Satellite-borne SAR (Synthetic Aperture Radar) system with anti-interference capability and working method thereof

Abstract

The invention discloses a satellite-borne SAR (Synthetic Aperture Radar) system with anti-interference capability and a working method thereof. The satellite-borne SAR system comprises a signal processor, a frequency synthesizer, a transmitter, a receiver, a high-power signal amplifier group, a circulator, a waveguide switch 1-3, a waveguide load 1-3, a waveguide filter 1-3, an amplitude-limiting low-noise amplifier 1-4, a one-out-of-four coaxial switch and a reflector antenna, the signal processor transmits a broadband intermediate-frequency transmission signal, the transmitter up-converts the broadband intermediate-frequency transmission signal to a radio frequency, the signal power is amplified by the high-power signal amplifier group, and the signal is transmitted to the reflector antenna through the circulator and is transmitted out; after radio frequency echoes reflected by the ground and interference signals sent by an interference source are received by the antenna, the signals are selected to enter one of the low-noise amplification paths through the circulators to the waveguide switches 1-3 to complete signal amplification, the signals enter the receiver through the one-out-of-four coaxial switch to be subjected to down-conversion to receive intermediate frequency, and echo data acquisition and analysis are completed by the signal processor. The invention has the advantages of flexible working mode, strong anti-interference capability, simple system composition, light weight and low heat consumption.

Description

Technical Field

[0001] This invention belongs to the field of spaceborne synthetic aperture radar (SAR) and relates to a spaceborne SAR system with anti-jamming capability and its working method. Background Technology

[0002] In the field of spaceborne SAR, resolution is the most important indicator. The resolution of spaceborne SAR has evolved from tens of meters initially to sub-meter levels, with the US Umbra Space satellite achieving a resolution of 0.25 meters. Along with the gradual improvement in resolution, the bandwidth of spaceborne SAR systems has also increased significantly, from tens of MHz initially to the current 1.2 GHz, and is expected to continue developing towards several GHz. However, with increasing bandwidth, spaceborne SAR becomes increasingly susceptible to interference from high-power ground sources. When the power of the interference signal saturates the low-noise amplifier on the spaceborne SAR receiver link, the spaceborne SAR will be unable to receive ground echoes and will lose its imaging function. Therefore, to meet the needs of future development of spaceborne SAR, there is an urgent need for a spaceborne SAR system and its operating method with anti-interference capabilities. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a spaceborne SAR system with anti-interference capabilities and its operating method. The system can operate normally without interference and without performance loss; even when encountering interference and losing some receiving signal bandwidth, the system can still perform imaging normally, thus improving the system's survivability in harsh electromagnetic environments.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: An anti-jamming spaceborne SAR system includes a signal processor, a frequency synthesizer, a transmitter, a receiver, a high-power signal amplifier group, a circulator, waveguide switches 1-3, waveguide loads 1-3, waveguide filters 1-3, limiting low-noise amplifiers 1-4, a 4-to-1 coaxial switch, and a reflector antenna. in: The signal processor is used to generate intermediate frequency (IF) transmission signals and send them to the transmitter, and to collect the IF echoes output by the receiver. It analyzes the collected data or directly frames and outputs the data. The signal processor also accepts external remote control signals to generate various control signals within the system and returns telemetry signals. A transmitter is used to upconvert intermediate frequency (IF) signals to the required radio frequency (RF) spectrum range. A high-power signal amplifier array is used to amplify the low-power radio frequency signal output by the transmitter to the required power; A circulator is used to send a high-power transmit signal to a reflector antenna, and then send the radio frequency signal received by the reflector antenna to the receiving path. A reflector antenna is used to radiate high-power radio frequency signals and receive ground echoes and interference signals radiated from ground interference sources. Waveguide switches 1-3 are used to select the received signal to enter different receiving paths under the control of the signal processor; Waveguide filters 1-3 are used to filter out interference signals from the received signal; Limiting low-noise amplifiers 1-4 can withstand high-power leakage signals, preventing them from affecting subsequent electronic equipment, while simultaneously amplifying low-power received signals; A 4-to-1 coaxial switch is used to select one of the four received signals to enter the receiver under the control of the signal processor. The receiver is used to downconvert the received radio frequency signal to the required intermediate frequency and send it to the signal processor for acquisition; Waveguide loads 1-3 are used to block unused ports of the system, ensuring that only signals received by the antenna can enter the receiving path; A frequency synthesizer is used to generate the clock signal required by the signal processor and the local oscillator signal required by the transmitter and receiver.

