Circular polarizer-based multi-polarization array feeding system and calibration method thereof

Abstract

The application provides a circular polarizer-based multi-polarization array feeding system and a calibration method thereof, and relates to the technical field of radar semi-physical simulation.The system comprises an array and a calibration computer for running control software and issuing control instructions; a central control unit for receiving and executing the control instructions; a wideband switch matrix for routing and amplitude and phase control of radio frequency signals according to the control instructions; an antenna array comprising at least one antenna unit, the antenna unit comprising a circular polarizer and a dual-polarized horn antenna; the input end of the circular polarizer is used for receiving a radio frequency signal, and the output end is connected with the dual-polarized horn antenna, which is used for modulating the radio frequency signal into two linear polarization signals with a fixed phase difference and feeding them to the dual-polarized horn antenna; the dual-polarized horn antenna is used for radiating horizontally polarized, vertically polarized or circularly polarized electromagnetic wave signals according to the two linear polarization signals. The system can meet the needs of high-confidence simulation experiments.

Description

Technical Field

[0001] This application relates to the field of radar hardware-in-the-loop simulation technology, specifically to a multi-polarization array feeding system based on a circular polarizer and its calibration method. Background Technology

[0002] In the field of radar hardware-in-the-loop simulation, to test the performance of a rollable linearly polarized missile seeker, it is necessary to accurately simulate the radar reflection signal of a dynamic target using a three-element antenna array in an anechoic chamber. As the seeker rolls around its axis during flight, the polarization characteristics of the target's reflected signal change continuously relative to the seeker's receiving antenna. If the array antenna only radiates a fixed linearly polarized (horizontal or vertical) signal, this dynamic process cannot be accurately simulated, leading to a decrease in simulation confidence. Theoretically, the array antenna must radiate a perfectly circularly polarized signal to maintain a constant coupling relationship with the rolling linearly polarized seeker.

[0003] To generate circularly polarized signals, traditional methods employ dual-polarization independent feed channels, meaning each antenna element is equipped with two complete RF links to excite its horizontal and vertical polarization ports respectively, and circular polarization synthesis is achieved through complex amplitude and phase control. While this approach achieves high performance, it significantly increases hardware costs, system complexity, and the workload of research and development.

[0004] To reduce costs, existing technologies propose a combination of circular polarizers and dual-polarized horn antennas. A circular polarizer can easily convert a single input signal into two linearly polarized signals with a fixed phase difference, thereby exciting the dual-polarized horn antenna to synthesize a circularly polarized wave. However, due to the non-ideal characteristics of devices within a wide bandwidth, the antenna often radiates a non-ideal elliptical polarized wave with deviations in axial ratio and tilt angle. During the seeker's roll, this elliptical polarization characteristic causes the amplitude and phase of the synthesized target signal to change non-linearly with the roll angle. If calibration compensation data for ideal circular polarization or fixed linear polarization is simply applied, the synthesis accuracy of the triplet target will be severely degraded, failing to meet the requirements of high-precision RF simulation.

[0005] Therefore, the urgent technical problem to be solved in this field is: how to overcome the adverse effects of the actual elliptical polarization wave radiated by the antenna element under the premise of adopting a low-cost "circular polarizer + dual polarization horn" hardware architecture, and ensure that the triplet target signal can still maintain extremely high synthesis accuracy during the full-angle roll of the seeker, so as to meet the needs of high-confidence simulation experiments. Summary of the Invention

[0006] In view of the above-mentioned defects or deficiencies in the prior art, this application aims to provide a multi-polarization array feeding system based on circular polarizers and its calibration method;

[0007] In a first aspect, this application proposes a multi-polarization array feeding system based on a circular polarizer, comprising:

[0008] Array and calibration computer, used to run control software and issue control commands;

[0009] A central control unit, connected to the array and calibration computer, is used to receive and execute the control commands;

[0010] A broadband switching matrix, connected to the central control unit, is used to select and modulate the amplitude and phase of radio frequency signals according to control commands;

[0011] An antenna array, connected to the broadband switching matrix, includes at least one antenna element;

[0012] The antenna unit includes a circular polarizer and a dual-polarized horn antenna.

[0013] The input terminal of the circular polarizer is used to receive one radio frequency signal, and its output terminal is connected to the dual-polarized horn antenna to modulate the radio frequency signal into two linearly polarized signals with a fixed phase difference and feed them to the dual-polarized horn antenna.

[0014] The dual-polarized horn antenna is used to radiate horizontally polarized, vertically polarized, or circularly polarized electromagnetic wave signals according to the polarization signals of the two lines.

[0015] According to the technical solution provided in this application, the broadband switching matrix includes:

[0016] A precision amplitude and phase control unit is used to modulate the amplitude and phase of radio frequency signals in the microwave band.

[0017] The coarse control unit, consisting of multiple switching devices, is used to control the routing of radio frequency signals to the selected antenna element.

[0018] According to the technical solution provided in this application, the antenna array further includes:

[0019] A broadband amplifier array, connected between the broadband switch matrix and the antenna element, is used to amplify the signal power.

[0020] A frequency conversion array, connected between the broadband amplifier array and the antenna unit, is used to upconvert the signal to the millimeter-wave band.

[0021] According to the technical solution provided in this application, the antenna array further includes:

[0022] The antenna mounting structure is used to install and adjust the pointing and polarization direction of the antenna element; the antenna mounting structure can adjust the position of the antenna element in six degrees of freedom: front-back, up-down, left-right, azimuth, pitch and roll.

[0023] According to the technical solution provided in this application, the circular polarizer modulates the one radio frequency signal into two linearly polarized signals with equal power and constant phase difference.

[0024] According to the technical solution provided in this application, it also includes an array calibration system connected to the array and the calibration computer; the array calibration system includes a physical calibration system for spatially calibrating the antenna elements, and an electrical calibration system for electrically calibrating the amplitude and phase control devices, system path consistency and near-field effects of the broadband switching matrix.

[0025] Secondly, this application proposes a calibration method for a multi-polarization array feed system based on a circular polarizer, as described above. The method is executed by an array calibration system and includes the following steps:

[0026] The power supply system is controlled to make the selected antenna element radiate horizontally polarized and vertically polarized signals respectively; the original values ​​of the horizontal polarization amplitude and horizontal phase, as well as the original values ​​of the vertical polarization amplitude and vertical phase, are measured and obtained by the electrical calibration system.

[0027] For the target roll angle, based on the original values ​​of horizontal polarization amplitude and horizontal phase, and the original values ​​of vertical polarization amplitude and vertical phase, polarization synthesis calculation is performed to determine the amplitude compensation value and phase compensation value required for the equivalent linear polarization signal at the target roll angle when the antenna element radiates an elliptical polarization signal; the preset roll angle range is traversed to generate an amplitude and phase compensation table corresponding to the roll angle;

[0028] For the target triplet in the power supply system, under near-field conditions, the azimuth and pitch angle errors of its simulated target position relative to the theoretical position are measured using the electrical calibration system, and a near-field effect correction table is generated accordingly.

