A method for calibrating the pointing error of an active array-fed reflector multi-beam antenna

Abstract

This invention relates to a pointing error calibration method for an active array-fed reflector multi-beam antenna, belonging to the field of spaceborne multi-beam antenna technology; the method involves fabricating the antenna according to requirements; installing a calibration unit on top of the antenna's reflector; and selecting the feed array coordinate system O. f X f Y f ZhongX f axis and Y f All feed elements on the axis are used as simulation elements; the transmission phase of each feed element relative to the calibration element is obtained in the initial state to obtain X. f The transmission phase of each feed element on the axis relative to the calibration element is obtained as Y. f A table of the correspondence between rotation angle and phase is established for the transmission phase of each feed unit on the axis relative to the calibration unit; based on the measured phase and the table of the correspondence between rotation angle and phase, the on-orbit beam pointing error is obtained; this invention realizes the acquisition of the on-orbit beam pointing error of a multi-beam antenna without a ground calibration station.

Description

Technical Field

[0001] This invention belongs to the field of spaceborne multi-beam antenna technology, and relates to a method for calibrating the pointing error of an active array-fed reflector multi-beam antenna. Background Technology

[0002] Future active array-fed reflector multi-beam antennas will develop towards wide-area coverage, high-capacity communication, and flexible on-orbit applications. To improve communication capacity, it is desirable to use beams with narrower beamwidths to cover the service area to obtain higher gain and frequency reuse times. Narrower beams result in faster gain roll-off, thus placing extremely high demands on the pointing accuracy of multi-beam antennas.

[0003] Traditional multi-beam pointing error calibration systems require the establishment of ground calibration stations. Onboard sum and difference beams are formed, and the pointing error is calibrated using a single-pulse calibration system. The drawbacks are that the calibration station must be located at the center of the calibration beam, imposing stringent requirements on ground station site selection, resulting in extremely high difficulty and cost in ground station construction. Furthermore, for fully flexible communication satellites that will dominate the future communication satellite market, the service targets and communication needs of satellite users are unknown, making the construction of fixed ground calibration stations impossible. Therefore, traditional multi-beam pointing error calibration methods cannot meet the needs of future communication satellites. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a method for calibrating the pointing error of an active array-fed reflector multi-beam antenna, which enables the acquisition of the on-orbit beam pointing error of the multi-beam antenna without the need for a ground calibration station.

[0005] The solution of the present invention is:

[0006] A method for calibrating the pointing error of an active array-fed reflector multi-beam antenna includes:

[0007] Step 1: Fabricate the antenna according to requirements; install the calibration unit on top of the antenna's reflector;

[0008] Step 2: Establish the feed array coordinate system O on the antenna feed array. f X f Y f Select X f axis and Y f All feed elements on the axis are used as simulation elements;

[0009] Step 3: Obtain the transmission phase of each feed element relative to the calibration unit in the initial state.

[0010] Step 4: Establish the antenna coordinate system O b X bY b First, rotate the antenna's reflector around X. b Rotate along the axis, then around the Y-axis b Rotate the axis; according to step three Obtain X f Transmission phase of each feed element on the axis relative to the calibration element Obtain Y f Transmission phase of each feed element on the axis relative to the calibration element

[0011] Step 5: Based on the X-axis in Step 4 b Axis rotation angle, around Y b Axis rotation angle, X f Transmission phase of each feed element on the axis relative to the calibration element Y f Transmission phase of each feed element on the axis relative to the calibration element Establish a table showing the correspondence between rotation angle and phase;

[0012] Step Six: When the antenna is in orbit, measure the position of the feed array X at the antenna. f axis and Y f Measured phase of each feed element on the axis Based on the correspondence table between rotation angle and phase in step five, the beam pointing error on track can be found.

[0013] In the above-mentioned method for calibrating the pointing error of an active array-fed reflector multi-beam antenna, in step one, the calibration unit is installed at the edge of the top of the antenna reflector.