[0005] The present invention also includes the following technical features: Specifically, waveguide filter 1 among waveguide filters 1-3 is a high-pass filter, which passes signals with frequencies greater than or equal to... The signal, in which The center frequency of the radio frequency signal transmitted by the system.

[0006] Specifically, waveguide filter 2 among waveguide filters 1-3 is a band-stop filter, which passes signals with frequencies less than or equal to... or frequency greater than or equal to The signal, in which The bandwidth of the radio frequency signal transmitted by the system.

[0007] Specifically, waveguide filter 3 among waveguide filters 1-3 is a low-pass filter, allowing signals with frequencies less than or equal to... The signal.

[0008] Specifically, the switching of waveguide switches 1-3 and the 4-to-1 coaxial switch is controlled by a signal processor.

[0009] A method for operating the aforementioned spaceborne SAR system with anti-jamming capabilities, the system comprising five operating modes: 1) Mode 1: The signal processor generates an intermediate frequency (IF) transmission signal, the transmitter performs up-conversion, and the high-power signal amplifiers amplify the signal. The high-power signal passes through a circulator and is radiated by the reflector antenna. The signal received by the antenna passes through the circulator and enters the receiving path. In the receiving path, waveguide switch 1 switches to J1-to-J4, waveguide switch 2 switches to J1-to-J4, and a 4-to-1 coaxial switch selects the limiting low-noise amplifier 1 to connect to the receiver. The received signal is filtered by waveguide filter 1 and amplified by limiting low-noise amplifier 1 before entering the receiver. Inside the receiver, it is down-converted to an IF frequency. Finally, the signal processor completes the IF signal acquisition, frames, and outputs the signal. 2) Mode 2: The signal processor generates an intermediate frequency (IF) transmission signal, the transmitter performs up-conversion, and the high-power signal amplifiers amplify the signal. The high-power signal passes through a circulator and is radiated by the reflector antenna. The signal received by the antenna passes through the circulator and enters the receiving path. In the receiving path, waveguide switch 1 switches to J1 to connect to J4, waveguide switch 2 switches to J1 to connect to J2, and a 4-to-1 coaxial switch selects the limiting low-noise amplifier 2 to connect to the receiver. The received signal is filtered by waveguide filter 2 and amplified by limiting low-noise amplifier 2 before entering the receiver. Inside the receiver, it is down-converted to IF, and finally, the signal processor completes the IF signal acquisition, frame assembly, and output. 3) Mode 3: The signal processor generates an intermediate frequency (IF) transmission signal, the transmitter performs up-conversion, and the high-power signal amplifiers amplify the signal. The high-power signal passes through a circulator and is radiated by the reflector antenna. The signal received by the antenna passes through the circulator and enters the receiving path. In the receiving path, waveguide switch 1 switches to J1 to connect to J2, waveguide switch 3 switches to J1 to connect to J4, and a 4-to-1 coaxial switch selects the limiting low-noise amplifier 3 to connect to the receiver. The received signal is filtered by waveguide filter 3 and amplified by limiting low-noise amplifier 3 before entering the receiver. Inside the receiver, it is down-converted to IF, and finally, the signal processor completes IF signal acquisition, frame assembly, and output. 4) Mode 4: The signal processor generates an intermediate frequency (IF) transmission signal, the transmitter performs up-conversion, and the high-power signal amplifiers amplify the signal. The high-power signal passes through a circulator and is then radiated by the reflector antenna. The signal received by the antenna passes through the circulator and enters the receiving path. In the receiving path, waveguide switch 1 switches to J1-J2, waveguide switch 3 switches to J1-J2, and a 4-to-1 coaxial switch selects the limiting low-noise amplifier 4 to connect to the receiver. The received signal is amplified by the limiting low-noise amplifier 4 and then enters the receiver. Inside the receiver, it is down-converted to an IF frequency. Finally, the signal processor completes the IF signal acquisition, frames, and outputs the signal. 5) Mode 5: The signal processor does not generate an intermediate frequency (IF) transmission signal, and the system does not transmit a signal. The signal received by the antenna enters the receiving path after passing through the circulator. In the receiving path, waveguide switch 1 switches to J1-to-J2, waveguide switch 3 switches to J1-to-J2, and a 4-to-1 coaxial switch selects the limiting low-noise amplifier 4 to connect to the receiver. The received signal is amplified by the limiting low-noise amplifier 4 and then enters the receiver. Inside the receiver, it is down-converted to the IF frequency. Finally, the signal processor completes the IF signal acquisition and performs spectrum analysis.