[0029] During RF simulation, the amplitude and phase compensation table is called to compensate the power supply channel based on the real-time roll angle of the seeker, and the near-field effect correction table is called to correct the target position, so as to control the power supply system to synthesize a high-precision triplet target signal.

[0030] According to the technical solution provided in this application, after generating the amplitude-phase compensation table corresponding to the roll angle, the following steps are also included:

[0031] The elliptic polarization characteristics of the selected antenna element are evaluated based on the horizontal polarization amplitude, the original horizontal phase value, and the vertical polarization amplitude and the original vertical phase value.

[0032] Based on the evaluated elliptic polarization characteristics, the generated amplitude and phase compensation table is optimized to improve the overall synthesis accuracy when the antenna element radiates a non-ideal circularly polarized signal.

[0033] The optimization process includes at least one of the following methods:

[0034] Mark the confidence level of the amplitude and phase compensation table;

[0035] Based on the elliptic polarization characteristics, the weight of the signal contributed by the antenna element by the feeding system during target synthesis is adjusted.

[0036] According to the technical solution provided in this application, in the step of generating the amplitude and phase compensation table corresponding to the roll angle, the polarization synthesis calculation performed for the same selected antenna element and the amplitude and phase compensation table generated therefrom are simultaneously and independently adapted to the seekers of the horizontal polarization system and the vertical polarization system.

[0037] The amplitude-phase compensation table includes a first set of compensation parameters corresponding to the horizontal polarization seeker and a second set of compensation parameters corresponding to the vertical polarization seeker.

[0038] The step of performing RF simulation by calling the amplitude and phase compensation table based on the real-time roll angle of the seeker to perform amplitude and phase compensation on the feed channel includes the following steps:

[0039] Based on the linear polarization system of the seeker, select either the first set of compensation parameters or the second set of compensation parameters from the amplitude-phase compensation table;

[0040] Based on the real-time roll angle, the corresponding amplitude compensation value and phase compensation value are retrieved from the selected set of compensation parameters;

[0041] The amplitude and phase compensation values ​​are used to configure the amplitude and phase controllers of the corresponding channels in the power supply system.

[0042] According to the technical solution provided in this application, the step of traversing the preset roll angle range to generate the amplitude-phase compensation table includes the following steps:

[0043] The elliptic polarization axial ratio of the selected antenna element is compared with a preset axial ratio threshold.

[0044] If the elliptic polarization axis ratio is better than the axis ratio threshold, then the amplitude-phase compensation table is generated using the first traversal interval;

[0045] If the elliptic polarization axial ratio is worse than the axial ratio threshold, then the amplitude-phase compensation table is generated using the second traversal interval;

[0046] The second traversal interval is smaller than the first traversal interval.

[0047] Compared with the prior art, the beneficial effects of this application are as follows:

[0048] I. Precisely meets the simulation requirements of roll load while being compatible with multiple polarization systems: The core antenna unit design of this invention, through the integration of a circular polarizer and a dual-polarization horn, can flexibly radiate horizontal, vertical, and circularly polarized (actually elliptical polarized) signals with only a single-path feed. This allows it to perfectly simulate the dynamic polarization scenarios encountered by roll-linearly polarized seekers, while also being easily adaptable to different seekers with horizontal or vertical polarization systems, greatly expanding the application range and flexibility of the simulation system.

[0049] II. Significantly Reduced System Cost and Complexity: Compared to traditional circular polarization implementations that require dual-feed channels, this invention employs a hardware architecture combining a single-feed channel and a circular polarizer, eliminating the need for a complete set of parallel RF links, amplitude and phase control, and synchronization units. This significantly reduces the system's hardware cost, power consumption, size, and the complexity of design, integration, and debugging, achieving an effective balance between high performance and low cost.

[0050] Third, this invention lays the hardware foundation for high-precision calibration and improves system reliability: It explicitly defines the "circular polarizer + dual-polarized horn" as the core antenna unit. The inherent and characterizable elliptical polarization radiation characteristics of this unit provide a clear physical object and compensation model for subsequent implementation of targeted high-precision calibration algorithms. The systematic calibration design can directly apply to this hardware architecture, effectively compensating for its non-ideal characteristics. This ensures high precision in the final triplet target synthesis and high stability in simulation experiments from the source, reducing reliance on manual field adjustments. Attached Figure Description

[0051] Figure 1 A schematic diagram of the structure of the multi-polarization array feed system based on circular polarizers provided in this application;

[0052] Figure 2 A schematic diagram of the array electrical calibration system provided in this application;

[0053] Figure 3 A schematic diagram of system hardware and software communication provided for this application;

[0054] Figure 4 A flowchart illustrating the steps of the calibration method for a multi-polarization array feed system based on a circular polarizer provided in this application.

[0055] The text labels in the image represent:

[0056] 1. Array and calibration computer; 2. Central control unit; 3. Antenna array; 31. Dual-polarized horn antenna; 32. Circular polarizer; 4. Broadband switching matrix. Detailed Implementation

[0057] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0058] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0059] Example 1

[0060] As mentioned in the background section, in view of the problems in the prior art, this application proposes a multi-polarization array feeding system based on circular polarizers, such as... Figure 1 As shown, it includes:

[0061] Array and calibration computer 1, used to run control software and issue control commands;

[0062] The central control unit 2, connected to the array and calibration computer 1, is used to receive and execute the control commands;

[0063] Broadband switch matrix 4 is connected to the central control unit 2 and is used to select and modulate the amplitude and phase of radio frequency signals according to control commands.

[0064] Antenna array 3, connected to the broadband switching matrix 4, includes at least one antenna element;

[0065] The antenna unit includes a circular polarizer 32 and a dual-polarized horn antenna 31.

[0066] The input terminal of the circular polarizer 32 is used to receive one radio frequency signal, and its output terminal is connected to the dual-polarized horn antenna 31 to modulate the radio frequency signal into two linearly polarized signals with a fixed phase difference and feed them to the dual-polarized horn antenna 31.

[0067] The dual-polarized horn antenna 31 is used to radiate horizontally polarized, vertically polarized, or circularly polarized electromagnetic wave signals according to the polarization signals of the two lines.