[0014] In the above-described method for calibrating the pointing error of an active array-fed reflector multi-beam antenna, the method for establishing the feed array coordinate system in step two is as follows:

[0015] The origin O is the feed element at the center of the feed array. f ; Over O f The horizontal line is X f The axis is to the right, with the positive direction being to the right; passing through O f The vertical line is Y f The axis is upward, with the positive direction being upward.

[0016] In the above-described method for calibrating the pointing error of an active array-fed reflector multi-beam antenna, in step three, the transmission phase of all feed elements relative to the calibration unit... The method for obtaining it is as follows:

[0017] S31. The reflector position of the antenna remains unchanged, located at the origin O. f The feed element is used as the reference feed;

[0018] S32. Number the feed elements other than the reference feed element as 1, 2, ..., i, ..., N;

[0019] S33. Perform transmission phase simulation analysis on all feed units and the calibration unit; and normalize the phases of the other feed units numbered 1 to N obtained from the simulation with the phase of the reference feed to obtain the transmission phase of each feed unit relative to the calibration unit in the initial state.

[0020] In the above-described method for calibrating the pointing error of an active array-fed reflector multi-beam antenna, in step four, the antenna coordinate system O... b X b Y b The method for establishing it is as follows:

[0021] The origin O is the center point of the antenna's reflector. b ; Over O b The horizontal centerline of the reflector is X b The axis is to the right, with the positive direction being to the right; passing through O b The vertical centerline of the reflector is Y b The axis is upward, with the positive direction being upward.

[0022] In the above-described method for calibrating the pointing error of an active array-fed reflector multi-beam antenna, the antenna's reflector is rotated around X... b axis and Y b When the shaft rotates, it is a step rotation, with a step rotation angle of 0.01°.

[0023] In the above-mentioned method for calibrating the pointing error of an active array-fed reflector multibeam antenna, X f Transmission phase of all feed elements on the axis relative to the calibration element The method for obtaining it is as follows:

[0024] S41, The antenna's reflector rotates around X b Rotate the axis and record X. f Phase of each feed unit on the shaft at each step rotation angle X f Phase of all feed elements on the shaft at each rotation angle The phase of the feed source is normalized relative to the reference feed to obtain the normalized X. f Phase of all feed elements on the shaft at each rotation angle

[0025]

[0026] In the formula, The reference feed phase;

[0027] S42. Normalize Xf Phase of all feed elements on the shaft at each rotation angle The transmission phase of each feed unit relative to the calibration unit in the initial state in step three. Using this as a reference standard, normalization is then performed to obtain X. f Transmission phase of each feed element on the axis relative to the calibration element

[0028]

[0029] In the above-mentioned method for calibrating the pointing error of an active array-fed reflector multibeam antenna, Y f Transmission phase of all feed elements on the axis relative to the calibration element The method for obtaining it is as follows:

[0030] S51, the antenna reflector rotates around Y b Rotate the axis and record the Y-axis. f Phase of each feed unit on the shaft at each step rotation angle Y f Phase of all feed elements on the shaft at each rotation angle The normalized Y is obtained by normalizing the phase relative to the reference feed. f Phase of all feed elements on the shaft at each rotation angle

[0031]

[0032] In the formula, The reference feed phase;

[0033] S52, Normalize Y f Phase of all feed elements on the shaft at each rotation angle The transmission phase of each feed unit relative to the calibration unit in the initial state in step three. Using this as a reference standard, normalization is then performed to obtain Y. f Transmission phase of each feed element on the axis relative to the calibration element

[0034]

[0035] In the above-mentioned method for calibrating the pointing error of an active array-fed reflector multi-beam antenna, the method for establishing the correspondence table between rotation angle and phase in step five is as follows:

[0036] The vertical header of the relation table includes elements for the X-axis. b Axis rotation angle θ x and around Y b Axis rotation angle θy ;

[0037] The horizontal header of the relational table includes X f The transmission phase of each feed element on the axis relative to the calibration element and the Y f The transmission phase of each feed unit on the axis relative to the calibration unit.

[0038] In the above-described method for calibrating the pointing error of an active array-fed reflector multi-beam antenna, step six involves finding the on-orbit pointing error of the beam as follows:

[0039] The measured phase of each feed unit Substitute into the relation table in step five or Find the corresponding θ x or θ y This refers to the beam pointing error on track.