[0010] Specifically, the system's operating method includes: first entering mode 5, where the signal processor performs spectrum analysis of the received signal, and then selecting the subsequent operating mode based on the analysis results; The criteria for selecting the subsequent working mode are as follows: Step 1: Check if there is interference in the received signal; if so, proceed to the next step; if not, proceed to step 5. Step 2: Determine whether the highest frequency of the interference signal in the received signal is less than [a certain value]. If so, proceed to Mode 1; otherwise, proceed to the next step. Step 3: Determine whether the frequency of the interference signal in the received signal is within the range of... arrive If the range is specified, the subsequent work will proceed to mode 2; otherwise, proceed to the next step. Step 4: Determine whether the lowest frequency of the interference signal in the received signal is greater than [the specified frequency]. If so, proceed to mode 3; otherwise, proceed to the next step. Step 5, the follow-up work is in mode 4.

[0011] Compared with the prior art, the present invention has the following technical effects: a. This invention achieves interference signal filtering by first analyzing the frequency characteristics of the interference signal and then using a waveguide filter. It has strong anti-interference ability and is suitable for working in complex electromagnetic environments.

[0012] b. During the operation of this invention, the control values ​​of the waveguide switch and the coaxial switch can be configured to select signals of different frequencies, resulting in good flexibility in operation.

[0013] c. Compared with conventional spaceborne SAR systems, this invention only requires the addition of coaxial switches, waveguide switches, waveguide loads, waveguide filters, and limiting low-noise amplifiers. The number of additional components is small, the cost is low, and the engineering development cost and difficulty are reduced.

[0014] d. The system composition of the present invention is simple, and the components are easy to be made into broadband devices, which is in line with the development trend of large bandwidth and high resolution of spaceborne SAR systems. Attached Figure Description

[0015] Figure 1This is a block diagram of the spaceborne SAR system with anti-interference capability according to the present invention.

[0016] Figure 2 This is the signal flow diagram for the system operating mode 1 described in this invention.

[0017] Figure 3 This is the signal flow diagram for the system operating mode 2 described in this invention.

[0018] Figure 4 This is the signal flow diagram for the system operating mode 3 described in this invention.

[0019] Figure 5 This is the signal flow diagram for the system operating mode 4 described in this invention. Detailed Implementation

[0020] This invention provides a spaceborne SAR system with anti-interference capability and its operating method. The system includes a signal processor, a frequency synthesizer, a transmitter, a receiver, a high-power signal amplifier group, a circulator, waveguide switches 1-3, waveguide loads 1-3, waveguide filters 1-3, limiting low-noise amplifiers 1-4, a 4-to-1 coaxial switch, and a reflector antenna. The process involves: a signal processor transmitting a broadband intermediate frequency (IF) signal, which is then up-converted to radio frequency (RF) by the transmitter; a low-power RF signal output from the transmitter is amplified by a high-power signal amplifier group and sent to the circulator; the high-power RF signal received by the circulator is sent to the reflector antenna for transmission; the RF echo reflected from the ground and the interference signal emitted by the interference source are received by the antenna and then pass through the circulator to waveguide switches 1-3; the waveguide switches, controlled by the signal processor, select one of the four low-noise amplification paths for the RF echo signal and the interference signal; the RF echo and the interference signal are amplified in the low-noise amplification path, pass through a 4-to-1 coaxial switch to the receiver, are down-converted to the receiving IF, and finally the signal processor completes the echo data acquisition and analysis; and the frequency synthesizer generates the local oscillator required by the transmitter and receiver and the clock required by the signal processor. The system has multiple operating modes through the combination of waveguide switches, coaxial switches, waveguide filters and limiting low-noise amplifiers. It can achieve full-bandwidth imaging when there is no interference, or complete imaging using a portion of the bandwidth when there is interference. It has the advantages of flexible operation mode and strong anti-interference capability. In addition, the system has a simple composition, light weight and low heat dissipation, and is easy to implement in engineering.