[0068] Specifically, system hardware and software communication such as Figure 3As shown, the array and calibration computer 1 is a computer equipped with dedicated control and calibration software. The control software manages the operation of the entire feed system, such as selecting which antenna elements to activate, setting the frequency, power, and beam pointing of the radiated signal, etc. The calibration software is specifically used to drive subsequent calibration processes, process measurement data, and generate compensation tables. The computer is connected to lower-level devices via high-bandwidth, low-latency communication links such as fiber optic cables to ensure rapid and accurate command delivery. The central control unit 2, or CCU, is a bridge device between the computer and the RF hardware. It receives abstract control commands from the computer (such as instructing the triplet at position X to radiate a signal at angle Y) and translates them into a series of low-level control signals that can directly operate the hardware. For example, it controls specific switching channels in the broadband switching matrix 4 and sets the attenuation and phase shift of each channel in the precision amplitude and phase control unit. It is typically implemented by an FPGA or a high-performance microprocessor, responsible for real-time or near-real-time control timing. Broadband switching matrix 4: This is a key RF component for achieving flexible signal routing and distribution. Its broadband characteristics mean it can operate over a wide frequency range (such as the entire microwave band). The switch matrix is ​​essentially a reconfigurable network composed of a large number of RF switches. It can flexibly switch the input RF signal from the signal source to any designated antenna element channel in antenna array 3 according to CCU instructions. Antenna array 3: This is the RF signal radiating end of the system, composed of multiple antenna elements arranged according to a certain pattern. Each antenna element is an independent radiating module. Each antenna element consists of two key components fixedly connected: Circular polarizer 32: A passive microwave device. Its function is to simultaneously generate two linearly polarized signals at its output when an RF signal is fed from the input. The power of these two signals is basically equal (i.e., power equalization), and there is a fixed phase difference between them (usually 90° or -90°). This fixed phase difference is crucial for achieving circular or elliptical polarization radiation. Dual-polarized horn antenna 31: A horn-shaped antenna capable of simultaneously or independently radiating two orthogonally linearly polarized waves (usually horizontal and vertical polarization). It is directly connected to the output of the circular polarizer 32, receives the two-path polarization signals from the circular polarizer 32, and radiates them into free space.

[0069] Implementation Description: In the actual system setup, dedicated software is first installed and configured on the array and calibration computer 1. The computer is connected to the central control unit 2 inside the cabinet via fiber optic cable. The central control unit 2 is then connected to the controller of the broadband switch matrix 4 via a multi-channel control cable (such as GPIB, LAN, or a dedicated bus), and similarly connected to the active components (such as amplifier power supplies and inverter local oscillators) in the antenna array 3. The RF input of the broadband switch matrix 4 is connected to an external simulation signal source, and its multi-channel RF output is connected to the input of the antenna array 3 via RF cables. During manufacturing, each antenna element has its circular polarizer 32 output port precisely connected to the input port of the dual-polarized horn antenna 31 via an internal waveguide or coaxial cable, forming an integrated module. These antenna elements are mechanically mounted on the surface of the antenna array 3, and their RF input ports are connected one-to-one with the output ports of the broadband switch matrix 4 via cables. When the system is working, the control software on the array and calibration computer 1 generates control commands according to the simulation scenario requirements. The CCU controls the broadband switching matrix 4 to route the radio frequency signals generated by the signal source to the channels of one or a group of antenna elements (such as a triplet). After passing through the switching matrix, the signal enters the corresponding antenna element. Within this element, the signal first passes through the circular polarizer 32, where it is split into two linearly polarized signals with a fixed 90-degree phase difference. These two signals are then immediately fed into the two orthogonal ports of the dual-polarized horn antenna 31. The dual-polarized horn antenna 31 converts these two electrical signals into electromagnetic waves and radiates them into space. Due to the fixed phase difference between the two signals, the electromagnetic wave synthesized in space appears as a circularly polarized or elliptical polarized wave. If, through control, only one signal is allowed to pass (the other is closed or in phase), the antenna radiates a single linearly polarized (horizontal or vertical) wave.

[0070] The technical principle is described below: Traditional full-polarization control requires two independent RF feed links (dual channels) for each antenna element, which is costly. This implementation utilizes a single circular polarizer 32, requiring only a single input to automatically generate two signals with the correct phase relationship, driving the dual-polarized antenna to produce circularly polarized radiation. This eliminates a complete RF channel (including power divider, phase shifter, amplifier, cables, etc.), significantly reducing hardware costs and system complexity. Simultaneously, the rolling linear polarization seeker needs to be illuminated by a circularly polarized wave to simulate the reflection characteristics of a dynamic target. The core capability of the antenna element in this invention is to radiate circularly polarized / elliptical polarized waves, fundamentally satisfying this core physical requirement. This architecture clearly defines the polarization characteristics of each radiation source as non-ideal elliptical polarization, and its characteristics (axis ratio, tilt angle) are determined by the fixed combination of circular polarizer 32 + dual-polarized horn. This provides a clear and stable calibration target for subsequent calibration algorithms. The goal of calibration is to measure and compensate for the inherent characteristics of this fixed combination, making it behave like an ideal radiation source in the system. This is the hardware foundation for achieving high-precision simulation.

[0071] In a preferred embodiment, the broadband switching matrix 4 includes:

[0072] A precision amplitude and phase control unit is used to modulate the amplitude and phase of radio frequency signals in the microwave band.

[0073] The coarse control unit, consisting of multiple switching devices, is used to control the routing of radio frequency signals to the selected antenna element.

[0074] Specifically, the precision amplitude and phase control unit operates in the microwave band (e.g., S, C, X bands) and is responsible for precise, programmable amplitude attenuation and phase shifting of the radio frequency signal passing through it. Typically, it consists of multiple independent channels, each containing a digitally controlled attenuator and a digitally controlled phase shifter. The attenuator is used to precisely adjust the signal power, and the phase shifter is used to precisely adjust the signal phase. Its precision is reflected in the high resolution and accuracy of the control; for example, the attenuator may have 0.5dB steps, and the phase shifter may have 5.625-degree steps. These fine adjustment capabilities directly affect beam pointing accuracy and sidelobe levels. The coarse control unit consists of multiple switching devices (such as PIN diode switches, MEMS switches, or electromechanical relays) connected in a certain topology (such as tree or cross matrix) to form a large switching network. Its core function is routing, i.e., according to control commands, connecting the input signal to one or several of hundreds or thousands of output ports. It is not responsible for, or only responsible for, very coarse amplitude and phase adjustment (such as switch insertion loss); its main task is to open and close the signal path. The coarse control unit allows for flexible selection of antenna elements at different positions in the array to synthesize the target.