[0040] The advantages of this invention compared to the prior art are:

[0041] (1) This invention realizes the calibration of multi-beam on-orbit pointing error through the self-closed-loop link of the satellite communication payload, directly solving the engineering implementation bottleneck problem caused by the need to build a ground calibration station for traditional multi-beam satellites, and meeting the needs of satellite operators who want to avoid building a ground calibration station.

[0042] (2) This invention places a calibration unit on the structure of the reflector, analyzes the transmission phase of the calibration unit and each radiating element in the feed array in combination with the specific design parameters of the antenna, and then rotates the reflector around the antenna coordinate system to obtain the correspondence between the rotation angle and the phase change value of each radiating element, laying the foundation for subsequent error calibration.

[0043] (3) When the antenna is on track, the present invention tests the transmission phase between the calibration unit and each radiating unit. By comparing the corresponding relationship between the reflector rotation angle obtained from the ground simulation and the phase change value of each radiating unit, the rotation angle of the reflector relative to the theoretical design position around the X and Y axes of the antenna coordinate system is obtained, and then the on-track pointing error of the beam is obtained. Attached Figure Description

[0044] Figure 1 This is a flowchart of the multi-beam antenna pointing error calibration process of the present invention;

[0045] Figure 2 This is a schematic diagram showing the installation position of the calibration unit of the present invention;

[0046] Figure 3 The coordinate system O of the feed array of this invention f X f Y f Schematic diagram of the selection of the upper feed source unit. Detailed Implementation

[0047] The present invention will be further described below with reference to the embodiments.

[0048] This invention provides a method for calibrating the pointing error of an active array-fed reflector multi-beam antenna. By utilizing the self-closed-loop link of the satellite communication payload, the pointing error of the multi-beam antenna is calibrated on orbit. This directly solves the engineering implementation bottleneck caused by the requirement to build a ground calibration station for traditional multi-beam satellites, and meets the needs of satellite operators who wish to avoid building ground calibration stations.

[0049] Methods for calibrating the pointing error of active array-fed reflector multi-beam antennas, such as... Figure 1 As shown, the specific steps include the following:

[0050] Step 1: Fabricate the antenna according to requirements; install the calibration unit on top of the antenna's reflector. For example... Figure 2 As shown, the calibration unit is mounted on the top edge of the antenna's reflector.

[0051] Step 2: Establish the feed array coordinate system O on the antenna feed array. f X f Y f The method for establishing the feed array coordinate system is as follows:

[0052] The origin O is the feed element at the center of the feed array. f ; Over O f The horizontal line is X f The axis is to the right, with the positive direction being to the right; passing through O f The vertical line is Y f The axis is upward, with the positive direction being upward.

[0053] Select X f axis and Y f All feed elements on the axis are used as simulation elements, such as Figure 3 As shown.

[0054] Step 3: Obtain the transmission phase of each feed element relative to the calibration unit in the initial state. Transmission phase of all feed units relative to the calibration unit The method for obtaining it is as follows:

[0055] S31. The reflector position of the antenna remains unchanged, located at the origin O. f The feed element is used as the reference feed;

[0056] S32. Number the feed elements other than the reference feed element as 1, 2, ..., i, ..., N;

[0057] S33. Perform transmission phase simulation analysis on all feed units and the calibration unit; and normalize the phases of the other feed units numbered 1 to N obtained from the simulation with the phase of the reference feed to obtain the transmission phase of each feed unit relative to the calibration unit in the initial state.

[0058] Step 4: Establish the antenna coordinate system O b X b Y b Antenna coordinate system O b X b Y b The method for establishing it is as follows:

[0059] The origin O is the center point of the antenna's reflector. b ; Over O b The horizontal centerline of the reflector is X b The axis is to the right, with the positive direction being to the right; passing through O b The vertical centerline of the reflector is Y b The axis is upward, with the positive direction being upward.