[0021] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0022] Example: like Figure 1As shown, this embodiment provides a spaceborne SAR system with anti-interference capability. The system includes: a signal processor, a frequency synthesizer, a transmitter, a receiver, a high-power signal amplifier group, a circulator, waveguide switches 1-3, waveguide loads 1-3, waveguide filters 1-3, limiting low-noise amplifiers 1-4, a 4-to-1 coaxial switch, and a reflector antenna. Specifically, in this embodiment, the method of the present invention is used to design and operate an X-band spaceborne SAR. The operating frequency range of the system is 9GHz to 11GHz, and the signal bandwidth is approximately 2GHz. The interference signal frequency is 9.3GHz to 9.8GHz.

[0023] in: The signal processor is used to generate intermediate frequency (IF) transmission signals and send them to the transmitter, and to collect the IF echoes output by the receiver. It analyzes the collected data or directly frames and outputs the data. The signal processor also accepts external remote control signals to generate various control signals within the system and returns telemetry signals.

[0024] A transmitter is used to upconvert intermediate frequency (IF) signals to the desired radio frequency (RF) spectrum range.

[0025] A high-power signal amplifier group is used to amplify the low-power radio frequency signal output by the transmitter to the required power.

[0026] A circulator is used to send a high-power transmit signal to a reflector antenna, and then send the radio frequency signal received by the reflector antenna to the receiving path.

[0027] A reflector antenna is used to radiate high-power radio frequency signals and receive ground echoes and interference signals radiated from ground interference sources.

[0028] Waveguide switches 1-3 are used to select the received signal to enter different receiving paths under the control of the signal processor.

[0029] Waveguide filters 1-3 are used to filter out interference signals from the received signal.

[0030] Limiting low-noise amplifiers 1-4 can withstand high-power leakage signals, preventing them from affecting subsequent electronic equipment, while simultaneously amplifying low-power received signals.

[0031] A 4-to-1 coaxial switch is used to select one of the four received signals to enter the receiver under the control of the signal processor.

[0032] A receiver is used to downconvert the received radio frequency signal to the required intermediate frequency and send it to a signal processor for acquisition.

[0033] Waveguide loads 1-3 are used to block unused ports in the system, ensuring that only signals received by the antenna can enter the receiving path.

[0034] A frequency synthesizer is used to generate the clock signal required by the signal processor and the local oscillator signal required by the transmitter and receiver.

[0035] Specifically, waveguide filter 1 is a high-pass filter, allowing signals with frequencies greater than or equal to... The signal, in which The signal is the center frequency of the radio frequency signal transmitted by the system. In this embodiment, the signal is a signal with a frequency greater than or equal to 10 GHz, where 10 GHz is the center frequency of the radio frequency signal transmitted by the system.

[0036] Waveguide filter 2 is a band-stop filter that allows signals with frequencies less than or equal to 100 Hz to pass through. or frequency greater than or equal to The signal, in which This refers to the bandwidth of the radio frequency signal transmitted by the system. In this embodiment, the signal is a signal with a frequency of less than or equal to 9.5 GHz or a frequency of greater than or equal to 10.5 GHz.

[0037] Waveguide filter 3 is a low-pass filter, allowing signals with frequencies less than or equal to 100 Hz to pass through. The signal. In this embodiment, the signal is a signal with a frequency of less than or equal to 10 GHz.

[0038] The switching of waveguide switches 1-3 and the 4-to-1 coaxial switch is controlled by a signal processor.