[0075] Implementation Description: In actual hardware implementation, the broadband switch matrix 4 is typically installed in one or more standard chassis. The coarse control unit may be a large switch matrix module with one or more total input ports and N output ports (N corresponding to the number of antenna elements or channels). The fine amplitude and phase control unit consists of microwave devices such as digitally controlled attenuators, digitally controlled phase shifters, and amplifiers. The microwave devices within the fine amplitude and phase control unit are controlled by the signal processing board of the central control unit. The array feeding system generally operates from fine control to coarse control. The signal from the simulated signal source first enters the input terminal of the fine amplitude and phase control unit for amplitude and phase adjustment, then passes through the switch matrix for signal selection, and finally passes through the array elements for antenna radiation to synthesize a triplet target. For triplet synthesis, the coarse control unit needs to simultaneously route the signal to three adjacent antenna element channels, while the fine amplitude and phase control unit needs to independently set three different amplitude and phase values ​​for these three channels. The combination of these three values ​​determines the precise angle (azimuth and elevation) of the synthesized beam in space.

[0076] In a preferred embodiment, the antenna array 3 further includes:

[0077] A broadband amplifier array, connected between the broadband switch matrix 4 and the antenna unit, is used to amplify the signal power.

[0078] A frequency conversion array, connected between the broadband amplifier array and the antenna unit, is used to upconvert the signal to the millimeter-wave band.

[0079] Specifically, a broadband amplifier array is a collection of amplifier modules, each corresponding to one or more antenna channels. Its core function is power amplification. Connected after the broadband switch matrix 4, it means that all signals selected from the switch matrix need to be amplified by it before being sent to the antenna elements. It's called an array because it needs to provide amplification for multiple parallel channels, typically integrated into a multi-channel amplifier module. Its broadband characteristics ensure stable gain within the system's operating frequency band. A frequency converter array is a collection of frequency converter (upconverter) modules. Its core function is frequency conversion, specifically upconverting signals from lower frequencies to higher millimeter-wave bands. In radar simulations, to realistically simulate the operating frequencies of actual radars, it is often necessary to generate millimeter-wave signals (such as Ka-band and W-band). Directly generating and amplifying millimeter-wave signals is extremely costly and technically challenging. Therefore, the common practice is to perform flexible amplitude and phase control and amplification in the microwave band (such as the X-band), and then upconvert the microwave signal with the local oscillator signal to shift it to the desired millimeter-wave frequency. Each inverter module in the inverter array corresponds to one channel, ensuring that multi-channel signals can be synchronously frequency-converted.

[0080] Implementation Description: Inside the cabinet or mounting structure of antenna array 3, the signal flow is as follows: A microwave signal (e.g., X-band) from an output port of the broadband switching matrix 4, having undergone routing and precise amplitude and phase control, first enters the corresponding amplifier channel in the broadband amplifier array. This amplifier, according to the system design, provides the necessary gain (e.g., 20-30 dB) to boost the signal power to the required level to compensate for subsequent link losses and ensure sufficient radiated power. The amplified microwave signal is then fed into the corresponding inverter channel in the frequency converter array. Each inverter requires a highly stable, high-purity local oscillator signal as input. This local oscillator signal is typically distributed to all inverter channels by a common local oscillator source through a power divider network to ensure phase consistency of frequency conversion across all channels. Inside the inverter, the input microwave signal is mixed with the local oscillator signal to generate sum and difference frequency components, which are then selected by a bandpass filter to obtain the desired sum component (i.e., the millimeter-wave signal). For example, mixing an X-band signal with a Ka-band local oscillator may produce a W-band output signal. The millimeter-wave signal obtained after up-conversion is finally fed to the corresponding antenna element through a low-loss millimeter-wave transmission line (such as a waveguide). Thus, the signal completes the entire link from baseband or intermediate frequency to microwave control and then to millimeter-wave radiation.

[0081] In a preferred embodiment, the antenna array 3 further includes:

[0082] The antenna mounting structure is used to install and adjust the pointing and polarization direction of the antenna element; the antenna mounting structure can adjust the position of the antenna element in six degrees of freedom: front-back, up-down, left-right, azimuth, pitch and roll.

[0083] Specifically, the antenna mounting structure can be a large back frame (or array) with independent mounting interfaces and adjustment mechanisms for each antenna element. Each antenna element is fixed to a six-dimensional adjustment platform via a connecting flange. This platform is typically composed of precision mechanical components, such as: translation adjustment: achieved through precision screws and slides, equipped with a scale or grating ruler for position measurement and feedback; rotation adjustment (azimuth, elevation, roll): achieved through a precision rotary table (such as a worm gear structure), also equipped with an angle encoder. During initial system installation or periodic maintenance, high-precision optical measuring equipment (such as laser trackers or total stations) is used as part of the physical calibration system. The measuring equipment uses the coordinate system of the anechoic chamber as a reference to measure the actual position and angle of each antenna element. Based on the measurement results, the installer manually or electrically operates the six-dimensional adjustment platform under each antenna element, sequentially adjusting the front / back, up / down, and left / right screws to align with the phase center position, and then adjusting the azimuth, elevation, and roll knobs to align with the beam pointing and polarization direction. Once all adjustments are in place, the locking mechanism secures the platform, ensuring stability even under subsequent vibrations and temperature changes.

[0084] In a preferred embodiment, the circular polarizer 32 modulates the radio frequency signal into two linearly polarized signals with equal power and constant phase difference.

[0085] Specifically, power equalization refers to the fact that the power (or amplitude) of the two line-polarized signals output by the circular polarizer 32 is essentially equal within the target operating frequency band. Ideally, the power ratio of the two signals is 1:1 (i.e., 0 dB difference). In practical engineering, due to device manufacturing tolerances and frequency response, equalization means that the power difference between the two signals is kept within a very small range (e.g., within ±0.5 dB) within the required frequency band. Phase difference constancy refers to the phase difference between the two line-polarized signals output by the circular polarizer 32 maintaining a basically fixed value within the target operating frequency band. For generating circularly polarized waves, this fixed value is typically 90 degrees (for right-hand circular polarization) or -90 degrees (for left-hand circular polarization). In engineering, constancy means that the phase difference changes very little with frequency (e.g., fluctuating within ±5 degrees within the frequency band).

[0086] Implementation Description: The circular polarizer 32 that achieves this characteristic typically employs a mature microwave network structure. A common and high-performance implementation uses a 3dB 90° bridge (also known as a quadrature hybrid network). This device is a four-port network that, when a signal is fed from one port (input port), outputs two signals with equal amplitude (each receiving half the power, i.e., -3dB) and a 90-degree phase difference at the other two (through port and coupled port). The fourth port is an isolation port, typically connected to a matched load to absorb reflected power. In practice, the selected 3dB 90° bridge (i.e., circular polarizer 32) needs to undergo rigorous screening and testing within its nominal operating frequency band. During production, each circular polarizer 32 module undergoes full-band S-parameter testing using a vector network analyzer (VNA) to ensure that its amplitude balance and phase difference meet the preset power equalization and constant phase difference specifications before being assembled into the antenna element. For example, the test data requirements are: within the frequency band from f1 to f2, the difference between |S21| and |S31| (amplitude imbalance) ≤ 0.5 dB, and ∠S31 - ∠S21 (phase difference) between 85° and 95°. A circular polarizer 32 meeting the performance specifications is connected to a dual-polarized horn antenna 31. During connection, special attention must be paid to the electrical length consistency of the transmission lines, ensuring that the path length from the output of the circular polarizer 32 to the two input ports of the horn antenna is exactly the same to avoid introducing additional, uncontrollable phase differences that would disrupt the constant phase difference characteristic. This is typically achieved using precision-machined waveguide sections or phase-matching coaxial cables of equal length.

