Method for Calibration of Zero Range in All Directions of Digital Multibeam Spherical Phased Array Antenna

Abstract

This invention discloses a method for uniformly calibrating the zero-range values ​​in all directions of a digital multi-beam spherical phased array antenna, relating to the field of multi-beam antenna technology. Based on the technical characteristics of digital beamforming in digital multi-beam spherical phased array antennas, this invention completes the zero-range calibration in all directions of the digital multi-beam spherical phased array antenna by performing an internal closed-loop calibration within the primary digital beamforming element. This invention is simple, reliable, and easy to implement, and can meet the requirements for zero-range calibration in all directions for digital multi-beam spherical phased array antennas. Using this method, digital multi-beam spherical phased array antenna systems that meet engineering requirements can be designed in practical engineering applications.

Description

Technical Field

[0001] This invention relates to the field of multi-beam antenna technology, and in particular to a method for calibrating the uniformity of zero-value distance in all directions of a digital multi-beam spherical phased array antenna. Background Technology

[0002] Digital multi-beam spherical phased array antennas have gained increasing attention in recent years as a hot research area in the field of new antennas due to their multi-beam operation and full-space coverage capabilities, enabling simultaneous tracking and control of multiple space targets.

[0003] One important application scenario for multi-beam digital multi-beam spherical phased array antennas is the measurement of the orbits of space targets, including the measurement of target distance. For traditional parabolic antennas, the zero-range value of the antenna needs to be calibrated before measuring the zero-range value of a space target. This is done by setting up a calibration antenna and transponder in the far field, using the parabolic antenna to measure the zero-range value of the calibration antenna, and then subtracting the spatial distance between the parabolic antenna and the calibration antenna from the measured distance value to obtain the zero-range value of the parabolic antenna. Digital multi-beam spherical phased array antenna systems need to operate simultaneously on targets across the entire airspace, therefore the antennas need to be arranged on a spherical surface. Therefore, the design of a digital multi-beam spherical phased array antenna must ensure that the zero-range value of the system is consistent in all directions across the entire sphere, meaning that the difference in the zero-range value in each direction is less than the system specifications. Therefore, unlike traditional parabolic antennas, multi-beam spherical phased array antennas cannot rely on a single calibration antenna and transponder to complete the calibration of the uniformity of the zero distance values ​​in all directions of the entire sphere. Instead, a method that meets the requirements of digital multi-beam spherical phased array antennas and can calibrate the zero distance values ​​in all directions must be designed based on the technical characteristics of digital multi-beam spherical phased array antennas.

[0004] Therefore, this invention proposes a calibration method for digital multi-beam spherical phased array antennas based on the uniformity of zero-value distance in all directions of the inner closed-loop link. Summary of the Invention

[0005] The purpose of this invention is to provide a calibration method for the uniformity of zero distance values ​​in all directions of a digital multi-beam spherical phased array antenna. This method is simple, reliable, and easy to implement, and can meet the requirements for zero distance calibration in all directions of a digital multi-beam spherical phased array antenna. It also facilitates the design of a digital multi-beam spherical phased array antenna system that meets engineering requirements in practical engineering.

[0006] The specific technical solution is as follows:

[0007] This invention relates to a method for calibrating the uniformity of zero-range values ​​in all directions of a digital multi-beam spherical phased array antenna. The digital multi-beamforming function of the digital multi-beam spherical phased array antenna system is realized through a multi-level digital beamforming unit, and the multi-level digital beamforming unit is arranged in a tree structure. A primary digital beamforming unit is installed on a subarray of the antenna array, and the final digital beamforming unit is connected to a ranging unit.

[0008] In the primary digital beamforming unit of the subarray, the digital beam loops back to the downlink through the uplink to form a closed loop, and the distance zero value is measured on the closed loop link through the ranging unit to complete the distance zero value calibration of the subarray in that direction.

