402 to accurately measure the spatial coordinates of the center of the target ball 402.

[0049] First, the measuring fixture 401 is installed on the mounting surface of the feed array 300 to be calibrated; Next, the target ball 402 is placed in the center hole, and the laser tracker 403 measures the spatial coordinates of the target ball 402. Then drive the linear translation mechanism 100 to move the target ball 402 to the vicinity of the focal coordinates of the compacted field reflecting surface pre-calibrated in the darkroom; Then, the position and angle of the feed array 300 are finely adjusted by the fine-tuning mechanism (lifting adjustment rod, translation guide column, azimuth adjustment arc groove, etc.) until the center of the target sphere 402 coincides with the focal point of the reflector surface, and the error value is recorded. Repeat the measurement and adjustment until the overlap error between the center of the target ball 402 and the focal point of the reflecting surface is ≤0.02mm; Then measure the positions of the target balls 402 corresponding to the other four measurement holes, and adjust the level and orientation of the feed body to make the pointing error ≤0.2mm; Finally, remove the measuring fixture 401 and install the actual feed source. Since the actual feed source and the measuring fixture 401 are aligned on the same mounting reference plane, the feed source phase center coincides with the focal point.

[0050] Verification showed that the repeatability of the feed turntable when each surface moves to the test position is ≤0.02mm. In the dual-feed model, when rapid testing in bands 3-5 is required, the system enters multi-channel parallel testing. For example... Figure 5 As shown, six feeds (one pair of dual-polarization feeds for each band) for bands 3, 4, and 5 are installed diagonally at corresponding apertures on the feed array, increasing spatial isolation. During testing, the feeds in all three bands simultaneously transmit continuous wave swept signals, and a multi-channel receiver synchronously acquires the echoes. Frequency division multiplexing or filtering networks separate the signals for each band. Each feed is equipped with a polarization switch that can switch horizontal / vertical polarization in microseconds, enabling simultaneous acquisition of dual-polarization data.

[0051] Compared with traditional sequential testing, this solution reduces the testing time by about two-thirds, and avoids the repetitive positioning error introduced by mechanical movement because it does not require moving the array.

[0052] For bands 1 and 2 (low-frequency bands), a single-feed mode is used, meaning only one feed is operational, with its phase center coinciding with the focal point of the reflector. For bands 3 to 7 (high-frequency bands), a dual-feed mode is used, with both feeds operating simultaneously, and their geometric centers coinciding with the focal point of the reflector. All dual-polarized feeds in the dual-feed mode are equipped with polarization switches, enabling rapid switching of polarization modes via remote control. This supports rapid dual-polarization RCS testing, achieving the effect of simplified links in the low-frequency band and improved channel isolation in the high-frequency band while supporting rapid polarization switching. This solves the problem that a single-feed mode cannot balance link complexity and testing accuracy across a wide frequency band.

[0053] Vertical polarization refers to the electric field direction of both feeds in a dual-feed mode being vertical, and the same applies to horizontal polarization. Figure 6 These are the swept-frequency RCS curves for different transmit and receive angles under vertical polarization. Figure 7 This shows the swept-frequency RCS curves for different transmit and receive angles under horizontal polarization. Figure 6 , Figure 7As can be seen, when tested using the system of this invention, the RCS curves of each frequency band and angle are smooth and consistent, verifying the effectiveness of this invention in high-precision calibration, bi-station angle optimization and clutter suppression.

[0054] Example 2: This embodiment provides a compact field multi-channel broadband array feed method, applied to the system described in Embodiment 1. The method includes the following steps: Step 1: Install feeds of different frequency bands in the corresponding focal area 302 of the feed array 300. The feeds of band 1 and band 2 are installed using single-polarization single feed installation, while the feeds of bands 3 to 7 are installed using dual-polarization dual feed installation. The spacing between the dual feeds is preset by the feed spacing adjustable device.

[0055] Step 2: Drive the feed array 300 horizontally through the programmable linear translation mechanism 100 so that the phase center of the feed in the current target frequency band (single feed mode) or the geometric center point of the dual feed (dual feed mode) coincides with the focal point of the compact field reflector.