[0087] In a preferred embodiment, the system further includes an array calibration system connected to the array and calibration computer 1; the array calibration system includes a physical calibration system for spatially calibrating the antenna elements, and an electrical calibration system for electrically calibrating the amplitude and phase control devices, system path consistency, and near-field effects of the broadband switching matrix 4.

[0088] Specifically, the array calibration system is a hardware and software suite dedicated to the precise measurement, adjustment, and verification of the feed system. It connects to the array and calibration computer 1, receiving commands and feeding back data to form a calibration closed loop. The physical calibration system primarily addresses the mechanical accuracy issues of the feed system. It utilizes non-contact, high-precision measurement methods such as optics, lasers, or photogrammetry to measure the actual spatial pose (three-dimensional coordinates and three rotation angles) of each antenna element on the antenna mounting structure. Its core task is spatial position calibration, i.e., by comparing the measured data with the theoretical design position, it guides or automatically drives the six-degree-of-freedom adjustment mechanism to adjust the antenna elements to the correct position and direction, ensuring that the array's physical configuration conforms to the mathematical premises of beamforming. The electrical calibration system primarily addresses the consistency of the feed system's electrical performance and environmental errors. It calibrates and compensates for the system's electrical parameters by injecting and measuring radio frequency signals. Its calibration targets specifically include:

[0089] The amplitude and phase control device of the broadband switching matrix 4: that is, to calibrate each digital attenuator and digital phase shifter in the precision amplitude and phase control unit by code value (or key code value), to establish a precise correspondence table between the control code value and the actual attenuation / phase shift, and to eliminate the nonlinear error and discreteness of the device.

[0090] System path consistency: Measurements are taken of the insertion loss (amplitude) and insertion phase (electrical length) of each independent RF channel, starting from the signal input port, passing through the switch matrix, amplifier, frequency converter, and finally reaching the antenna element radiating aperture. These parameters are not consistent across channels due to slight differences in cable length, connector loss, and device performance. The electrical calibration system needs to measure these differences to provide data for subsequent amplitude and phase balance compensation. A schematic diagram of the electrical calibration system is shown below. Figure 2 As shown;

[0091] Near-field effect: In compact or half-field simulation environments, the distance between the radiation source (triple pair) and the seeker under test does not meet the far-field condition, leading to a difference between the spherical wavefront and the plane wavefront, resulting in a systematic deviation in the simulated target angle. The electrical calibration system measures and models this geometrically induced error through specially designed tests (such as measurements at multiple locations using calibration probes), generating a correction table.

[0092] Implementation Description: The physical calibration system and the electrical calibration system typically operate in a time-sharing manner, but share some computing resources and control interfaces. Physical Calibration Implementation: A laser tracker is set up in an anechoic chamber. The computer runs physical calibration software, controlling the tracker's laser beam to sequentially aim at pre-installed reflective target spheres on each antenna element. The software records the three-dimensional coordinates of each target sphere and calculates the actual azimuth, elevation, roll angle, and phase center position of each antenna element using an algorithm. The software compares the measured data with the theoretical model and generates adjustment instructions. Engineers, based on these instructions, manually or via a motorized adjustment platform, operate the six-dimensional adjustment mechanism of each antenna element until the error meets the requirements (e.g., position error <0.1mm, angle error <0.01°). Electrical Calibration Implementation: The electrical calibration system hardware typically includes a multi-port vector network analyzer (VNA), a multiplexer, a calibration LNB (fixed on a high-precision turntable) as a standard receiver, and necessary signal and local oscillator sources. The calibration software controls the entire process: Device calibration: The VNA is directly connected to the input / output terminals of the precision amplitude and phase control unit under test via cable. It iterates through the attenuation and phase shift codes, recording the S21 parameters for each code value, and generating a device lookup table (LUT). Path calibration: The control turntable aligns the center receiving antenna of the calibration LNB with the antenna element under test. The calibration software controls the feeding system to make the element radiate a signal (first horizontally polarized, then vertically polarized), and the VNA measures the amplitude and phase of the received signal. It iterates through all antenna elements to obtain the raw amplitude and phase data matrix for all channels. Near-field calibration: In the near-field region of the anechoic chamber, the control turntable drives the calibration LNB to receive signals radiated by specific triplets at multiple known spatial locations. Using the phase comparison principle of the interferometer, the actual pointing of the wavefront formed by the triplets is deduced and compared with the theoretical pointing to generate a near-field error correction table.

[0093] Example 2

[0094] This application provides a calibration method for a multi-polarization array feed system based on a circular polarizer, as described in Embodiment 1. The method is executed by an array calibration system, such as... Figure 4 As shown, it includes the following steps:

[0095] S1. Control the power supply system to make the selected antenna element radiate horizontally polarized and vertically polarized signals respectively; measure and obtain the original values ​​of the horizontal polarization amplitude and horizontal phase, as well as the original values ​​of the vertical polarization amplitude and vertical phase of the antenna element through the electrical calibration system.

[0096] S2. For the target roll angle, based on the original values ​​of horizontal polarization amplitude and horizontal phase, and vertical polarization amplitude and vertical phase, polarization synthesis calculation is performed to determine the amplitude compensation value and phase compensation value required for the equivalent linear polarization signal at the target roll angle when the antenna element radiates an elliptical polarization signal; the preset roll angle range is traversed to generate an amplitude and phase compensation table corresponding to the roll angle.

[0097] S3. For the target triplet in the power supply system, under near-field conditions, the azimuth and pitch angle errors of its simulated target position relative to the theoretical position are measured using the electrical calibration system, and a near-field effect correction table is generated accordingly.

[0098] S4. During RF simulation, the amplitude and phase compensation table is called to perform amplitude and phase compensation on the feed channel based on the real-time roll angle of the seeker, and the near-field effect correction table is called to correct the target position, so as to control the feed system to synthesize a high-precision triplet target signal.