[0009] The zero-range values ​​of all subarrays on the antenna array surface of the digital multi-beam spherical phased array antenna system are measured one by one and recorded as Δ1~Δn. The zero-range values ​​of each subarray are calibrated, and the maximum difference of the zero-range values ​​of the subarrays is obtained by comparison.

[0010] The maximum difference Max(δ) is the maximum difference between the system-defined zero distance in each direction and the maximum difference δ. 系统给定 By comparing the results, the uniformity calibration of the zero-range values ​​in all directions of the entire digital multi-beam spherical phased array antenna system is completed.

[0011] Furthermore, the digital multi-beam spherical phased array antenna system is divided into an uplink and a downlink, including: an array element antenna, a duplexer, a T / R module, a multi-stage digital beamforming unit, and a ranging unit. The multi-stage digital beamforming unit constitutes a digital beamforming subsystem, wherein the array element antenna, duplexer, and T / R module are connected in sequence, the T / R module is connected to the primary digital beamforming unit, the final stage digital beamforming unit is connected to the ranging unit, and the primary digital beamforming unit and the subsequent stage digital beamforming unit are connected through a data cable.

[0012] Furthermore, the primary digital beamforming unit, along with the connected array element antenna, duplexer, and T / R assembly, are mounted together on the antenna array surface. One primary digital beamforming unit corresponds to one subarray. The secondary digital beamforming unit and the ranging unit are both installed in the equipment room. The primary digital beamforming unit and the secondary digital beamforming unit are connected via data cables.

[0013] Furthermore, in the FPGA of the primary digital beamforming unit, an uplink beamforming module and a downlink beamforming module are set up, and an uplink distance zero value switch is set on the uplink and a downlink distance zero value switch is set on the downlink. The two working states of the switches are set by the uplink distance zero value switch and the downlink distance zero value switch, forming a normal working state and an inner closed-loop distance calibration state respectively.

[0014] Under normal operating conditions, the uplink distance zero-value switch points to the uplink beamforming module, sending the uplink digital beam signal to the uplink beamforming module for processing; the downlink distance zero-value switch points to the downlink beamforming module, sending the beam signal processed by the downlink beamforming module to the subsequent processing stage via the downlink.

[0015] In the inner closed-loop distance calibration state, the uplink distance zero-value switch and the downlink distance zero-value switch are mutually connected. Then, the digital beam signal of the uplink is directly looped back into the downlink through the connected uplink distance zero-value switch and downlink distance zero-value switch, forming a closed loop.

[0016] Furthermore, in the primary digital beamforming unit of the subarray, the digital beam loops back to the downlink via the uplink to form a closed loop, and the distance zero value is measured on the closed loop link by the ranging unit to complete the distance zero value calibration of the subarray in that direction. Specifically:

[0017] The selected beam in the primary digital beamforming unit of the subarray is switched to the inner closed-loop range calibration state. The uplink digital beam signal is looped back to the downlink directly through the uplink and downlink range zero-value switches to form a closed loop. The ranging unit measures the zero-value of the distance through the closed loop link to complete the zero-value calibration of the subarray in this direction.

[0018] Furthermore, the step of sequentially measuring the zero-range values ​​of all subarrays on the antenna array surface of the digital multi-beam spherical phased array antenna system and recording them as Δ1 to Δn, and completing the zero-range value calibration of each subarray, specifically involves:

[0019] Select a subarray on the antenna array and control the switching of the selected beam in the primary digital beamforming unit of the subarray to the inner closed-loop range calibration state. The selected digital beamforms the inner uplink and downlink closed loop.

[0020] The ranging unit measures the zero distance value through the closed-loop link of the digital beam and records it as Δ1;

[0021] After the measurement is completed, the switching control of the beams in the primary digital beamforming unit of the subarray is restored to normal operation.

[0022] Select the next subarray on the antenna array, and similarly control the switch of the selected beam in the primary digital beamforming unit of the subarray to the inner closed-loop range calibration state. Complete the zero-range measurement of the subarray in this direction in the above manner and record it as Δk, where k is the selected kth subarray.