[0056] Step 3: Select either single-feed mode or dual-feed mode according to the target frequency band, and control the polarization switch to achieve rapid testing of dual-polarization radar cross section; Specifically: Select either a single-feed mode (bands 1 and 2) or a dual-feed mode (bands 3 to 7) based on the target frequency band. For the dual-feed mode, if it is necessary to adjust the bi-position angle, the spacing between the two feeds can be pre-adjusted (e.g., 100mm to 200mm) using the adjustable feed spacing device. During testing, select the desired polarization mode (horizontal polarization, vertical polarization, or alternating polarization) by controlling the polarization switch, and start the RCS frequency sweep test. When it is necessary to quickly acquire RCS data for bands 3, 4, and 5, there is no need to move the linear translation mechanism; directly enter the multi-channel parallel test mode. At this time, the feeds of the three frequency bands transmit and receive simultaneously, and the three-band dual-polarization data acquisition is completed in one go with the help of the multi-channel receiver.

[0057] Step 4: When it is necessary to complete the full-band coverage test from band 1 to band 7, the feed array 300 is moved sequentially to the first to fourth translation test points using the programmable linear translation mechanism 100 (the fifth translation test point is used for dual feed spacing adjustment). Each translation test point completes the test for the corresponding frequency band. The entire switching process is completed automatically without manual intervention.

[0058] Preferably, a calibration step is included before step 1: phase center alignment is performed using a high-precision calibration component, which includes a measuring fixture 401 and a laser tracker 403. The measuring fixture 401 simulates the feed installation state, and the laser tracker 403 measures the position of the target ball 402 so that the error of the mounting surface of the feed array 300 coinciding with the focal point is ≤0.02mm.

[0059] Throughout the entire testing process, the instruments, equipment, and RF cables within the feed room 200 remained fixed, thus ensuring that the electrical length of the RF channel remained constant. There were no phase errors introduced by cable bending or movement, guaranteeing the high accuracy and repeatability of the wideband sweep frequency test.

[0060] Actual testing has verified that when using the method of this invention to perform full-band RCS testing from band 1 to band 7, no manual replacement of the feed source is required throughout the process, whereas traditional solutions typically require seven manual disassembly and reassembly operations. The overall testing time is reduced by about 60%, mainly due to the combination of automatic translation switching and multi-channel parallel transmission and reception. At the same time, the standard deviation of multiple measurements on the same target is improved by about 40%, because the positional deviation of manual installation and the phase disturbance caused by cable movement are avoided.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0062] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for feeding a compact field multi-channel broadband array, characterized in that, include: Feed sources of different frequency bands are installed in the corresponding focal regions of the feed array. Feed sources for band 1 and band 2 are installed in the focal regions on both sides of the feed array, while feed sources for bands 3 to 7 are installed in the focal region in the middle of the feed array. The feed source for band 1 is a feed source for P-band to L-band, the feed source for band 2 is a feed source for P-band to L-band, the feed sources for bands 3 to 5 are feed sources for C-band to Ka-band, and the feed sources for bands 6 and 7 are feed sources for S-band to C-band. The feed array is driven to move horizontally to different translation test points by a programmable linear translation mechanism, so that the phase center of the target frequency band feed or the geometric center of the dual feed coincides with the focal point of the compact field reflector. Select either a single-feed mode or a dual-feed mode based on the target frequency band. Use a single-feed mode for feeds in bands 1 and 2, and a dual-feed mode for feeds in bands 3 to 7. During multi-channel parallel testing, a dual-feed mode is adopted, in which the six feeds of band 3, band 4 and band 5 are installed diagonally at the corresponding apertures of the feed array. That is, the two feeds of each frequency band are diagonally distributed, and each feed is controlled to transmit and receive radar cross section test signals simultaneously to obtain radar cross section measurement data. The feed sources for bands 1 and 2 are large-aperture single-polarization single feed sources, which are installed at the fourth translation test point and the first translation test point, respectively; the feed sources for bands 3 to 7 are dual-polarization dual feed sources, the third translation test point is used to install the feed sources for bands 3 to 5, and the second translation test point is used to install the feed sources for bands 6 and 7.