[0099] Specifically, the original values ​​of horizontal / vertical polarization amplitude and phase refer to the complex form (amplitude and phase) of the signal received at the far field or standard probe when only the horizontal polarization port (or vertical polarization port) of the antenna element is excited, obtained through actual measurement by an electrical calibration system. It includes all inherent gain, phase center, and fixed offset introduced by the link of the antenna element in that polarization state. Polarization synthesis calculation: Its physical principle is that any elliptically polarized wave can be decomposed into a vector synthesis of two orthogonal linearly polarized waves with specific amplitude and phase relationships. Conversely, given the complex amplitude (A) of the two orthogonal components (i.e., horizontal and vertical polarization components) of an elliptically polarized wave... H ∠φ H and A V ∠φ V By calculating the amplitude and phase of the elliptically polarized wave induced on a linearly polarized antenna of arbitrary orientation, we can determine the magnitude and phase of the signal. This calculation process is called polarization synthesis. The equivalent linearly polarized signal requires amplitude and phase compensation values: this is the objective of the calculation. For a linearly polarized seeker at a certain roll angle θ, the signal induced on it by the elliptically polarized wave radiated by the array antenna is equivalent to a linearly polarized signal radiated from a virtual ideal linearly polarized antenna. To enable the feed system to simulate the effect of this virtual signal, we need to apply a compensation value (A) to the actual channel. comp(θ) ,φ comp(θ) This compensation value incorporates both the channel's inherent imbalance and the additional effects of elliptic polarization. Amplitude and phase compensation table: This is the output of the calculation. A data structure that discretizes continuous roll angles θ (e.g., from 0° to 360°, with a step size of 1°), where each angle index corresponds to a set of calculated amplitude compensation values ​​A. comp(θ) and phase compensation value φcomp(θ) This is used for real-time simulation lookup. Near-field effect correction table: This is an independent compensation table for specific geometric errors. It stores the azimuth and elevation angle corrections (ΔAz, ΔEl) required to compensate for angle measurement deviations caused by the near-field spherical wavefront at different target positions (triple positions).

[0100] Implementation method description:

[0101] Step 1 (Measurement of Basic Data): The calibration software, through the central control unit 2, controls the broadband switching matrix 4 and the precision amplitude and phase control unit to select one antenna element in sequence. First, configure the system to output only horizontally polarized signals (e.g., close the vertical polarization path, or set both signals to be in phase). The control turntable aligns the calibration LNB with the element, and the vector network analyzer measures and records the amplitude M of the received signal. H and phase P H Then, switch the configuration to output only the vertically polarized signal (either the two signals are out of phase, or only the vertical path is enabled), measure again at the same location, and record the amplitude M. V and phase P V This pair (M) H ,P H M V , P V This is the original value of the cell. Repeat this process for all cells in the array that need to be used.

[0102] Step Two (Core Calculations and Table Creation): For each antenna element, the calibration software reads its raw values. For each preset discrete roll angle θ... i (For example, if i ranges from 0 to 359), the software performs the following calculations:

[0103] Convert the original value to complex form: H = M H × exp(j× P H V = M V × exp(j× P V ).

[0104] Based on the seeker polarization system (assuming horizontal polarization), calculate the equivalent induced signal: S(θ) i ) = H × cos(θ i ) + V× sin(θ i ).

[0105] From S(θ) i Extract amplitude A from ) comp(θi) = abs(S(θ i and phase φ comp(θi) = angle(S(θ i)).

[0106] (θ) i A comp(θi) , φ comp(θi) The amplitude and phase compensation table for this cell is stored. After traversing all angles, the complete table for this cell is generated.

[0107] Step 3 (Near-field Calibration and Table Establishment): The calibration software controls the turntable to move the calibration LNB to a theoretical target position (Az0, El0) in the near-field region of the anechoic chamber. Then, the feed system is controlled to activate the triplet antenna simulating that position to radiate the signal. After multiple receiving antennas on the calibration LNB receive the signal, the direction of arrival of the synthesized wavefront (Az0, El0) is measured through phase comparison processing. meas El meas The calculation error ΔAz = Az0 - Az meas ,ΔEl = El0 - El meas Repeat this process by selecting a series of theoretical locations within the near-field region to generate a table indexed by the theoretical locations and storing the correction values ​​(ΔAz, ΔEl).

[0108] Step 4 (Synthetic Application): During RF simulation, the simulation master computer informs the array control software that it needs to simulate a target located at (Az, El) with a seeker roll angle of θ. The array control software executes:

[0109] Find the near-field effect correction table based on (Az, El) to obtain the correction amount (ΔAz, ΔEl), and calculate the actual required beam pointing angle (Az+ΔAz, El+ΔEl).

[0110] Based on (Az+ΔAz, El+ΔEl), the theoretically required excitation amplitude and phase (Az+ΔAz, El+ΔEl) of each of the three antenna elements participating in the synthesis are calculated using a beamforming algorithm. theory , φ theory ).

[0111] For each element, based on the current roll angle θ, look up the amplitude and phase compensation table for that element to obtain the compensation value (A). comp(θ) , φ comp(θ) ).

[0112] Combining the theoretical value with the compensation value, we obtain the final command value issued to the precision phase control unit: A final =A theory × A comp(θ) ,φ final =φ theory +φ comp(θ) .

[0113] Central control unit 2 according to Afinal and φ final By configuring attenuators and phase shifters for each channel, a high-precision target signal can be synthesized.

[0114] In a preferred embodiment, after generating the amplitude-phase compensation table corresponding to the roll angle, the following steps are further included:

[0115] The elliptic polarization characteristics of the selected antenna element are evaluated based on the horizontal polarization amplitude, the original horizontal phase value, and the vertical polarization amplitude and the original vertical phase value.

[0116] Based on the evaluated elliptic polarization characteristics, the generated amplitude and phase compensation table is optimized to improve the overall synthesis accuracy when the antenna element radiates a non-ideal circularly polarized signal.

[0117] The optimization process includes at least one of the following methods:

[0118] Mark the confidence level of the amplitude and phase compensation table;

[0119] Based on the elliptic polarization characteristics, the weight of the signal contributed by the antenna element by the feeding system during target synthesis is adjusted.

[0120] Specifically, in the evaluation phase: for each measured unit, the software reads its (A) H , φ H A V , φ V First, normalize them to complex vectors H. vec and V vec Then, calculate the synthesized elliptic polarization parameters: the total vector E. total = H vec +V vec ×exp(j×π / 2) (assuming the goal is right-hand circular polarization). In reality, H... vec and V vec The relative phase between them is Δφ = φ V - φ H Ideally, circular polarization requires Δφ = ±90°. Elliptic parameters can be calculated using standard algorithms, such as calculating the Stokes parameters and deriving the axial ratio and tilt angle from them. A simplified axial ratio estimation formula is: axial ratio ≈ 20 × log10((|H| + |V|) / ||H| - |V||) (when Δφ is close to 90°). The software calculates the axial ratio (AR) and tilt angle (τ) of the element.