[0023] After completion, the switching control of the beams in the primary digital beamforming unit of the subarray is restored to normal operation.

[0024] Repeat the above steps to complete the distance zero-value measurement of all subarrays on the entire antenna array of the digital multi-beam spherical phased array antenna system, and record them as Δ1 to Δn, where n is the number of subarrays in the system, and complete the distance zero-value calibration of each subarray.

[0025] Furthermore, after completing the distance zero-value measurement of all subarrays on the entire antenna array of the digital multi-beam spherical phased array antenna system, the distance zero-values ​​Δ1 to Δn of all subarrays are recorded, where n is the number of subarrays in the system, and their maximum difference Max(δ) is calculated:

[0026] Max=MaxΔ1~Δn)-MinΔ1~Δn)

[0027] Among them, Max(Δ1~Δn) is the maximum value of Δ1~Δn; Min(Δ1~Δn) is the minimum value of Δ1~Δn.

[0028] Furthermore, the maximum difference Max(δ) is compared with the maximum difference δ of the system-set zero distance in each direction. 系统给定 To perform a comparison and complete the uniformity calibration of the zero-range values ​​in all directions of the entire digital multi-beam spherical phased array antenna system, the specific steps are as follows:

[0029] Determine whether Max(δ) is less than or equal to δ 系统给定 , where δ 系统给定 This is the maximum difference between the zero distance values ​​in each direction given during system design;

[0030] If Max(δ)> 系统给定 If the system fails to meet the consistency requirements of the zero-value distances in all directions, the system needs to be investigated for problems.

[0031] If Max(δ)≤δ 系统给定 If the consistency of the zero-distance values ​​in all directions of the system meets the index requirements, then the average zero-distance value of the system is calculated, specifically:

[0032] The system's mean distance to zero = mean(Δ) + mean(δ) 前端 ),

[0033]

[0034] Where, δ 前端 The distance to the front end is zero.

[0035] Furthermore, the tightly coupled array element antenna, duplexer, and T / R assembly are referred to as a front end, and its zero-range value is called the front end zero-range value δ. 前端i Let represent the distance to zero of the i-th front end. The collected test data is processed as follows:

[0036]

[0037] Where m represents the total number of front-end units in the entire antenna array.

[0038] In a digital multi-beam spherical phased array antenna system, the range null value is primarily introduced by the link between the primary digital beamforming unit and the final-stage digital beamforming unit. This invention adds a range null value calibration function to each beam in the primary digital beamforming unit. This function involves directly switching the uplink beam signal to the downlink of that beam within the FPGA of the primary digital beamforming unit, completing a closed loop for that beam in the primary digital beamforming unit. Through this closed loop, the range null values ​​in all directions of the multi-beam spherical phased array antenna can be calibrated, meeting the system's requirement for consistent range null value calibration in all directions.

[0039] The beneficial effects of this invention are as follows:

[0040] 1. The method for uniform calibration of zero-range values ​​in all directions of a digital multi-beam spherical phased array antenna provided by the present invention completes the calibration of zero-range values ​​in all directions of the digital multi-beam spherical phased array antenna by performing an internal closed loop in the primary digital beamforming unit. By calibrating the zero-range values ​​in all directions of the antenna array, the inconsistency of zero-range values ​​in all directions of the digital multi-beam spherical phased array antenna is reduced, solving a key problem in the design of digital multi-beam spherical phased array antenna systems.

[0041] 2. The method for uniformly calibrating the zero-value distance in all directions of a digital multi-beam spherical phased array antenna provided by this invention does not require the design of complex circuits, is relatively simple to implement, consumes fewer resources, and reduces system design costs. This invention only utilizes the existing equipment in the system without adding any additional equipment, and implements the uniformly calibrated zero-value distance in all directions through software algorithms, which facilitates automated operation and reduces system design costs.