[0039] like Figures 1 to 5 As shown, this embodiment also provides a method for operating a spaceborne SAR system with anti-jamming capabilities. The system includes five operating modes, and the operating method for each mode includes: 1) Mode 1 The signal processor generates an intermediate frequency (IF) transmission signal, the transmitter performs up-conversion, and the high-power signal amplifiers amplify the signal. The high-power signal passes through a circulator and is radiated by the reflector antenna. The signal received by the antenna passes through the circulator and enters the receiving path. In the receiving path, waveguide switch 1 switches to J1-to-J4, waveguide switch 2 switches to J1-to-J4, and a 4-to-1 coaxial switch selects the limiting low-noise amplifier 1 to connect to the receiver. The received signal is filtered by waveguide filter 1 and amplified by limiting low-noise amplifier 1 before entering the receiver. Inside the receiver, it is down-converted to IF, and finally, the signal processor completes IF signal acquisition, frame assembly, and output.

[0040] 2) Mode 2 The signal processor generates an intermediate frequency (IF) transmission signal, the transmitter performs up-conversion, and the high-power signal amplifiers amplify the signal. The high-power signal passes through a circulator and is radiated by the reflector antenna. The signal received by the antenna passes through the circulator and enters the receiving path. In the receiving path, waveguide switch 1 switches to J1 to connect to J4, waveguide switch 2 switches to J1 to connect to J2, and a 4-to-1 coaxial switch selects the limiting low-noise amplifier 2 to connect to the receiver. The received signal is filtered by waveguide filter 2 and amplified by limiting low-noise amplifier 2 before entering the receiver. Inside the receiver, it is down-converted to IF, and finally, the signal processor completes the IF signal acquisition, frame assembly, and output.

[0041] 3) Mode 3 The signal processor generates an intermediate frequency (IF) transmission signal, the transmitter performs up-conversion, and the high-power signal amplifiers amplify the signal. The high-power signal passes through a circulator and is radiated by the reflector antenna. The signal received by the antenna passes through the circulator and enters the receiving path. In the receiving path, waveguide switch 1 switches to J1 to connect to J2, waveguide switch 3 switches to J1 to connect to J4, and a 4-to-1 coaxial switch selects the limiting low-noise amplifier 3 to connect to the receiver. The received signal is filtered by waveguide filter 3 and amplified by limiting low-noise amplifier 3 before entering the receiver. Inside the receiver, it is down-converted to IF, and finally, the signal processor completes the IF signal acquisition, frame assembly, and output.

[0042] 4) Mode 4 The signal processor generates an intermediate frequency (IF) transmission signal, the transmitter performs up-conversion, and the high-power signal amplifiers amplify the signal. The high-power signal passes through a circulator and is then radiated by the reflector antenna. The signal received by the antenna passes through the circulator and enters the receiving path. In the receiving path, waveguide switch 1 switches to J1-J2, waveguide switch 3 switches to J1-J2, and a 4-to-1 coaxial switch selects the limiting low-noise amplifier 4 to connect to the receiver. The received signal is amplified by the limiting low-noise amplifier 4 and then enters the receiver. Inside the receiver, it is down-converted to an IF frequency. Finally, the signal processor completes the IF signal acquisition, frames, and outputs the signal.

[0043] 5) Mode 5 The signal processor does not generate an intermediate frequency (IF) transmission signal, and the system does not transmit a signal. The signal received by the antenna enters the receiving path after passing through the circulator. In the receiving path, waveguide switch 1 switches to J1-to-J2, waveguide switch 3 switches to J1-to-J2, and a 4-to-1 coaxial switch selects the limiting low-noise amplifier 4 to connect to the receiver. The received signal is amplified by the limiting low-noise amplifier 4 and then enters the receiver. Inside the receiver, it is down-converted to the IF frequency. Finally, the signal processor completes the IF signal acquisition and performs spectrum analysis.

[0044] The system works as follows: first, it enters mode 5, where the signal processor performs spectrum analysis of the received signal, and then selects the subsequent working mode based on the analysis results.

[0045] The criteria for selecting the subsequent working mode are as follows: 1) Is there any interference signal in the received signal? If so, proceed to the next step; if not, proceed to step 5.

[0046] 2) Determine whether the highest frequency of the interference signal in the received signal is less than [a certain value]. If yes, then proceed to Mode 1; otherwise, proceed to the next step.