[0121] Optimization processing stage: Scheme a (marking confidence): The software presets several axial ratio thresholds, for example: AR ≤ 1 dB is high confidence, 1 dB < AR ≤ 3 dB is medium confidence, and AR > 3 dB is low confidence. According to the calculated AR value, the software writes the corresponding confidence identifier (such as H, M, L) in the compensation table file header of this unit or a global overall unit performance table. Scheme b (adjusting weight): The software presets a weight adjustment function w factor = f(AR). For example, define an attenuation function: w factor = 1 / (1 + k × (AR - AR0)), where AR0 is the reference axial ratio (such as 1 dB) and k is the attenuation coefficient. For a calculated AR, obtain w factor (between 0 and 1). In subsequent simulations, when this unit is selected to participate in synthesis, the proportional factor of the final applied excitation amplitude will be jointly determined by the original beamforming weight and this w factor , that is, w factor × A final .

[0122] Application of the optimization result: If Scheme a is adopted, in the resource scheduling algorithm of the simulation system, when three units need to be selected from the candidate unit pool to form a triple, the algorithm will preferentially select high-confidence units and avoid low-confidence units under the same conditions. If Scheme b is adopted, when calculating the final excitation command for each channel, the software will read the w factor of this unit and multiply it by the amplitude command. This means that for a unit with poor polarization characteristics, its radiation power will be actively reduced, thereby reducing the impact of its non-ideal characteristics on the overall synthesized field.

[0123] In a preferred embodiment, in the step of generating the amplitude-phase compensation table corresponding to the roll angle, for the same selected antenna unit, the polarization synthesis calculation performed and the amplitude-phase compensation table generated therefrom are simultaneously and independently adapted to the seeker of the horizontal polarization system and the vertical polarization system;

[0124] wherein, the amplitude-phase compensation table includes a first set of compensation parameter sets corresponding to the seeker of the horizontal polarization system and a second set of compensation parameter sets corresponding to the seeker of the vertical polarization system;

[0125] When performing radio frequency simulation, the step of performing amplitude-phase compensation on the feed channel by calling the amplitude-phase compensation table according to the real-time roll angle of the seeker includes the following steps:

[0126] Select the first set of compensation parameter sets or the second set of compensation parameter sets from the amplitude-phase compensation table according to the linear polarization system of the seeker;

[0127] Based on the real-time roll angle, the corresponding amplitude compensation value and phase compensation value are retrieved from the selected set of compensation parameters;

[0128] The amplitude and phase compensation values ​​are used to configure the amplitude and phase controllers of the corresponding channels in the power supply system.

[0129] Specifically, the calibration software integrates two parallel polarization receiver model calculation modules. The two modules start synchronously while traversing each roll angle θ, but use different receive vector projection formulas. Module 1 (corresponding to the first parameter set): It simulates the receiving behavior of an ideal horizontally polarized antenna. Its calculation formula is based on: an elliptical polarized wave (from H = A...). H ∠φ H and V = A V ∠φ V The synthesized signal is projected onto a horizontally polarized antenna with a azimuth angle of θ. Its complex form is: S H(θ) = H×cosθ+ V × sinθ. Then, the software calculates A. compH(θ) = |S H(θ) | and φ compH(θ) = arg(S H(θ) Module Two (corresponding to the second parameter set): It simulates the receiving behavior of an ideal vertically polarized antenna. Its calculation formula is based on the induced signal from an elliptically polarized wave projected onto a vertically polarized antenna with a azimuth angle of θ. Its complex form is: S V(θ) = -H ×sinθ + V ×cosθ. Then, the software calculates A. compV(θ) = |S V(θ) | and φ compV(θ) = arg(S V(θ) Data Structure and Storage: For each antenna element, the software creates a dual-channel table structure in memory and final storage. This structure uses the roll angle θ as the primary index. Under each θ entry, two pairs of data are stored side-by-side: (A compH(θ) ,φ compH(θ) ) and (A compV(θ) , φ compV(θ) Internally, this can be a two-dimensional array with two column groups, or two independent but angle-synchronized one-dimensional arrays. The key is to ensure clear data relationships for easy and rapid retrieval. Dynamic selection mechanism during simulation: During RF simulation, the system flow adds a pre-decision step to step four above. When the array control software receives instructions from the simulation master controller, which include the key parameter of the seeker polarization system (e.g., enumerated value: H...),... POL or V POL )back:

[0130] If the system is HPOL Then, when the control logic calls the compensation table for each participating synthesis unit, it automatically and consistently reads the first set of parameters (A) from each angle entry. compH(θ), φ compH(θ) (This is used for subsequent calculations;)

[0131] If the system is V POL Then the control logic automatically and consistently reads the second set of parameters (A) from each angle entry. compV(θ) , φ compV(θ) (This is used for subsequent calculations.)

[0132] In a preferred embodiment, the step of traversing a preset roll angle range to generate an amplitude-phase compensation table includes the following steps:

[0133] The elliptic polarization axial ratio of the selected antenna element is compared with a preset axial ratio threshold.

[0134] If the elliptic polarization axis ratio is better than the axis ratio threshold, then the amplitude-phase compensation table is generated using the first traversal interval;

[0135] If the elliptic polarization axial ratio is worse than the axial ratio threshold, then the amplitude-phase compensation table is generated using the second traversal interval;

[0136] The second traversal interval is smaller than the first traversal interval.

[0137] Specifically, after completing the initial horizontal / vertical polarization measurements of an antenna element, the calibration software immediately invokes the evaluation algorithm to calculate the elliptic polarization axial ratio (AR) of that element. Simultaneously, the software reads the preset global axial ratio threshold (AR) from the configuration file. th For example, the system might be configured with AR. th = 2.0 dB.

[0138] Adaptive Decision Making: Software Comparison of AR and AR th Decision A: If AR ≤ 2.0 dB, the software determines this unit has excellent performance. It will set the first traversal interval Δθ for this unit. coarse Δθ coarse The value is also preset, for example, 5°. This means that when generating the compensation table for this unit, the roll angle θ will start from 0° and increase in increments of 5° until 360°, for a total of 360 / 5 + 1 = 73 points sampled. Decision B: If AR > 2.0 dB, the software determines that the performance of this unit requires close attention. It will set a second traversal interval Δθ for this unit. fine Δθ fine The value is also preset and satisfies Δθ fine <Δθ coarseFor example, 1°. This means that when generating the compensation table for this unit, the roll angle θ will be densely sampled in steps of 1°, for a total of 360 / 1 + 1 = 361 points.