[0042] 3. The method for uniformly calibrating the zero-value distance in all directions of a digital multi-beam spherical phased array antenna provided by this invention is simple and quick to operate, and facilitates system design. It proposes specific quantitative test indicators for the ranging function design of a digital multi-beam spherical phased array system, and gives specific factors affecting the quantitative indicators. This facilitates optimization and trade-offs according to specific circumstances during the design of the digital multi-beam spherical phased array antenna, and enables the design of a digital multi-beam spherical phased array antenna system that meets engineering requirements in engineering practice. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described 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 of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort, wherein:

[0044] Figure 1 This is a schematic diagram of the uplink and downlink of a digital multibeam spherical phased array antenna;

[0045] Figure 2 This is a schematic diagram of the layout of a digital multibeam spherical phased array antenna device;

[0046] Figure 3 This is a schematic diagram of the link for zero-value calibration of the closed-loop distance within a digital multibeam spherical phased array antenna.

[0047] Figure 4 This is a schematic diagram of the inner closed-loop distance calibration control of the primary digital beamforming unit;

[0048] Figure 5 This is a flowchart of the method for calibrating the zero-range values ​​in all directions of a digital multibeam spherical phased array antenna. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0050] It should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0051] Example 1

[0052] Because digital multi-beam phased array antennas are deployed across the entire spherical surface, it is impossible to calibrate the uniformity of the zero-range values ​​in all directions of the array using a single calibration antenna and transponder. Therefore, it is necessary to consider calibrating the zero-range values ​​in all directions of the spherical array. This embodiment provides a method for uniformly calibrating the zero-range values ​​in all directions of a digital multi-beam spherical phased array antenna, specifically including:

[0053] The digital multi-beamforming function of the digital multi-beam spherical phased array antenna system is realized through multi-level digital beamforming units, which are arranged in a tree structure. One primary digital beamforming unit is installed on a subarray of the antenna array, and the final digital beamforming unit is connected to a ranging unit.

[0054] In the primary digital beamforming unit of the subarray, the digital beam loops back to the downlink through the uplink to form a closed loop, and the distance zero value is measured on the closed loop link through the ranging unit to complete the distance zero value calibration of the subarray in that direction.

[0055] The zero-range values ​​of all subarrays on the antenna array surface of the digital multi-beam spherical phased array antenna system are measured one by one and recorded as Δ1~Δn. The zero-range values ​​of each subarray are calibrated, and the maximum difference of the zero-range values ​​of the subarrays is obtained by comparison.

[0056] The maximum difference Max(δ) is the maximum difference between the system-defined zero distance in each direction and the maximum difference δ. 系统给定 By comparing the results, the uniformity calibration of the zero-range values ​​in all directions of the entire digital multi-beam spherical phased array antenna system is completed.

[0057] See Figure 1 and Figure 2 First, we analyze the distance zero value of the digital multibeam spherical phased array antenna system.

[0058] like Figure 1 As shown, the uplink and downlink of a digital multi-beam spherical phased array antenna system mainly consist of four parts: array element antenna, duplexer, T / R assembly, digital beamforming subsystem, and ranging unit. The digital beamforming subsystem is further divided into multiple stages of digital beamforming units based on the antenna size. The primary stage digital beamforming unit is connected to the T / R assembly, while the final stage digital beamforming unit is connected to the ranging unit. For example... Figure 2 As shown, the primary digital beamforming unit is mounted on the antenna array, meaning one primary digital beamforming unit corresponds to one subarray on the antenna array. The subsequent digital beamforming units and ranging units are installed in the equipment room. The subsequent digital beamforming units are all other levels of digital beamforming units besides the primary ones. The primary and subsequent digital beamforming units are connected via data cables, the length of which varies from several meters to tens of meters depending on the antenna size. The array element antennas, duplexers, and T / R modules are connected to the subarray using a tight coupling method.