[0060] First, rotate the antenna reflector around X. b Rotate along the axis, then around the Y-axis b The antenna's reflector rotates around the X-axis. b axis and Y b When the shaft rotates, it is a step rotation, with a step rotation angle of 0.01°.

[0061] According to step three Obtain X f Transmission phase of each feed element on the axis relative to the calibration element Obtain Y f Transmission phase of each feed element on the axis relative to the calibration element

[0062] X f Transmission phase of all feed elements on the axis relative to the calibration element The method for obtaining it is as follows:

[0063] S41, The antenna's reflector rotates around X b Rotate the axis and record X. f Phase of each feed unit on the shaft at each step rotation angle X f Phase of all feed elements on the shaft at each rotation angle The phase of the feed source is normalized relative to the reference feed to obtain the normalized X. f Phase of all feed elements on the shaft at each rotation angle

[0064]

[0065] In the formula, The reference feed phase;

[0066] S42. Normalize X f Phase of all feed elements on the shaft at each rotation angle The transmission phase of each feed unit relative to the calibration unit in the initial state in step three. Using this as a reference standard, normalization is then performed to obtain X. f Transmission phase of each feed element on the axis relative to the calibration element

[0067]

[0068] Y f Transmission phase of all feed elements on the axis relative to the calibration element The method for obtaining it is as follows:

[0069] S51, the antenna reflector rotates around Y b Rotate the axis and record the Y-axis. f Phase of each feed unit on the shaft at each step rotation angle Y f Phase of all feed elements on the shaft at each rotation angle The normalized Y is obtained by normalizing the phase relative to the reference feed. f Phase of all feed elements on the shaft at each rotation angle

[0070]

[0071] In the formula, The reference feed phase;

[0072] S52, Normalize Y f Phase of all feed elements on the shaft at each rotation angle The transmission phase of each feed unit relative to the calibration unit in the initial state in step three. Using this as a reference standard, normalization is then performed to obtain Y. f Transmission phase of each feed element on the axis relative to the calibration element

[0073]

[0074] Step 5: Based on the X-axis in Step 4 b Axis rotation angle, around Y b Axis rotation angle, X f Transmission phase of each feed element on the axis relative to the calibration element Yf Transmission phase of each feed element on the axis relative to the calibration element Establish a table relating rotation angles to phases. The method for establishing this table is as follows:

[0075] The vertical header of the relation table includes elements for the X-axis. b Axis rotation angle θ x and around Y b Axis rotation angle θ y ;

[0076] The horizontal header of the relational table includes X f The transmission phase of each feed element on the axis relative to the calibration element and the Y f The transmission phase of each feed element on the axis relative to the calibration element. See the figure below:

[0077]

[0078] Step Six: When the antenna is in orbit, measure the position of the feed array X at the antenna. f axis and Y f Measured phase of each feed element on the axis Based on the correspondence table between rotation angle and phase in step five, the beam pointing error on track can be found.

[0079] The method for determining the on-orbit pointing error of the beam is as follows:

[0080] The measured phase of each feed unit Substitute into the relation table in step five or Find the corresponding θ x or θ y This refers to the beam pointing error on track.

[0081] Example

[0082] The invention will now be described in further detail using a typical multi-beam antenna as an example:

[0083] (S1): The antenna parameters are selected as follows: aperture 2.6m, focal length 3.0m, number of feed sources 127, antenna operating at 30GHz, calibration unit aperture selected as 1 wavelength, calibration unit located at the top of the reflector, as follows. Figure 2 As shown.

[0084] (S2): Select feeds located on the X and Y axes of the feed array. For example, select feeds such as... Figure 3 As shown:

[0085] ① Phase change analysis was performed on feeds 8, 14, 38, 50, 92, and 110 on the X-axis of the feed array to obtain the relationship between the phase change and the antenna rotation angle around the Y-axis;

[0086] ② Phase change analysis was performed on feeds 11, 17, 44, 56, 101, and 119 on the Y-axis of the feed array to obtain the relationship between the phase change and the antenna rotation angle around the X-axis;

[0087] Using the method provided by this invention, the correspondence between the rotation of the reflector around the antenna coordinate system and the phase transformation was obtained. The actual simulation results show that the example is consistent with the conclusions of this invention, namely:

[0088] ① When the reflector rotates around the X-axis of the antenna coordinate system, it mainly affects the phase of the elements on the Y-axis of the feed array. The phase of the elements on the X-axis of the feed array changes slightly, but the change is very small and can be ignored.