2. The method for feeding a compact field multi-channel broadband array according to claim 1, characterized in that, The translation test point also includes a fifth translation test point, which is equipped with a feed spacing adjustable device. The feed spacing adjustable device includes two mounting holes, and the distance between the two mounting holes can be adjusted to 90mm, which is used to adjust the feed spacing and dual station angle in the dual feed mode.

3. The method for feeding a compact field multi-channel broadband array according to claim 2, characterized in that, In dual-feed mode, the dual-feed spacing is adjusted by the feed spacing adjustable device located at the fifth translation test point to control the dual-station angle to be no greater than 0.9°; The bistatic angle β satisfies the following relationship with the feed center distance d and the focal length f of the reflector: β = 2arctan(d / (2f)), and the measurement error caused by the bistatic angle in each frequency band is less than 0.1dB.

4. The method for feeding a compact field multi-channel broadband array according to claim 3, characterized in that, The minimum center-to-center distance between the two mounting holes of the adjustable feed spacing device is 90mm, and the corresponding minimum bi-station angle is 0.18°.

5. The method for a compact field multi-channel broadband array feed according to claim 1, characterized in that, The step of installing feeds of different frequency bands in the corresponding focal regions of the feed array also includes a calibration step: Phase center alignment is performed using a high-precision calibration component, which includes a measuring fixture and a laser tracker. The measuring fixture is detachably mounted on the mounting surface of the feed array and has five measuring holes on its top. The center hole is used to mount a target ball, and the center of the target ball coincides with the phase center of the feed. The position of the target ball is measured by a laser tracker and compared with the focal point of the reflective surface, so that the error of the feed mounting surface coinciding with the focal point is ≤0.02mm and the repeatability of the feed turntable is ≤0.02mm.

6. The method for feeding a compact field multi-channel broadband array according to claim 1, characterized in that, The first and fourth translation test points each have only one mounting hole; there are a total of 10 feed sources for bands 3 to 7, which are installed at the corresponding holes of the second and third translation test points, covering the S-band to Ka-band.

7. A compact field multi-channel broadband array feed system, applied to the compact field multi-channel broadband array feed method according to any one of claims 1 to 6, characterized in that, include: A linear translation mechanism is used to drive the feed array to move linearly in the horizontal direction; The feed room is located above or to the side of the linear translation mechanism and is used to house the feed turntable and cabinet. The feed array is installed on the moving end of the linear translation mechanism. The feed array includes multiple feed mounting holes and multiple focal areas symmetrically distributed along the horizontal line of the array center. The multiple focal areas correspond to multiple translation test points. The first translation test point is used to install the feed for band 1, the fourth translation test point is used to install the feed for band 2, the third translation test point is used to install the feeds for bands 3 to 5, the second translation test point is used to install the feeds for bands 6 and 7, and the fifth translation test point is equipped with a feed spacing adjustment device. The feed spacing adjustment device includes two mounting holes, and the distance between the two mounting holes can be adjusted to 90mm, which is used to adjust the feed spacing and dual-station angle in the dual-feed mode. The linear translation mechanism moves the feed array to different translation test points, so that the phase center of the feed installed in the corresponding focal region coincides with the focal point of the compacted field reflector, or so that the geometric center point of the dual feeds coincides with the focal point.

8. A compact field multi-channel broadband array feed system according to claim 7, characterized in that, The horizontal movement range of the linear translation mechanism is 0~6.00 meters, and the repeatability of the feed turntable is ≤0.02mm; the feed array includes 14 feed holes for simultaneously installing multiple broadband feeds of different frequency bands.

9. A compact field multi-channel broadband array feed system according to claim 7, characterized in that, The feed room is equipped with double doors at the rear, and cover plates are provided above and behind the feed room to suppress coupling noise between the feed and the reflector; the ground between the feed room and the reflector is covered with high-cone absorbing material.

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