[0059] Because the array element antenna, duplexer, and T / R assembly use a tightly coupled connection method and are mass-produced, the consistency of their zero-range values ​​can be tested at the factory to ensure they meet system performance requirements. A tightly coupled array element antenna, duplexer, and T / R assembly is called a front-end, and its zero-range value is called the front-end zero-range value, denoted by δ. 前端i Let represent the distance to zero of the i-th front end. The collected test data is processed as follows:

[0060]

[0061] Where m represents the total number of front-end units in the entire antenna array.

[0062] Based on the above analysis, the key to determining whether the uniformity of the zero distance values ​​in all directions of the digital multi-beam spherical phased array antenna system meets the system requirements lies in controlling the uniformity of the zero distance values ​​in the uplink and downlink from the ranging unit to the primary digital beamforming unit.

[0063] See Figure 3 The digital multi-beam spherical phased array antenna system of the present invention forms a closed loop within the primary digital beamforming unit, directly looping the uplink digital beam signal back into the downlink link to form a closed loop. In this way, the ranging unit can close the uplink and downlink loops through the primary digital beamforming unit, and then perform zero-range measurement on the closed-loop link to obtain the zero-range value of the link.

[0064] The specific design of closed-loop operation is as follows: Figure 4 As shown in the diagram, in the FPGA of the primary digital beamforming unit, a switch is designed on both the uplink and downlink, namely an uplink distance zero-value switch and a downlink distance zero-value switch, and the switches are configured with two operating states: normal operation and inner closed-loop distance calibration. In the normal operation state, the uplink distance zero-value switch points to point ①, meaning the uplink digital beam signal is sent to the uplink digital beamforming module for processing, and the downlink distance zero-value switch points to point ②, meaning the beam signal processed by the downlink digital beamforming module is sent to the subsequent processing stage through the downlink. In the inner closed-loop distance calibration state, both the uplink distance zero-value switch and the downlink distance zero-value switch point to point ③. At this time, the uplink digital beam signal directly loops back to the downlink beam link through point ③ to form a closed loop.

[0065] See Figure 5 The inner closed-loop distance zero value calibration begins by configuring the ranging unit and beam number for calibrating the zero distance value in the system.

[0066] Select a subarray on the antenna array and control the switching of the selected beam in the primary digital beamforming unit of the subarray to the inner closed-loop range calibration state to form an inner uplink and downlink closed loop for the selected beam.

[0067] The ranging unit completes the zero distance measurement of the closed-loop link through the uplink and downlink closed loop of the beam and records it as Δ1. After completion, the switching control of the beam in the primary digital beamforming unit of the subarray is restored to normal working state.

[0068] Select the next subarray on the antenna array, and similarly control the switching of the selected beam in the primary digital beamforming unit of the subarray to the inner closed-loop distance calibration state. Complete the zero-range measurement of the closed-loop link in the above manner and record it as Δk, where k is the selected kth subarray.

[0069] After completion, the beam switching control in the primary digital beamforming unit of the subarray is restored to normal operation.

[0070] The next step is to determine whether the zero-range values ​​of all subarrays in the entire antenna array have been calibrated. If the zero-range values ​​of all subarrays in the antenna array have not been calibrated, then the next uncalibrated subarray is selected and the zero-range value is measured according to the process described above.

[0071] After completing the distance zero-value measurement for all subarrays of the system and recording them as Δ1 to Δn, where n is the number of subarrays in the system, calculate their maximum difference Max(δ):

[0072] Max=MaxΔ1~Δn)-MinΔ1~Δn)

[0073] Among them, Max(Δ1~Δn) is the maximum value of Δ1~Δn; Min(Δ1~Δn) is the minimum value of Δ1~Δn.

[0074] Determine if Max is less than or equal to δ 系统给定 , where δ 系统给定 This represents the maximum difference between the zero-distance values ​​in each direction, given during system design. If Max > δ 系统给定 If the consistency of the zero values ​​of the distances in all directions of the system does not meet the requirements, the system needs to be investigated for problems.