[0089] ② When the reflector rotates around the Y-axis of the antenna coordinate system, it mainly affects the phase of the elements on the X-axis of the feed array. The phase of the elements on the Y-axis of the feed array also changes with the angle and cannot be ignored, so it needs to be corrected.

[0090] (S3) and (S4): Rotate the reflector about the antenna's Y-axis by 0.433° (θ) y | idea Then rotate -0.25° (θ) around the X-axis. x | idea This simulates on-orbit beam pointing deviation. Under these conditions, phase analysis of the feed array is performed to obtain equivalent... The rotation angle θ of the reflector about the antenna coordinate system is calculated using the method presented in this paper. (x,y) Analyze the value θ (x,y) Compared with the theoretical rotation value θ (x,y) | idea By comparison, the calculation accuracy of this method is verified, that is, the calibration accuracy of this method for on-orbit pointing error is obtained.

[0091] ① Obtain the rotation angle θ of the reflector around the Y-axis of the antenna coordinate system. y

[0092]

[0093] ② Obtain the rotation angle θ of the reflector around the X-axis of the antenna coordinate system. x

[0094] First, using the already obtained angle θ of the antenna's rotation around the Y-axis... y Based on its influence on the Y-axis phase of the feed array, the phase on the Y-axis of the feed array is corrected. Finally, the antenna deflection angle around the X-axis is calculated according to the corrected final phase, as shown in the table below:

[0095]

[0096]

[0097] As can be seen from the table above, the reflector rotation angle value around the antenna coordinate system obtained by applying the method provided by this invention is significantly different from the theoretical rotation angle value. The estimation error is less than 0.003°. That is, this method can be used to achieve beam pointing error on orbit. Small calibration error At 0.003° This ensures high-precision on-orbit beam pointing calibration.

[0098] This invention achieves on-orbit pointing error calibration of multi-beam satellites through a self-closed-loop link in the satellite communication payload, directly solving the engineering implementation bottleneck caused by the requirement to build ground calibration stations for traditional multi-beam satellites, and meeting the needs of satellite operators who wish to avoid building ground calibration stations.

[0099] This invention places a calibration unit on the structure of the reflector, analyzes the transmission phase of the calibration unit and each radiating element in the feed array in combination with the specific design parameters of the antenna, and then rotates the reflector around the antenna coordinate system to obtain the correspondence between the rotation angle and the phase change value of each radiating element, laying the foundation for subsequent error calibration.

[0100] This invention tests the transmission phase between the calibration unit and each radiating unit when the antenna is in orbit. By comparing the correspondence between the reflector rotation angle obtained from ground simulation and the phase change value of each radiating unit, the rotation angle of the reflector relative to the theoretical design position around the X and Y axes of the antenna coordinate system is obtained, and thus the on-orbit pointing error of the beam is obtained.

[0101] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for calibrating pointing errors of an active array fed reflector multi-beam antenna, the method comprising: Comprise: ​ Step one, according to the demand to make antenna; The calibration unit is installed on the top of the reflector of the antenna; The calibration unit is installed on the edge of the top of the reflector of the antenna; Step two, establish the feed array coordinate system O on the feed array of the antenna f X f Y f ; select all the feed units on the X f axis and Y f axis as simulation units; Step three, obtaining the transmission phase of each feed unit relative to the calibration unit in the initial state Step four, establish the antenna coordinate system O b X b Y b ; rotate the reflector of the antenna around the X b axis first, then around the Y b axis; obtain the transmission phase of each feed unit relative to the calibration unit on the X axis according to step three f axis according to step three axis according to step three f axis according to step three Step five, the rotation angle of the X b axis, the rotation angle of the Y b axis, the rotation angle of the X f axis, the transmission phase of each feed unit relative to the calibration unit Y f axis, the transmission phase of each feed unit relative to the calibration unit establish a corresponding relationship table of the rotation angle and the phase Step six, measure the real phase of each feed unit on the X f axis and Y f axis According to the corresponding relation table of the rotation angle and the phase in step five, the on-orbit pointing error of the beam is found.