[0047] 3) Determine whether the frequency of the interference signal in the received signal is within the range of... arrive If the range is specified, the subsequent work will proceed to mode 2; otherwise, proceed to the next step. 4) Determine if the lowest frequency of the interference signal in the received signal is greater than [the specified frequency]. If so, proceed to mode 3; otherwise, proceed to the next step. 5) Follow-up work is in Mode 4.

[0048] Specifically, in this embodiment, interference signals were detected in the spectrum. The highest frequency of the interference signal was 9.8 GHz, which is lower than the center frequency of the system's transmitted signal of 10 GHz. The system then operated in mode 1.

[0049] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0050] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0051] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A spaceborne SAR system with anti-jamming capability, characterized in that, The system includes a signal processor, a frequency synthesizer, a transmitter, a receiver, a high-power signal amplifier group, a circulator, waveguide switches 1-3, waveguide loads 1-3, waveguide filters 1-3, limiting low-noise amplifiers 1-4, a 4-to-1 coaxial switch, and a reflector antenna. in: The signal processor is used to generate intermediate frequency (IF) transmission signals and send them to the transmitter, and to collect the IF echoes output by the receiver. It analyzes the collected data or directly frames and outputs the data. The signal processor also accepts external remote control signals to generate various control signals within the system and returns telemetry signals. A transmitter is used to upconvert intermediate frequency (IF) signals to the required radio frequency (RF) spectrum range. A high-power signal amplifier array is used to amplify the low-power radio frequency signal output by the transmitter to the required power; A circulator is used to send a high-power transmit signal to a reflector antenna, and then send the radio frequency signal received by the reflector antenna to the receiving path. A reflector antenna is used to radiate high-power radio frequency signals and receive ground echoes and interference signals radiated from ground interference sources. Waveguide switches 1-3 are used to select the received signal to enter different receiving paths under the control of the signal processor; Waveguide filters 1-3 are used to filter out interference signals from the received signal; Limiting low-noise amplifiers 1-4 can withstand high-power leakage signals, preventing them from affecting subsequent electronic equipment, while simultaneously amplifying low-power received signals; A 4-to-1 coaxial switch is used to select one of the four received signals to enter the receiver under the control of the signal processor. The receiver is used to downconvert the received radio frequency signal to the required intermediate frequency and send it to the signal processor for acquisition; Waveguide loads 1-3 are used to block unused ports of the system, ensuring that only signals received by the antenna can enter the receiving path; A frequency synthesizer is used to generate the clock signal required by the signal processor and the local oscillator signal required by the transmitter and receiver.

2. The spaceborne SAR system with anti-interference capability as described in claim 1, characterized in that, Waveguide filter 1 among waveguide filters 1-3 is a high-pass filter, allowing signals with frequencies greater than or equal to... The signal, in which The center frequency of the radio frequency signal transmitted by the system.

3. The spaceborne SAR system with anti-interference capability as described in claim 1, characterized in that, Waveguide filter 2 among waveguide filters 1-3 is a band-stop filter, which allows signals with frequencies less than or equal to... or frequency greater than or equal to The signal, in which The bandwidth of the radio frequency signal transmitted by the system.

4. The spaceborne SAR system with anti-interference capability as described in claim 1, characterized in that, Waveguide filter 3, one of the waveguide filters 1-3, is a low-pass filter that allows signals with frequencies less than or equal to... The signal.

5. The spaceborne SAR system with anti-interference capability as described in claim 1, characterized in that, The switching of waveguide switches 1-3 and the 4-to-1 coaxial switch is controlled by a signal processor.