[0075] If Max≤δ 系统给定 If the consistency of the zero-distance values ​​in all directions of the system meets the index requirements, then the average zero-distance value of the system is calculated. Specifically:

[0076] The system's mean distance to zero = mean(Δ) + mean(δ) 前端 ),

[0077]

[0078] Where, δ 前端 The distance to the front end is zero.

[0079] Based on the technical characteristics of digital beamforming in digital multi-beam spherical phased array antennas, this invention proposes a zero-range calibration method for digital multi-beam spherical phased array antenna systems based on an inner closed loop. This method is simple, reliable, and easy to implement, and can meet the requirements for zero-range calibration of digital multi-beam spherical phased array antennas in various directions. Using this method, digital multi-beam spherical phased array antenna systems that meet engineering requirements can be designed in engineering practice.

[0080] The above description is merely a preferred 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 conceived by those skilled in the art within the technical scope disclosed in the present invention without creative effort 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 defined in the claims.

Claims

1. A method for calibrating the uniformity of zero-range values ​​in all directions of a digital multi-beam spherical phased array antenna, characterized in that: The digital multi-beamforming function of the digital multi-beam spherical phased array antenna system is realized through multi-level digital beamforming units, which are arranged in a tree structure. One primary digital beamforming unit is installed on a subarray of the antenna array, and the final digital beamforming unit is connected to a ranging unit. In the primary digital beamforming unit of the subarray, the digital beam loops back to the downlink through the uplink to form a closed loop, and the distance zero value is measured on the closed loop link through the ranging unit to complete the distance zero value calibration of the subarray. Complete the distance null values ​​of all subarrays on the antenna array surface of the digital multi-beam spherical phased array antenna system one by one, and record them as follows: The distance zero values ​​of each subarray are calibrated, and the maximum difference between the distance zero values ​​of the subarrays is obtained by comparison. ; Maximum difference The maximum difference from the system-defined zero distance in each direction By comparing the results, the uniformity calibration of the zero-range values ​​in all directions of the entire digital multi-beam spherical phased array antenna system is completed.

2. The method for calibrating the uniformity of zero-range values ​​in all directions of a digital multi-beam spherical phased array antenna according to claim 1, characterized in that: The digital multi-beam spherical phased array antenna system is divided into uplink and downlink, including: array element antenna, duplexer, T / R module, multi-stage digital beamforming unit and ranging unit. The multi-stage digital beamforming unit forms a digital beamforming subsystem. The array element antenna, duplexer and T / R module are connected in sequence. The T / R module is connected to the primary digital beamforming unit. The final stage digital beamforming unit is connected to the ranging unit. The primary digital beamforming unit and the subsequent stage digital beamforming unit are connected through data cables.

3. The method for calibrating the uniformity of zero-range values ​​in all directions of a digital multi-beam spherical phased array antenna according to claim 2, characterized in that: The primary digital beamforming unit, along with the connected array element antenna, duplexer, and T / R assembly, are mounted together on the antenna array surface. One primary digital beamforming unit corresponds to one subarray. The secondary digital beamforming unit and the ranging unit are both installed in the equipment room. The primary digital beamforming unit and the secondary digital beamforming unit are connected via data cables.

4. The method for calibrating the uniformity of zero-range values ​​in all directions of a digital multi-beam spherical phased array antenna according to claim 1, characterized in that: In the FPGA of the primary digital beamforming unit, an uplink beamforming module and a downlink beamforming module are set up, and an uplink distance zero value switch is set on the uplink and a downlink distance zero value switch is set on the downlink. The two working states of the switches are set by the uplink distance zero value switch and the downlink distance zero value switch, forming a normal working state and an inner closed-loop distance calibration state respectively. Under normal operating conditions, the uplink distance zero-value switch points to the uplink beamforming module, sending the uplink digital beam signal to the uplink beamforming module for processing; the downlink distance zero-value switch points to the downlink beamforming module, sending the beam signal processed by the downlink beamforming module to the subsequent processing stage via the downlink. In the inner closed-loop distance calibration state, the uplink distance zero-value switch and the downlink distance zero-value switch are mutually connected. Then, the digital beam signal of the uplink is directly looped back into the downlink through the connected uplink distance zero-value switch and downlink distance zero-value switch, forming a closed loop.