2. The method of claim 1, wherein: In the step two, the establishment method of the feed array coordinate system is: Take the feed unit in the center of the feed array as the coordinate origin O f ; the horizontal line passing through O f is the X f axis, and the right direction is positive; the vertical line passing through O f is the Y f axis, and the upward direction is positive.

3. The method of claim 2, wherein: In step three, the transmission phases of all feeder units relative to the calibration unit are determined The acquisition method is as follows: S31, the reflector position of the antenna is unchanged to be located at the coordinate origin O f the feed unit at the coordinate origin O as a reference feed S32, the other feed units except the reference feed are numbered 1, 2, …, i, …, N; S33, transmit phase simulation analysis is performed on all the feed source units and the calibration unit; and the phases of the other feed source units numbered 1 to N obtained through simulation are normalized with the phase of the reference feed source, to obtain the transmit phase of each feed source unit relative to the calibration unit in the initial state 4. The method of claim 3, wherein: In step four, the antenna coordinate system O b X b Y b The establishment method is: The center point of the reflector of the antenna is taken as the coordinate origin O b The horizontal midline of the reflector of O passes through X b b The vertical midline of the reflector of O passes through Y b b ​​​ 5. The method of claim 4, wherein: the plurality of beams are formed by a plurality of active array feed reflector antennas; and the plurality of active array feed reflector antennas are controlled by a plurality of beam steering controllers. The reflector of the antenna rotates around the X b axis and the Y b axis. When the reflector rotates, it is a step rotation with a step rotation angle of 0.01°.

6. The method of claim 5, wherein: X f Transmission phase of all feed elements on the axis relative to the calibration element The acquisition method is: S41, the reflector of the antenna rotates around the X b axis, record X f the phase of each feed unit on the axis at each step rotation angle X f the phase of all feed units on the axis at each rotation angle normalize relative to the reference feed phase, obtain normalized X f the phase of all feed units on the axis at each rotation angle In the formula, is the reference feed phase; S42, normalizing X f Phase of each feed unit at each corner on the axis Phase of each feed unit relative to the calibration unit at the initial state in step three As a reference standard, normalizing X f Phase of each feed unit relative to the calibration unit on the axis 7. The method of claim 5, wherein: the plurality of beams are formed by a plurality of active array feed reflector antennas; and the plurality of active array feed reflector antennas are controlled by a plurality of beam steering controllers. Y f Transmission phase of all feed elements on the axis relative to the calibration element The acquisition method is: S51, reflector of the antenna rotates around Y b axis rotates, record Y f phase of each feed unit on the axis at each step rotation angle Y f phase of all feed units on the axis at each rotation angle normalize relative to the reference feed phase, obtain normalized Y f phase of all feed units on the axis at each rotation angle In the formula, is the reference feed phase; S52, normalizing Y f Phase of each feed unit at each corner on the axis Phase of each feed unit relative to the calibration unit at the initial state in step three Y is normalized again as a reference standard f Phase of each feed unit relative to the calibration unit on the axis 8. The method of claim 1, wherein: In the step five, the establishment method of the corresponding relationship table of the rotation angle and the phase is: The longitudinal table header of the relationship table includes the rotation angle θ around the X b axis x and the rotation angle θ around the Y b axis y ; The horizontal table header of the relationship table includes X f The transmission phase of each feed source unit on the axis relative to the calibration unit and Y f The transmission phase of each feed source unit on the axis relative to the calibration unit.

9. The method of claim 8, wherein: In the step six, the method for finding the on-orbit pointing error of the beam is: The measured phase of each feed unit is brought into the relationship table in step five The relationship table in step five Or The corresponding θ is found x Or θ y That is the beam on-orbit pointing error.

Images