[0139] Perform differentiated traversal and calculation: After the decision is made, the software generates a specific angle sequence θ for that cell based on the determined step size. list = [0, Δθ, 2Δθ, ..., 360]. Then, for each angle θ in this sequence... i Polarization synthesis calculations are performed to obtain the compensation value at that angle. Finally, a value is generated that corresponds to the number of data points and θ. list Compensation table corresponding to the length.

[0140] Metadata Recording: In the generated compensation table, the software records the traversal interval Δθ used when generating the table as metadata. This may be used in subsequent operations such as real-time interpolation to ensure the correct application of the interpolation algorithm.

[0141] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. The above descriptions are merely preferred embodiments of this application. It should be noted that due to the limitations of written expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of this invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of this application.

Claims

1. A multi-polarization array feeding system based on circular polarizers, characterized in that, include: Array and calibration computer (1) is used to run control software and issue control commands; The central control unit (2) is connected to the array and calibration computer (1) and is used to receive and execute the control commands; A broadband switching matrix (4) is connected to the central control unit (2) and is used to select and modulate the amplitude and phase of the radio frequency signal according to the control command. The antenna array (3) is connected to the broadband switching matrix (4) and includes at least one antenna element; The antenna unit includes a circular polarizer (32) and a dual-polarized horn antenna (31). The input of the circular polarizer (32) is used to receive one radio frequency signal, and its output is connected to the dual-polarized horn antenna (31) to modulate the radio frequency signal into two linearly polarized signals with a fixed phase difference and feed them to the dual-polarized horn antenna (31). The dual-polarized horn antenna (31) is used to radiate horizontally polarized, vertically polarized, or circularly polarized electromagnetic wave signals according to the polarization signals of the two paths. The broadband switching matrix (4) includes: A precision amplitude and phase control unit is used to modulate the amplitude and phase of radio frequency signals in the microwave band. The coarse control unit, consisting of multiple switching devices, is used to control the routing of radio frequency signals to the selected antenna element.

2. The multi-polarization array feeding system based on circular polarizers according to claim 1, characterized in that: The antenna array (3) also includes: A broadband amplifier array is connected between the broadband switch matrix (4) and the antenna unit for power amplification of the signal; A frequency conversion array, connected between the broadband amplifier array and the antenna unit, is used to upconvert the signal to the millimeter-wave band.

3. The multi-polarization array feeding system based on circular polarizers according to claim 1, characterized in that: The antenna array (3) also includes: The antenna mounting structure is used to install and adjust the pointing and polarization direction of the antenna element; the antenna mounting structure can adjust the position of the antenna element in six degrees of freedom: front-back, up-down, left-right, azimuth, pitch and roll.

4. The multi-polarization array feeding system based on circular polarizers according to claim 1, characterized in that: The circular polarizer (32) modulates the radio frequency signal into two linearly polarized signals with equal power and constant phase difference.

5. The multi-polarization array feeding system based on circular polarizers according to claim 1, characterized in that: It also includes an array calibration system connected to the array and calibration computer (1); the array calibration system includes a physical calibration system for spatially calibrating the antenna elements, and an electrical calibration system for electrically calibrating the amplitude and phase control devices, system path consistency and near-field effects of the broadband switching matrix (4).

6. A calibration method for a multi-polarization array feed system based on a circular polarizer as described in any one of claims 1-5, characterized in that, The method is performed by an array calibration system and includes the following steps: The power supply system is controlled to make the selected antenna element radiate horizontally polarized and vertically polarized signals respectively; the original values ​​of the horizontal polarization amplitude and horizontal phase, as well as the original values ​​of the vertical polarization amplitude and vertical phase, are measured and obtained by the electrical calibration system. For the target roll angle, based on the original values ​​of horizontal polarization amplitude and horizontal phase, and the original values ​​of vertical polarization amplitude and vertical phase, polarization synthesis calculation is performed to determine the amplitude compensation value and phase compensation value required for the equivalent linear polarization signal at the target roll angle when the antenna element radiates an elliptical polarization signal; the preset roll angle range is traversed to generate an amplitude and phase compensation table corresponding to the roll angle; For the target triplet in the power supply system, under near-field conditions, the azimuth and pitch angle errors of its simulated target position relative to the theoretical position are measured using the electrical calibration system, and a near-field effect correction table is generated accordingly. During RF simulation, the amplitude and phase compensation table is called to compensate the power supply channel based on the real-time roll angle of the seeker, and the near-field effect correction table is called to correct the target position, so as to control the power supply system to synthesize a high-precision triplet target signal.

7. The calibration method according to claim 6, characterized in that: After generating the amplitude-phase compensation table corresponding to the roll angle, the following steps are also included: The elliptic polarization characteristics of the selected antenna element are evaluated based on the horizontal polarization amplitude, the original horizontal phase value, and the vertical polarization amplitude and the original vertical phase value. Based on the evaluated elliptic polarization characteristics, the generated amplitude and phase compensation table is optimized to improve the overall synthesis accuracy when the antenna element radiates a non-ideal circularly polarized signal. The optimization process includes at least one of the following methods: Mark the confidence level of the amplitude and phase compensation table; Based on the elliptic polarization characteristics, the weight of the signal contributed by the antenna element by the feeding system during target synthesis is adjusted.

8. The calibration method according to claim 6, characterized in that: In the step of generating the amplitude and phase compensation table corresponding to the roll angle, the polarization synthesis calculation performed for the same selected antenna element and the amplitude and phase compensation table generated therefrom are simultaneously and independently adapted to the seekers of the horizontal polarization system and the vertical polarization system. The amplitude-phase compensation table includes a first set of compensation parameters corresponding to the horizontal polarization seeker and a second set of compensation parameters corresponding to the vertical polarization seeker. The step of performing RF simulation by calling the amplitude and phase compensation table based on the real-time roll angle of the seeker to perform amplitude and phase compensation on the feed channel includes the following steps: Based on the linear polarization system of the seeker, select either the first set of compensation parameters or the second set of compensation parameters from the amplitude-phase compensation table; Based on the real-time roll angle, the corresponding amplitude compensation value and phase compensation value are retrieved from the selected set of compensation parameters; The amplitude and phase compensation values ​​are used to configure the amplitude and phase controllers of the corresponding channels in the power supply system.

9. The calibration method according to claim 6, characterized in that: The process of traversing the preset roll angle range to generate the amplitude-phase compensation table includes the following steps: The elliptic polarization axial ratio of the selected antenna element is compared with a preset axial ratio threshold. If the elliptic polarization axis ratio is better than the axis ratio threshold, then the amplitude-phase compensation table is generated using the first traversal interval; If the elliptic polarization axial ratio is worse than the axial ratio threshold, then the amplitude-phase compensation table is generated using the second traversal interval; The second traversal interval is smaller than the first traversal interval.

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