5. The method for calibrating the uniformity of zero-range values ​​in all directions of a digital multi-beam spherical phased array antenna according to claim 4, characterized in that, In the primary digital beamforming unit of the subarray, the digital beam loops back to the downlink via the uplink to form a closed loop. The distance zero-value measurement is then performed on the closed-loop link by the ranging unit to complete the distance zero-value calibration of the subarray. Specifically: The selected beam in the primary digital beamforming unit of the subarray is switched to the inner closed-loop range calibration state. The uplink digital beam signal is looped back to the downlink directly through the uplink and downlink range zero-value switches to form a closed loop. The ranging unit measures the zero-value of the distance through the closed loop link to complete the range zero-value calibration of the subarray.

6. The method for calibrating the uniformity of zero-range values ​​in all directions of a digital multi-beam spherical phased array antenna according to claim 5, characterized in that, The distance null values ​​of all subarrays on the antenna array surface of the digital multi-beam spherical phased array antenna system are measured one by one and recorded as follows: Complete the zero-distance calibration of each directional subarray, specifically as follows: Select a subarray on the antenna array and control the switch of the selected beam in the primary digital beamforming unit of the subarray to the inner closed-loop range calibration state. The selected switch forms the inner uplink and downlink closed loop. The ranging unit measures the zero distance value through the closed-loop link of the digital beam and records it as Δ1; After the measurement is completed, the beam switching control in the primary digital beamforming unit of the subarray is restored to normal operation. Select the next subarray on the antenna array, and similarly control the switch of the selected beam in the primary digital beamforming unit of the subarray to the inner closed-loop distance calibration state. The ranging unit completes the zero-range measurement of the subarray through the closed-loop link of the digital beam and records it as Δk, where k is the selected k-th subarray. After completion, the switching control of the beams in the primary digital beamforming unit of the subarray is restored to normal operation. Repeat the above steps to complete the distance null value measurement of all subarrays on the entire antenna array of the digital multi-beam spherical phased array antenna system, and record it as follows: , Given the number of subarrays in the system, complete the zero-distance calibration of each subarray.

7. The method for calibrating the uniformity of zero-range values ​​in all directions of a digital multi-beam spherical phased array antenna according to claim 6, characterized in that, After completing the distance zero-value measurement of all subarrays on the entire antenna array of the digital multi-beam spherical phased array antenna system, the distance zero-values ​​of all subarrays are recorded. , Given the number of subarrays in the system, calculate their maximum difference. : in, for The maximum value; for The minimum value.

8. The method for calibrating the uniformity of zero-range values ​​in all directions of a digital multi-beam spherical phased array antenna according to claim 7, characterized in that, Maximum difference The maximum difference from the system-defined zero distance in each direction To perform a comparison and complete the uniformity calibration of the zero-range values ​​in all directions of the entire digital multi-beam spherical phased array antenna system, the specific steps are as follows: Discrimination Is it less than or equal to? ,in, This is the maximum difference between the zero distance values ​​in each direction given during system design; like If the system fails to meet the consistency requirements of the zero-value distances in all directions, the system needs to be investigated for problems. like If the consistency of the zero-distance values ​​in all directions of the system meets the index requirements, then the average zero-distance value of the system is calculated, specifically: ， ， in, The distance to the front end is zero.

9. The method for calibrating the uniformity of zero-range values ​​in all directions of a digital multi-beam spherical phased array antenna according to claim 8, characterized in that, The tightly coupled array element antenna, duplexer, and T / R assembly are referred to as a front end, and its zero-range value is called the front end zero-range value. , indicating the first The distance from the front end to zero is used to process the collected test data as follows: in, This indicates the total number of front-end units in the entire antenna array.

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