6. A method for operating a spaceborne SAR system with anti-interference capability as described in any one of claims 1 to 5, characterized in that, The system includes 5 working modes: 1) Mode 1: The signal processor generates an intermediate frequency (IF) transmission signal, the transmitter performs up-conversion, and the high-power signal amplifiers amplify the signal. The high-power signal passes through a circulator and is radiated by the reflector antenna. The signal received by the antenna passes through the circulator and enters the receiving path. In the receiving path, waveguide switch 1 switches to J1-to-J4, waveguide switch 2 switches to J1-to-J4, and a 4-to-1 coaxial switch selects the limiting low-noise amplifier 1 to connect to the receiver. The received signal is filtered by waveguide filter 1 and amplified by limiting low-noise amplifier 1 before entering the receiver. Inside the receiver, it is down-converted to an IF frequency. Finally, the signal processor completes the IF signal acquisition, frames, and outputs the signal. 2) Mode 2: The signal processor generates an intermediate frequency (IF) transmission signal, the transmitter performs up-conversion, and the high-power signal amplifiers amplify the signal. The high-power signal passes through a circulator and is radiated by the reflector antenna. The signal received by the antenna passes through the circulator and enters the receiving path. In the receiving path, waveguide switch 1 switches to J1 to connect to J4, waveguide switch 2 switches to J1 to connect to J2, and a 4-to-1 coaxial switch selects the limiting low-noise amplifier 2 to connect to the receiver. The received signal is filtered by waveguide filter 2 and amplified by limiting low-noise amplifier 2 before entering the receiver. Inside the receiver, it is down-converted to IF, and finally, the signal processor completes the IF signal acquisition, frame assembly, and output. 3) Mode 3: The signal processor generates an intermediate frequency (IF) transmission signal, the transmitter performs up-conversion, and the high-power signal amplifiers amplify the signal. The high-power signal passes through a circulator and is radiated by the reflector antenna. The signal received by the antenna passes through the circulator and enters the receiving path. In the receiving path, waveguide switch 1 switches to J1 to connect to J2, waveguide switch 3 switches to J1 to connect to J4, and a 4-to-1 coaxial switch selects the limiting low-noise amplifier 3 to connect to the receiver. The received signal is filtered by waveguide filter 3 and amplified by limiting low-noise amplifier 3 before entering the receiver. Inside the receiver, it is down-converted to IF, and finally, the signal processor completes IF signal acquisition, frame assembly, and output. 4) Mode 4: The signal processor generates an intermediate frequency (IF) transmission signal, the transmitter performs up-conversion, and the high-power signal amplifiers amplify the signal. The high-power signal passes through a circulator and is then radiated by the reflector antenna. The signal received by the antenna passes through the circulator and enters the receiving path. In the receiving path, waveguide switch 1 switches to J1-J2, waveguide switch 3 switches to J1-J2, and a 4-to-1 coaxial switch selects the limiting low-noise amplifier 4 to connect to the receiver. The received signal is amplified by the limiting low-noise amplifier 4 and then enters the receiver. Inside the receiver, it is down-converted to an IF frequency. Finally, the signal processor completes the IF signal acquisition, frames, and outputs the signal. 5) Mode 5: The signal processor does not generate an intermediate frequency (IF) transmission signal, and the system does not transmit a signal. The signal received by the antenna enters the receiving path after passing through the circulator. In the receiving path, waveguide switch 1 switches to J1-to-J2, waveguide switch 3 switches to J1-to-J2, and a 4-to-1 coaxial switch selects the limiting low-noise amplifier 4 to connect to the receiver. The received signal is amplified by the limiting low-noise amplifier 4 and then enters the receiver. Inside the receiver, it is down-converted to the IF frequency. Finally, the signal processor completes the IF signal acquisition and performs spectrum analysis.

7. The operating method of the spaceborne SAR system with anti-interference capability as described in claim 6, characterized in that, The system's operating method includes: first entering mode 5, where the signal processor performs spectrum analysis of the received signal, and then selecting the subsequent operating mode based on the analysis results; The criteria for selecting the subsequent working mode are as follows: Step 1: Check if there is interference in the received signal; if so, proceed to the next step; if not, proceed to step 5. Step 2: Determine whether the highest frequency of the interference signal in the received signal is less than [a certain value]. If so, proceed to Mode 1; otherwise, proceed to the next step. Step 3: Determine whether the frequency of the interference signal in the received signal is within the range of... arrive If the range is specified, the subsequent work will proceed to mode 2; otherwise, proceed to the next step. Step 4: Determine whether the lowest frequency of the interference signal in the received signal is greater than [the specified frequency]. If so, proceed to mode 3; otherwise, proceed to the next step. Step 5, the follow-up work is in mode 4.

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